Crankshaft Question

[slick6732]

New to the forum, so if I am posting in wrong place I apologize.
I recently purchased a 1987 turbo t, with a spun crank. Seems the guy that owned it before me over rev'd it at the strip. Knocks upon start up and goes away, then knocks around 2k rpm. Only started once to see how bad it was!
Anyways my question is how far can you have the crankshaft turned safely without further issues, Not planning on racing it, I rescued it from the drag scene and am planning on restoring it back to the car it once was. Although the occasional tuner may have to get a lesson...
Your knowledge would be greatly appreciated.

 

[84BuickGNYorkPA]

Tear it down see what you got to work with, the current motor in my car has the crank turned .020 (twenty thousands). As far as rescuing the motor from the track goes, many of these cars are at home at the track, it's all in the tune.

Chuck

 

[slick6732]

was referring to the previous owners sleeper look, Rust, dead paint. just want to do the car a little justice as far as cosmetics and tlc. Motor wise, Beast! Thanks for the info on specs !!!! .020 was as far as i wanted to go

 

[Pronto]

Whatever you do, make sure you use a shop that is familiar with the TB. Post your location so someone nearby might recommend a shop.

 

[87buickracer]

New to the forum, so if I am posting in wrong place I apologize.
I recently purchased a 1987 turbo t, with a spun crank. Seems the guy that owned it before me over rev'd it at the strip. Knocks upon start up and goes away, then knocks around 2k rpm. Only started once to see how bad it was!
Anyways my question is how far can you have the crankshaft turned safely without further issues, Not planning on racing it, I rescued it from the drag scene and am planning on restoring it back to the car it once was. Although the occasional tuner may have to get a lesson...
Your knowledge would be greatly appreciated.

I know a guy running a 20/30 crank on stock bottom end and running 11.00 in the 1/4 on a good tune..I wouldn't go past 20/20 myself on a high 10 sec motor...

 

[slick6732]

My location is Muncie, Indiana
Not a 10 sec car, mid 11's. Just want to make sure I do it right the first time, The crank in it is stock size, well before the spun bearing so hoping it can be done under 20/20
Thanks for all the advice.

 

[slick6732]

Been reading, Not a good sign I know.....(Have the bug). Another question has now jumped into my over active mind. I have a crank out of n/a 3.8 that is unhurt, stock size that probably just needs dipped and polished and would be like new. I know the turbo cranks have the fillets for strength, But has anyone had any luck with a stock n/a crank in a mid 11 motor. just a thought, dont want to set myself up for failure. Thanks again for all of the knowledge you all have shared with me. You all are great!!!!

 

[Nasty Wendy]

NA cranks have been usued successfully but given the price drop that the turbo cranks have had since forged cranks became readily available it doesn't make sense to use a NA crank. The rolled fillets are there for a reason.

 

[Red Regal T]

Been reading, Not a good sign I know.....(Have the bug). Another question has now jumped into my over active mind. I have a crank out of n/a 3.8 that is unhurt, stock size that probably just needs dipped and polished and would be like new. I know the turbo cranks have the fillets for strength, But has anyone had any luck with a stock n/a crank in a mid 11 motor. just a thought, dont want to set myself up for failure. Thanks again for all of the knowledge you all have shared with me. You all are great!!!!

I read a post within the past few weeks, the poster lamenting he couldn't find a turbo crank. If I had a standard NA crank, I'd use it over a 20/20 turbo crank. NA cranks do have rolled fillets on the mains, but not the rod journals and people have run them into the high 10s. Having a crank cut is a crap shoot anyway.

 

[84BuickGNYorkPA]

.02 under is the size of the diameter, which would be .01/side of the crank, really not a lot of metal, less then 3 hairs from your head side by side.

Chuck

 

[LOT]

crank

Used to live close to Muncie. There is a shop just off the by-pass (inside the by-pass) but I don't remember the name or street. A man and his wife work it. He did a turbo crank for me. Fast turn around and good work and price. If you keep your turbo crank and I suggest you do. Have him mike it and make sure you can get bearings for the size it will end up being. Also, very important, have him or whoever to leave it on the BIG side of the finished size. He'll know what you mean. Best of luck in the cold North.

 

[esm]

crank

i bought just bought a turbo crank from Cotton performance that he just cut .10
for $500 --- a steel crank wasnt in my budget because i had to change the balancer and flywheel --

 

[WE2Regal]

If anyone is interested, I have a couple of brand new NA cranks I'd sell cheap. They are in perfect condition.

 

[getchasum]

I would not be concerned with using a 30/30 crank if that's all I had. For all who are.....please send me all the cranks over .020 :biggrin:

 

[Just a Six??]

I would not be concerned with using a 30/30 crank if that's all I had. For all who are.....please send me all the cranks over .020 :biggrin:

Me Too!!! I'll take them! I know some at 40 & working fine altho not for racing. I have raced a 30-30 crank in the 11's many times without issues. Since I have spares I'm using a 10-10 & have no worries running into the 10's. It's all in the tune as the headgaskets will probably let go before the crank ever does.
I'm sure it's possible the crank will break & they have for others but not just because it's a 20-30 or 30-30 I'll bet. My $$ goes on the headgaskets popping first.

 

[slick6732]

N/A Crank

O.K The Turbo crank is not usable, the thrust journal is in bad shape. past tolerance untouched! Back to the N/A crank!!! Any thoughts would be great. I am seriously considering using it, just dont want to do it all for another failed crank.