Buick 350 into 83 Cutlass - 307 out

[tobyp]

I tried to put together a starter from the cores I had in the basement and only succeeded at stabbing myself in the hand with a screwdriver.......

So I went to the parts store and bought a reman starter for like $40, as I should have to begin with.

I found the original V6 power steering setup and installed it. (incidentally I also found the original V6 frame pads...DOH I guess I didnt "need" to weld the 350 frame pads on there!)

I kept the 307 radiator hoses, though I had to "sleeve" the water pump side of the lower hose. The 307 fan shroud works real well but I had to put a 1.5" spacer on the fan to tuck it in.

Non ac Buick alternator bracket with the original V6 alternator (the 307 unit had the post in a bad location for passenger side mount)

Anyhow, the real update is that I started the car today just real quick to see if it would fire. Started right up, and no codes immediately.

I am pleased that the distributor is functioning.

I did have to get creative with the steel fuel pump to carb line - trimmed and shaped most of it then went to a rubber section behind the distributor that goes to the carb.

I still need to fab up the 2.5" Y pipe and stick an O2sensor on there somewhere.

Then I can tune it.

I'll grab some pics soon.

Ken,

Remember that I did this complete swap before. As for teh starter get a mini starter they work much better and if you run anything but stock exhaust it frees space. Many pics of that install look all to familiar 🙂

 

[techg8]

I have been playing with it a little bit, working out some bugs and attendint to the little details.

Its doing well excepting one problem I am currently working through.

The car backfires out the exhaust on the primary main circuit.

Ignition set at 12 BTDC with the diagnostic lead grounded
Idle is fine. Tunes well on the meter.
Also, stabs at WOT are fine - revs up well.

I can ease into the throttle until about where the mains come online, and the engine starts breaking up and backfiring out the exhaust.

I have been changing small things in the carb to no avail as yet. one thing at a time......


I will keep after it and post results.

 

[techg8]

Well the backfire out the exhaust seems to be a result of the electronic advance. I had initially thought it might be an overly lean condition.

I have tinkered with the carb internals all I care to, and nothing improved the situation. I ran the carb with the MCS plug pulled - full rich - and still had the backfire. Tried some starting fluid sprayed in the primaries while backfiring to see if added fuel would eliminate it....nope.

I tried retarding the distributors initial setting to see the effect and it helped. To eliminate the backfire though I had to so severely retard the initial setting that the engine runs like crap.

with the timing light I watched the timing from idle on up. Idle and off idle are fine but once it gets to ~1750rpm or so, the computer adds a ton of timing and it stumbles, backfires bad. the engine breaks up so badly I cant tell the timing when its doing it.

I started thinking it might be a problem with the module so I swapped it out for another I had, to no avail. Same results.

Very good tuneable idle, excellent WOT....but part throttle and lean cruise backfiring out the exhaust.

I swapped in the Stock chipped ECM, looking for a less aggressive timing curve and it seemed to help, but still backfired.

The engine runs GREAT without the ECM, timed for about 35 deg BTDC total.

I am considering two options now - find an ECM/Chip from a 350 setup somewhere OR go without the computer.

I am leaning towards eliminating the computer for simplicity's sake.

any thoughts on the backfiring?

 

[olds307 and 403]

You could try an earlier 307 chip, supposedly less aggressive timing or maybe a sbc chip. The swirl port engines had a ridiculous of timing.

 

[techg8]

good idea on the chips. Some trial and error would find a workable solution.

however

for the time being I have deleted the CCC system. I want to drive the car and am tired of messing with it.

maybe I will revisit the CCC on the 350 at a later date.

 

[DoubleV]

Your symptoms sound like your EGR isn't working correctly. Lots of part throttle timing advance compensates for the diluted mixture from EGR. If the EGR isn't working, you still get all that part throttle advance and your engine can't handle it.

 

[techg8]

Your symptoms sound like your EGR isn't working correctly. Lots of part throttle timing advance compensates for the diluted mixture from EGR. If the EGR isn't working, you still get all that part throttle advance and your engine can't handle it.

Good info, thanks.

The 350 is a 1972 vintage, non EGR

I will have to come up with something to replicate the EGR or approximate its function If I intend to keep this ECM/chip

 

[Bonnewagon]

Ken, I'd say dump the CCC and go old school. And the Buick 350 never had much timing in the old days as they are under square motors, more stroke than bore. My '68 LeSabre 350 initial timing was set at like 0º and preferred full manifold vacuum to have a great idle, and so timing went away under acceleration, until WOT. Even when I swapped in a low compression '74 350 which took like 4º it still wanted the full manifold vacuum. Ported vacuum only caused pinging. The advanced timing found on EGR equipped motors was only possible because of the exhaust gas dilution EGR uses. Once you get this sorted out it will be some fine set up.

 

[techg8]

I am sure I can hunt up a mid 70s SBB 350 intake w/EGR passages. but then its probably heads too - I think the EGR on the SBB was towards the rear. something to follow up on.

Maybe I will try the setup on my 73 SBB 350 test stand initially

anyhow in the meantime its running great non CCC

thanks for the info guys I will keep this thread updated with any progress.

 

[Bonnewagon]

"anyhow in the meantime its running great non CCC" -there ya go. Why would you add EGR if you didn't have to? Just go with pre-EGR timing specs like what a '72 used. Another tidbit- Buick changed compression by dishing the pistons, so for all intents and purposes, heads are heads. But then I found when I swapped in the '74 2 barrel 350 and I added the '68 4 barrel intake, that the '74's EGR passages went through the intake and into the heads at each intake port. Thus I ended up plugging the in-head passages with Marine Tex. My point being that a Buick EGR intake needs corresponding EGR heads.