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318 performance questions need help

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318 performance questions need help

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Old 03-11-2018, 08:35 AM
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Question 318 performance questions need help

I just dropped my 1984 dodge 318 off at the engine shop, Ive done a lot of reading on this motor already I'm going with the comp cam 268h cam kit. I'm keeping the stock heads I have a edelbrock aluminum dual plane intake, and a edelbrock 600cfm four barrel carb. My main question is can I get 10:1 compression out of this motor with stock heads? The motor is getting all new pistons and the heads are getting freshened up as well so I figured why not bump the compression up a little. Another question is what is the stock compression of a 84 dodge d100 318? The cam kit instructions say for best performance of the cam kit for compression to be 9:1 to 9:5:1. I'm not trying to make 400hp I'm just trying to make a nice reliable fun driving truck I'm after torque more than horsepower.
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Old 03-11-2018, 08:48 AM
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THe engine shop should be able to get you to what you want 9.5.1 or 10.0.1... Should be your choice...
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Old 03-11-2018, 08:56 AM
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Thanks for the response Bob, I guess what I'm curious about is there much to gain 9:1 to 10:1? I know the stock heads can only flow so much so before I make the decision on compression I'm wondering whats the most compression I can get out of the stock heads.
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Old 03-11-2018, 09:29 AM
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If your just looking to stick with the Iron heads that you have. My suggestion would be to, have the heads ported and gasket matched and a good 3 angle valve job. Set the compression at 9.5.1 and a 270* cam. should run good from Idle to 5500 to 6000... Just my 2 cents...
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Old 03-11-2018, 09:38 AM
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Ok sounds good that was what I was after, so hopefully the comp cam kit I bought should be perfect for what I'm trying to do.
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Old 03-11-2018, 03:42 PM
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I have ran the Comp Cam Extreme 268H in a 9.5.1 360 Small block create engine with smog 360 heads. I used a 2800 stall converter in a truck with a little to tall of a rearend gear 2.73 ratio. And a 33" tall tire. With the Cali blend fuels we have to run and as heavy as the truck was. It tended to ping if you stepped into the throttle too hard... I never was too happy with that set up. Sold that to a guy that drove it till he wrecked it ! (about 70,000 miles later)
But your 318 should be a little more forgiving, Just cant leave them pistons too far down in the hole....
Who's doing the work up in the Truckee area? Hope it's a Mopar guy?
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Old 03-11-2018, 04:51 PM
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HP gains will be minimal, if you plan any towing/hauling 10:1 is a bad idea. I would go 9:1, our 318 truck engine with a XE254H cam was 8.5:1 compression based on what our trusted builder suggested. Engine has great power and torque no pinging with trailer on.
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Old 03-11-2018, 04:55 PM
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The motor is getting built by a shop that I have used before he is doing 4 mopar motors now including mine, my truck is a standard cab short box d100 and has a 4speed 833 transmission with a 2:73 or a 3:23 gear I cant remember ill have to recheck the codes. I'm going to be lowering the truck so my tire size will be short and I will be running 93 octane in this truck so I shouldn't have any pinging issues.
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