Trans slipping or other problem

[Jemaddux]

79 Blazer, was running 3 something gears in rear and I had zero power when driving on 38 inch tires. Changed over to 488 gears and still zero power. I have'n got the engine running as good as I would like but it still has a lot of power on a fresh rebuild. When I step on the gas the truck moves but I couldn't get a chirp out of the tires if my life depended on it. I am guessing on the trans but have no idea how to know if it is slipping or not. Its a TH350 married to a NP203 that is soon to be changed to a NP205.

Thanks for the help

 

[southernspeed]

If your 203 is still full time I doubt you'll get your tyres to chirp! I have a fresh 350TBI in my '78 with full time 203 and the only time you hear the tyres compaining is when turning out of a junction hard...and that's with a locker in the rear!

 

[Kiwi John]

The guys here will help you for sure.
first check would be the fluid level in the trans/torque converter.
Is it full on the dipstick (with engine running)?
Is it clean?
When was it last changed?
Are brakes binding?
Good Luck.

 

[HarryH3]

Is the engine revving quickly when you take off? If so, then the trans could be slipping.

If the engine doesn't seem to rev higher than it should, then you might just have a torque converter that has a very low stall speed. A low stall converter will grab before the engine gets a chance to rev up into it's power band and make the rig seem really sluggish off the line.

 

[Jemaddux]

The converter is one from P.A.W.. It was suppose to be for a truck/towing. I have no idea how to tell what I should be using and what I shouldn't be using. So if anyone has a idea of what I should have in there I would love to hear. The engine revs up as the truck is taking off and seem to higher then it should. Once it gets moving it goes pretty well.

 

[southernspeed]

If you haven't got a tach see if you can get a timing light with tach or laptop with EFIlive or a similar programme so that you can moniter revs then do a stall test. It should stall out at around 1800 +-100 rpm with a towing/rv converter. I've got a TCI towng/rv one and I love it. I had their Saterday night special truck one before and it was awful, stalling out at 2300. Way too high for our sort of use.(unless you've got a real peaky motor ofcourse!)

 

[Jemaddux]

So to make sure. I should have a tach on the engine, then have the engine running. Go ahead and put it in gear and with the foot on the break bring the rpm up to what ever until it stalls????

 

[southernspeed]

That's about it, but it doesn't actually stall. It's just a phrase. The revs will climb to a certain level and no more. When they won't go any higher, that's your 'stall' point. Don't hold it there for more than a few seconds.