Im getting ready to swap out my 083 heads on my L98 for some AFR's. They are 190's with 68 cc. The block has stock pistons and stock deck height. I figure I will lose some compression going to the afrs, but what can I do besides decking the block or milling the heads?

Will a different head gasket help at all, Or will I just have to accept the loss and go on?

I plan on going to a 383 later on, so I will be reusing the heads on it. I would like to keep the heads at 68cc's.



What head gasket would be the best for me to use? Afr suggests felpro 1003, but I think that is too thick.

thanks.

Use the head gasket they suggest. They probably know more about what works and what doesn't, what causes trouble and what doesn't, than the rest of us all put together.

Yes your CR will go down. In addition to the mechanical change that lowers it, you're also going from iron to aluminum, which increases the heat loss out of the compressed mixture; so instead of adding a half-point or whatever like you need, you're going backwards. Oh well. Accept it and move on, because there's not a whole lot you can do about it right now, without making irreversible changes you'll regret later; or taking unnecessary risks from using the wrong gaskets.

Do your block right when you "go to a 383"; which includes zero-decking it; and pick the right pistons to give the CR you need at that point.

Use this one from the General #10105117
It's .028 and works well.
But by all means stay away from Fel Pro too many people have had problems with the 1003.

Ive generally used KB HYPEREUTECTIC or SEVERAL BRANDS of FORGED pistons (mostly from SUMMIT,JEGS,or J&E and TRW, , getting tighter than about .036 quench has generally led to indications that the pistons have come very close to contact at times, I try to stay in the .037-.045 range simply because I personally feel that getting the max quench is FAR LESS IMPORTANT that avoiding piston to head contact.BTW I generally use AFTERMARKET (H) style rods, with 7/16" rod bolts by ARP and floating pin pistons and SELDOM build engines that exceed 7000rpm , theres not much to be gained in my opinion by spinning over 7000rpm except potentialy increased valve train problems ,if thats any help, and I generally use SOLID LIFTER CAMS in a serious 355 due to thier effective opperating rpm band (4500-7000rpm,Ive noticed that STOCK chevy 3/8" rod bolts on STOCK reworked rods DO TEND to stretch more!
I built a 355 with .028 quench and 12.7:1 cpr(ON REQUEST) that had light contact and needed to use thicker gaskets, so thats MUCH TOO CLOSE
look at this
http://www.vips.co.uk/demos/mech/con_rod/vm_anim.htm

BTW YES BEFORE YOU ASK...cylinders to cylinder variations should be minimized but don,t get crazy if some cylinders have a thousanth or so more or less, rods and pistons do vary in dimensions, don,t get crazy over a thousandth or so varriation

run less than about .035 thousands and at high rpm levels the pistons might hit the cylinder heads, run more than about .044 thousands the QUENCH effect of forceing the fuel air mix to the center of the cylinder from the cylinders edge area looses both speed and effectiveness, remember the quench area must be so tight that virtually all the fuel/air mix is forced into the center area and none is allowed to burn untill its squirted into the burn area increaseing turbulance and burn efficiency
in theory the much better quench, combined with the shorter more compact area the flame front needs to cover and the far higher turbulance combine to allow more of the pressure to build AFTER the crank passes TDC on the end of compression and begining of the power stroke

its mostly an advantage in that you get a more even burn in the cylinder and less chance of detonation.
look, it takes approximately 40 thousands of a second for the flame from the ignition to cross a 4.25" bore,at low rpms and still takes about 15 milliseconds at high RPM due to the much faster movement of the compressed fuel air mix in the cylinders, lets look at what that means
if the chevy plug is located 4/5ths of the way to one side thats a time of about 32 thousands for the pressure to build as the flame travels 3.4" in the chevy but in a compact combustion chamber it could only take the cylinder flame front less than 10-20 thousands of a second to travel acrossed the combustion chamber for a complete burn at low rpms, this of course speeds up as the swirl and turbulance increase with increased engine RPMs but the ratios stay similar.[b] this results in more useable energy WORKING on the piston AFTER IT PASSES TOP DEAD CENTER ON THE POWER STROKE. BUT MODERN WEDGE combustion chambers use increased QUENCH to speed the flame front and lower the burn time combined with a smaller combustion chambers [color:"red"] look at this chart[/color]
http://www.iskycams.com/ART/techinfo/ncrank1.pdf

keep in mind that the cylinder pressure starts, builds to a peak and drops off all before the piston moves more than about 1/2 inch away from TDC and that if your wasteing 10-20 degrees of rotation compressing the burning mix in a slow to ignite combustion chamber your wasteing engine power

http://naca.larc.nasa.gov/reports/1939/naca-tm-914/



things to read
http://chevyhiperformance.com/techarticles/94138/

http://www.theoldone.com/archive/quench-area.htm



http://racehelp.com/article_racing-10.html

Dyno Don

What bad things have been happening with the Felpro 1003?
Will that GM head gasket be ok with the aluminum heads?

grumpyvette

Thanks for the info and the links. I will study them.

