Thread: SB350 Engine not reaching even half its potential power

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Hello

I have a later 70's 350 SB with a 600 CFM Holly (Vacume 2nds) with a H.E.I ignition.

Symptoms :
- Engine starts fine, idles lovely, drives lovely as long as you do not expect much power from her..

When you are driving, if you put your foot down to the floor the motor does not bog down, it just starts to give missing like symptoms and gradularly gets up to speed but definately not full power.

What I have tried so far..

1. Replaced Plugs
2. Replaced HT Leads
3. Replaced Coil, Cap, Rotor
4. Rebuilt Carberator
5. Bypass the secondarys with a screw (noughty I know)

All cylanders were around 140-145psi for the compression test. The #2 cylander was at 120psi though, I have not factored this into the issue.

Another thing to note is the plugs fowl up something cronic.

Now I have taken the vacume hose off the vacume advance for the dizzy and sucked on it.. the mechanisum moves..

I am really stumped.. So in a nutshell, if you load the engine up with your foot planted, it does not want to perform. I have set float bowl levels correctly for both chambers also, this really has me stumped hehe

Cheers in advance for any ideas

Leyton

if your not flooding it then late seventies answers your question if the long block is stock. large chamber heads with small runners and low compression with much milder cam profiles made it so by 1978 the most powerful small block available was 210 horse. remember that was in 1978, if your engine hasn't been rebuilt since then it's probably worn-out and producing significantly less.

Replace the fuel filter?

You could also have a cracked timing gear. It could be flexing when you are trying to put more power to it. I had that happen on a stock SB 327 one time.

Bug

Has the motor been apart? Maybe the cam is in 180 Degrees off? If it hasn't been apart it needs to be rebuilt.