[69chevyLWB]

Bought a 935056 scat crank for a 383 im building and put the crank in and one piston/rod combo and on the down stroke the piston bottom hits the cranks counter weights. 5.7 rod. nowhere does it say on summit website that it has to be 6.0 or longer rod and was wondering if i can just grind off the excess to make it pass and go from there or should i return the crank and get a different one that will work? probe forged pistons. scat 5.7 cap screw rods.
thanks,
Logan

[hcompton]

No you need the pistons fpr 5.7 rods. Call summit and tell them you they sent the wrong kit. Or you will need the longer rods. The pistons will not be at the correct deck height with the wrong rods. Since pins are moved since they are nade for longer rods. I wouldnt cut anything until you speak with them.

[hcompton]

Oh wait are you using stock pistons it wont work. You have to have stroker pistons. Usally a balanced kit is better then just buying parts.

[69chevyLWB]

The pistons are for 5.7 rods. everything is fine except for the pistons hitting the crank that is the only problem. this is not a kit i bought all of it separately.

[hcompton]

Originally Posted by 69chevyLWB

The pistons are for 5.7 rods. everything is fine except for the pistons hitting the crank that is the only problem. this is not a kit i bought all of it separately.

Are the pistons for a 383 or 350. 383 have the piston pin location moved so they dont hit the crank or push out of the cylinder. 383 pistonsnare also shorter to allow for the crank being larger. Only thing you should need to clearence is the block where the rod bolts get close to the wall of the block. I think you got parts miss match somewhere. I wouldnt cut on the pistons.

Is the deck hieght correct?

Just ran a google search the crank is for 6.0 inch rods only.

[techinspector1]

Originally Posted by hcompton

Just ran a google search the crank is for 6.0 inch rods only.

OOOOOOoooooops.....

[cdminter59]

You need to contact Summit Racing asap to return the 400 crankshaft you purchased. This is the correct part number for the crankshaft you need. Scat Series 9000 Cast Pro Comp Stroker Lightweight Crankshafts 935050 - SummitRacing.com. It is reasons like this it is best to buy a complete rotating assembly. I am sure that if you had called Summit Racing to order a rotating assembly with the pistons of your choice they would have made one up. I purchased a rotating assembly with the pistons I chose for my 454 from CNC-Motorsports.

[hcompton]

Doesnt help now but summit has kits that use your stock rods and they sell you crank and pistons. But i like to buy the balaned rotating assembly with the balancer and flexplate. These usally make it cheaper in the long run most of the work is done before you go to the machine shop.

Hope this helps.

[69chevyLWB]

Thanks for your help but i know that the crank is for 6.0 rods now. im just saying that summit said northing at all about needing 6.0 rods. just bought another stroker crank. this one is from eagle because scat doesnt make a 3.75 stroker thats internally balanced that will take 5.7 rods. problem solved. just have to send the crank back to summit.

[hcompton]

Originally Posted by 69chevyLWB

Thanks for your help but i know that the crank is for 6.0 rods now. im just saying that summit said northing at all about needing 6.0 rods. just bought another stroker crank. this one is from eagle because scat doesnt make a 3.75 stroker thats internally balanced that will take 5.7 rods. problem solved. just have to send the crank back to summit.

Jegs is the same way with the web site info being very lacking. I always search the parts i need and buy from jegs usally is cheaper and ppl seem to be more in the game. Summit always sends me the wrong ****.

[oldbogie]

Originally Posted by 69chevyLWB

Thanks for your help but i know that the crank is for 6.0 rods now. im just saying that summit said northing at all about needing 6.0 rods. just bought another stroker crank. this one is from eagle because scat doesnt make a 3.75 stroker thats internally balanced that will take 5.7 rods. problem solved. just have to send the crank back to summit.

Actually whether or not you can get to internal balance with either the SCAT or Eagle crank has everything to do with the weights of the pistons and rods selected and whether or not you're willing to step up to the cost of Mallory metal slugs in the counterweights if the pistons and rods prove too heavy for the counter weight masses. This appies as much to what is advertized as internally balanced or externally. If I were you I wouldn't breath a sigh of relief untill this thing shows up at the balancing shop and they mock it up to see whether it'll balance inside or not.

Frankly for a street engine where the RPMs will seldom if ever hit in the upper 5000's or higher the difference between internal external balance is almost a moot point as on a crank pin to crank pin basis even internally balanced engines are not in balance from pin to pin they mightily depend upon the counterweights at the extreme ends of the shaft to put the assembly into balance as a whole. Therefore, there are substantial out of balance forces working on the inboard mains of 2, 3 and 4. This is why 4 bolt blocks are on the 2,3 and 4 main unless you're looking at a real race block that does 4 bolts on all the mains. So the externally balanced engine only moves some counter weight a little further toward the crank ends by placing the final balance up on the flywheel/flexplate and front damper. This puts a little more load on the number 1 and 5 journal while it creates little or no change to 2,3 or 4.

This is not as simple as the advertisers would suggest by data ommision or inclusion. You're not home free till the balance shop speaks.

Bogie

[techinspector1]

Originally Posted by 69chevyLWB

Thanks for your help but i know that the crank is for 6.0 rods now. im just saying that summit said northing at all about needing 6.0 rods. just bought another stroker crank. this one is from eagle because scat doesnt make a 3.75 stroker thats internally balanced that will take 5.7 rods. problem solved. just have to send the crank back to summit.

Measure all dimensions carefully on the Eagle crank. There have been issues.

[lmsport]

Eagle will tell you what bobweight they balanced the crank to so you can tell if your bobweight is even close. All cranks from Eagle and Scat have to be balanced unless purchased in a kit that is a balanaced assembly.

[hcompton]

This is why its best to buy a balanced rotating assembly then take it to the machine shop to be finished off. At least they had some monkey stand there with a dumpster full of pistons and a scale and kit something that is close before you walk into the shop. That way it will balance without major exspense. I have done them balanced and slap together. External balanced always works and works ok to 6k rpm. Internally balanced can lead to issues of how good the shop was that balanced the ***. And if you gave them parts that can be balanced together. One piston way to heavy or light and things get out of whack quickly and costly. One too light and all other 7 pistons need to be machined to match up. Been there done that. Stay external until your in the fully forged range if possible. Internal does not have any great advantanges unless your all out racing or running above 7k rpm. Street car its not needed.