That's pretty crazy. I dont think I am going to mess with porting them myself

I cleaned them up good and scraped the gasket surfaces clean. (Not clean like polishing, just cleaning carbon build up). I really can tell how good the cast is on them now. They are very good for a factory head. Not what Im used to. I don't think a professional job is in my budget... I was going to do them as a project and to save money. I may just have them checked and milled and do springs.

What thickness head gasket should I go with for my set up? The cam specs I mentioned are, or are very close, to what Im going with. I'm pretty sure I will mill to 62cc.

Im not even sure what an LS6 gasket thickness is... I could go with stock and let the cc decrease up the compression, or I could get a little more with a thinner head gasket.. any ideas?

 

Well..............just to give you something to think about.........

The factory head gasket is about .051" compressed. And "most" LS motors have a negative deck clearance, meaning the piston protrudes out of the block, typically in the .005"-.008" range.

So.....example....we will use .006" piston out of the hole as a standard, as well as 3.898 bore, 3.622 stroke and 6.089 for rods....all which are stock numbers.

When using these as "standards"....we will manipulate the static compression ratio (SCR) and dynamic compression ratio (DCR) using the combustion chamber and head gaskets thickness.

Using a 228 XER lobe on a 112 center line your ABDC (intake close point) at the base of the ramp becomes 70.5* and I will use that as a standard in these examples.

Example 1.....a stock head gasket thickness (.051") with a stock 243 chamber (64.5cc chamber) will yield roughly a 10.60 SRC and a DRC of 8.10. And a quench of .045".

Example 2.....a stock 243 chamber with a .045" gasket will yield a SCR of 10.80 and a DRC of 8.20. And a quench of .039"

Example 3.....a milled head to 62cc and a stock gasket yields....11.00 SCR and a 8.30 DCR. And a quench of .045"

Example 4.....a milled head (62cc) with a ..045" gasket would yield.....11.10 SCR and a DRC of 8.40. And a quench of .039"

And remember that the gasket and chamber=SCR which will not change once the engine is together.....but the DRC will be dependent on your cam choice.

And typically anything above 8.7 DCR is considered border line on pump gas without pulling timing. And the SCR really does not mean squat....its the DCR that makes the power. But I will say it takes a decent SRC to accomplish a adequate DRC.

Here is a little insight on quench..........
Tighter "quench" (and I hate that terminology) will result in more squish turbulence (better terminology). Any increase in charge turbulence (squish, tumble, or swirl) will increase flame speed. Any increase in flame speed is a good thing, both for BMEP (less time and heat losses), and for detonation tolerance (if the normal flame front can consume the charge end gases during the fuel's autoignition delay period, no detonation will occur). So yes, you will not need as much timing for MBT, but it's not due to detonation limits, it's because the engine NEEDS less timing for MBT (a smaller burn angle results with a faster flame speed).

Now having said that, there is a limit for clearance, too tight and the squish is suppressed. How tight you can go and still have effective squish depends on the depth of the quench area of the heads/pistons (ie. the radial length).

Thanks...................FYI, example 4 will feel and be the quickest.....

 

Cool pictures.

Im a fan of double springs myself. PRC .650's would be good.

 

Yeah, I vote doubles also....those are doubles in my pics. And about the PRC's.....I think that spring is way over kill for a 228 cam (which is the cam the OP has mentioned). I had a set of PRC .675's on a larger cam a year ago...and @ max lift on my cam .645" they had a pressure over the nose of 435lbs (installed @ 1.8")....that is a tough life for a stock lifter....

I would recommend staying under or around 400lbs max over the nose for stock lifters. Keep the ramp rate modest and 400 over the nose should be a walk in the park.........


Thanks......and my 243 heads made killer power !!!

 

Yeah I have PRC .675's on my LS3 heads, praying my stock rockers last till I upgrade the trunions. Lol

 

You guys think double springs is best even for my mild setup?

 

PLEASE dont remind me!!!!..... For those of you here that are playing hooky with a heavy spring and stock lifters, i have a thread for you to search......




IMO if you stay with that duration in the cam+ the lift u chose, i dont really see a reason to go with a dual spring. It wouldnt hurt anything if you did, just add a lil extra weight.

 

Not understanding why upgrading your rockers is gonna help the pressure from the springs on your lifters. You may wanna do both...

 

Sorry, edited it. I meant rockers. Im sure the LS7 type lifters can handle it. I had a bigger cam with similar valve springs on LS1 lifters for years. They all lasted fine.

 

Ok there we go....yes the LS7 should fine. That is what i upgraded to here take a look at this....

http://forums.corvetteforum.com/c5-t...-bad-juju.html

 

I remember reading your thread. I broke a valve spring and rocker arm on my old setup that damaged a lifter also and killed a cam lobe. Much worse then yours. The lobe looked a v-groove pulley.

 

Op.....dont forget the stock rocker arms need a trunion upgrade. It is very cheap insurance and very easy to install. Takes about an hour to do all 16 with a shop press. The comp trunion kit goes for about $125.


Thanks......

 

I used Advanced Induction and was very pleased with their work.

 

Ill add that to my growing list of expenses. That or full roller rockers. It is looking like it will be awhile before I do anything. I am just glad to have picked up the heads for now. I will have a better budget and be happier if I wait for now.

 

Remember your only option is 91 Octane when configuring your head package.

Mike V

 

Thank you . I already have a tune for 91 octane. Ill be making sure everything goes smoothly.

 

They did a great job on my 243s

 

So AI vs. TEA....who wins?

 

Not to hyjack but op & I are in similar situations.
Me: LS6 intake; 228r; LT(no carb); full exh; Full Vortex to TB; & currently a Shi*#y tune.
I picked up 243's.
Thought is to at least port match & get good tune.
Problem is a clown I work with (w/a 9sec LS1 stang who tunes it himself & i therefore do respect his efforts) says this 243 effort is a waste of time. High $ heads aint gonna happen. I'm a mechanic w/2 kids not an orthodontist....

I dont think its a waste since I gotta pony up for a retune on the cam install anyway.
Heads are paid for & sittin in garage.

OP & I are going 241 to factory (not hi $ reworked) 243's.
So it's really worth it right? I think so but I (we) would like some knowledgeable feedback
Thanx to all & OP for the space & maybe we'll both learn more.
Mark

 

I think the heads are very worth while. Especially if you are installing them yourself. The heads are cheap, and the labor free. Just some work involved.
From what I gather, the 243's are good for .580ish lift without a p&p. With a p&p they are in the .600 and up range. This would mean (in my case) that the 224/228 .583/.588 114 cam I am going with will be very close to full potential with non-ported 243 heads.
I for one will not be spending that kind of money. Of course there would be some gain. But not worth it in my case IMO.
I also gather that bolting on 243's on a stock car is good for 10-15whp. Whereas a cam car would see in the 30-40whp range. This is because the cam and heads work off of each other. The heads aren't increasing the power as much as they are releasing the rest of the cams power.
Then, you have the ability to deck the surface down to 62 or 60 cc, (do the math on your compression). And kick up the torque a bit that way too.
I got the heads because I knew how good they would be for my set up. I only asked for parts and build recommendations. They will be a great upgrade for your cam car.