New 383 won't go over 2000 RPM

[Fuel35]

I just

 

[Fuel35]

I just replace my 2000 volvo 5.7gs with a 420hp 383. It will start but will not go over 2000 rpm. When you get to 2000 rpm under load it bogs down and seems to flood out. I have a holley 750 does that sound too big?

 

[gbeltran]

I think I'd be calling the folks who did the engine. So many variables here. Carb new? It's not too big for that size engine but you might be happier with something smaller. Who set up the carb, and which version is it? Distributor setup, timing, etc. Fuel pump/system up to par?

 

[Bondo]

I think I'd be calling the folks who did the engine. So many variables here. Carb new? It's not too big for that size engine but you might be happier with something smaller. Who set up the carb, and which version is it? Distributor setup, timing, etc. Fuel pump/system up to par?

Ayuh,.... Welcome Aboard,.... I've got another question to go along with these questions,.....


What killed the old motor,..??

 

[jadams94ta]

Still having problem with this boat . He took the 750 off and put a smaller rebuilt holley on it . Right now it has a flame thrower billet distributor on it .the fuel pump is a edelbrock performer fuel pump. the old motor had leak down in the cylinders which started right after he got the boat . Nothing from the old motor was used on this motor . boat runs good at the dock once its under load it wont go over 2000 rpm

 

[Maclin]

Some ideas....

• Ignition timing advance not working.
• Valve lash too tight.

 

[MikDee]

Some ideas....

• Ignition timing advance not working.
• Valve lash too tight.

I concur, plus one more item to check is your firing order, it could be 2 spark plug wires crossed?

 

[dennis461]

I'd pull the timing cover off and make sure the cam is not off by one tooth.

 

[jadams94ta]

We can checked the timing advance and the plug wires .it will rev fine at the dock but under load it won't

 

[Maclin]

Regarding timing, there is an initial advance setting. There is also the advance that occurs as RPM rises, and is all in by 2500 rpm, this is called total advance.

If you are saying that the initial advance is correct, and the timing advances as RPMs rise and is at the correct Total advance specification, and all spark plug wires are on ion correct order then that leaves valve lash and maybe fuel delivery.

If the engine surges at 2000 rpm, then it could be fuel delivery issues. If the engine just hovers at 2000 rpm then it is probably ignition or valve lash.

Has the engine's compression been checked since received or installed?

 

[jadams94ta]

We are going to check the valve lash this week . I'm thinking that's what it may be we notice yesterday that's the engine was pulling enough vacuum to pull open the secondary's on the carb

 

[Scott Danforth]

your not going to generate enough velocity to open the secondaries without a load (in neutral at the dock). the way a vacuum secondary carb works is that if you dont need the secondaries, it would use them.

check the fuel supply from the tank, to the anti-siphon valve to the pump to the carb
check the ignition system - double check the timing and firing order
put a vacuum gauge on the manifold, that will help indicate if you have wrong valve lash, etc.