simpleold

I got this project a 1967 oldsmobile cutlass 4-door hardtop with an olds 330, it is a project. I have already done some things to it, installed HEI, new spark plugs, new water pump, new fuel pump, cleaned the gas tank, new spark plug cables, rebuilt the 4 barrel Quadrajet carb, and new radiator, I did not like how it drove as it started very slow in gear, and very hard to pick up speed

I thought it was the ST300 transmission failing, so I replaced it and put a 3-speed TH350 transmission in it, a very straightforward swap, after the transmission swap it got a little bit better but still, it has trouble picking up acceleration, one example if I press the pedal half throttle it will hardly move, then I put it in neutral without letting go off the throttle and the engines revs high, engine works very good while is not under load, I checked for vacuum leaks and did not seem to find any, it did the same thing with the ST300 transmission I am at lost here any help. PLEASE!!???

Olds64

The car should at least creep forward when you take your foot off the brake with the engine idling. Speaking of, have you done any work to the brakes yet? One of the drums/calipers could be sticking.

simpleold

I put new drums and brakes including wheel cylinders all around, let me check the adjustment on the wheels. , one key thing I disconnected the HEI vacuum advance, and seems to run a bit better not excellent but better, any advice on why that happened?

simpleold

I put new drums and brakes including wheel cylinders all around, let me check the adjustment on the wheels. , one key thing I disconnected the HEI vacuum advance, and seems to run a bit better not excellent but better, any advice on why that happened?

Fun71

The mechanical advance may be different between the original points distributor and the HEI. It likely depends upon if it’s a GM HEI or an aftermarket brand.

OLDSter Ralph

What is your initial timing with the HEI ?

Fun71

Just a thought - do you have the TH350’s kickdown cable and vacuum modulator connected properly? The kickdown cable needs to be adjusted properly as well. If it’s not, the transmission could stay in 3rd gear when you floor the pedal, and the acceleration would be dismal (I had that happen before).

Rallye469

I just sorted through a good running but failing under load 330 and it was largely due to timing and vacuum I believe.

Time it with no vacuum advance and go from there.

simpleold

I will try all of the above, and keep you posted thank you!

simpleold

Yes both connected!

simpleold

Unsure I did not use timing light, but it starts right up, just fails under load, I will use timing light this time, what is the timing I should use? is a stock 330 oldsmobile engine

simpleold

I will check all wheels Tommorrow thank you for the advice

simpleold

I used an after market HEI

simpleold

Thank you I thought I was the only one going crazy, will recheck timing and vacuums thank you again

Sugar Bear

Was the wiring modified to provide full battery voltage to the HEI vs. through the original resistance wire to the original coil?

simpleold

That is a good one I don't think so, I will run it directly through battery power, just to test that before going to mess with wires.
Great advise I will try that Tommorrow too, thank you again.
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simpleold

Just an update I advance the timing just a little bit unknown to what degrees, as the engine is missing the timing marks, however car now accelarates as it should love my four door oldsmobile cutlass hardtop. Thank you everyone for all the advise provided.