Crate 350 in 85 k5 can’t get up to highway speed

[73kay]

Hey all,

I just dropped a crate 350 in my 85 k5. I reused the dizzy, exhaust, intake and carb (Quadrajet) and went to get gas for it today. Painful trying to get up to speed (60-65). I even had to literally floor it to maintain 60.

I have 3.08, 30in AT tires on 15in wheels with the 700r4. I have a c10 short bed with the same crate engine but with 3.40, headers, Edelbrock intake and carb. Talk about a difference.

Things going thru my head:

1. Maybe a cam lobe got wiped. (Init breakin oil/filter didn’t look bad)
2. That’s just 3.08s

I appreciate any feedback, been planning on 3.73s but they may come sooner than I thought if this is a normal “dog k5”

[rpmerf]

What is your all in timing?

What do the plugs look like?

Have you adjusted the carb? Different engine may need different jets and rods.

Plugged exhaust - could be the cats.

You don't have something like a brake locked up do you?

[73kay]

Thanks for the feedback, timing is set to 12 before TDC. I’m gonna take a look at plugs this afternoon. Carb hasn’t been messed with just yet. What’s interesting is I don’t feel a substantial power increase with the 350 over the 305 that had serious cylinder water damage on the passenger side head that limited any good compression and tons blowby.

[rpmerf]

Make sure weights are advancing.

Vacuum advance hooked up?

Wires arcing? How is the cap and rotor?

EGR hooked up? Closing completely?

Vacuum leak? Spray carb cleaner around and listen for a change. One at a time, pull off lines and cap them to see if the RPM drops.

Choke releasing completely?

[73kay]

Well found one of the issues. Drives so much better but carb falls on its face when I get into it. I should of found that when swapping motors. Anyways planning to rebuild the carb anyway but so much better!!!

[rpmerf]

Glad it was something simple!

Good info on Quadrajet tuning:
http://www.capitalcorvetteclub.ca/at...ng%20Paper.pdf