Ls with a glide i have heard that you have to run regulator to reduce converter charge pressure? It has been said that to much converter charge pressure will knock the thrust out on the ls.

Then i have also read that the cause is the adapter for the crank pilot to go from the standard sbc converter to the ls engine.

Any opinions here about this subject?

I think the issue is due to the pull out on the converter not being set up correctly. I'm running into a issue on a TH400 to LS right now.

My issue is that I bought a off the shelf TH400 converter. You really need to have a longer snout on the converter to reach the crank correctly. Im running a genV LS crank and if the converter had a .400" to .450"longer snout so I wouldn't need an adaptor it would all fit great.

That's exactly what one transmission guy said.

We haven't seen any charge pressure/thrust issues with a Powerglide. The TH400s we do jet the pump to help in that area.

The LS pilot spacer doesn't cause an issue unless the converter/spacer is installed incorrectly.

proper converter installation is 1/8" to 3/16" of converter pull out(spacing between conv and flexplate before bolting up), with a minimum of 1/8 pilot engagement(making sure it doesn't bottom out)

-Dalton

Well dang now i'm really torn. I have several people say they have had problems with thrust failures.
I haven't measured the pull out yet but i did slide the converter out till it bottomed in the crank and it isn't against flex plate yet. I see where if someone bolted it up like mine is now it would knock the thrust out.

I currently have .145" space when the converter is pushed all the way back. (Which is in spec). However with the crank adaptor installed and the convert pulled all the way out I still have .080" gap between the converter and flexplate this leave me with a .065” pull out. Without the adaptor the converter will pull all the way up to the flexplate. The snout on the converter is not long enough to register in the crank without the adaptor. I’m not blaming any manufacture it’s just a tolerance stack issue and who knows what is out of spec if at all. Measured the converter it looks correct. The solution for me now because I need this in the car this weekend is to have a .125” thick shim made that will go between the transmission and engine. I have installed longer Trans dowels in the block so it should not be a issue. The .125” shim will allow me to run the crank adaptor and add .125” spacers between the converter and flexplate. This will get me to about .145” pull out on the converter with no binding on the crank adaptor. The next converter will be custom built and will have a longer snout to eliminate the crank adaptor.
The other option would be to machine .100 of the converter snout. I didn’t want to modify a converter that we may need to resale some day.

This message has been edited. Last edited by: 1leg,

pump gear is .375,need to pull out 1/2 of that and not be bottomed out in crank.must have room to flex.

I talked to a local converter shop that can ad .300 to my converter and have had more than one tell me that's the amount that needs to be added. I will measure how much clearance i have tonight and make a decision on what to do.

After looking a little closer at my converter last night, i had 5/32" clearance with the converter all the way back. When pulled out the converter was bottoming out in the pilot adapter before the converter touched the flywheel.
I am taking the converter today to have .300 added to the pilot and do away with the adapter.

LS "shouldn't" have any problem with thrust unless something else is going on, say, clogged trans cooler, restricted quick connect fitting(s), pinched or kinked cooler line(s), etc.

The GM LS V8's and the SBF are strikingly similar in a lot of ways...actually...I think LS heads will fit a SBF. Interesting. Anyway...

Lots of guys running PG's behind SBF's, specifically the 8.2 deck SBF's (289, 302 based)-and they are notorious for knocking the thrust out because the thrust has a small surface area, not a lot of problems if everything's set up properly. Even the stock block 8.2 deck engines. The stock 8.2 deck blocks are very weak which lets things move around more than they're designed to. About 450hp is the maximum on those, reliably, and even then they better have a good tune.

Another issue I see (and have personally experienced) is crankshaft quality. Specifically the thrust surface(s) and the machining. If the crankshaft's thrust surface has any machine marks left on it, even minute, it seems to have a higher tendency to eat the bearing up. Cheap chinese cast and some forged crankshafts are notorious for this. They can be polished, and probably SHOULD be before installing. If left alone, many times the engine will run a half season then the crank gets to walking back & forth, in my case I noticed it while checking the timing-the balancer would walk away from the timing cover about 1/4" while running. Pulled it apart and found the thrust gone, completely gone, destroyed the crank, rods and crank had been hitting the block, all rod bearings torn up, obviously the crank was junk as was the block. Good thing it was a cheap junkyard 302 block and a cheap crankshaft from China. Bad part is, even though they're cheap, so am I, and rebuilding--even a $1000 rebuild--still costs money, which I don't always have.

quote:

Originally posted by rs72z:
After looking a little closer at my converter last night, i had 5/32" clearance with the converter all the way back. When pulled out the converter was bottoming out in the pilot adapter before the converter touched the flywheel.
I am taking the converter today to have .300 added to the pilot and do away with the adapter.

Good Move