The Definitive D15B7 / A6 / ZC Cam Post

The 2011 B7/A6/ZC Write Up

I’ve been noticing more and more people asking about B7s lately. I’ve received lots of emails from people asking about my setup. Yes, it's been covered, but I threw this together and have tried to strip it down as basic and simple as possible for an easy read. And updated some things about this subject so everything about the swap is in one post. Lets all thank the godfather, Mr. Bone (aka Transzex), for this whole B7/A6 fiasco.

I’ve borrowed a couple photos from DSO members for this post.

You want to get more power out of your B7 and you’ve heard that throwing in an A6 cam will give you a good bump. Before you run out to the garage and throw in any cam, lets go over some info. It’s not quite plug n play. There are some issues that need to be resolved during and after installation.

New Note - Automatic B7 Engines

According to Transzex aka Bone (who has experience with an A6 cam setup with an auto
tranny), the verdict is that you lose power as well as suffer in gas mileage. A direct quote-
"A6 + Z6 intake + slushbox = slower and worse gasmilage over stock B7 cam and intake."
Something to consider before proceeding with this upgrade on an automatic trans B7.


What year A6 cam do I have?

There are two types of A6 cams. The 88 and 89-91 cams are indexed differently. Here are the facts –

The 88 A6 cam does not require a different cam gear to properly time it. The B7 or any PM3 gear will work just fine.

The 89-91 A6 cam requires a Y7, Y8 or adjustable cam gear to get your cam timing back to “zero”. If you choose to use your B7, A6 or any other PM3 cam gear, the timing will be 4.75* (half a tooth) advanced or retarded (depending on how you put it on).

What if I have a ZC cam?

The 89-91 ZC cam is indexed the same way as the 89-91 A6 cam. You will need a Y7, Y8 or adjustable cam gear to properly time it.

The 88 carb’d ZC cam has a hideous fuel pump lobe sticking out at the distributor end of the cam. It’s very, very identifiable. I’ve heard that these are crap from people who have tried them. However, I’ve never used one and don’t have an opinion.

Notice the fuel pump lobe on the '88 carbed ZC cam to the right -



How do I tell the A6 and B7 cam apart?
The A6 cam lobes are visually bigger than the B7. You can sit them next to each other and
tell right away. This applies to the ZC cam as well. They will be visibly bigger then the B7's.

How Do I tell if I have an 88 or 89-91 A6 cam?
As stated, the key way on the two cams are different. I've set up a visual example below. You will notice that the 88 A6 cam with the B7 cam gear lines right up at top dead center. And will do so when you've slid your timing belt on it. However, the 88-91 A6 cam will be visibly advanced or retarded (half a tooth) when you've slid the timing belt on. The example below shows the 91 A6 cam visibly advanced. This is why the Y8 gear corrects this.



The ZC cam is slightly different than the A6 cam. The measurements below will show you the difference.



What is the difference between the A6/B7/PM3 and a Y8 cam gear?

They are indexed differently. Half a tooth (4.75*) difference because of block height.

Cam Gear Timing

When the B7 cam gear is set up, it uses the 3 and 9 o’clock markers on the gear. These should line up with the top of the cylinder head for TDC. You do not use the 7 o’clock mark to time the gear. This stays true with the Y7/Y8 gear. After installation, you time the cam as if it were stock. Using the 3 and 9 o’clock markers.

You can advance an adjustable cam gear to bring back any low end loss. Generally, 1 or 2 degrees is all it takes. Some people also choose to retard the cam 2 degrees and set base ignition timing to 18*. It’s all personal preference and the kind of driving you are doing with the car. A cam retarded 2* with dizzy timing set at 18* btdc will give you more top end power.

There's no point in doing this upgrade unless your engine is timed properly.
You can actually lose power by installing a A6 or ZC cam and jacking the timing all up. Both dizzy and mechanical must be done properly.



Aftermarket Cam Gears

If you line up an adjustable cam gear with an OEM cam gear (example : adjustable Y8 with OEM Y8 gear), you will find that the gear is indexed incorrectly 99% of the time. Even from the bigger/better aftermarket companies. People who already have this installed should check their cam gear. One of my gears was off by about 3.5 degrees. The one I am using now was off by 2 degrees. It needed to be advanced 2* to line up with the Y8 gear correctly. And we all know that 2* is a lot when tuning and dialing in an engine.

One way to Be sure your cam timing is correct is to set your ignition timing to 16* with a timing light before you remove the original B7 cam. Then do not move the dizzy during the removal process. Install the A6 or ZC cam, install the adjustable cam gear and then adjust the cam timing until the dizzy timing lines back up to 16* again. Then you know you're really at "zero". After that, you can retard or advance as desired.

Again, check your adjustable cam gear. You will most likely be surprised. My original Y8 gear
from the same company was indexed perfectly..where as my replacement wasn't. Check it.

I drive my B7 setup as a city car / daily driver. I have my ZC cam advanced 2* and street tuned. Base ignition timing is at 18*. This has given my engine a very responsive feel from low all the way through the power band. Which makes it fun as a daily.

Imperative Tasks

You need to adjust your valve lash after messing with your cam / cam gear. Don’t ignore this. If you can swap a cam, you can adjust your valve lash.

Intake – .007-.009
Exhaust - .009-.011

Dizzy Timing

There are 4 lines on your crank pulley. The lone white one is TDC. There is a little group of three to the left (or towards front of engine), These three are 14, 16 and 18* BTDC. The one closest to the front of the engine is 18*, the red middle line is 16* and the one to the right of that is 14*.

Set dizzy timing from 16* to 18* BTDC. To be sure your engine is running proper, you can read your plugs –

Reading Spark Plugs - Link

It’s also imperative that you use a timing light/gun to set your timing. Not using a gun will result in any or a combination of the following - decreased power, detonation, shitty gas mileage. Use one.

The Heads

The B7 and A6 head are the same casting. The difference between them are the cam and springs. However, Honda ran out of B7 springs in Mid ’93 and had to dig into the A6 surplus. So if you have a mid ’93 and beyond B7 head, you’re already running A6 springs anyway. If you want higher revs (above 7000) with an older B7 head, it’s advised that you upgrade your springs and retainers.

Bolt-ons

In addition to the A6 or ZC cam, these bolt-ons will help you achieve power gains
Z6 or aftermarket intake manifold
4-2-1 Header
Cold Air Intake
2” Cat back exhaust

More power? More Compression?

You can pull the head and have it milled to bump up compression. Typically, the head gets milled about .044. At this point, you’ll want to have your ECU socketed so the engine can be tuned.

Tuning
It’s not absolutely neccessary, but tuning this setup after everything is installed will give you the most power gains. A well tuned setup can see 120-135 at the wheels. You’d be surprised how well these engines perform with a little help.

In my personal opinion, I can't stress enough the knowledge you will gain
about engines and especially your own engine if you learn to street tune
yourself. Read as much as you can about timing, fuel maps and reading
spark plugs. You will learn exactly what your engine likes and dislikes.
For example, my engine really responds to pretty aggressive timing
slope to 3k rpm..but after that, it's repsonds MUCH better to a decent but
not super aggressive amount of timing (aggressive meaning more than
29-30* at WOT) from 3k and up to 7k. I have NoTec friends who have ran
much more timing without issue. However, I've tried this amount of timing
in my car and I actually lost a lot of power. So getting to know what your
engine likes in a grassroots style will help you learn tons.

My B7/ZC setup –




Hope this consolidates everything into one post. And I sincerely hope
it inspires more NoTec builds.

-Jay