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Discussion Starter #1
D-series Camshaft removal
D15b1/b2/b7, D16a6 Rocker arm bolt sequence for removing the camshaft.:
D15z1, D16z6 Rocker arm bolt sequence for removing the camshaft.:
z6 cylinder head removal
D16y5,7,8 96-98 Cam removal
Valve adjustment/inspection for D16y7, D16y8

D16 Camshaft Comparison

How Camshafts Work
by Karim Nice

Online articles dealing with Camshafts
Thanks to:

Cam installation articles:
Engine Tuning: Droppin' ZEX-tasy
We show how to install a cam.
By Import Tuner Staff
If computing camshaft specifications wasn't hard enough, Honda had to toss VTEC cam profiles into the mix. This has made cam designers re-think all that they have learned in order to set up added horsepower in VTEC trim.

ZEX is one such company that has mastered the SOHC VTEC grind. Overshadowed by the mighty DOHC engine, the single-over-head model has always been thought of as an inferior powerplant. ZEX has brought new meaning to the SOHC engine with their new billet camshaft. The company claims that the cam is superior to all other drop-in cams so we decided to give the cam the 2NR torture test..................

Power Tech: Camshafts
Lift your Performance to New Heights
Text Michael Ferrara

Among all the components that make up an engine, the camshaft plays the most significant role in determining the behavior and character of the engine. As for the engine's behavior, most OEM camshafts offer idles that are smooth and polished. A radical aftermarket full-race camshaft may produce an idle that is rough and raw. As for character, one camshaft may regulate an engine to produce massive low-end torque, while a different camshaft in that same engine may soften up the power production at the low end while allowing the engine to pull strong up to redline. Understanding the function, design, and limitations of the camshaft will allow you to maximize your performance experience.

Function of the Camshaft

The four-stroke process that occurs in your car's engine is as follows: intake, compression, power, exhaust. While the crankshaft's position, crankshaft's stroke and rod length ultimately determine where the piston will be in the cylinder at any given degree of rotation, it's the camshaft that determines the position of the intake and exhaust valve during all four strokes. An engine's camshaft(s) is/are responsible for the valve timing in the engine. Proper valve timing is critical for any four-stroke automotive engine to operate at maximum efficiency. When the valves open, how high the valves open (lift), and for how long they stay open (duration) all determine the performance characteristics of the engine. In the performance symphony, the camshaft is the conductor of valve events. It orchestrates which instruments play (intake or exhaust valves), when they play (opening and closing events) and how loud they play (valve lift). Whereas OEM conductors (cams) offer a classical sound, aftermarket cams can really make your engine rock.

The Band of Power
As mentioned earlier, the camshaft will determine an engine's character. The engine's character in terms of power production is often termed the "powerband." Where does the engine begin to make power? Where does the engine begin to fall off in power production? Is the power delivery flat and consistent or aggressive and peaky? These questions are answered in the description and understanding of the engine's powerband. Some powerbands are narrow, while other are deemed broad. Some are peaky, some are flat. An engine that makes appreciable power from only 6000 to 8000 rpm (a range of 2000 rpm) would be considered to have a narrow powerband. A comparable-sized engine that makes power from 3000 to 7000rpm (a range of 4000 rpm) might be considered to have a broad powerband. More so than any other internal components of the engine, the camshaft and its complimentary valvetrain components will establish the powerband of the engine.

The Ideal Cam
So how do you get the perfect cam? The cam that has tremendous low-end torque, a 10,000 rpm redline, an idle like mom's car and a powerband from idle to redline doesn't exist. Fortunately, an aftermarket performance camshaft that optimizes the rest of your performance combination to provide the performance that you desire probably does exist. Dollar for dollar there is a good chance that aftermarket cam(s) may be the best performance investment that you make.

Lift, Lobes and Symmetry
For every action, there is always a reaction. From a performance standpoint, the faster a valve opens and reaches full-lift, the better. Why? Horsepower is directly related to how much air and fuel can be stuffed into the cylinder. Air and fuel can't get into the cylinder unless the valves are open. Camshafts that quickly open the valves are said to have an aggressive lobe profile. Unfortunately, the laws of physics govern the maximum amount of possible valve acceleration or "aggressiveness." If the camshaft profile tries to accelerate the valve too fast, excessive wear or valvetrain problems can occur. When returning a valve to its seat, a camshaft once again cannot do this too fast or the valve slams into the valve seat (sometimes valves even bounce off the seat). Most modern cam designs optimize valve acceleration rates by designing camshafts with asymmetric lobes. This style of lobe lifts the valve faster than it lowers the valve. Quite simply, asymmetric lobe designs can be utilized to maximize the performance available while increasing the durability of the valvetrain.

