Comp ratio and a query.....

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Blue
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Re: Comp ratio and a query.....

Post by Blue »

I bet the piston will be far enough below deck for it to work. Another thing to think about is if you deck the block you will need to have either have the intake faces of the heads milled or the intake milled, apart from the cost those parts will then only fit your engine. Maybe not a deal breaker but something to be aware of. I would check the cost of decking and milling the cost might surprise you and not in a good way.
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Dave81
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Re: Comp ratio and a query.....

Post by Dave81 »

Yeah, I'll be looking into that next.
Hughes got back to me and said the only option is to work the heads for more combustion chamber, circa 3 to 4 cc to get the comp down into the 10s. Not doing that and finding somebody to work the heads will be an issue.

Next alternative is a cometic head gasket that had a crushed depth of 0.070 or 0.080. That would put mme in the low 10s comp ratio, but I've seen a couple of negative reviews about them.

Cometic MLS Head Gaskets
Head Gasket, MLS, 4.080 in. Bore, .070 in. Compressed Thickness,

0.070 with pistons 0.02 in the hole gives 10.22:1 Scr and 8.54:1 Dcr.

That gives a margin of error I believe and should be good for what I want.

Think I've
Dave Tildesley.....MMA-081
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Dave999
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Re: Comp ratio and a query.....

Post by Dave999 »

Cometic gasket is going to need surface ground heads and block....smoothness needs to be better than standard skim... its another process x4 in your case to add to cost + VAT

Dave
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Dave81
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Location: Worcestershire

Re: Comp ratio and a query.....

Post by Dave81 »

Hey Dave, just realised that doing what I'm proposing will screw the Quench and give me 0.090". They suggest less than 0.060 is required with 0.040 being a sweet spot.

Back where I was.......🤦
Dave Tildesley.....MMA-081
72 Dodge Dart
73 Plymouth Duster - SOLD

I wanna go so FAST i think i'm going to DIE!..........Then i'll shift into second!

"My Car is a work in progress, Probably never gonna get finished, never gonna have the money to Bananarama!!"
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