1972 307 cam selection... HELP!

[pjmoreland]

I have a set of 3998991 heads on my 350, and from what I have read and experienced, these heads are not performance oriented at all. They are low compression and they have small valves. They do, however, seem to make decent low end torque. My plan is to install some Vortec heads I pulled off a 98 GMC at a wrecking yard last weekend. I know you already mentioned the rear end, but I think switching to a 3.73 would be my top priority in your situation. A 3.07 is a pretty extreme highway ratio to have with a 700R4. Switching the gear ratio could really transform the way your truck drives.

[RustyBucket]

Originally Posted by pjmoreland

.... I know you already mentioned the rear end, but I think switching to a 3.73 would be my top priority in your situation. A 3.07 is a pretty extreme highway ratio to have with a 700R4. Switching the gear ratio could really transform the way your truck drives.

If you find that your truck is lazy or doesn't want to cruise comfortably in O.D. you might pull the shifter down 1 bump and run third gear. 3rd gear on the 700r4 is 1.00.... just like a 350 turbo in top gear. The 700r4 has a good low first gear(3.06) to get your truck rolling.
I have a 700r4 w/3.08 rear in my '71 GMC and a mild 350 engine & it's responsive enough. It really drives better & gives better mileage if I don't let it go into OD unless I'm running 70+mph. on the Interstate. It's on275/60/15's. Yeah, I'd like to have a 3.73 posi in the GMC & the Blazer both but can't justify spending the $$$$.

[BROWN 70]

hi, summit 1102 is pretty close to what your looking for. good low and midrange power. good luck, BROWN 70

[SpicedIcePirate]

Originally Posted by RustyBucket

If you find that your truck is lazy or doesn't want to cruise comfortably in O.D. you might pull the shifter down 1 bump and run third gear. 3rd gear on the 700r4 is 1.00.... just like a 350 turbo in top gear. The 700r4 has a good low first gear(3.06) to get your truck rolling.
I have a 700r4 w/3.08 rear in my '71 GMC and a mild 350 engine & it's responsive enough. It really drives better & gives better mileage if I don't let it go into OD unless I'm running 70+mph. on the Interstate. It's on275/60/15's. Yeah, I'd like to have a 3.73 posi in the GMC & the Blazer both but can't justify spending the $$$$.

I will do that if it wants to down shift a bit m,uch, or if I'm trying to pull a trailer or something of that nature.

It'll do 65-70mph without begging to downshift most of the time. But 75 is the sweet spot for flat land.