Hi

I have a few problems with my 1970 oldsmobile tronado. I had found that recently When the car is accelerating normally or lightly it will rev really high before shifting.

Also when say the car is shifting from 2to3 it revs very high in 2 then shifts into 3 but the car only will only rev for about 5 more seconds, in 3, then it would stall as if its not getting fuel. I will add that when the car is in park I can rev it very high with no problems.

I Have driven the car no more than 40km within the last year as I have been working at it in the garage. But I have recently noticed this issue now and are sure I did not have this issue when I bought the car.

If anyone has information regrading this give me a yell.

Thanks

 

How does the fluid look? Is it full? Do you know the last time the filter was changed?

 

Havent changed the fluid or filter since I've had the car. Give that a try first but from the looks of the fluid it seems ok.

 

Late shifting on the TH350/400/425 transmissions is nearly always due to problems with the vacuum modulator. The vac modulator senses manifold vacuum to determine engine load: high vacuum = light throttle opening = low engine load and early shifting; low vacuum = heavy throttle opening = high engine load and thus late shifting. The vac modulator has a diaphragm connected to manifold vacuum by a pipe that moves a valve and thus regulates line pressure and shift points. If the diaphragm is bad or the pipe has come loose, the trans thinks there is low vacuum (ie, at atmospheric pressure) and thus the trans shifts late.

Start by checking the vacuum line to the vac modulator. Be sure it's connected then put a vacuum gauge on it and check that there is vacuum at the connection to the modulator. If so, change the modulator.

 

Matt, under load ( when you are driving the car it will use more fuel ) as opposed to when you are just sitting there reving the engine without a load on it. You might want to check the fuel pump, the the fuel filter..If they check out then replace the fuel line with a larger size. Factory was probably 5/16th I would replace it with 3/8".
Hope this helps.