Types of Engines
There are two basic styles of piston engines in production today, the overhead-valve engine (OHV) and the overhead-cam engine (OHC). Overhead valve engines rely on valve lifters, pushrods, rocker arms and a camshaft which rests in the engine's cylinder block. Examples of OHV engines include most of the domestic V8 and V6 engines manufactured over the last 50 years.

Knowing the Specs
Since we have already explored the basics of camshafts, we will now attempt to unlock the mysteries surrounding camshaft specifications. Since the camshaft(s) influence when an engine starts making power, when it stops producing power, maximum power output, fuel economy, idle quality, and engine efficiency, it is important to understand camshaft specifications. With this basic understanding, you will be better able to select the camshaft(s) that will keep you ahead of the competition.

Lift and Duration
The basic function of a camshaft is to open and close the engine's valves. On many applications, a single camshaft controls the opening and closing events of all the valves in an engine. Other applications may implement as many as four camshafts to control the valve events. Regardless of the number of cams, the rules that apply for single camshaft engines also apply to those with multiple camshafts. The most well-known camshaft specifications are lift and duration. Most manufacturers give specifications for lift at the valve, instead of at the camshaft. On some applications that don't use a rocker assembly these two lifts may be the same. If you need to convert from lift at the camshaft lobe to lift at the valve, use the following equation.

Valve Lift = Lobe Lift x Cam Follower Ratio
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Author Message
Old School Dog

Joined: Nov 29, 2003
Posts: 107
Location: Florida

Posted: Thu Feb 26, 2004 5:49 am Post subject:
Lift is nothing more than a measurement of the maximum distance the valve is opened. Assuming all other specifications remain the same, choosing a camshaft with more lift will increase the flow of air and fuel into an engine and the flow of exhaust out of an engine. As a result, more power can be made. In many cases, camshafts that have increased lifts over stock specifications and near stock duration will offer increased performance without making measurable sacrifices in "driveability". Everything has a limit and cylinder heads will generally reach a point where airflow no longer increases with an increase in valve lift. Before you order that mega-lift cam, please consider the following: when valve lift is dramatically increased, the possibility of valve to-piston contact, coil bind at the valve spring and valvetrain interference is also increased. To avoid bent valves, broken retainers and thin wallets, always use the necessary complimentary valvetrain components and check valve-to-piston clearance when recommended by the camshaft manufacturer.

Along with how high a valve is opened, how long it remains open also influences the performance of an engine. If you are trying to fill a glass at the sink, how much you open the faucet or valve, as well as how long you have that valve open will determine how much water fills the glass. How long you keep the faucet turned on is a simple measure of duration. The duration specification of a camshaft is measured in crankshaft degrees of which there are 720 in one complete four-stroke cycle. However, the problem with camshaft duration figures is that different manufacturers measure this duration at different valve lifts. The Brand-A manufacturer might measure duration as soon as the valve is lifted .015 of an inch off its seat until it returns to the same lift, while the Brand-C manufacturer might not start measuring until the valve is .050 inch off the seat. The result is that if we had both companies measure the same camshaft, Company-A might measure 306 degrees of duration (measuring at a minimum lift of .015"), while Company-C would measure 256 degrees of duration (measuring at .050"). In essence we have two completely different numbers for the same camshaft. Luckily, most camshaft manufacturers now provide duration figures at either a minimum lift of 1mm (Japan's industry standard measure) or a minimum lift of .050" (the traditional U.S. hot rod standard). When duration comparisons between two camshafts are being made, only compare the figures if the measurements have been taken at the same minimum lift.

Duration and Power
More lift translates into more power and torque across the powerband for most cases. In general, increased duration will shift the torque and horsepower peak to a higher rpm. All other specifications being the same, increasing duration yields more top-end and mid-range power while sacrificing low-end torque. As a result of the shifting of the powerband upstairs to higher rpms, a longer duration camshaft, when used with the appropriate valvetrain components, will also raise an engine's redline. One rule of thumb is that every 10 degree increase in duration (measured at 1mm or .050") will shift the torque peak and redline up by 500 rpm.

