CAT Cranks

[86 TR]

Are the CAT cranks a good choice for a crank?? Anyone out there running one in there cars??? Do they require alot of machine work to get right??? I need a crank for my current buildup and Im having a lot of trouble finding a stock turbo crank so now Im thinkin about goin with one of these cranks.

I can buy one for $359.00. What do you guys and gals think????

 

[mikestertwo]

A friend of mine bought one and sent it back The key slot was too big. Some of the rod journals were undersize. The radius on the rod journals were too big. The bearings would have to be tapered to fit. The hash marks on the back of the crank where the seal rides was too aggressive and would tear the seal up.

 

[TLIMITED]

There Is A Std.stock Crank On Ebay Right Now Under Grand National.

 

[V8Assassin]

Any More Info?

Do any of the senior members have any more information on this subject. My next setup will include a cat crank, K-1 rods and JE pistons. Would like to hear more from more educated members.

 

[Rodney87GN]

I'm using a Cat crank with K1 rods. Motor was just done so I don't have many miles or any track times yet. My 2 cents....find a Buick guy that know what's up with these cranks. Yes it will need minor machine work to make it work right but any competent machinist should be able to handle that. Weber Racing did my motor and knew what they needed to do with the Cat crank. Also I know DLS offers the Cat cranks so they can't all be that bad.
http://www.turbobuick.com/forums/engine-tech/231459-cat-products-have-you-used-them.html

 

[V8Assassin]

Thank You!!

I'm using a Cat crank with K1 rods. Motor was just done so I don't have many miles or any track times yet. My 2 cents....find a Buick guy that know what's up with these cranks. Yes it will need minor machine work to make it work right but any competent machinist should be able to handle that. Weber Racing did my motor and knew what they needed to do with the Cat crank. Also I know DLS offers the Cat cranks so they can't all be that bad.
http://www.turbobuick.com/forums/engine-tech/231459-cat-products-have-you-used-them.html

Thank you for the reference, very helpful info.

 

[Under Pressure]

I used a cat crank nice piece (w/K1's) it had a .005 run out on journals . It did required 2 slugs of moly to balance it with my setup. for the $ its a great piece . I would used it agian. I did use a BHj balancer in the balancer did have to be clearenced to not gaul the snout of the crank when i installed it.Also minor work done wooddrift key no big deal though...

 

[1985GN]

cat crank and k1 rods here lots of abust and been 138mph so far on a little more then mild tune...more to come out of it this year...

 

[87we410877]

A friend of mine bought one and sent it back The key slot was too big. Some of the rod journals were undersize. The radius on the rod journals were too big. The bearings would have to be tapered to fit. The hash marks on the back of the crank where the seal rides was too aggressive and would tear the seal up.

The crank key can be bought from webber racing for a small cost of about 20 bucks. The journals are supposed to have a radius. This is why you have to use the correct type of bearing. I think its the P series. Theres H and P its one of the two have a radius in it. And i think thats just on the mains. If my memory serves me correctly, the bearings dont even come close to the taper in the journal since they are alot smaller in width than the rod journal itself. Ive had one in my car for about 1000 miles and about 20 passes at 123-127 with no problems. My machinist also checked for straightness and it was fine. They all come from the same place, CAT, EAGLE, SCAT, its the machining company that determines the name on it. Do a search and you'll find tons fo stuff.

 

[ek02]

I used a piece of .002 shim stock on each side of the woodruff key on my CAT stroker crank in my 4.1. It's available from Goodson.com in a package of various sizes. You can insert it with the key and then use a razor blade to score and break off the excess. The mains I am using are Federal Mogul FEM-107M 3/4 groove. The old Kenne Bell mains were fully grooved, but no longer available. The Federal 6-3755APA is too wide for a CAT crank, but will work on a stock turbo crank. The 6-3755AP is the narrow bearing and works fine. Both numbers are discontinued, but will cross over to other manufacturers. Any good stock width performance rod bearing is OK. The BHJ balancer has to be honed to fit with a slight press fit and has to be installed with a tool. I used a long bolt and a bearing from an A/C clutch tool. If you use a stroker crank with a roller cam and CAT or K-1 rods, the rods hit the cam. Stock rods with ARP bolts will clear. The CAT and K-1 rods hit at the end of the threads. I ground mine so a .060 feeler guage will fit between the cam and rod when rotated. Be aware that advancing or retarding the cam has an affect on the clearance. 4 degrees either way makes it .010 tighter. I'm still waiting to get everything balanced, so hopefully the rods won't be too out of whack.

 

[QuickWrench]

ek02,

Do you think .060" is enough clearance between the rods and cam lobes? Maybe it should be, but the bottom end on these things is like a flexi-flyer. Hopefully the better crank will help keep things in place?

 

[ek02]

The instructions with my JE Pistons say to be sure the piston bottom to crank counterwieght clearance is .060 minimum, so I think .060 on the crank to cam clearance should work. The forged crank should not flex, considering how short it is compared to a V8.

 

[casper]

I'v got two stock GM cranks for sale 450 each

 

[QuickWrench]

I'v got two stock GM cranks for sale 450 each

PM me with details/location. Thanks

 

[chris]

cranks

I'v got two stock GM cranks for sale 450 each

Are these new or used?

 

[casper]

New

 

[Blown&Injected]

Are the CAT cranks a good choice for a crank?? Anyone out there running one in there cars??? Do they require alot of machine work to get right??? I need a crank for my current buildup and Im having a lot of trouble finding a stock turbo crank so now Im thinkin about goin with one of these cranks.

I can buy one for $359.00. What do you guys and gals think????

They are fine but they are not a drop in part.

If I needed a crank I would just get a stroker kit

 

[J-B Racing]

I just put one in my New Short Block. The Only Mod was the Keyway. I could not get the Balancer in.
Other than that it's OK...


Joe

 

[Blown&Injected]

Expensive Balancer

Need to hone expensive balancer to fit the crank

Special key made

Expensive flex plate

Machine to fit expensive flex plate

I'm sure I left something out...

 

[J-B Racing]

Expensive Balancer

Need to hone expensive balancer to fit the crank

Special key made

Expensive flex plate

Machine to fit expensive flex plate

I'm sure I left something out...

Actually all I had to do is File a little the Keyway groove on the Balancer and it went quite well..
Sorry for others who had a harder time.