olds 307 and 403

Ok, so I know my maybe 1600 stall converter isn't helping performance but it feels pretty dogish. I have played around with base timing, anywhere from 17 to 23, equaling 36 to 38-40, I have positive stop. It comes in around 3000 RPM. I just changed the fuel filter and checked the air flap tension and cam, both fine. I did adjust any valves, some were loose. The big changes were a TH350 with low stall, was a 2004R with a 2300 stall. Also a change from a Performer with 1" spacer to a Performer RPM intake and 1.72 true roller rockers, I had a tick with the stock rocker arms and bridges. It went from 1/4 block burnouts to just doggy performance. Thoughts? Yes a 2500 stall Hughes converter is next on the list.

svnt442

The gearing change between the two transmissions will make a big difference along with the low stall.

coppercutlass

how tight is the preload. I learned there is a huge difference between .040 and ,020. I would have ran .005 but sold the engine.

olds 307 and 403

I haven't measured the preload but it should be on the tighter side. What is the best way to measure? I am getting full throttle, wife pushed the pedal while I looked. I plan on a compression test this weekend. The oil pressure is very good so no bottom end issues.

shiftbyear

can you post pics of the engine, maybe someone will spot something. I would observe that the carb opens fully while someone steps on the gas. Also, is the kickdown linkage adjusted differently on the new trans. Good luck.

olds 307 and 403

Yes, full throttle observed with my wife pushing the pedal. I adjusted the kick down looser, was kicking down too much in town. It may be the leaner part throttle adjustment, I can adjust part throttle mixture in 5 minutes with a screw driver. I am running a dual snorkel air cleaner, hoses to the fenders with the K&N air flow chrome top. Only using premium, non ethanol 91 fuel and most of the old fuel, treated with stabilizer has been ran through. It may be stall, taller first gear, slightly leaner mix, turned down 1.5 turns and maybe the slow advance curve. The motor runs smooth through the rpm's, a bit choppy at idle but always has, I will also check for obvious vacuum leaks, adjust mixture screws, all three, vacuum leaks and compression test. I may just may be expecting to much, a leaner mixture and no stall is probably the issue but I will be investigating and tuning this weekend.

Cutlass Fan

Going from a performer intake (0 to 5500 rpm) to a performer RPM (1500 to 6500 rpm) is likely what killed your low end power.

Fun71

I did the same swap and all it took was readjusting the secondary air door to get the low end performance back to where it was previously. I had a writepup on Oldspower many years ago detailing the swap, tuning afterwards, and final performance observations.

coppercutlass

Half a turn.on a 3/8 poly lock is appx. .040. So 1/4 is .020 etc etc.

cutlassefi

lemoldsnut

Did I read this right it has 2:78 gears?

olds 307 and 403

I think it is a tune issue. I will swap secondary rods and put back the timing and primary mixture where it was. I notice improved performance with the choke part way on.

olds 307 and 403

Yes. I know they are not ideal but should still lay a one wheel peel.

coppercutlass

the 350 olds that's in my Pontiac Bonneville wont smoke em with a 3.08 and that engine went 13.7's in my 72. It takes a lot to move a full weight car. specially a b body in my case. What helped my Pontiac move faster was a fast timing curve and a lot of initial fuel shot on the edelbrock.

olds 307 and 403

I may go lighter springs in the distributor. I did find richening the part throttle A/F ratio not only made it feel faster, it ran faster at the track when it was in the 88. Of course mileage went in the toliet big time.

olds 307 and 403

Well, changing the fuel filter seemed to help a lot. I adjusted the carb a bit as well. I actually got rubber on one launch. It pulled to 90 mph no problem, maybe a quicker advance curve and definitely more stall, it is killing it off the line.

Cutlass Fan

Thanks for the info. I was just going by what I've read on here and other places. I'll defer to your experience!

olds 307 and 403

The car runs considerably better with carb adjustments and a new fuel filter. I plan on a compression test, quadruple checking the valve adjustment and trying lighter springs in the HEI. I still think it may need a slightly richer APT setting. I am hoping the compression test is a good as the oil pressure, it was 140 to 142 psi when it had #8 heads with a Performer 204/214 cam. The motor runs great and uses probably the least amount of oil of any of my vehicles.

olds 307 and 403

I went through the valves again, turned the APT one turn richer and tried different advance springs, changed very the advance curve little, maybe even slower, along with the whole car. I may try my Chinese HEI with Ignitor 3 module and add a positive stop, hopefully it will have a faster curve. Compression test tomorrow, if I can find my gauge.

olds 307 and 403

Well, the track was a no go yesterday. I have a leak at the dipstick to case, which is a big tech no no. My other tube was pinched and I need a locking trans dipstick. Also the Mallory Breakerless is giving me fits, stalling when coming to stop. A misfire is occurring, for some reason the reluctor to pick up self adjusted so there was no gap. I readjusted and still a miss and almost stalling was still there.