Simple head upgrade

JSF55 · Post by **JSF55** » Tue Jul 28, 2009 11:08 am

I've been offered some later 1999 ? heads, i know these come with better valve guides and larger ports, but have already spent a fair amount of time porting my heads, but don't have the newer design seals, is it a worthy upgrade for the cost of a few gaskets ?

chodjinn · Post by **chodjinn** » Tue Jul 28, 2009 12:58 pm

bear in mind the later heads have smaller combustion chambers therefore will affect the compression ratio; 28cc vs. 36cc.

CastleMGBV8 · Post by **CastleMGBV8** » Tue Jul 28, 2009 2:03 pm

But not if you use the composite head gaskets they were meant to have.

Kevin.

ChrisJC · Post by **ChrisJC** » Tue Jul 28, 2009 2:24 pm

I think you'll find that the later heads have exactly the same ports as the earlier heads.... So I'd stick to the earlier heads.

Chris.

Post by **katanaman** » Tue Jul 28, 2009 6:39 pm

I am with Chris, the newer heads don't flow any more, they only have the potential to flow more as the have thicker port walls so can be ported further.

JSF55 · Post by **JSF55** » Tue Jul 28, 2009 6:50 pm

so money would be better spent on new bulleted valve guides and whilst there out, a bit more porting

Paul B · Post by **Paul B** » Tue Jul 28, 2009 7:55 pm

JSF55 wrote:so money would be better spent on new bulleted valve guides and whilst there out, a bit more porting

Stop messing with it John. Look at the 'fun' you had with fuel injection experiment.

Or are you getting the urge for more power?

JSF55 · Post by **JSF55** » Tue Jul 28, 2009 9:28 pm

Got too do something over the winter ....

chodjinn · Post by **chodjinn** » Wed Jul 29, 2009 12:31 pm

CastleMGBV8 wrote:But not if you use the composite head gaskets they were meant to have.

Kevin.

you can use any of the gaskets, tin or composite, with any of the heads.

topcatcustom · Post by **topcatcustom** » Wed Jul 29, 2009 2:09 pm

chodjinn wrote:
CastleMGBV8 wrote:But not if you use the composite head gaskets they were meant to have.

Kevin.
you can use any of the gaskets, tin or composite, with any of the heads.

With 10 bolt heads and tin gaskets you will raise the compression ratio, with composite gaskets the compression ratio will not change. Of course due to smaller combustion chambers in the newer heads and more volume in the cut outs of the composite gaskets.

TC

JSF55 · Post by **JSF55** » Wed Jul 29, 2009 2:29 pm

I had the heads on the car skimmed and fitted composites as a "belt and braces" approach, the block leaked

so after a good dose of kalimex it was water tight, i thought these heads with tins would gave a bit CR and a boost in performance? suppose i could spend those long winter nights in work porting these a bit

chodjinn · Post by **chodjinn** » Wed Jul 29, 2009 2:59 pm

topcatproduction wrote:
chodjinn wrote:
CastleMGBV8 wrote:But not if you use the composite head gaskets they were meant to have.

Kevin.
you can use any of the gaskets, tin or composite, with any of the heads.
With 10 bolt heads and tin gaskets you will raise the compression ratio, with composite gaskets the compression ratio will not change. Of course due to smaller combustion chambers in the newer heads and more volume in the cut outs of the composite gaskets.

TC

I was pointing out that Kevin might have given the (slightly wrong) impression that you could only use composites with the later heads. Of course, they came with composites from the factory hence his comment, but I don't know one build on this forum that is factory. The gaskets are interchangable which is a good thing, and yes, you can play around with the type of heads and gaskets to tweak the compression ratio.

For example, mine are the 36cc heads, and I'm using comp gaskets to help lower the CR a bit more (0.7 I believe).

However, given the fact my engine hasn't actually been run yet, and I have reservations about the build quality anyway, it might be a good time yet until I know for certain! bah!