I have a set of pistons that I will be using when I go to the 383.

Speedpro powerforged #L2491f30 with a 5.7 rod.


Oh yeah, the cam I will be using in the 350 with the afr heads is the comp xe282hr-12 grind. With 1.5 rr's, Team-G intake and a 750 holley with 1 5/8 Lt headers.

I hope to have a good street/strip motor untill I step up to the 383. I dont plan on cranking the 350 over 5800 rpm.

thanks for the advice.

Quench has less and less importance the lower your CR. With .025" of deck clearance from a stock deck block, and the CR in the neighborhood of 8.9-9:1 with aluminum heads, quench is something you (a) don't have to worry about, and (b) can't get right no matter what you do anyway.

Now whenever you build a new short block, then it'll be time to optimize it.

I'm not even going to comment on the Fel Pro thing. I'd recommend doing what the head mfr says. After all, any warranty or support you need, will come from them, and not from any of us here. Now if somebody else is willing to take that over, then by all means do what they say.

TRW pistons are even farther down in the hole than stock. Usually by .020" to .025". The rationale being, it's better from their point of view, to provide parts that survive in case a block has inadequate deck clearance for whatever reason but leave a little power on the table, than to go for absolute max power and have pistons crash into heads.

Yeah, When I go to the 383, I will have the block decked with the pistons I use. I will be looking for around 10.5-1 with the aluminum heads.

Yeah, that would be the right thing to do, at that time.

However, I'd recommend re-thinking the TRW pistons for that type of buildup. For a couple of reasons. First, you'll most likely end up having to cut .040" or .050" off your block to zero-deck it to those. Second, the TRWs are intended by their design as something more along the lines of a heavy-duty replacement (like for trucks and such) as opposed to a high-perf type of piston. While they work OK in many cases for a hot street setup, they are quite heavy, as well as having the rebuilder's piston deck height issue.

More suitable pistons for that type of a buildup aren't that expensive, and are widely available; SRP, JE, etc. are probably more where you want to be looking. You won't need anything wild or unusual or custom, just yerbasic plain-vanilla flat-top with 2 valve reliefs and the correct compression height to go with whatever stroke and rod length you end up using. That setup with 68cc heads is about perfect for a hot street 383.

Yes, that gasket works with alum. heads.
Check out these pics:

Another one:

here is the link for the Piston specs. It says 0.020 deck clearance. Speedpro piston specs

Looks like things might be looking up in my budget. I might be able to go straight to the 383.

I may pick up a good eagle crank and take the block in to be checked and decked. The one I will use is already bored 30 over and clearanced for the crank and rods. Maybe shoot for 10-1 or 10.5-1 on the compression with about a 35-40 quench. That sound about right?

That means .020" more than stock. Stock being about .025", plus or minus (mostly plus) some production tolerances. It therefore means, you'll have to deck the block .040" - .050" or thereabouts, to get to zero deck clearance.

In other words, if you put those in a stock block, you could put it together with no head gasket at all, and you'd still have too much "quench".

I'd still recommend not using those; the money you'll save compared to JE or SRP or other entry-level high-perf pistons, will diappear fast in the overall expense; and you'll remember the hassle of getting intakes to fit, and all that, long after you've forgottne the $50 or whatever that it would have taken to buy the right pistons.

Also, I'd say you want 10.5:1 minimum; 10 is too low. For that cam anyway. And with less cam, you're not using the heads to their full potential, but rather, wasting part of your money on those.

Get real flat-tops, zero-deck the block to them, and run the 68cc heads. That's why AFR made them that size. It sets them up just right for what you're doing.... which is a very common and effective thing to do nowadays. Don't think you're going to re-invent the wheel better than it already is, in some shape other than the one it already is (round). Any other shape isn't as good. Same with that engine combo.

Get your Eagle stuff as their "kit", it will come with the right pistons, and it's the cheapest way.

BTW, Don:

That 1003 is classic over-torque failure. The results of improper assembly can't logically be blamed on the gasket. I sure wouldn't diss a whole mfr's product line because the castings they're in between warp when somebody tightens the bolts too tight.


bluegrass:

http://store.summitracing.com/partde...SP%2DB12011030
http://www.eaglerod.com/2003Catalog.pdf go down to page 21 of the file; the one I put in from Summit, is the B12011 in the .030" over bore. That'll give you some idea of what you get at that price.

