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Discussion Starter #1
head milled .040
block milled .015
Fj dist. 2 layer MLS head gasket
delta 272-2 cam

is this enough to worry about piston to valve clearance issues?

CR should be around 11-11.4:1

Thanks for any advice!!
 

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with the 272-2 you must be running a vtec head and for it not to be 13+.1 Im guessing your using a z6 head? If you do(which I think you would be fine) clay the motor, you need to make sure and lock vtec in since that lobe is larger then the others.
 

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You have moved the valves about 0.060"closer and increased valve lift. I would clay it to be sure.
 

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Discussion Starter #5
with the 272-2 you must be running a vtec head and for it not to be 13+.1 Im guessing your using a z6 head? If you do(which I think you would be fine) clay the motor, you need to make sure and lock vtec in since that lobe is larger then the others.

No, B7 head, A6 cam reground from delta to 272-2
 

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Discussion Starter #6
You have moved the valves about 0.060"closer and increased valve lift. I would clay it to be sure.

ok, yea i figured i should, but i also thought since anything i ever want to do to a honda has been done amillion times before that someone may know the clearance and how much room i have to work with
 

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Clay it and be done. Delta does the 272 and 272-2 for a few motors. If he says its fine then run the bitch and be done with it.:fingersx:
 

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272 vs 272-2 is nothing to do with vtec. The 272 is a grind optimised for NA and the 272-2 is optimised for a turbo. Both are designed for about the power band to be in the range a bit above what a stock cam gives. I have not been able to confirm, but probably about 500 to 1000rpm higher. The 272 and 272-2 are designed to be reground on a stock cam and into a stock head with maybe better springs.

They are about the biggest cam that is cheap and easy to fit, so high performance street or budget race.
 

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Mr. Smith, you are really getting annoying. I've noticed you spouting off junk for a little while now, probably trying to pad your post count.

You don't have a darned clue about the compression ratio. You REALLY have no clue about the cam this guy is running. So, please, for your own good, STFU.

OP:

You are likely going to have piston to valve issues unless you clearance the pistons slightly since the pistons are going to be sticking up out of the block by at least .013".

However, if you have milled .015" off the block the pistons are going to stick out of the block and unless you clearance the head for the pistons, they will come very close to hitting.

Furthermore, there is no such )(#*$)(*#$* this as a 2-layer MLS headgasket for Hondas, and if there is, you need to not use it as it won't seal properly. (There are three layers for a real reason, and you and I both are not able enough to come up with a two layer gasket.) For ALL SOHC BUILDS, just get an OEM Y-series headgasket. They are cheap, available, extremely high quality and rarely fail as long as they are installed correctly. Using this gasket in your engine with the head mill and block will will necessetate the chambers being spot faced to clear the pistons and give AT LEAST .030" clearance from the piston to the head, but not more than .050" for effective quench.

What you end up with for a static compression ratio, I don't know, because you have to increase the volume of the chamber (slightly) and increase the volume of the valve reliefs in the pistons (slightly) which, overall, will lower your static compression ratio. However . . . The engine will be extremely efficient, as as long as you pay attention carefully to your induction and exhaust sides, you will have an engine that will handily outperform most builds, as long as it is tuned well.

An engine like this will likely need very little ignition advance to make maximum power. I would recommend no more than a total timing of 20*BTDC at projected peak torque in order to prevent detonation. However, once tuned, it will likely want a little bit more than that while running on cheap gas, too, since the chamber design will be set up to very quickly and completely burn the air/fuel mix in the chamber.

You will likely want to at the very least clean up the ports on the head, too, as this sucker will want as much air as you can get. A cam gear will be a good thing, too, so you can find the optimal IVC (Intake valve closing) angle, which IS different for D15s versus most D16s (though you may want to start with the stock D16A6 IVC angle, as that is proven extremely effective for D15s).
 

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Discussion Starter #13
Mr. Smith, you are really getting annoying. I've noticed you spouting off junk for a little while now, probably trying to pad your post count.

You don't have a darned clue about the compression ratio. You REALLY have no clue about the cam this guy is running. So, please, for your own good, STFU.

OP:

You are likely going to have piston to valve issues unless you clearance the pistons slightly since the pistons are going to be sticking up out of the block by at least .013".

However, if you have milled .015" off the block the pistons are going to stick out of the block and unless you clearance the head for the pistons, they will come very close to hitting.

Furthermore, there is no such )(#*$)(*#$* this as a 2-layer MLS headgasket for Hondas, and if there is, you need to not use it as it won't seal properly. (There are three layers for a real reason, and you and I both are not able enough to come up with a two layer gasket.) For ALL SOHC BUILDS, just get an OEM Y-series headgasket. They are cheap, available, extremely high quality and rarely fail as long as they are installed correctly. Using this gasket in your engine with the head mill and block will will necessetate the chambers being spot faced to clear the pistons and give AT LEAST .030" clearance from the piston to the head, but not more than .050" for effective quench.

What you end up with for a static compression ratio, I don't know, because you have to increase the volume of the chamber (slightly) and increase the volume of the valve reliefs in the pistons (slightly) which, overall, will lower your static compression ratio. However . . . The engine will be extremely efficient, as as long as you pay attention carefully to your induction and exhaust sides, you will have an engine that will handily outperform most builds, as long as it is tuned well.

An engine like this will likely need very little ignition advance to make maximum power. I would recommend no more than a total timing of 20*BTDC at projected peak torque in order to prevent detonation. However, once tuned, it will likely want a little bit more than that while running on cheap gas, too, since the chamber design will be set up to very quickly and completely burn the air/fuel mix in the chamber.

