Head gasket thickness on a 511

[Bluefish]

How tight can ya go on head gasket thickness on a 511 with a Icon dish piston and steel rod? .040 gasket ok? Piston is .002" positive.

 

[Dajkzo]

Hi,

I'm running zero deck with Icon pistons and a Fel-Pro 1009 which is .039" compressed. Piston movement/rock is the real issue. I wouldn't think .038" is an issue, but you can look at various gaskets which are .045. You'll still get the quench effect at .043" clearance.

 

[Bluefish]

Hi,

I'm running zero deck with Icon pistons and a Fel-Pro 1009 which is .039" compressed. Piston movement/rock is the real issue. I wouldn't think .038" is an issue, but you can look at various gaskets which are .045. You'll still get the quench effect at .043" clearance.

Might be safe and go with the .045 gasket.

 

[gkent]

I'm at .035"

 

[Jeremiah]

How tight can ya go on head gasket thickness on a 511 with a Icon dish piston and steel rod? .040 gasket ok? Piston is .002" positive.

My zero deck 511 has .041 Cometics. 400 block 4.375x4.25 w/ 6.535 rod, -12.5cc dish Diamond pistons at 1.32 CH. With ported Victors it came out around 11.25. Runs on pump gas but i feed it 110 and c12.

Stick car

 

[Curiousyellow71]

We try to do .040 pretty much on anything with a closed chamber. .038 is close enough not a problem. Some guys get by .028... Maybe for a street build that didnt do a lot of rpms...never did one that tight.
Aluminum rods are the only time we run more then .040...or open chamber where it doesn't really matter and we use whatever to get the scr.

 

[biomedtechguy]

Stick car

 

[Bluefish]

My zero deck 511 has .041 Cometics. 400 block 4.375x4.25 w/ 6.535 rod, -12.5cc dish Diamond pistons at 1.32 CH. With ported Victors it came out around 11.25. Runs on pump gas but i feed it 110 and c12.

Stick car

My 511 was also 11.26:1, ran fine on pump 93 without any signs detonation. I did mix a gallon or 2 of 110 from time to time just for the smell. 3 gallons or more 110 per tank with 93 pump and it didn't seem to like it. I just had my victors shaved to 67cc chamber and will put me at 12.5:1 range depending on gasket. Looks like I will be fine with the .038 quench. I was just concerned about the piston rock that I was told to measure which I measured .049 on one side and .037 on the other at TDC. A .045 gasket gives 12.44 and a .040 gasket gives 12.6:1 compression. Not sure the extra .016 would mean much.

 

[biomedtechguy]

Not sure the extra .016 would mean much.

I'll take that opportunity to echo IQ52 Jim and say high compression ratios are not mandatory for good power output, and there are better ways to extract power.
I'd rather not have to worry about damage from detonation than to try to squeeze out a few ponies by walking the edge of the upper limit of CR, and wind up having to excessively retard the timing and/or run expensive race fuel or additives when the motor is supposed to run on pump gas.
Having said that, I have looked into and asked about ignition systems and other means as well as build specifications that would allow for "turning up" the power output of a particular engine when high octane fuel is available, and then "turning it back down" to run on 93 octane pump gas without any detonation problems.
Turbocharging and Supercharging makes that a much more straightforward option, because higher octane generally allows for more boost and vice/versa. My quest for that flexibility is with a normally aspirated engine, although a nitrous spray plate setup is an option, and higher octane in the S.A.F.E. fuel tank is something I plan on doing.

 

[Bluefish]

I'll take that opportunity to echo IQ52 Jim and say high compression ratios are not mandatory for good power output, and there are better ways to extract power.
I'd rather not have to worry about damage from detonation than to try to squeeze out a few ponies by walking the edge of the upper limit of CR, and wind up having to excessively retard the timing and/or run expensive race fuel or additives when the motor is supposed to run on pump gas.
Having said that, I have looked into and asked about ignition systems and other means as well as build specifications that would allow for "turning up" the power output of a particular engine when high octane fuel is available, and then "turning it back down" to run on 93 octane pump gas without any detonation problems.
Turbocharging and Supercharging makes that a much more straightforward option, because higher octane generally allows for more boost and vice/versa. My quest for that flexibility is with a normally aspirated engine, although a nitrous spray plate setup is an option, and higher octane in the S.A.F.E. fuel tank is something I plan on doing.

Yep I agree. I know of a 632 chevy with 10.5:1 compression running deep into the 8's. My situation is a little different. I use the Edelbrock victor head and for whatever reason they need big compression to perform correctly. Did my research and anyone going fast with this head has 12.5:1 or more compression. Anything less than 11.5:1 and they are very disappointing.

 

[383man]

I am at .045 for my quench but I have seen some run as tight as .030 to .035. I would not run it that tight with aluminum rods and a lot of piston to wall clearance. Mine came out at .045 which I wanted as I did not want it to tight. But you should be ok at .038 with steel rods. Ron

 

[Bluefish]

I am at .045 for my quench but I have seen some run as tight as .030 to .035. I would not run it that tight with aluminum rods and a lot of piston to wall clearance. Mine came out at .045 which I wanted as I did not want it to tight. But you should be ok at .038 with steel rods. Ron

Ok, thanks Ron.

 

[malex]

505. .002 in the hole, running a .036 cosmetic head gasket.

 

[Cranky]

Did a 500" at .019 once.....by mistake. The owner wanted to help and knew how to wrench but we were against the clock. There were lots of 'petty' machine work to do so he bolted on the heads while I was doing some mill work and him thinking that I had checked deck height and me thinking he was going to. It ran a 10.0 off the trailer in a 3600 lb car, checked the plugs which looked a bit dark so he leaned it out a hair and made two more passes until he lit up the funny gas. Bye bye cylinder on the 4th pass I know some some roundy rounders that do .025 with small blocks and live but they don't use the funny stuff...

 

[Bluefish]

Did a 500" at .019 once.....by mistake. The owner wanted to help and knew how to wrench but we were against the clock. There were lots of 'petty' machine work to do so he bolted on the heads while I was doing some mill work and him thinking that I had checked deck height and me thinking he was going to. It ran a 10.0 off the trailer in a 3600 lb car, checked the plugs which looked a bit dark so he leaned it out a hair and made two more passes until he lit up the funny gas. Bye bye cylinder on the 4th pass I know some some roundy rounders that do .025 with small blocks and live but they don't use the funny stuff...

I have found after calling Felpro that a .039 gasket may not be .039 once torqued to crush. I measured composite and it measured .045, Felpro says they crush .003-.004, so that gives me about .040-.041” quench if this is true. Plenty of clearance.