Compression Ratio
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Cross-Country
Joined: Aug 2012
Posts: 53
Likes: 2
From: Sioux Falls
Pin hight is 1.644. Ill have to meause the dish after work today.
I want to make my pickup keep up with my brothers jeep. Afew years ago we went on an overland trip for about 2 weeks. The biggest rocks we had to jump over were about knee high. I want to put 33's on it and it has 3.89 gears already. I also want it to be pretty quick on the street too. Well out run most of the 4 bangers around here anyway. I was hoping to get this enging to run like the 390 gt my dad had when I was young but Im not sure what I need to get that done. Im going to put a NV4500 behind it too but time will tell how quick i get that done.
I want to make my pickup keep up with my brothers jeep. Afew years ago we went on an overland trip for about 2 weeks. The biggest rocks we had to jump over were about knee high. I want to put 33's on it and it has 3.89 gears already. I also want it to be pretty quick on the street too. Well out run most of the 4 bangers around here anyway. I was hoping to get this enging to run like the 390 gt my dad had when I was young but Im not sure what I need to get that done. Im going to put a NV4500 behind it too but time will tell how quick i get that done.
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Joined: Apr 2004
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390 pistons with that pin height were originally flat top 410 pistons, good for 10.5 compression in the 410, which was a 390 with a 428 crank and those pistons.
In a 390, they sit over .100 down the hole, so compression is in the low 8s or worse with the dish. Fine for pulling max loads up mountain passes all day, but poor for power and economy.
In a 390, they sit over .100 down the hole, so compression is in the low 8s or worse with the dish. Fine for pulling max loads up mountain passes all day, but poor for power and economy.
Hotshot
Joined: Jul 2005
Posts: 13,834
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From: Middle Tn.
Your asking your engine to do two differant things and a compromise will get you neither. To beat the 4 bangers you need horsepower and speed to push those 33's over knee high rocks you'll need torque as in low end grunt. Shoot for the middle ground and you may not be happy on either end.
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Cross-Country
Joined: Aug 2012
Posts: 53
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From: Sioux Falls
I've been looking around and a set of aluminum heads are just about as much as a good port and polish with bigger valves in the heads. My dad is nerous about them cause he is afraid of warping if the engine overheats. What is your opinion on them?
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Joined: Apr 2004
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First, you don't let it overheat. Proper cooling, good quality pumps, hoses, block plugs etc are part of the build. That and a temp gauge AND idiot light to catch your eye.
Second, millions of oem motors are iron/aluminum and they work fine.
Second, millions of oem motors are iron/aluminum and they work fine.
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