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Old 08-25-2019, 09:34 PM   #1
73kay
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Crate 350 in 85 k5 canít get up to highway speed

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 didnít look bad)
2. Thatís 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 ďdog k5Ē
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1953 3100 235 T5
1976 c10 shortbed 350 WC T5
1985 K5 Blazer 350 700R4 208
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Old 08-26-2019, 06:12 AM   #2
rpmerf
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Re: Crate 350 in 85 k5 canít get up to highway speed

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?
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Old 08-26-2019, 07:27 AM   #3
73kay
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Re: Crate 350 in 85 k5 canít get up to highway speed

Thanks for the feedback, timing is set to 12 before TDC. Iím gonna take a look at plugs this afternoon. Carb hasnít been messed with just yet. Whatís interesting is I donít 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.
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1953 3100 235 T5
1976 c10 shortbed 350 WC T5
1985 K5 Blazer 350 700R4 208
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Old 08-26-2019, 09:11 AM   #4
rpmerf
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Re: Crate 350 in 85 k5 canít get up to highway speed

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?
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Old 08-26-2019, 09:05 PM   #5
73kay
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Re: Crate 350 in 85 k5 canít get up to highway speed

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!!!
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1953 3100 235 T5
1976 c10 shortbed 350 WC T5
1985 K5 Blazer 350 700R4 208
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Old 08-27-2019, 06:20 AM   #6
rpmerf
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Re: Crate 350 in 85 k5 canít get up to highway speed

Glad it was something simple!

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