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Joined: Jan 2002
Posts: 89
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jan 2002
Posts: 89 |
I have a 3.90 ring and pinon in my 55 pickup. Iam turning 1987 rpm at 65 mph .Is that high for long runs? any other option on changing to another ring and pinon ? thanks for any info mark47
mark47
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
Something is wrong here. With a 3.90 and anything close to the original tires size you will be trning about 3000 RPM at 65 MPH.
Gene Schneider
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Joined: Jan 2002
Posts: 89
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jan 2002
Posts: 89 |
you are probably right. I bought the truck and it is stock other than the previous owner installed a 700 R4 automatic and it has 215-85-16 tires. I believe the rear end is a 3.90 because he told me he did not change that. Based on that is how I came up with the RPM of 65.
mark47
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Joined: Apr 2008
Posts: 1,194
ChatMaster - 1,000
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ChatMaster - 1,000
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The trans you have is an overdrive transmission.
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Joined: Jan 2007
Posts: 1,441
ChatMaster - 1,000
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ChatMaster - 1,000
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You might have to do some tweeking to the carb (if original) if you use o/d alot,I put a T-5 behind my 235 and had to re jet the carb and put a lighter power valve spring in it. Those motors are not designed to go that slow and I had the gas mileage go down after I did the trans and rear end swap,I still have not got it where I like it but working on it.
VCCA #45194
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Joined: Jan 2002
Posts: 89
Shade Tree Mechanic
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Shade Tree Mechanic
Joined: Jan 2002
Posts: 89 |
Thanks guys. Thats all good advice.
mark47
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