You will likely want to at the very least clean up the ports on the head, too, as this sucker will want as much air as you can get. A cam gear will be a good thing, too, so you can find the optimal IVC (Intake valve closing) angle, which IS different for D15s versus most D16s (though you may want to start with the stock D16A6 IVC angle, as that is proven extremely effective for D15s).
thanks for all the advice, my machinist that is doing the head is also trying a valve arrangement called a poly-quad where 1 intake and 1 exhaust is larger, while 1 intake and 1 ex is stock in a X pattern, apprearantly David Vizard ( a friend of my machinist) is having great success with it...

Oh and here is the 2 layer HG i was referring to=

FJ Distributors
 

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*giggles*

Unlike most people on this website, I know who Mr. Wizard is, and I am familiar with the polyquad concept. I am VERY, VERY interested in the results of this. I'm going to be trying something with a similar concept but in a different manner.

That is not a 2-layer headgasket. There is no such thing as a 2-layer Honda MLS headgasket, unless you foolishly modify a gasket itself. The stock MLS headgasket compressed to about .027" thick.
 

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Polyquad has a very nice scientific ring to it but it means nothing other than a snazzy sounding name. Poly means many and quad means four.

I am guessing the idea is to induce some swirl in the chamber by biasing the flow. Swirl has proved useful for fuel economy but not for power. The larger valve will still be shrouded so it will not flow any more than the std valve except at very low lift.

An easier way to achieve the same thing without shrouding a valve is to use the Colt cams tri flow system. Another trendy marketing name where they open one valve a bit before the other and so set up some swirl. It seems to work, or at least not do any harm.

David Vissard has done some very good work maybe 30 years ago, especially on Ford 105E engines but also on some SB Chevies and BMC A series.

In more recent times in my opinion, his work has been more about selling his name for profit. Poly quad seems to fit well with that concept.
 

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i hope this isnt off topic and im not trying to hijack the thread but i had a quick question.

which will bump the compression ratio higher? decking the block or shaving the head, or will the result be the same??

i would think that shaving the head will bump the CR more since your making the combustion chamber smaller...

im asking because the OP shaved the head alot more then the block was decked. also getting rid of that much material wont effect the timing belt? can the tensioner handle the extra slack? or is it just the cam timing that will be effected?
 

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If the chamber is the same dia as the bore, it makes no difference. Its pretty obvious if you think about it.

You can't take to much off the block as the pistons start to protrude to much and hit the head. Also think about it.

Once you mill dowm on the head to the point that the chamber is smaller than the bore, you need to take more off the head than the block to reduce the compression the same amount.
 

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Polyquad has a very nice scientific ring to it but it means nothing other than a snazzy sounding name. Poly means many and quad means four.

I am guessing the idea is to induce some swirl in the chamber by biasing the flow. Swirl has proved useful for fuel economy but not for power. The larger valve will still be shrouded so it will not flow any more than the std valve except at very low lift.

An easier way to achieve the same thing without shrouding a valve is to use the Colt cams tri flow system. Another trendy marketing name where they open one valve a bit before the other and so set up some swirl. It seems to work, or at least not do any harm.

David Vissard has done some very good work maybe 30 years ago, especially on Ford 105E engines but also on some SB Chevies and BMC A series.

In more recent times in my opinion, his work has been more about selling his name for profit. Poly quad seems to fit well with that concept.
He's absolutely trying to cash it, but, I have learned a LOT from him and his work (especially about airflow and what part of ports are important).

I happen to think that the Polyquad concept is one worth exploring. The A6/B7 head is actually a head I would try this on, since it suffers from very little shrouding compared to the VTEC-style heads with their valves pushed to the very corners of the chamber. (My least favorite parts of those heads, which is a real shame since I like some of their ports!)

i hope this isnt off topic and im not trying to hijack the thread but i had a quick question.

which will bump the compression ratio higher? decking the block or shaving the head, or will the result be the same??

i would think that shaving the head will bump the CR more since your making the combustion chamber smaller...

im asking because the OP shaved the head alot more then the block was decked. also getting rid of that much material wont effect the timing belt? can the tensioner handle the extra slack? or is it just the cam timing that will be effected?
As Pat pointed out it really depends. With most D-series (except the D15) you have .5-1mm before the pistons end up even with the deck. That isn't a whole lot to take off. You can usually take off more from almost all the heads (up to 2.7mm in some cases) depending on how big your balls are. So, IMO, you can get more SCR (Static Compression Ratio) from whacking the head a whole darn bunch than from most blocks before running into issues of piston to head contact, though, I think that as long as you have the piston even with the deck and at least a .027" head gasket (stock MLS headgasket thickness, for the record), the engine will be fine. Close . . . but fine.
 

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Discussion Starter #19
Polyquad has a very nice scientific ring to it but it means nothing other than a snazzy sounding name. Poly means many and quad means four.

I am guessing the idea is to induce some swirl in the chamber by biasing the flow. Swirl has proved useful for fuel economy but not for power. The larger valve will still be shrouded so it will not flow any more than the std valve except at very low lift.

An easier way to achieve the same thing without shrouding a valve is to use the Colt cams tri flow system. Another trendy marketing name where they open one valve a bit before the other and so set up some swirl. It seems to work, or at least not do any harm.

David Vissard has done some very good work maybe 30 years ago, especially on Ford 105E engines but also on some SB Chevies and BMC A series.

In more recent times in my opinion, his work has been more about selling his name for profit. Poly quad seems to fit well with that concept.
really...thats funny because on back to back dyno runs he has seen gains of over 100 whp on race engines, and 7% more power on a bone stock production engine...so there is something to this, more than just selling something....
 

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If you believe everything that is "printed" on the internet, yes. Though, I do happen to think there is something to the setup.

Like I said before, I am REALLY interested in seeing how this engine works once it's all together.
 
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