I'm doing a head/cam install this winter (dart pro 1 205cc) and I was wondering what people are running for head gaskets (type and thinkness). Is there any issues with running a thinner head gasket (.041") over the stock piece (i.e. tendency to blow a gasket, fitment issues, etc.)? Anything you would recommend?

 

Nobody out there running head gaskets?

 

use gm gaskets or cometic.
Gm gaskests are pretty thin
The mls felpro are too thick

 

I believe the stock thinkness of the GM gaskets are .056". I remember reading that some people run .041".

 

Unless you post all the details of your build; cam specs, head chamber size, etc...no one can recommend you anything..

You need to calculate your compression ratio (especially dynamic compression), to see what thickness might be best for you.
Also, consider p/v clearance if you're running a sizable cam. A thinner gasket obviously reduces that clearance.

There's no inherent issues with running a thinner gasket, but with a small/midsize cam and planned high static compression, your dynamic compression might become too high (would need higher octane fuel or reduced timing to avoid knock).
And no matter what, I would not recommend a gasket thinner than .040" to maintain adequate quench. (piston to head clearance).

I'm using .040" Cometic gaskets with a 240/244 cam, 59cc heads (milled .025"), and 1cc piston notches.
My resulting static compression is 11.67:1, and dynamic of 8.77:1.

I took my compression as I high as I possibly could for pump gas, and yes it runs fine with no knock on 93 oct.

 

Also would like to add that you should find out your piston to deck height and try to use a gasket that will keep your quench distance between .032" and .038". On an LS1 or LS6 the piston comes out of the hole from .004" to .008". Optimum quench will allow you to run higher compression without knock due to the turbulence it creates in the combustion chamber.
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What I would suggest is use a Cometic .040" gasket. Then as Y2KVert4me suggested figure your DCR to be 8.7:1 max and set your chamber size to that if using 93 octane. If 91 I wouldn't go higher than 8.5:1 DCR.
HOWEVER, as Y2KVert4me stated, you will need to verify your PtoV clearance. .100" min on the intake and .080" min on the exhaust. If it's any tighter, you will need to notch your pistons or go with a different cam

 

I am unnotched........

 

On the Dart LS1 205 and 225's the chamber is 3.970" wide, so you will need a gasket with a minimum 4.060 bore. Dart recommends either the stock GM 6.0L MLS (4.060 bore, .056 thick) or Fel Pro 1161L and 1161R MLS (4.100 bore, .053 thick). The person I talked to at Dart said the Fel-Pro MLS were a better gasket than the Cometic, which is why I went with the 1161L and 1161R for my Dart 225's that I'm installing over the next few weeks.

Post more information on your expected combination for more complete information.

 

I think I posted this before, first measure the chamber width on the Darts. I think they are fairly wide so you need to be conscious of the bore as well, I don't think the standard 3.910 gaskets will work. As for thickness, all stated above should be used. There are several DCR calculators available to figure it out. You will need the cam specs at 0.006" and 0.050" lift (0.006" will be used for DCR calculations).

 

Sorry about not posting the specs:

Dart pro 1 205cc with 62 cc chambers
Comp Cams 228/230 .571/573 112
Fast 90
planned head gasket thinkness: .041

I can't imagine that I'll have any PTV clearance issue with that setup. I'd like to run the thinner gasket but I was worried about the intake manifold fitting correctly or other similar issues.

 

You have the two specs backwards:

Intake: .080 minimum
Exhaust: .100 minimum

I would add that these are old school very safe minimum values. If you know absolutely, positively all of the specs of your engine build and use the correct valve springs you can go closer.

 

Are you using stock rockers?

 

One quick method, find out how much milling people are getting away with using that cam on stock heads. The Darts have less drop so if you can get any information at all on clearances with stock heads you can plan accordingly. Measure during installation, but plan ahead of time. I am doing some things in the spring and will be planning my installation over the next few months. I also write a procedure so I don't miss anything during disassembly/re-assembly.

 

Yes, I was planning on going with stock rockers

Valve springs are th beehive psi springs

 

oops, you're right. My bad, exhaust gets chase up and intake chases down...

 

I didn't know the Dart had a chamber that wide. I would still use an .040" gasket though to give a tighter quench.

 

I'm going with Cometic .040's on my up-coming head swap.

 

Just to be clear. If the stock gasket is .056 and the replacement is .040 thick there won't be any fitment issues? I would atleast expect a potential issue with the intake manifold. Granted its only .016 of a diff. Any thoughts.

 

No issue's with using the thinner head gasket.

 

Thinner no problems as long as you have the PTV with your cam. However, if using Cometics they are a little more finicky on the surface preparation than the GM gaskets. I am going to go over my deck with a flat board sander to prep the surface once its clean. This means taking precautions about the sanding residue, etc. I have a few things figured out in my head (maybe that's why it always hurts ) to ensure no particles go into the lifter bores or cylinders. Probably total overkill, but I also bought a Snap-on machinist's straight edge to I can verify the surfaces meet gasket requirements. I just did some searching for my original posts when I bought the heads, I measured 3.96" chamber width. Its not a problem at all with the head, you just need to correctly account for it in your gasket selection. I am running the GM 6.0 LS2 gaskets right now with a bigger bore than the LS1 gasket. Since Cometic offers so many options, finding the one you need shouldn't be an issue. Also, my installation in the spring will use a larger bore Cometic 0.040" gasket as well. But those chambers will be "special".

When are you going to start your installation?