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I have a 1973 Mustang and I'm rebuilding the engine. I ordered a new crank, connecting rods, pistons, pins, rings, bearings, cam, etc. I had the engine bored .030. I'm going to be running about 10.35 : 1 compression on stock iron 2v heads. The pistons are TRW forged racing with chromemoly rings(if that matters). I just wondered if this compression ratio will require me to retard my timing or run race fuel. If it does what can I do to reduce the ratio to a safe level without ordering new pistons or heads cause I'm on a very limited budget. Thanks.
 

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cam II is how much. Closed chambers allow you to run more compression with out pinging. I hope I'm wrong,but I don't think it will run without detonation problems. Octane boosters don't help either. All the open chambers that I've had with stock compression had enough problems.
 

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You can always have the tops cut on the pistons...IIRC, the TRW flattops (LxxxxF) have a top similar to the domed TRW's I run in the race car and are thick enough to cut a dish into. Any automotive machine shop with a lathe can easily do it. Shouldn't take over an hour. I'd suggest dynamically balancing the engine if you weren't planning to, if you make this modification.

Knowing your volumes and true C/R would go a long way to determining whether the extra expense is necessary. I've found advertised C/R's tend to be "optimistic"...real world ones are usually lower. If you end up under 10:1, you should be OK on pump gas if you don't build too much cylinder pressure at low rpms (eg small cam and low numerical rear gears)

Hope that helps!
 

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your on the hairy edge of problem. I prefer not to play there without a good reason. your only talking 2 HP per .1 ratio. by loosing 10 HP you'll gain confidence of not having a problem now or with any reformulated epa regulated fuel in the forceable future. Aluminum heads would help the issue. There is far more horsepower to be found in flow and RPM than in compression. Thats why a superchaged car uses low compression pistons and pumps more air to build pressure.
 
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