early engine in an 85

[BuickOldsPontiac]

I am not sure on the timing curves on the late 307s....

The final thing that can be done (and it saves you any hassle of rewiring anything) is having the ECM reprogrammed. I would consider it a last step if either of the following occur:

1. The timing curve really needs changed (but not the inital timing as that is NOT ECM controlled).
2. You want to be 110% sure you got every last bit of potential out of the new 350.

Finally if you did remove the ECM (and make all the required changes), there are ways to keep your AC. I think it might require some rewiring though.

Whatever you do, share some pictures. I am sure that Olds 350 will leave you looking like this --->

 

[celticsam]

Be glad to post pictures... Here's a picture of the car...as bought.

 

[DoubleV]

As far as the lean carbs, I am not sure. Since the ECM is controlling the fuel delivered via the primaries, it means during closed loop operation the amount of fuel is a function of the 02 readings therefore it shouldn't be to lean or rich. Or another way to say it, if the ECM doesn't see the right amount of fuel it will add or remove it as necessary.

Later 307 carbs have a very lean idle circuit. Also lean accelerator pump ( easily modded ).

I've seen the timing tables for a later 307 and they're really off from anything 'normal'. Sure the 350 would run just fine, but it's going to be held back. Plugging in a ealier ECM would work if the pins are correct but the only way to know for sure would be to get a GM service manual and check them. I believe an 84 ECM would work because in 84 they changed alot of crap around under the hood which matches what the later 307's were like. 83 and ealier were a bit different, so they would likely have some minor things that were different.

Celticsam if you decide to decomputerize your car, get a good Qjet, not an Edelbrock carb. Also, an Edelbrock Performer intake will give you nothing for performance. You're best bet is an early 307 A4 aluminum intake. And no, you don't need the O2 sensor to take readings from both pipes if you do true duals.

 

[L92 OLDS]

Finally if you did remove the ECM (and make all the required changes), there are ways to keep your AC. I think it might require some rewiring though.

IIRC, in 85-86' GM modified the AC compressor clutch wiring so that the ECM could cut out the compressor at WOT. Your 84's AC compressor should work just fine without the computer. The 83-84' H/O's have a switch near the gas pedal which cut out the compressor at WOT. I ditched the ECM in my 86' and installed the H/O cut out switch.

 

[celticsam]

I watched your video. Nice. Reminds me of the first Olds I built...an 87 403 Cutlass that I "cloned" into a 442 tribute car. Sold it to a guy in Connecticut... I just found his cardomain site...looks like he sold it as well... Shame...I miss that old girl even though it wasn't polished (mechanically) when I sold it.