I bought a 75 chevy truck today, it has a 454 and turbo 400. I was wondering what the engine should run at for rpm- I took it down the highway and at 55mph it ran at about 3200 rpm, it seemed kinda high to me but maybe a big block runs at higher rpm. The engine and trans have been rebuilt. I am planning on putting the engine/tranny in my 69 Chevelle. I was wondering if i need to strengthen up the suspension if i'm goingto install a bigblock. I am goingto put in the larger coil springs but is there anything else that should be done. Thanks in advance
-Jesse

Hello. sounds about like it should be. I had a 69 396 and it used to run about that at 65 mph. You may want to check the rear end ratio,as that will make a difference in rpms thru out the whole range. The higher the number the lower the gear ratio is, and each jump in gear ratio will change the rpms about 100 or so one way or the other depending on is you go higher(lower number) or lower(higher number).
Later

Jesse, Do you know what ratio your Chevelle has? The truck must have 373 or 411's. My car runs about 2600 rpm with 308's and 15" tires. Engine shouldn't make much difference.
Mike
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Mike J
Unchartered DSRA Member
If it ain't broke, fix it anyway...

I'm not sure, i swapped rearends from a 70 chevelle. My old rear end was 2.73. I have to look up the cast number yet. Can you tell the ratio by counting the ring gear and pinion gears some how?

Sure! Just count the ring and divide by the pinion. The question that always drives me nuts is "If I turn the driveshaft one time the left wheel turns 1/4 of a turn, what is the ratio?" I have a 3.30, 8.8 in Ford in the coupe and it came out 3.285 this way.
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docchevy Remember Physics explains everything!

Hey docchevy, your making it harder and less accurate that way. Turn the wheel one time around (360) and count the driveshaft revolutions. A chalk mark is a great reminder.

....uh, just so's yer prepared, get the correct oil pan(for a chevelle)


otherwise you're gonna be pissed....
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If ya ain't drivin' it, it's just junk in the garage...

I built a '70 chevy with a 12 bolt 3.73 posi in it.
I ran around 3,000 at 65 mph.

Justice
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I like it loud, fast, $ shiny!

THAT big block will snack on your suspension and spit that crap out!
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EL CAMINO!