Okay so I did a 305 to 350 Swap (Rebuild from 73' chevelle)on 1991 RS, and were hopefully wraping up the swap. PROBLEM!!! My mechanic keeps setting the proper timing to the car but he says it keeps jumping after being set on its own. We did new plugs, correct firing order with new wires (Accell), and lined up everything with first spark plug and everything. He sets it using the timing light and then it will jump from i believe he said 12 degrees to 20 degrees. Don't quote me on that because im not sure of the exact numbers. Installed a new fan and thermostat yesterday, still climbs to 220 degrees. The coolant is flowing but the reservoir looked like a guyser after driving it for 5 minutes very easy. Maybe my distributor from the 305? Or my module? Maybe both? Help PLease?

-Long tube headers
-Flowmaster American Thunder 3" setup
-Still using the original TBI from the 305.

 

Do you know that you have to disconnect ECM timing control when setting initial timing with a light?

 

No I didn't know, How do you do that? Thanks for the help!

 

The is a brown wire under the hood, near the firewall, on the passenger side. Un-plug the connector to disengage ECM timing control. Set the timing to 6 deg. then reconnect the wire.

 

Hmmmmm hate to say it but coolant gushing from the reservoir sounds like compression getting into the cooling system.

Dan

 

if your only hitting 220 deg....it shoudn't be 'gushing'.....that's not much past were the factory runs them....what temp thermostadt did you put in?? what kind of fan do you have? eletric/mechanical? you shouldn't be overheating at 220....pressure in cooling system due to failed head gasket probably