I'm going to be doing a cam swap very soon, and popping the heads at the same time. And just to add a little more compression I was wanting to go with some thinner head gaskets, but I've been told by a guy at the performance shop here that the only thinner head gaskets you can get are steel shim gaskets, and he said those leak. I don't want leaky head gaskets. Does anyone have any experience with this, or know of any regular fel-pro type composite gaskets that are thinner? I thought I remembered seeing before that fel-pro made a thin comp. head gasket. Any input is appreciated, thanks.

 

He's right. You will regret putting steel shim gaskets in there. They rarely last very long. Use a regular FelPro blue one. The factory used steel shim, and practically every one I've ever torn down had leaks usually in multiple places. The motor will run better with head gaskets that seal than with ones that don't but give higher CR on paper.

The thin (.018" or whatever it is) FelPro ones are steel shim.

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"So many Mustangs, so little time..."
ICON Motorsports

 

to add just a little to what RB said, you'll never notice any preformance gain from changing head gaskets or raise the compression any great amount.

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ICON Motorsports

1st & 3rd
MM Black Diamond 538 F&AM

 

Well, I know it's not a huge increase, but I've already milled my heads .030, and don't wanna go anymore on them. I think I'm still just under 9to1 compression, and thought this would be just enough to bump it up into the range I want. I can run on 87 octane for god sakes. I'm running flat top, 4 valve relief, forged full floating pistons, in a 350 block bored .030 over and stock heads milled .030. I don't know how far down in the hole the pistons are, I've never had that checked. Where do you guys think I'm at? I can crank up my timing as much as I want with 87 octane and never get any detonation or ping. Although I do have a rather large cam in it right now at 235 duration. Thanks for everyones input.

 

you could go with fel pro head gasket #1094. with more compression, you should feel it, but i wouldn't expect it to feel like nitrous or anything.

 

Yes, go with a Fel-Pro pt#1094. It is .015ths thick vs .039ths. This should add a little over 1/2 of a point of compression. Also this gasket is a "embossed shim with precision rubber coating, 4.100 bore" so it won't leak.
Paul

 

BAB,

If you're planning to remove the heads, you might want to consider a set of used heads from an LB9. If you've shaved 0.030" and the CR is still under 9:1, your chambers are probably way too big to provide a reasonable compression. The steel shim gaskets (or even copper ones) will only mean that you will be removing the heads again soon. Maybe then you'll have a set of L98 heads recovered from the bone yard and prepped for your engine.

This is all based on the presumption that your Berlinetta has the 305 with flat-tops, not the dished pistons. If you have dished pistons, you might be throwing away your money on a cam change and any performance enhancements.

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Later,
Vader
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"What a Day..."
Adobe Acrobat Reader

 

Oh no, the 305 has long been gone. I'm running a 350 bored .030 over and 882 heads with what use to be 76cc before they were shaved. So with flat top 4 valve relief pistons, where do you think this puts me at? All I know is I never seem to get detonation or any ping. Think this is because of the big cam and relatively low compression right now? I'm putting in a Comp Cams Extreme Energy designed specifically to my specs, 224/231 duration at .050, 478/481 lift with a 108 lobe seperation. They told me this cam is very good for low compression motors and actually boosts compression. Maybe that alone will be enough. About that fel pro gasket you guys mentioned, does anyone have experience with it, and are you sure it won't leak?

 

Your problem is the 76cc heads.

 

Yeah, I know, but till I get money for new heads, since I'm doin this cam swap anyway, I just wanted to do the best I could to bump it up some.

 

interested in a set of 461 camel humps? im thinking of parting with a set. 2.02/1.60 w/hardened seats, new guides, tapped for 7/16 studs & guideplates, pushrod holes reamed for 3/8 pushrods, decks milled .010. heads are bare and ready for assembly.

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85 IROC 350 11:1keith blacks,.555lift erson roller cam,1.5 crane roller rockers,edelbrock intake,holley 4150 750dbl pumper, nitrous oxide,full length heddman headers,true dual exhaust, 11"stall converter, 700R4, 3.73 locker

 

Nah, thanks anyway. But I already got my springs and roller rockers for these heads. Besides, it wouldn't be that much of an upgrade for the cost. I'm just gonna wait till I can get some good alluminum ones. Thanks.

 

I've got almost the exact same setup. 350 .030 over with 882 heads just rebuilt no enhancements and I'm using the felpro 1094 gasket. 10000 mile since the rebuild and no problems yet. I talked to the guy that machined my engine and he said that the embossed steel shim gaskets were fine.