What .....you think this is the only case of this happening?
You should not assume someone has made a mistake unless you know the facts.
These were torqued properly and I personally have had this happen one too many times, that is why I feel it is neccessary to alert others to what might happen.

BTW: I have never had a GM gasket fail.

The bolts were not overtorqued.

Would those pistons be ok for a SC or turbo motor?

The only reason I thought about using those is because of a package deal with the heads/cam/ other parts from a friend.

I could sell them or save them for another build. Its not a have to use them kinda thing.

Thanks for the advice.

Yes; but ONLY IF the rest of the motor was built accordingly.

Which means, if you don't put some form of forced induction on it, it's going to be slug slow.

You don't build a killer N/A motor, and then "maybe on down the road" slap a turbo or blower on it. Likewise, you'll be SORELY DISAPPOINTED in the results, if you actually DO build a blower/turbo motor, and then DON'T put the force on it. Reason being, the CR requirements are vastly different; cams are different; and alot of other things need to be thought through.

I'd strongly recommend, on the blower/turbo thing: either fish or cut bait, BEFORE you start buying parts. One or the other. You can't have it both ways. The more you optimize it for the one, the more the other will suffer. The best you can hope for is to have something that's only half-crippled in both modes.

BTW, you guys can protest all you want about those head bolts not being over-torqued; the gasket tells otherwise. Kind of like a corpse giving the lie about its murderer's alibi. "Yes your honor, I just happened to be walking through the woods on opening day of squirrel season, and I saw him point his shotgun at the back of his head right in the middle, and pull the trigger 2 times. He looked real depressed about something. Cross my heart and hope to die." Ummmmm..... ssssssuuuuuurrrrrrrre. I don't care what words I hear, the forensics tell the real story. They may have been tightened to what you thought was a correct torque; the wrench might even have read some value that was "within spec"; but according to the gasket, the bolt holes in the block were pulled out, and the head was warped upwards, by the excess clamping force right there. That place, right there, just like that, is where they ALWAYS fail from over-torquing. Next time, stop at 60 ft-lbs instead of going to the high side of the spec, and it'll probably do better.

So what youre saying is the areas of the gasket at the bolts (and likely where the bent fire ring is) would be thinner. They werent.

No, that's not really what I'm saying....

All I know is what I see. When I see that, I know the bolts were too tight. I've seen it happen too many times. Cletus decides he's going to make his motor "stronger" by tightening the bolts a little extra, and then head gaskets that look EXACTLY LIKE THAT (except usually they've progressed a little further) is what come back out of the motor when it doesn't run right and gets torn down.

Forensics is a good way to look at it. You can get all the verbal testimony you want, even from well-intentioned but genuinely misinformed people; but the physical evidence does not lie. If the guy's DNA is present at the scene of the crime, then he was present at the scene of the crime. If the bullet has the barrel's pattern on it, then it went through that barrel. And so on. No matter how convinvcing the alibi.

And, I know which one I will believe every time when they're contradictory.

You really are something, trying to apply some theory to automotive that doesn't apply.
I have another set of those gaskets to post that came apart .....but you would most likely concoct something to fit these too...so i guess I will just let this die.
BTW: in all my years of putting engines together I never lost a head gasket until I used some of those.

Sure it is. Here's what you said:

"the bolt holes in the block were pulled out, and the head was warped upwards, by the excess clamping force right there."
A localized compressive force, as you are saying, on a compressible gasket... well, I think you get the idea.

Fel-Pro sure knows what I do, they are on at least their 3rd major revision of the 1010. I seriously doubt thats coincidence.

Yeah, I know to build either a na or either a turbo/sc motor. Cant have both!! Im just getting a real good deal for bunch of part. The pistons just happen to be part of it. For the price im paying, the pistons might as well be free. (good friend deal)

I will end up going with my L98 block with the afr heads and the comp cam for now. That will give me somemore hp/tq and I can think about the 383 build for a while.

thanks

I heard of the 1010's failing, but not the 1003. What can you do.


bluegrassz,

The propper way is to choose all of the components before you purchase, mock up the assembly, deck as needed, and run it.

In your situation honestly, i'd mill the heads to around 62cc if you can go that far. (you should, check with afr). Although the aluminum heads take some heat out of the chamber, as sofakingdom explained, they don't 'lower your compression ratio', they let you run a more aggressive spark advance profile. With your stock pistons, the valve reliefs are about what -6cc ? You're gonna end up around 9.5:1 max with a reasonable quench.

How far can you mill the heads? I'd deck the block so the pistons are .005" in the hole, run a .039-.040 gasket, and mill the heads to bring your c/r as close to 10:1 as possible, unless your planning on a blower.

