305 to 350 motor swap

[scuddigi_687@yahoo]

Hello folks, I have a 1993 chevy caprice LS. The original motor WAS a 305tbi i wanted more power so I swapped that for a 350tbi out of a 1994 chevy g30. I also used the original 350 computer, tbi,manifold, etc. My problem is I have no check engine light but I notice a slightly high idle, also it missed slightly as well, when this engine was in the van it idled fine and there was no engine sputter, I feel it also when I drive and 2x's it shut off on me. My trans is the 700r4 with a corvette servo, and 410 gear ratio. Don't know if that matters but before I take it back to the shop I just wanted to know some home remedies. Any help or additional answers will suffice. Thank you. Oh and no I did not tune it up, the g30 has no emmision connections besides the o2 sensor, and my 305 smog pump is on the belt routing but connected to nothing.

[silicon212]

Check for any vacuum leaks - a vacuum leak may confuse the computer into thinking the throttle is part open and adjust fuel accordingly.

[scuddigi_687@yahoo]

Okay silicon 212 I will check tomorrow how many line are on it if you don't mind answering?

[silicon212]

Originally Posted by scuddigi_687@yahoo

Okay silicon 212 I will check tomorrow how many line are on it if you don't mind answering?

Coming from the base of the distributor there will be two harnesses - one has 3 wires and interfaces with the distributor cap, the other has 4 wires and interfaces with the vehicle OBD system. This is the one you're interested in.

If you have an older distributor that has a vacuum advance can on it, that's your problem. You need the EST distributor (electronic spark timing).

[scuddigi_687@yahoo]

Alright silicon, I changed the plugs finally, there were bocsh platinums in it, BOOOOOO, I switched them for AC's cr43ts's the idle went down a little but the miss is still there slightly also I got the regular HEI not the optispark I'm doin the vacuum line chevks tomorrow

[silicon212]

Originally Posted by scuddigi_687@yahoo

Alright silicon, I changed the plugs finally, there were bocsh platinums in it, BOOOOOO, I switched them for AC's cr43ts's the idle went down a little but the miss is still there slightly also I got the regular HEI not the optispark I'm doin the vacuum line chevks tomorrow

I understand you have 'regular HEI' but the vacuum advance variety last saw duty in model year 1980 on the Caprice/Impala - beginning in 1981, the cars were equipped with 'electronic spark timing' aka the Computer Command Control system. You cannot interchange these distributors with the older variety - you MUST use an EST distributor. This looks like the older one except without a vacuum advance can, and with that aforementioned 4-wire EST harness.



If you still have Code 42 on your MIL, that's likely to be the issue.

[scuddigi_687@yahoo]

Naw I see what you are saying my distbutor is diff from that my ign coil is a remote set up it doesn't sit on top of the cap. They made this the final set-up before that optispark or 8 coil pack set up both distibutors are the same I had that set up like yours before but in a different car.

[silicon212]

Originally Posted by scuddigi_687@yahoo

Naw I see what you are saying my distbutor is diff from that my ign coil is a remote set up it doesn't sit on top of the cap. They made this the final set-up before that optispark or 8 coil pack set up both distibutors are the same I had that set up like yours before but in a different car.

Sorry I misread the model year (read it as 1983)... yours is still the HEI but there will be two plugs at the base (your car has the same dist that mine has). Both plugs come out of the module, one has a pink and a white wire on it - this goes to the ign coil, the other has 4 wires and as above, it needs to be plugged in to work.



The connectors you see in both have the EST connection on the right (the 4-pin connector).

[scuddigi_687@yahoo]

All right tHAT PINK WIRE has a seperate harness, if it doesn't can I slipce into the harness what color wire?

[scuddigi_687@yahoo]

OKAY people here's is the update, new cap, rotor, plugs, wires, a 350 fuelpump, tps sensor, iac motor and after all that it was the relay connected to the fuel pump. The car runs strong now. No surging or wierd idleing. NOW my new question is what set of headers can I use and still retain my air conditioning also I heard about this chip enhancement for tbi 350's what is that and what cam can I use to get more power but not trip my check engine thanks folks!.