Gearing and tire opinion?

[RamAirZ]

I'm going to be getting some new tires for my 67' C10 4x4 when I get moved in June, and I am thinking about going with 35x12.50-15 size. It had them on it before but the previous owner kept them and slapped 31's on it that he had. My question is this, is 3.73 gear not "enough" for 35's? Now I know this matters on alot of other things too so here's some specs. I'm plannig on building a low-rpm (under 5500rpm redline), 383 TPI setup instead of my gen III plan, reason being it will make KILLER torque (I will be using the truck for towing my other projects and get through the offroad areas in minnesota), and I can use the motor that is already in the truck for the basis of the build. Talking to my machinist I should make well over 400rwtq and probably just a hair over 300rwhp, and torque peaking early and staying flat for the most part (most TPI systems suck at anything over 4500, but I will port mine out and siamese for a little more flow, this won't be a race truck), and I am running the SM420 (might be the 465 haven't seen the truck in person yet my brother in law picked it up for me, but should be the 420 if it's original). The 3.73 gear and 35" tire will put my highway speed right around what 2100rpm@60mph, which is what my 98' GMC was at with a 33" tire and 4.56 gears (overdrive). That truck pulled out awesome and towed good. Do you think 3.73 would work well with this setup? Maybe 4.10?

[special-K]

3.73`s a bit high.But,with TPI and a motor built for torque you`d get by.You won`t need to worry about power over 4,500 rpm,regardless.I`d want at least 4.10s since you`re towing.Figure with 4.10s and 35s you`ll be right about at 3.73 corrected ratio.You`ll be using granny to start the trailer rolling to save the clutch,I think.

[FormerMember]

Originally Posted by special-K

3.73`s a bit high.But,with TPI and a motor built for torque you`d get by.You won`t need to worry about power over 4,500 rpm,regardless.I`d want at least 4.10s since you`re towing.Figure with 4.10s and 35s you`ll be right about at 3.73 corrected ratio.You`ll be using granny to start the trailer rolling to save the clutch,I think.

Agreed... I'd prefer to see a lower gear set.

[RamAirZ]

Ya that's what I was thinking last night, 4.10's would probably be good. I think even with the mildly ported TPI (which should flow up to around 5000-5200 at most) and the proper camshaft and everything it should still be a blast to drive

[wibilly]

ever think of keeping the 3.73s and putting 33's on it. sounds like a good plan for your engine sounds like how i'm building my 406. what are your cam specs and what heads and valve size

[RamAirZ]

Ya I was thinking about the 3.73 and 33 idea too. The camshaft I am looking at is a Comp Cams extreme 4x4 camshaft, specs:

Part Number 12-239-3
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS X4 262H-11
Description

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Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.462 0.48
Duration At 0.006 Tappet Lift 262 270

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Valve Timing At 0.006
Open Close
Intake 24 58
Exhaust 70 20

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These Specs Are For The Cam Installed At 107 Intake CL
Intake Exhaust
Duration At 0.05 218 226
Lobe Lift 0.308 0.32
Lobe Separation 111


I haven't picked out the heads yet but looking at a set of RHS vortec's with multi-bolt pattern, also looking at there aluminum's with 2.02/1.60 valves, but I think the vortecs will be better in working with the low rpm setup with 1.94/1.50 valves