During teardown to upgrade the cam I noticed the crank endplay was excessive (0.075"!). There were small signs unside the timing cover (from the lower gear and chain) and on the starter (from the flexplate). The flexplate and crank is definately being pushed forward. Could the converter be ballooning or is the transmission pushing the converter forward? The TH-350 transmission was really beefed up ~3500 miles ago. The torque converter is a TCI breakaway. I recall during the initial install of the converter that the clearance was minimul, say 1/16". I pulled the motor yesterday and measured from the trans. flange (bellhousing) to the converter mounting flange and got 0.947". I also noticed the bolts that hold the flexplate to the crank were rubbing on the back of the block. These bolts are now one thread shorter. Picture attached...
The same thing happened to a friend of mine (martian on this board). It was the convertor. Apparently the convertor's fluid intake was much higher than it couild get out, so it ballooned out and pushed the crank forward. Best i can remember it ruined 2 engines before they figured out it was the convertor ou:
Craig, not enough clearance between the converter and flexplate may have been the cause. I believe you require a minimum of 3/16". I went through this when installing a Coan coverter on my th350. The input shaft on a th350 has a tappered snout which is approx 1/8 to 3/16" which needed to be ground off in order to provide me with enough clearance at the flexplate. On a th400 the end of the input shaft is pretty much square with the splines. After I ground off the end, it gave me the clearance I needed. I don't know if this helps you or not, just a thought. Good luck, Jim
I agree, not enough clearance from the start. How much clearance should there have been 1/4"? Good input guys. Could the trans. pump cause this? The converter checked consistant with another one I have. Hard to tell if it's ballooned. Looks like the thrust bearing is almost gone on one side but I don't think the crank ever rubbed the block. The pan was quite clean but the cut filter showed lots of very fine particles. I have a BOP TH-400 that I'm thinking of having built to replace the TH-350, since I'm determined to go faster (mid 11's is the goal).
Check the Converter Craig, I had a converter balloon on an 11 second '86 T Type I had which did the same thing. I would have the convertor cut apart by a reputable transmission shop/ rebuilder and inspected before you make your decision as to the cause. In the case of my '86 T-Type, the converter looked fine externally, but the stator was completely trashed when cut apart. You are really just taking a guess until this is done. I don't want to bum you out, but I would hate to see you waste another set of thrust bearings. Thanks and good luck, Ken
Before you have them cut open the converter, simply have them do an end-play check (if they're good at what they do they'll have the tools). If it balooned on you, I'd expect the stator clearances to be pretty sloppy. May have ruined the thrust washers/Torrington bearings as well. Devon
Don't worry guys the TCI will not go back in this car. I will probably either go with the TORCO I have or a new converter altogether. Originally I had the TORCO installed, it stalled at ~3250, but after a month or so it started to slip more and more. It was guaranteed so I sent it back and put the original TCI back in. TORCO supposedly fixed it, they even paid for shipping. This all happened about 3000 miles ago. Now I need to decide whether to re-install the TORCO or another converter. I know converters can be expensive, but until now I always went with the more affordable route (TCI breakaway was $170, and the TORCO was $200). I've got 3.42's and 27.25" tires. I have run the 413 cam but will probably go back with the TA 286-08H cam. Converter or converter company suggestions?
I filled out the spec. sheet on the Coan website earlier today, we'll see what converter they recommend.
Got the recommendations today: Option one, COA-20320-2 258mm Maxumum Performance custom built converter...$877.50 :eek2: Option two, 11" Race converter...$661.50 Option three, 10" Max Performance converter...$665.00 I was hoping for $600 max. Opinions/advice? Engine spec.'s 480 HP @ 5400 and 530 TQ @ 3900, with (future planning) potential 150 shot. 3.42 gear w/27.25 diameter drag radials. Current times in sig. Here's my other thread that deals with what I found with the engine http://www.v8buick.com/showthread.php?p=728619#post728619
Dont try to slide by on a converter, i also ballooned a converter, almost locked the crank on the block webbing...it was not pretty. Put the coan 4500 stall, went 4 years with a trans brake, leaving at 3200 r's///NEVER had any engine damage since due to converter...whats an extra $100 bucks....alot less than a engine rebuild....Not many converter companies understand what converter a HP BUICK needs...Coan does. :Smarty:
Craig, if you order the maximum converter, ask them what the difference is between the 258mm and the 265mm. Looking on their website it looks to be the difference in the clearance issues with a th350 and the th400. Your running the th350 correct? If so you may need the 265mm. I got the 258 and had clearance issues. I don't think the 265mm converter was avalible when I bought mine. Just a thought. Jim
Good input guys! You are correct I was running the TH-350, but will be going back with a TH-400 that I already have. Just trying to allow for more potential with the combination... in process. It's going to take some time, It may be late summer before she's back on the road o No:
