The Stovebolt Site Forums The Shop Area Engine Shop 4 speed question

I'll keep it short and sweet, installed a patrick's ring and pinion kit on my 58'short bed about a year and a half ago, noticed a slight drop in 4th gear torque instantly, have recently noticed a greater drop in torque in 4th. 2nd and 3rd have great response and plenty of torque, 4th seems really slow, if at all to pick up rpms. Wondering if any one else might have a similar situation or any ideas as to what might be occuring. Any help or suggestions are greatly appreciated.

Sorry to say, but installing higher ratio gearsets & having the engine power to pull them are two seperate things. If not, we could all 'high gear it' & run 200 MPH at Bonneville. Trucks push a lot of wind & are hard to go fast in.
Doug

I guess we are talking about a 235 and the 3.38 gears. You are absollutely correct in that you feel less torque. The rear ratio is a torque multiplier, and 3.38 is much less of a multiplier than 3.90. That being said, a 235 in good shape should not have any problem pulling the 3.38 gears, but it might not do it in record time. If you are having deminished capacity, or lessoning performance, it may be something as simple as timing or valves out of adjustment, or something more serious like low compression from worn rings. More inforrmation is needed. Have you done a tune up? Compression test? Adjusted the valves? Poor performance can also be from lower quality gasoline, stuck float in the carbuerator, clogged fuel or air filter, or even points that are out of adjustment.

The factory put 3.90 gears in your truck because it transmitted good torque and acceptable fuel economy for the time. I wouldn't expect your truck to be a rocketship with higher gears.

timing or valves out of adjustment

X2

Let me give you guys some additional info. I've installed a Holley Weber carb from Tom Langdon as well as his mini HEI kit , a compression test was done about a year and a half ago but I don't remember the exact numbers, I rememer being pleasantly surprised by them. Why such a drop off in torque from 3rd to 4th? I'll check the timing over the weekend. I've not ever adjusted the valves so I will look into them as well. I'll give an update on Monday if all goes well.

So, did the Holley and HEI happen before or after the rear gear change? The gear change is a constant, the truck will perform the same day 1 after the gear change as it will years and miles there after. If your are saying, after a year and a half the torque drop in 4th gear is greater, then it's time to do a health check on the motor, tune the carb (not rebuild...yet), check the timing and the vacuum advance.

I doubt having two carbs on the motor will recover the performance it had with the 3.90's. But, in any case it should not lay flat in 4th gear.

That holley weber carb may have wiped out your rings. Do another compression test, dry and then wet.