A Closer Look-Valve Timing
Believe it or not the explanation of lift and duration has been somewhat simplified. If we only look at lift and duration, we only know how high a valve is lifted and for how long. What lift and duration fail to tell us is when the valves are opened and closed. If we know that the complete four-stroke cycle contains 720 degrees of crankshaft rotation and the intake stroke (when the piston moves down the cylinder when the intake valve is open) makes up one-fourth of the cycle, we easily deduce that the theoretical duration of the intake cycle is 180 degrees (one-fourth of 720). If we could instantaneously open the intake valve at TDC (the beginning of the intake stroke) and have the intake charge immediately start flowing into the cylinder until the piston was at BDC (the end of the intake stroke, 180 degrees later) where the intake valve would instantaneously slam shut, we might have an engine that would run well with only 180 degrees of intake duration.

Early Intake Valve Opening
In practice, there are many advantages to opening the intake valve early and closing it late. By initiating the opening the intake valve early, the intake valve has time to get to a lift where appreciable flow will begin. On a well-designed cylinder head teamed with a free-flowing exhaust, the pressure in the cylinder when the valve is opened early may be lower than atmospheric, so the intake charge actually gets sucked in (in practice, the exhaust valve is still open when the intake valve begins to open). The benefits of early intake valve opening are very rpm dependent. At low engine speeds, extremely early intake valve opening may cause exhaust gases to be sucked into the intake manifold causing erratic idle and other problems. At higher engine speeds, this same amount of early intake valve opening will have no adverse effects since the intake manifold is not operating under a vacuum condition.

Late Intake Valve Closing
Now that we understand why we need to open the intake valve early, let's take a close look at the closing of the intake valve. The reason we leave the intake valve open past Bottom Dead Center (BDC) is inertia: objects at rest tend to stay at rest, objects (or a mass of air in the case) in motion tend to stay in motion. Since we have an intake charge in motion we can experience additional filling of the cylinder while the piston dwells (or remains in place) at the bottom of its stroke at BDC. On engine with high rod length-to-stroke ratios, the piston may dwell around BDC for 20 degrees of crank rotation before the piston starts to move up the cylinder. During this time the flowing intake charge continues to fill the cylinder. If the intake valve closes too late, the piston may pump some of the intake charge out of the cylinder through the intake valve and back into the intake manifold. This reverse flow is obviously undesirable. As you may have guessed, the optimum closing of the intake valve is also very rpm dependent.

Exhaust Valve Open Early
Since we have a good understanding of the intake side out the equation let's take a look at the exhaust side. The major difference in dealing with the exhaust side is that the average pressure in the cylinder is probably more than six times the average pressure during the intake cycle. This makes the task of releasing the exhaust gases easier than trying to get the intake charge into the cylinder. During the power stroke, the majority of horsepower is generated during the first 90 degrees or first half of this 180 degree cycle. This being the case, opening the exhaust valve early has little effect on killing power. In fact, power is usually increased since the residual pressure is released from the cylinder so the piston doesn't work as hard to push the remaining gases out when it begins its upward movement on the exhaust stroke.

Exhaust Valve Closing Late
Keeping the exhaust valve open after TDC can also have benefits. If the exhaust valve is kept open after TDC, the intake valve will also be open at the same time. When both intake and exhaust valves are open at the same time, it is termed valve overlap. The ideal amount of overlap depends on rpm. Higher rpms tolerate more overlap and the intake charge can be drawn into the cylinder due to the draft caused by the exhaust gases leaving the cylinder. When overlap gets excessive, exhaust gas can make its way into the intake manifold, diluting the intake charge. A diluted intake charge limits power production, so a careful balance must always be struck.

The Bottom Line
A camshaft may look simple, but its job is no easy task. Understanding the function, design and limitations of aftermarket cams will allow you to make educated decisions about getting the right cam(s) for your car. Remember to rely on the experts. The wealth of knowledge that the major cam companies possess is incredible. While it is great to have an understanding of cams, there are enough self-proclaimed engineers in the world. Nine times out of ten, the specialist at the cam company will know more than you (that's his or her job). The value of your performance education is identifying the one out of ten instances that you may encounter. As always, remember to consider that the camshaft(s) are just one element of the performance combination. All of the parts in the combination need to work together to produce the maximum in power and reliability. Camshafts will only do there job effectively when complimented with the correct valvetrain component. Installation of the camshaft and complimentary valvetrain components must also be done correctly. Failure to do so will result in a loss of performance and the potential for component damage.

VTEC: Powerband Optimizer

Many bad explanations of the VTEC advantage have been given in the past. The advantage is simple: VTEC allows the engine to perform as if the cams were switched to a different profile at a set rpm. The low profile can optimize idle, meet emissions and provide good bottom-end torque. The high-profile lifts the valves higher and opens the valves longer to improve power at higher rpms.

VTEC does not allow for higher peak power to be made. If a set of non-VTEC cams were ground to match the VTEC high-lobe profile the same power would be made. However, the Non-VTEC cam would not have near the performance of the VTEC cam at lower rpms. Driveability, fuel efficiency and idle quality would all suffer.

The end performance result of VTEC technology is an engine that has an incredible broad powerband.
Related Diagrams:


3,414 Posts
Discussion Starter #2
Volumetric Efficiency

Does this sound correct?

Air Capacity (cfm): Since an engine is actually little more than an elaborate air pump, it’s ability to perform work—measured in horsepower and torque—is a product of its capacity to inhale and exhale air. An engine’s theoretical air capacity is a product of its rpm and displacement, divided by two (since only half of the engine’s cubic capacity is being displaced during each stroke). For purposes of rating airflow (i.e. via a carburetor), this formula is converted to a quotient reflecting cubic feet per minute (cfm) by dividing both sides of the equation by 1,728, the number of cubic inches in a cubic foot. The reduced formula for cfm:

Rpm x displacement

Note: To convert CC to inches times the CC by 0.0610237441

Volumetric Efficiency: How efficiently an engine actually pumps air, compared to its air capacity (as calculated above) determines its volumetric efficiency. Theoretically, an engine’s maximum efficiency is highest at its torque peak. This can be determined by a chassis dyno. Actual airflow, on the other hand, must be determined with an airflow meter. The relationship between the actual and the theoretical (times 100) is the engine’s true volumetric efficiency or:

Airflow cfm x 100
.....Rated cfm

Volumetric efficiency has a lot to do with performance. Gains in volumetric efficiency has a lot to do with performance. Gains in volumetric efficiency—by turbocharging, supercharging, or intercooling, for example—result in greater output.

Let’s say a D16Z6 engine with a displacement of 97 cubic inches (1590cc) produces its maximum torque at 7,000 rpm, Using the formula mentioned earlier, the engine’s theoretical cfm is :

97 x 7,000 = 196

Now let’s say the engine’s actual measured airflow at 3,500 rpm turns out to be 80 cfm. Volumetric efficiency, expressed as a percentage of theoretical capacity, can be calculated as:

150 x 100 = 76.5 (percent)

Why Horsepower is Calculated At Sea Level:

An important factor in figuring volumetric efficiency is elevation relative to sea level, at which the engine is operating. As elevation rises, oxygen levels are reduced, reducing an engine’s volumetric efficiency. The typical drop in horsepower at any rpm level is approximately three percent per 1,000 feet of elevation. To figure how much horsepower you’ve lost at a specific elevation, use the formula:

Elevation (ft.) x .03 x hp at sea level

Example: The D16Z6 produces 125 horsepower at 6,600 rpm at sea level. At 5,000 feet, that engine’s output loss—suffering from RVES (reduced volumetric efficiency syndrome) –can be calculated as:

5,000 x 0.03 x 125 = 19 horsepower

At 5,000 feet, this engine is now producing only 106 horsepower at 6,600 rpm. At 10,000 feet, the same engine is capable of producing only 87 horsepower at 6,600 rpm.

If you see any mistakes let me know.


3,414 Posts
Discussion Starter #3 (Edited)
Ignition timing/Cam Gear timing/Timing Belt Questions

Many thanks to:
and others who have contributed information to threads that have been added here.
88-91 si cam in a b2/b7 head using a y7 cam gear to correct for the half-tooth error
cam gear setting for si cam in dx?

Advancing my timing question

1) Igntion timing.......advancing the ignition timing beyond 2-3 degress of stock setting may require a higher octane gasoline to prevent pinging/detonation

2) Cam timing...........advancing the cam timing will trap MORE air/fuel mix in the cylinder at low-mid rpms. The result will be higher combustion pressures. This may require a higher octane gas also. You can advanced the cam too far and damage the vales.

3)worst case issue........advancing the cam timing without readjusting the igntion timing afterwards will equal a combo of 1) and 2) and you can hurt parts.

