Very impressive.
Did that bring the pistons above deck, or do you an idea what the compression worked out to?
1/4 mile times with 3.23 gear
- Thread starter abdywgn
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Did that bring the pistons above deck, or do you an idea what the compression worked out to?
scatpackbee
Well-Known Member
Pistons were .026” above deck as block surface was milled .008”
With a 68 cc combustion chamber volume static compression ratio was 9.8 to 1.
I know claimed compression ratio on a factory ‘69 340 is 10.5 to 1 with 63 CC’s combustion chamber volume, but my virgin ‘69 X heads measured combustion chamber volumes at 75 CC’s.
I had the heads milled .024” to bring the chamber volume down to 68 CC’s.
scatpackbee
Well-Known Member
Yes 75 cc's, believe it or not.
When I attended a Performance Seminar put on by Herb McCandless at Moparfest he mentioned that he'd measured dozens of X head combustion chambers and they were mostly between 70-75 cc's. I remember him saying the 340's were rarely a true 10.5-1 compression ratio from the factory.
dartindanno
Well-Known Member
My X heads measured in at 76 CC's. Huge difference switching to the 60 CC Trick Flows
My X heads measured 74 cc's
thesiren74
Well-Known Member
Done 13.06 with the big block in 45° weather and a 2,500 stall converter and 28" tires ,13.04 with the small block on 25" tires open headers and a 3,500 stall converter with 3.23s.
14.06 in my old 67 GTX, bone stock through the manifolds, in the heat of the summer, in the heat of the day, at the Mopar Nats. That was on BF Goodrich 15” tires and Magnums, straight out of the fun field. I thought it did pretty good
A stock 225 in a 3500 car running mid 16's, I find that hard to believe
3.23 don't necessarily mean compromised gearing, a light car with a short tire and engine making power at low rpm eg. Under 5000 rpm especially with a power adder 3.23 even less could be optimal gearing. High hp Low peak rpm power and high mph = not much rear gearing needed. That's why I don't get people against nitrous, good way to make high gearing more optimal and or start with a 440+ even for modest power.
Back in 1982>85, '71 no's match 340Cuda, 727, all steel, stock suspension+long shocks, snubber clamped springs
As bought, Stock 340 motor, stock 2.02 heads, 3500stall, 484.284, Dual plane, 750DP, small hdrs, 3.55's 8x26" slicks, best 13.28@101+
Upgrades in 1985, 4.30's, 10x28's, DC. .590 sft cam, race hdrs, 4200TA stall, 850DP, H/Strip dominator, best 12.39@108+
As bought, Stock 340 motor, stock 2.02 heads, 3500stall, 484.284, Dual plane, 750DP, small hdrs, 3.55's 8x26" slicks, best 13.28@101+
Upgrades in 1985, 4.30's, 10x28's, DC. .590 sft cam, race hdrs, 4200TA stall, 850DP, H/Strip dominator, best 12.39@108+
Guess I should update what happened last year.... 12.96 @ about 104 mph with 3.23's, the gear ratio in the title. Still stock converter & 904. Finally getting back to the car and making changes. Next time out it will be quicker
Love how you prove just basic hot rodding can give great results to bad people insist on complicating it up $$$$$
keep up the good work. -