-- Joe

no, im not planning on a SC or turbo.

Afr says I can flat mill those heads .006 per cc, or angle mill them .008 per cc. They have a thick deck on them.

I would prefer flat mill to angle mill. You might have problems with header fitment with the angle mill depending how much material was removed.

Angle mill changes the valve angle. More power.

-- Joe

Angle milling can be expensive. You usually have to mill the heads, than the intake, than worry about Header problems. If you have Hooker longtubes, you know what I mean. Than it is usually wise to recheck pushrod length.

Yeah, my friend is running a 408 with angle milled heads. Its a screamer, but he didnt mill them enough to have to mill the intake.

Im running hedman Lt's.

So now 1003's and 1010's are failing? I've got a motor built with these gasket's (1010's) that will be going in the T/A as soon as I get off my butt and do it. I've replied to a few threads about the 1010's and have been told to use 1003's..... but now? Does gm make a gasket that is about .039 thick compressed and for use with aluminum heads? And is 60 ft lbs really all that is needed? AFR's site says 65 or 70 I can't remember.

Spec for SBCs is 60-65 ft-lbs. Sometimes lower, if using fine thread nuts & studs.

Using Teflon thread sealer, which is an extremely good lubricant (better than oil even), lowers the torque required to obtain a given clamping load; or conversely, increases the clamping load for a given torque. The specs were written long before it was commonplace.

I wouldn't worry too much about the 1010s.... as long as you torque(d) them correctly.

so sofa,i get the lowered coefficent of friction as related to clamping force vs.torque thing.my question is,what is the acceptable torque spec with the newer thread lubricants?
given a standard of 65 lbs. for an sbc,what percentage torque reduction do the better lubes require?
it also seems that when you reduce torque you end up with a bit thicker compressed thickness,maybe not much,maybe more than expected.
if i get my tax return back in time,i might just do a few trial asemblies with different gaskets to provide some real world answers to these questions as i am right at that point of assembly.
wish i had a sponsor!
Eric B

I just pulled the heads off my L98. It was the 4-valve releif flattops. No dish at all. Everything looked great. I also got the head gaskets off in one piece. I will try to mic them and see how thick they are. I was just glad to see the flattops will very little carbon. The cylinder walls looked great also.

Looks like my pistons are 22 in the hole. The heads a 68cc, but are being milled. We are trying to get 4 to 5 numbers out of them. I think I will go with the gm gasket to keep from loosing compression, plus my engine builder said he really likes that gasket.

At Dyno Don's shop he has noticed that sometime in 1990 or 1991 GM started installing flat-top 4 valve relief pistons in the 350's. This will raise the compression over the previous years. My 1989 had the 4 valve relief pistons but were dished.

So with the pistons down .022 in the hole you should deck the block around .010. That would give you a .040 quench with the GM .028 gasket.

I see we are still harping on overtorque. Because you apparently think some people havent been around the road, I will step down to your level and harp on what I've done since you have left no other avenue.

I used to work in a parts store/machine shop, for 6 years. I couldnt tell you how many heads I worked on, or how many I bolted down. I still live in the same town, and see some of the people around I used to deal with. I dont hear any complaints. I worked at some repair shops as well and did my share of heavy line work. You dont want to know some of those stories. I never had a problem until these so called 'performance' gaskets recently. Release torque wasnt any different on any bolt (I have a habit of checking these things when problems arise), so I'd say its highly unlikely there was a problem to begin with. You can keep harping all you want, how many 1010's have you used personally in the past 10 years? I've used 2, both failed. I wont touch them again. I've used countless 7733's, never had one let go. While you say pictures dont lie, neither do statistics. I dont personally know of any 7733 or any other SBC gasket I've used (GM, ROL, Victor, Pioneer, et al) that has failed ,and I have 2 destroyed 1010's on my hand out of... 2 used. Sorry but if I am making a mistake its got a funny way of showing itself. Nevermind I know builders that are friends that have had the same problem. And we all know that parts NEVER fail or have design issues, its always the person. I'm sure thats why they are going to MLS, they had such a bulletproof problem free product to begin with. Do you have stock in Fel Pro or something? Sure seems like it, cant be the part.

BTW as you know, I posted this up in a few places with pictures to boot. Really was curious what the problem was, if it was something I did. The second time around I was really careful to check for any signs of bolt problems and nothing pointed there. Then I had friends tell me they'd seen it before and were using other gaskets instead to avoid it. Thats about all the proof I needed myself.

I got my heads back and we cc'ed them. Looks like 60cc's.

We figured the compression at around 10.3 to 1.