Tunning with a zex 53900
Originally Posted by OZ Racing
either way you still see a power gain on NA setups..

mine is at 2 deg retard @ 18 BTDC

I thought advancing your timing on stock would produce power gains....but retarding does as well?
Originally Posted by transzex
1 degree retard, 19 BTDC ignition timing for NA.

you're missing mista's point. there is cam timing, and ignition timing. two separately adjustable timing points.

mista is saying run -1deg on the cam gear, and 19deg BTDC on the ignition timing.

yep, exactly.

3,414 Posts
Discussion Starter #4 (Edited)
The Great Half-Tooth debate
"You walk 1/2 way into a forest, are you 1/2 way in or 1/2 way out???"

1/2 tooth off cam gear? d15 to d16?
testing this week will be a Y7/Y8 cam gear with a A6 cam in a D15B7 motor,
Why you ask????????
It is known that the cam timing error is 4.75 degrees (1/2 tooth) on the cam install.......
Everyone is saying the Y7/Y8 stock gears are indexed 5 degrees off th 88-95.
End result is less than .25 degree difference. You get more than that error from the crank keyway slop.

installed a6 cam in b2 problems need help.
the D15 block is shorter in height than the D16, thus causing a half tooth error in the cam indexing.​
This is why you have to index the D16 motors with the 7 o'clock pointer.​
360 degrees / 38 teeth cam gear = 9.5 degees​
cam spins as 1/2 crank speed, so 9.5 degrees / 2 = 4.75 degrees, or a half tooth.​
From the same thread:​
Originally Posted by slowdxracer
hey just a quick question. i am planning to do the same thing he is doing but my engine is a d15b7. does the 5 degress advance or retard apply to my engine too? thanx
It is 4.75 degrees, and yes the same applies for the D15B7.​
The motor I figured all this crap out on!!!!!!​
D15B7/A6 crack monster........​
a6 cam in a d15b7 head, will it work?
The only dynograph I know off that shows the power difference of both cam settings.​
From Sept 1999.......​
Adjustible cam timming
is the DC cam gear for 92-95 and your putting it on a 98 motor??????​
1/2 tooth error.

Cam gear and timing
Z6 cam in a Y8 motor?​
1/2 tooth error again.​

3,414 Posts
Discussion Starter #5 (Edited)
Camgear. Worthless, as I've read.
As Bone Mentioned, a camgear does have a decent effect on SOHC power curves ... I did the Dyno Pulls below to find out what cam gear setting had on my mild D16Z6 ... A picture is worth a thousand words ....​
Blue curves: D16Z6 engine, modified Z6 exhaust manifold, cold air intake, 2.25'' mandrel bent exhaust, HiFlow Cat, Zex 59300 cam, Y8 intake manifold, B18b throttle body,stock fuel and ignition maps, Cam - 0, Ignition timing at 18 btdc​
Red curves: D16Z6 engine, modified Z6 exhaust manifold, cold air intake, 2.25'' mandrel bent exhaust, HiFlow Cat, Zex 59300 cam, Y8 intake manifold, B18b throttle body, stock fuel and ignition map, Cam 2 degree advanced, Ignition timing at 18 btdc​
Green curves: D16Z6 engine, modified Z6 exhaust manifold, cold air intake, 2.25'' mandrel bent exhaust, HiFlow Cat, Zex 59300 cam, Y8 intake manifold, B18b throttle body, stock fuel and ignition map,Cam 2 degree retarded, Ignition timing at 18 btdc​
With a bit more fine tuning in 1/2 degree intervals I might have been able to get a bit more high rpm power.​
Question about the z6/y8 cam gears...
inquiry on d16y8 cam gears
Tunning with a zex 53900

y7 and right cam gear choice ?
tuning, advice?
Cam gear difference?

3,414 Posts
Discussion Starter #6 (Edited)
Adjustible cam timing
Thanks to Builthatch for the following post:​


DC stopped making cam gears about a year before they were bought out by AEM...DC had a firesale for old stock and that is why you can see these cam gears for such low prices nowadays, however, there is another reason they stopped making them, and this reason is detailed below. I actually made a claim to AEM about it last spring, and after a back and forth with AEM tech Robert Greene, the error i detailed was confirmed and i finally was rewarded with a CORRECTLY indexed AEM unit to replace the erroneous DC cog.​

stock Y8 gear- note keyway is offset from vertical axis, however, TDC mark and side marks form perfect cross. CORRECT for Y8​

