ENGINE GURUS:my 355 build,opinions on head gasket

[bosephus]

Here's my build:350 block bored .020 over,sealed power H345NP hyper flat top piston with 5 cc of valve relief,stock crank,stock rods resized with ARP bolts,lunati roller cam with .535/.550 lift and 231/239 duration @ .050 lift.,Heads are AFR 180,1.5:1scorpion roller rockers.My deck clearance measured out at .036. I have both a composite(.041 compressed) and a steel shim(.015 compressed) head gasket.AFR says I can use the steel shim gasket but I would probably have to mill the heads the next time they came off.Would the quench/squish be too much with the composite gasket(.036 deck + .041 gasket)?Compression ratios would be @9.97:1 with the shim and 9.41:1 with the composite.I dont want to have to mill a brand new set of AFR heads to change a head gasket but I also dont want detonation issues either!Any advice would be appreciated.Thanks

[swb85]

Originally Posted by bosephus

Here's my build:350 block bored .020 over,sealed power H345NP hyper flat top piston with 5 cc of valve relief,stock crank,stock rods resized with ARP bolts,lunati roller cam with .535/.550 lift and 231/239 duration @ .050 lift.,Heads are AFR 180,1.5:1scorpion roller rockers.My deck clearance measured out at .036. I have both a composite(.041 compressed) and a steel shim(.015 compressed) head gasket.AFR says I can use the steel shim gasket but I would probably have to mill the heads the next time they came off.Would the quench/squish be too much with the composite gasket(.036 deck + .041 gasket)?Compression ratios would be @9.97:1 with the shim and 9.41:1 with the composite.I dont want to have to mill a brand new set of AFR heads to change a head gasket but I also dont want detonation issues either!Any advice would be appreciated.Thanks

The comp gasket would net you a quench of .077"......way too wide. Have you already assembled the shortblock? Best solution is to deck the block, but if you're already assembled then you'll want to use the shim gasket for sure. You really want to try and get that quench height between .040-.045 if you can.........

[bosephus]

The short block is already assembledThis is my first build and I keep making mistakes(thats how you learn).

[Marv D]

I have never had a steel shim gasket work out well with aluminum heads. If you try it spray them with coppercoat and don't scrimp of retorquing the head multiple times (about every 10-20 heat cycles for the first 500-800 miles isn't 'too much' with a steel shim IMO) ESPECIALLY with a questionable block deck surface.

[Captainfab]

You can have custom made head gaskets from Cometic, but they are a little $$. Those pistons seem to be a ways down in the hole, but then again those are budget pistons. If it were me, I'd tear that short block back down and get it decked. If I'm not mistaken, you should be able to reuse everything you have in there now.

I have not figured out why all the off the shelf composition head gaskets are so thick. Unless you have a zero deck height, you'll have too wide of a quench.

[mongoose]

Originally Posted by Marv D

I have never had a steel shim gasket work out well with aluminum heads. If you try it spray them with coppercoat and don't scrimp of retorquing the head multiple times (about every 10-20 heat cycles for the first 500-800 miles isn't 'too much' with a steel shim IMO) ESPECIALLY with a questionable block deck surface.

is that just the straight steel ones? have you ever used the rubber ones IE felpro 1094?

[GMR-PERFORMANCE]

When settting up a engine all of the math needs to be done up front before anything else.

You have a head that is 64 cc, using a flat top piston that is a -5cc valve relief, and pistons are .036 in the hole, using a .041 HG and when you do that math you have 9.46.1 static,
add the cam into the equation and you end up with 177 CCP @ sea level and a corrected of 8.69.1. Unless this cam does not close at 41.4 on the intake,... you are going to have a tough time on pump gas with that build. Add into that fact the HR cams build dynamic compression at a fast rate you would need to back the compression off for that cam. OR choose a cam with a later intake closing point.
Cam I looked up is a
VDSC-282 is that correct??

One other thing you will need to check the spring set up that cam is listing 105 on the seat, the afr is around 135 so that should be addressed as well.

We do this for a living and I cannot tell you how many engines a year we have to re-do for customers that got a bit mixed up in the process and have a few things going sideways in the build. You are not too far into this to stop and get it sorted out. Just my opinion.

There was another guy that had a issue like this and had to go back into the engine to correct this problem his was pinging.

Steve

[Marv D]

Originally Posted by mongoose

is that just the straight steel ones? have you ever used the rubber ones IE felpro 1094?

I thought you were saying you had a embossed steel shim you were comtemplating using. That should be sprayed with a sealer. Some use aluminum paint, I like coppercoat,, just a preferance.

I've only used the 1094 on one moor,, a mild 355 and it was to help bandaid a motor build with a set of KB hypers with the reduced compression height (some of the builder pistons put the dam piston 0.060" down the hole from a ZERO deck. WHY??? Have no idea.. stupid if you ask me) But the guy had similar issue, low compression, too much cam, big tube headers and 3" exhaust. It was a TURD!!

My solution would be the same as Steve, swb and the captian,,,,, pull the motor down, and have the deck cut to 9.000 and use a 0.039" FelPro 1010 or 1003,, whichever you prefer. I think you will be happier in the end if you do.