Car surges at low rpm, not the engine but the car itself. If I apply slight pressure to the brake it stops surging. If I accelerate, it stops. It did this with the old engine and is continuing to do it with this new engine. Iím suspecting something worn between the universal joint and the rear end.
I would expect vibration from a worn U-joint. Has the rear axle been rebuilt?
Car jerks ? You mean those know-it-all blowhards at car shows ???
Maybe a bad pinion bearing or u- joint or driveshaft bushing or all of the above.
Thanks for the responses, I have found a thread
that kind of covers what's going on, so I will try and solve the issue.
Steve, Royce, your thoughts are what came to mind initially, so I'll ck it out.
Burger's mind works like mine does. I reacted to the thread title the same way....
If the Polly sign is 25Ĺ", it's one of mine.
How does the engine idle? Sometimes the fuel mixture tends to "load up" at low speeds. Caused by a rich mixture. This would change when you open the throttle or apply the brake.
Other things could be ignition problems. Try retarding the spark when you are running very slowly. This might smooth things out.
This is what I think is happening. You have some fuel mixture problems or spark too advanced which cause the engine to run rough at very slow speed. This in turn is amplified by some slack somewhere in the drive train. Could be in the U joint or the rear axle.
This problem is quite similar to a front wheel shimmy which appears when you hit a small bump and then the wobble begins because of loose parts in the steering system.
Hope this helps.
Burger, Dick, sorry for the misleading title,
Steve, yup it is 25-1/2". Are you the maker. I bought them from "Vics" in Seattle. Very nice work.
Norman, I will try your suggestions changing timing and fuel mix. The engine is running a Texas T distributor and it had a
Texas T modern carb on it, but I replaced it with a rebuilt Holly NH. I'd be surprised if either the timing or fuel mix was the problem as it did the same thing with the original engine that was running a timer, buss coils ans a different Texas T Carb. But then strange things do happen.
Its sounds like fire or lack of or carb issues. Just what i would check but i haven't had Ts all my life. Tim
I jacked up the rear of the car and I can move each tire about 4 inches back and forth. Then I checked the movement on two other T's and they moved also, but only about 2".
How do I determine what is causing the difference, or is this not the cause of my herky jerky movement?
Has the rear axle been rebuilt with bronze thrust bushings? Try pulling each rear wheel in and out with the rear end jacked up off the floor.
I like Burgers comment.
Do you mean movement 4 inches radially, or 4 inches in and out? In and out would be very dangerous. There should be no noticeable in and out movement.
The radial movement can come from any or all of many sources, such as gear lash, universal joint wear, or differential wear. There is usually some radial movement, but 4 inches at the rim, seems like too much.
There is virtually no in/out movement with the wheels jacked up.
Norman, it is radial movement, sorry for not being clearer.
I have been fooling with the mixture and timing and am making some progress. It's either getting better or I'm getting used to it ;)
This forum is awesome, thanks for all the helpful tips.
I am far from an expert on such matters, but you might consider double checking your coils. My 24 coupe gets a little herky jerky when one of the coils vibrates slightly up and out of position. Once I slide it back down into a firm position in the box, it runs smoothly. Hope your problem is something that simple.
Really couldn't see this as a drive train problem. Especially without accompanying noise but decided to wait & see till the guys came around. Fuel & ignition. Your float level could be so low you,re starving. Coils: what shape are they in? (Replaced caps, HCCT'd?). Lastly your driving habits.
When I started making signs about 25 years ago I got the steel blanks from a local barrel factory. Those were 25.5", so that has been the size of the round signs ever since. I sold the business, but the signs are still being made.
No coils, well it has one as well as a Texas T distributor. Also a rebuilt Holly NH that was rebuilt by Mark Chaffin, so I doubt there's a float issue.
I'm thinking I'm on the right track by following the previous advice tuning the carb mixture and timing. It seems to be improving.
As a side note, I had the same issue with my crate engine 66 Mustang. In that case a brand new intake manifold was improperly machined and caused a lean miss that took forever to find. Internal leak.
It might just be driving technique. You may need to wind up higher in low gear before dropping into high.
Royce, good point, but I have two other "T"s that don't suffer this problem. Of course I could be an inconsistent driver ;)