AEM Y8 gear- exact match to OE gear, CORRECT for Y8​

DC Y8 gear- note, like the stock y8 gear, side marks are on-point and keyway is offset, BUT, note that TDC marks are 4 degs away from vertical axis of stock y8 gear, though sides match. INCORRECT for everything​

AEM Z6 gear- note vertical axis bisects keyway CORRECT for Z6​

Yet another erroneous gear. Golden Eagle piece for a y8, yet compare it to the Z6 gear up top, no difference! offset keyway, nothing...WEAK!​
New thread​
by jlacoy82​

2,205 Posts
gftgrill said:
I'm the first person to catch this (i think)

aren't the jg cam gears 88 - 00. as in they are marked the same. and they do not have the adjusted mark for the y8 that only a few companies do (golden eagle, aem).

this is an old thread I started. to see the difference in the y8 versus other cam gears.

if I'm thinking correctly. the jg cam gear you bought for a 96-00 is still marked for the 88-95 engines. so you will want to set that cam gear to 0 degrees and it will be perfect.

a pic of your cam gear will help.

right, look at the keyway space on the gear. if it pretty much lines up with the top mark on the gear, it's for 88-95. if it's about 5 dgrees to one side or another, it's a y8.

The H Badge is it!
91 crx
5,657 Posts
so basically, it will work. but to make ur car run u need to set it to 4.75 degrees advanced OR retard to make it at zero degrees.

to use a 96-00 cam gear on an a6:
4.75 degrees = 0 degrees.

What SOHC_Rules would do:
I personally would set the cam gear to 5 or 6 degrees advanced and then put it on. If you want most of your power on the top of the power band, i suggest 5 or 6 degrees retarded.
NOTE: the above tips only apply to putting a 96-00 cam gear on a 88-95 sohc motor.

ridin on rotas
1,980 Posts
SOHC_Rules said:
so basically, it will work. but to make ur car run u need to set it to 4.75 degrees advanced OR retard to make it at zero degrees.

to use a 96-00 cam gear on an a6:
4.75 degrees = 0 degrees.

What SOHC_Rules would do:
I personally would set the cam gear to 5 or 6 degrees advanced and then put it on. If you want most of your power on the top of the power band, i suggest 5 or 6 degrees retarded.
NOTE: the above tips only apply to putting a 96-00 cam gear on a 88-95 sohc motor.
yes if the gear is marked for a y8. but most companies are lazy and mark all 88-00 cam gears the same. meaning that these companies are making cam gears for 96-00 incorrectly.

AEM and golden eagle correctly make two seperate cam gears for 88-95 and 96-00. even though they are interchangable.

so if your jg cam gear is marked like mine is. then you want to set it to 0 degrees because that is the correct 0 degree mark for an a6, z6, but not the correct mark for a y8.

ridin on rotas
1,980 Posts
SOHC_Rules said:
i think u should re-read my post guy, i specifically said a 96-00 cam gear will work on a 88-95 sohc motor at 4.75 degrees retarded or advanced.. u basically took what i said and made it one long pointless post.. what are u webster's diction-fuckin-ary???
I know, but I was pointing out that there are 2 96-00 cam gears. it depends on which one he has as to wether or not it needs to be adjusted. if you advance or retard a 96-00 that is marked for a 88-00, then you're setting the timing WRONG.


0 Posts
So basically 88-00 and 92-00 cam gears are basically all marked for the 88-95 crowd, and even some of the 96-00 cam gears are still marked the same as the 88-00's? Is that basically it?

I've already read though that other thread on cam gears, and came up with nothing searching HT. Are the newer 96-00 Edelbrock gears marked correctly for a y8? Or are they like the golden eagle ones they mark 0 at the "valley" in the teeth, and not at the "peak"??

ridin on rotas
1,980 Posts
jlacoy82 said:
So basically 88-00 and 92-00 cam gears are basically all marked for the 88-95 crowd, and even some of the 96-00 cam gears are still marked the same as the 88-00's? Is that basically it?

I've already read though that other thread on cam gears, and came up with nothing searching HT. Are the newer 96-00 Edelbrock gears marked correctly for a y8? Or are they like the golden eagle ones they mark 0 at the "valley" in the teeth, and not at the "peak"??

yes. you need to compare it to this VVV and see how the keyway is lined up with the teeth to see if it is for a 88-95 or 96-00

builthatch said:
this is a correct y8 gear- notice the keyway is about 4 degrees to the left of the '0' centerline and 1st cylinder TDC...

this is a stock y8 gear for reference- again, notice the keyway is about 4 degrees to the left of the "up" 1st cylinder TDC mark

this is a z6 gear, with the keyway inline with the 1st cylinder TDC mark, its hard to see cuz the mark on the gear is black as well...the edelbrock mentioned in this thread looks like this one...

this is another gear that is supposed to be a y8 gear (kommonsense's maybe?), but...its got the keyway inline with the '0' and the 1st cylinder TDC mark, just like a z6 gear-
the edelbrock cam gear I picked up is supposed to be 96-00, but it is really 88-95. even though the cam gear still works, I have it set 4 degrees Advanced.

