I'm looking at summit, and they offer the GM vortec heads # 12558060 and there own summit brand Vortec heads # 151124 that seem like a better head for less money. but the cc on both heads are a little different...Im wondering if there a difference in power, i e compression or flow, If anyone has experience with these heads please say so, as im trying to pick some good vortec style heads in the next couple of days !

 

Take your pick, just make sure they are able to handle your cam. Stock vortecs are limited.

 

I was wondering about cc on the two different heads if that would make a difference?

 

Depends on what engine you are putting them on?
If going on a fresh build then the engine can be built to get a desired comp ratio with any size chamber

If going on a stock engine then most likely the larger chamber Summit version will give a lower CR ( less power ) than what you have now
Again depends what engine you currently have; chamber size varies widely across the years
If the GM version has smaller chambers than your current head then it will raise the CR

 

Your right, I need to find out what the stock cc are on a 1992 L98 350 iron head is. I'm sure it's around here some where.

 

64cc

 

So at 64cc , the GM Vortec head will maintain you stock CR ,the Summit heads will lower it

 

couldn't a thinner head gasket be used to bring up the cr?

 

I don't like the shim style head gaskets.Not much bite in them and you really need to have the deck finish to handle/help seal them long term.

The Vortec engines have a head gasket issue in part because of less head bolts and in part because of the gaskets.I'm not sure if that isn't the reason why we are finding so many cracked used Vortec heads too.

Far and away better to machine parts and have the proper pistons for the proper SCR using a .039 head gasket.

 

Gary, I saw a recent Hot Rod story where they said to never use those shim tyope gaskets with the leter model 'lightweight' heads.

I was suprise to read this, the least 2 smallblocks i built, I used the shims, and coated them with a copper spray. Had no issues.

 

I wonder why they would build a head that lowers it ?

 

Arer you talking CC and compression ratio?

GM has offered many CC heads over the years depending on the application.

58 cc, 64,cc and 76cc are the most common.

Higher compression is not always better.

 

The two heads you posted are, 64cc and 67cc. A very minor difference, heck some oe heads may see that much of a variation from chamber to chamber.

Certianly not enough to notice a differecne in power on a mild build.

 

Good point ! I hope they turn out ok, i just got them in Sat

 

Strokers increase comp so larger cc is used for lower compression for street pump gas deals. Thats ofcourse you cant find proper pistons to give the ratio you are looking for. Between head size and piston you can dial in what you need.

Other reason to lower... Booost

 

?

 

The edit should read less intake bolts.

I'm going to go back to what I said at first.Why the hell would you invest into anything that has a history of cracking??. Then cut them even more on a thin casting,then use a shim gasket.Just doesn't make much sense.

 

Why would intake bolts effect the head gasket?

 

John I admitted to the mistake,ya know.............................??.

 

so what is the stock compression of a 1992 350 Z ? Does anybody know what the new heads will make it?

 

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I thank you for wanting to help Irocz442, But please, Don't post your for sale items on these pages ! Thanks

 

If you do plan on running more lift something like this would be appropriate.

https://sdparts.com/details/scoggin-...ter/sd8060arpm

I'm not saying its the best option as when I bought this package 8 years ago it was only $900, but just for an idea. Vortecs do require a special intake manifold, just something to consider.

 

The EnqineQuest vortecs are very nice. I got mine fully assemled with guide plates and screw in studs for less than 800 new.

 

Thanks, I bought the summit brand vortec heads, that are good for more lift and i have the correct lower intake, I was just not sure if i needed to lower the com from a 67 to a 64, If that really made much difference..

 

Oh sorry. I thought you wanted to know the best Gm Vortec head castings, the best is the 0062 sorry but that's the truth.

 

Exactly.. You would use the only Two size Gm Vortec head gaskets thats the choices nothing else.

 

What do you intend to run for an INTAKE manifold gasket?
It depends somewhat on your choice of intake manifold.
I had been running the OEM Vortecs (with an RPM Air Gap inatke) for years with the Fel-Pro MS90131 without any trouble. Now that I've moved up to the RHS Vortec (Pro Torker) ,I've found that engine is uisng a lot of oil and plugs 6 and 8 are oil fouled. A typical intake gasket failure. Now I'm on the look-out to see who has done what.
Here are a few of the choices. Some of the plastic carrier type with silicone beading (which is the 90131 as well as the GM 12529094 and the 1255 which I believe is a Printoseal type of gasket on a composite paper.


Fel-Pro 1255 composite gasket. Printoseal on composite paper


Fel-Pro MS90131. Original edition of this gasket similar to GM 1259094. Plastic/nylon carrier with silicone bead.


Fel-Pro MS908000T. The latest version of the MS90131.

 

It's not installed yet, but on my mock-up, the Fel Pro 1255 seemed to be a good fit with my Edelbrock TPI base. I did a lot of reading and this seemed to be the preferred gasket with aftermarket intakes.

 

Wow, Thanks for the info, I hadn't even put much thought into it yet ! But, I guess I better, thanks for the info.