Buick 350 into 83 Cutlass - 307 out

[jetsetw31]

Hmm that's food for thought. My Olds 350 will not idle below 1100 rpm or it will shut down. And at 1100 rpm, you hear the lope of the cam and the CCC is trying to maintain it. I thought of putting a chip in it, Just have to wait for funds. I've done this swap on a friends '85 442 and it was flawless. The car had power everywhere, running solid 13.9's all day. It was a stock cammed '71 350 sbo. It even passed the emissions test. My '88 sings above 2000 rpm. I've run out of road before it runs out of power. That is why i like the cam. But i may just re-cam it a little milder and see what happens.
I also thinking of swapping out the distributer to a '77 HEI i had laying around. I'll dummy the CCC connection and see if the CCC will run the car with just the MAP, and the O2 input. I'm doing this because i am getting a timing surge while at cruise speeds. I checked the fuel system and all was well. It turned out the CCC was moving the distributer dwell. It was crazy. I unplugged it and the car smoothed out. Of course I got a check engine light with that. So I'll see what happens with that also.
T

 

[techg8]

As a followup.....

I have driven the car quite a bit now and the driveability is very good.

Cold startup isnt the best even with the choke operating correctly but once it warms just a little, it evens right out.

WOT power is what you would expect from a stock Buick 350, though I havent got it to the track for any runs with timeslips. It can peel the tires right off which is nice. I would imagine it would run in the low 15s

The real curiosity I had was about the Gas mileage, and now Ive got some data. And it isnt as good as I thought it might be.

This setup gets 11-12 mpg around town and only marginally better on the highway.

The real frustration comes in that the system resists tuning. Any aftermarket chip gives too much part throttle timing which causes backfiring out the exhaust. but The only way to change timing is with a chip.

I suspect that the poor gas mileage is due mainly to some deficiency in the part throttle timing curve. After all, the O2 sensor and mix solenoid should be maintaining 14.7 to 1 or thereabouts AFR. The trans isnt slipping and the brakes arent dragging.

When I ran points, This engine liked 21 degrees initial with 14 degrees mechanical, for35 degrees total, and then another 10 or 15 degrees vacuum advance.

Currently with the EST distributor I have it running about 20 degrees initial and it gets about 35 degrees at part throttle. Perhaps the missing degrees at part throttle are killing my gas mileage.

Maybe I will just turn the EST dist to get that 45 or so at part throttle (30 initial)and see what that gets me, aside from a hard start and hot battery cables .

Anyhow thats where its at right now.

 

[olds307 and 403]

Funny Olds had a ridiculous timing curve on their swirl port engines. I have the TBI on my Olds 350 in my 4x4. I have 50 max part throttle, 45 full throttle, running 22 base with the EST disconnected. Anymore and hard starts would occur, you can just hear it a bit. The sbc calls for 0 factory, that means 25 or so timing advance. I tried 2 degrees base with the EST disconnected, backfired and ran like sh*t. It ran like crap under 10 base. I didn't know Buick liked as much initial as the Olds.

 

[online170]

All this ECM stuff is way over my head, but it sounds good. No MPG calcs after switching to the Monte E4ME?


My 71 Buick 350 got close to 20mpg in the city with the Rochester 2jet. Highway was 17ish. The 2jet was funny like that. I didn't take note of the timing, but I think it was set as per the factory recommendations. 8* at 600rpm in gear, or whatever that sticker says on the rad support. Vac advance was hooked up.


I switched over to a Holley 750 dbl pumper, and the hwy mileage was about 15, and city was slightly worse. The carb was tuned slightly rich to give max power, and no regard for fuel economy. Timing was 34* total, with stock distributor, which made for something like 26* initial. My original starter didn't like that. No vac advance with the holley.


The engine was a bit weird. It had perfect compression and ran like new, but the bearings were all copper. Maybe just neglected for oil? The car had a TH350, stock converter, 2.73 rear gears, and 265/60/15 Tires.

 

[Bonnewagon]

"This engine liked 21 degrees initial " That's odd. My '68 Buick 350's crank timing was 0º and I ran the dist vacuum advance to full manifold vacuum to get a great idle, which would be similar to your initial crank timing. But of course the timing retarded as rpm's rose and vacuum went away. That motor disliked a lot of timing advance in the midrange, but it was high compression. My '74 350, low compression, still only took 6º crank timing and also wanted full manifold to the distributor. I guessed this was because the Buick 350 is an over-square motor with a lot of stroke, and responded differently to timing advance than a high-revving short stroke motor would. Both motors ran a Q-jet and got very good mileage.

 

[techg8]

No MPG calcs after switching to the Monte E4ME?

The figures I have were using the Chevy E4ME with a chevy CCC system, The Olds carb would not tune on the chevy system - it got over rich codes all the time and ran like junk. The Olds carb would tune correctly with the Olds CCC system, but the swirl port ECM has waaay too much timing at part throttle and would backfire bad out the exhaust.

I am going to push the timing as far forward as I can without adverse effects and see how it does.

There is one calculation that I was making that I guess I should confirm is correct. The original rear for this car, and thus the speedomoter/odometer gear, was 2.41 ratio.

I have changed the car to a 2.73 ratio without changing the speedo/odo gear in the trans. SO I have been calculating out the difference in mileage when finding my MPG.

Correct me if I am wrong: If the odometer reads out 100 miles on the 2.41 speedo gear, then the real mileage would be ~88miles because of the 2.73 rear gearset. I get this by taking 2.41/2.73=.88

 

[techg8]

/shrug?

10 degrees more advanced got me hard starting, lots more responsiveness heavy throttle, and backfiring/stuttering part throttle.

10 degrees more retarded got me poor idle and stuttering/lack of power.

set back to the specs in the last post, it runs great.

Its been a fun experiment but I think I am done tinkering with this system on this engine.

I think that the CCC system would work better and perhaps get better mileage on an engine more similar to the original intended application.

IE 307 Olds CCC system swapped onto a smog era 403 olds
or 305 Chevy CCC swapped onto smog era chevy 350

I know its been done a million times.....anyone have gas mileage numbers from that type of a swap?

Performance wise, the system I set up on the SBB 350 idles and runs well, and has lots of power at WOT. But the whole exercise was to try to get optimum gas mileage along with the good power, and my experiment failed at that.

Time to start working on the forced induction SBB 350 again

 

[techg8]

"This engine liked 21 degrees initial " That's odd. My '68 Buick 350's crank timing was 0º and I ran the dist vacuum advance to full manifold vacuum to get a great idle, which would be similar to your initial crank timing. But of course the timing retarded as rpm's rose and vacuum went away. That motor disliked a lot of timing advance in the midrange, but it was high compression. My '74 350, low compression, still only took 6º crank timing and also wanted full manifold to the distributor. I guessed this was because the Buick 350 is an over-square motor with a lot of stroke, and responded differently to timing advance than a high-revving short stroke motor would. Both motors ran a Q-jet and got very good mileage.

On points, I had 21 initial, 14 mechanical and about 10 vacuum to manifold vacuum.

This was because the 350 distributor didnt have much mechanical built in it (14 deg) and I wanted to achieve the total of 35 in by @2500 that the Buick 350 likes. without modifying the dist. ~45 degrees wouldnt ping on my 72 350 even on 87 pump gas, I believe because of the abysmal compression ratio ~7.5:1

Its just what worked on that engine. I ran 14.9 in the 1/4 mile with that setup in my 72 Skylark.