3,414 Posts

3,414 Posts
Discussion Starter #18 (Edited)
Honda/Acura Distributor Codes

Part No.ModelYearsEngine
TD - 01U Civic 88 - 91 1.5L
TD - 02U Civic88 - 89 1.5L & 1.6L Si
TD - 03U Civic88 - 91 1.6L ZC 1ST GEN
TD - 18U Civic90 - 91 1.5L & 1.6L Si
TD - 22U Civic89 - 91 B16A 1ST GEN
TD - 31U Accord 90 - 91, 94 - 95 2.2L
TD - 41U Civic + Del Sol 92 - 951.5L
TD - 42U Civic + Del Sol 92 - 951,5L & 1.6L Si
TD - 43U Civic88 - 89 1.6L ZC
TD - 44U Civic + Del Sol 92 - 95 1.6L VTEC
TD - 52U Accord 92 - 93 2.2L
TD - 52U Passport 96 - 97 2.6L
TD - 52U Prelude 92 - 95 2.2L NON-VTEC
TD - 59U Accord 92 - 93 2.2L
TD - 59U Passport 96 - 97 2.6L
TD - 59U Prelude 92 - 95 2.2L NON-VTEC
TD - 60U Prelude 92 - 952.2L VTEC INT. COIL
TD - 61U Prelude 92 - 952.2L & 2.3L VTEC EXT. COIL
TD - 63U Civic 96 - 00 1.6L
TD - 73U Civic 96 - 00 1.6L
TD - 73U Accord 98 - 00 2.3L
TD - 76U Accord 96 - 97 2.2L
TD - 77U Prelude 97 - 00 2.2L
TD - 80U Civic 96 - 00 1.6L
TD - 80U Del Sol 96 - 97 1.6L NON-VTEC
TD - 86U Civic 92 - 00B16A 2ND GEN & B18C
TD - 89U Prelude 97 - 01 TYPE S H22A
TD - 97U CRV 97 - 00 2.0L

Part No.ModelYearsEngine
TD - 03U Integra 88 - 91 ZC 1ST GEN
TD - 23U Integra 90 - 91 1.8L MAN/AUTO
TD - 44U Integra GS-R 92 - 95 B17A & B18C
TD - 55U Integra 91 - 95 1.8L
TD - 84U Integra GS-R 96 - 98 B18C
TD - 85U Integra 96 - 00 1.8L

4,585 Posts
Posted by SOHC-Turbo

Ok, I think that this site needs more good tech info, so here is an excellent write up discussing how to properly break-in an engine. This is how I broke in my engine when it was brand new, so I know that this method works well. There was a thread a while back that had a lot of misinformation from a lot of people, so this should clear it up.

One of the most asked questions is how do I break in my new motor? The short answer is that no break-in is necessary. The only thing that is necessary is to seat the rings. All clearances and fitments should be perfect after blueprinting and precision assembly. So how many miles do you have to drive it to seat the rings? The cylinders are round, the rings are round, the bore is freshly honed and therefore your engine should be ready for tuning immediately. They will continue to seat better over a short period of time but you should be ready to go tune right away.
Do I need to drive it 500 miles before I tune it? Absolutely not. How about 50 miles? No. Perhaps the best thing to do is to drive it all the way to your trailer and tow it to a competent tuner. In second position on the “things NOT to do list” is trying to break in an un-tuned engine by driving it. Too lean an air/fuel will begin to heat and distort parts, too rich will wash the oil off the cylinders causing premature wear. What is in first place on the “things NOT to do list”? Boost on an un-tuned motor. Within 2 to 3 seconds the pistons and cylinders can be ruined.
Well I did put in a new base map or I’m just running off the stock Honda computer. Can’t I drive it like that for a few miles? I’m not even boosting. Well what is the base map? Just someone’s idea of what numbers will start your car. Just an educated guess by someone who does not have a clue what components you are running in your set-up. It’s not intended to drive on for any extended period of time. The same with that stock Honda computer. It could be ok but it could also be dangerously wrong.

