Converter Problem/Question

[Kingpen]

as in my other thread,Im trying to figure out IF I have a torque converter problem.I have changed just about everything on the car chasing a problem.My car has steadily lost E.T. over the last 3 years for what I think is no reason,maybe Im wrong,maybe there is a reason & I have not realized it yet.I have put a new fuel system from Pump to Reg including new line,have tried both #8 & #10 line to front,#6 & #8 to carb-no difference either way,numerous carbs including Holleys,which by the way was only about 2 hun at the most diff.have been through motor 3 times with new pistons,diff ring set ups,even as far as putting in a 43# crank(350 chevy 295/327hp) and have not seen any improvement,took 43# out & put back stock GM too.nothing seems to change how fast it will run.Even from corrected air of 1100' to 4000'(normal for here in summer) never any more than .04 in E.T.the air change alone should be worth 10-15 hundreths.
So,i decided to make a drastic change,I put my bracket short block under th SS heads.377 ci with final comp ratio at about 12.3-1,yes the pistons weighs about 80 grams more and the rods about 50grams more-and I put some titanium valves in the heads to help with the aggressive SS cam.....final result---you could put the e.t. slips beside each other and thought it was same car on same day.......notta!
I guess my question is -will a converter "go bad" with out being "broken" and oh by the way-still be very consistent!I made 5 runs with .02 all night.the car has lost about .18-.22 in the 1/8 mile that i cant seem to get back.in fact ive always thought the car should have been about .08 quicker any way so really chasing 3 tenths..I have a converter being sent that Ill try to see ,but i have a hard time beleiving it because its never been broken and is still consisten..my converter is 9 years old but have been sending it in evry 2-3 years for freshen and they always say"looks good" when they cut it apart...............ANY IDEAS...I have been throgh all on the car except for a "new" converter......Vic Penrod

[buzzinhalfdozen]

Maybe it's just me but from all the work you just described hell i'd have just thrown a converter at it . Problem solved or not it seems much easier than all the engine swapping and parts replacing. JMO. Joe

[Mark Yacavone]

Need more info:
60' time (before and after)

converter flash rpm

trap rpm

[Whalen3186]

From my experience, a bad converter will make you think its everything but a bad converter. We are kind of going through the same thing now.

[Kingpen]

as far as rpm-it never really has changed.it always seems to go to about 6100 rpm at the hit and falls to about the same on gear change,trap rpm is usually between 81-8300 rpm on 1/4 but most of my racing is done on 1/8 bracket track and trap rpm has been around 7000-7200..the 60' times have slowed along with the overall et...was always around 1.36-1.38-now you cant drag it any faster than 1.39-usually fall in the 1.4-1.42 range..the main reason I havent just put another converter in is (1) every time I done something with the engine was because it was usually freshen up time anyway & (2)it always stays consistent-just getting slower over time.

[Mark Yacavone]

There's only a few things that can go wrong with a converter. Most of them are very noticable.
If the sprag doesn't hold or slips off the line ,stall speed will decrease dramatically.
If the sprag slips downtrack ,it won't do it consistently, so the numbers in the middle will vary.
If a pilot thrust bearing goes away, it will increase the clearance between the pump and the turbine and the stall and trap RPM will most likely increase.
Same for broken fins , but you'd have to have more than one or two broken.
In the last three cases mentioned , you'd have metal everywhere in the trans and the whole deal wouldn't last long.
My guess: The converter is not your problem.

[7820]

In my case it was the converter and Mark figured out for me. I had all sorts of poblems at the Pontiac Heaven Race at Speedworld. Thought it was ignition related.....changed everything. Talked to Mark and he nailed it.....rolled the sprag. Took it out when I got home and yep......rolled the sprag. No longer have a sprag of that type...I now have a mechanical diode.

When I launched the car it would slowly accelerate. Instead of running 9.0's at 150 I was running 10.80's at 146.

Thanks for the help Mark.

[Mark Yacavone]

Originally Posted by 7820

In my case it was the converter and Mark figured out for me. I had all sorts of poblems at the Pontiac Heaven Race at Speedworld. Thought it was ignition related.....changed everything. Talked to Mark and he nailed it.....rolled the sprag. Took it out when I got home and yep......rolled the sprag. No longer have a sprag of that type...I now have a mechanical diode.

When I launched the car it would slowly accelerate. Instead of running 9.0's at 150 I was running 10.80's at 146.

Thanks for the help Mark.

You're welcome, and that's why we have a m/d in Alex Kadar's 455 GTO . Man, those 455's are tough on roller sprags.