So what exactly do I do at the first engine start-up? Pull the spark plugs and crank the motor with your starter for a maximum of 30 seconds or until you see the oil pressure gauge begin to register. Re-install the plugs and wires and fire up that candle. While keeping one eye on the oil pressure gauge, use your other eye to scan for fuel leaks. If there are no fuel leaks, look under the motor for any major oil or coolant leaks. If that is ok, run the engine for 5 to 10 minutes while keeping an eye on the temperature and pressure gauges. Keep the rpm’s between 1000-3000. Shut the engine down and double-check everything. You are now ready for tuning.

But my engine was already tuned from my previous set-up. Well, what happened to your previous set-up? Did you melt a stock piston or crack a cylinder? No problem because now you have forged pistons and sleeves? Wrong. Although you now have stronger components that will take more abuse, you are still not right on your air fuel mixture. Get that thing tuned properly ASAP.

OK, I did it my way instead of yours and now I’m burning a lot of oil. What happened? Well basically you scarred up the skirt of the piston, messed up the surface of the cylinder wall and maybe even egg shaped the cylinder. New pistons are tapered smaller on the top to larger at the bottom of the skirt. Your piston to wall clearance is measured at the bottom of the skirt. As the engine warms up to operating temperature, the upper portion of the piston begins to expand slightly. The bottom of the skirt does not expand much. When you boost in a lean condition, the upper part of the piston expands quickly. Since the ring land area is cut smaller than the tapered skirt below it, the first part of the piston that pushes into the cylinder wall is just below the oil ring. Thus you will see the worst scarring on your piston right under the ring lands where the excess heat is the highest

The more heat that is generated, the harder the piston pushes into the cylinder wall. The uninformed would blame the piston damage on bad piston to wall clearance. Untrue. If that were the problem, the damage would show up at the very bottom of the skirt. What has happened is that you have expanded your piston to the point that it has just ground itself into the cylinder wall. Keep expanding the piston by super heating it and it will push your cylinder egg shaped and maybe even balloon out the cylinder slightly. At the same time this is happening, your ring lands will begin to distort to where they will never seal properly again. Sometimes after doing this, the engine will still run but it will be a smoker. This all happens in a few seconds of high boost with a lean air fuel ratio. Also it can happen from 500 freeway miles of driving where the tune up is off enough to build excess heat at a slower rate, thus doing the same damage over a longer period of time…but the end results are the same. Death to your pistons and cylinder walls.

OK, I’m just going to turn the fuel pressure way up and run extra fat, that way I won’t hurt anything. If you run too rich, you will “wash out” the rings. First, excess fuel will run down the cylinders taking the lubricating oil with it. This promotes direct metal-to-metal contact between the rings and the cylinder wall. This contact does several things. The upper ring begins to wear quickly. The middle ring is actually designed as a tapered oil scraper (it is not used for compression control at all) and the taper will begin to wear down to where it becomes flat rather than angled. When that happens, it can no longer control oil away from the combustion chamber. The last thing that happens is that pretty cross hatch design begins to wear off of the cylinder wall. While most people think that the cross hatch is there to help seat the rings, it also has a secondary purpose. That is to hold microscopic amounts of oil in the grooves to help lubricate ring to cylinder walls. With the walls smooth and no oil control help from the middle ring and a tired upper ring, oil will begin to mix with fuel in the combustion chamber. When this happens, your 93 octane fuel probably hits a value of about 80. Then detonation comes into play and begins to beat holes in the pistons, among other things.

So whom can I blame for this mess? The blind machinist that honed my piston to wall clearance? That poor quality Brand X piston manufacturer? The idiot pro engine builder that assembled my block? My ex-friend that helped me put this all together? Those ignorant engineers that gave me a bad base map with my engine management system? The guy on the internet message board whose buddy knows that it takes at least 1000 miles of break in before you can tune an engine properly? All of the above? Probably none of the above. Go look in a mirror and ask…who started this engine and had no idea what the air fuel ratio was? Who just wanted to jump on it one time to see if it would haul? Who didn’t know that their injectors were at 100% duty cycle at 4000 rpm but they wanted to see how it would run at 6000 rpm? Why it was you. Get that thing tuned right away. You will notice that the more you drive a tuned motor, the stronger it will feel. This is just the rings seating in their final 5-10% as they thank you for tuning first.
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