Scat SB 400 Crank Question

[Sydmoe]

I am rebuilding my OMC 5.7 and I was planning on stroking out the motor by using a SB 400 crank and rods. My question is has anyone had any experience with these Scat forged cranks I see on ebay. Are they any good for marine use? Is the quality decent?<br /><br />Any info is appreciated.

 

[Ryoken]

Re: Scat SB 400 Crank Question

its what i just put in my 383 for my Blazer. very nice crank....

 

[Boomyal]

Re: Scat SB 400 Crank Question

Scat is a reputable brand for stroker cranks. There are a whole lot of other details you need to consider before you install a stroker crank, ie piston volume, piston compression dimension, cylinder head volume, compression ratio, deck height, etc. Do your homework.

 

[bluewater19]

Re: Scat SB 400 Crank Question

That crank will stand up to any abuse you will throw at it. I would look for a marine cam with 112 deg lsa and around .460-.480 lift with duration in the low 200 deg area that will keep reversion out of the picture. The real qusetion is will the out drive handle that kind of torque?

 

[Boomyal]

Re: Scat SB 400 Crank Question

Aw heck Bluewater, Sydmoe can just use a teeny little prop. Turn it into an un-tunneled jet drive.

 

[f_inscreenname]

Re: Scat SB 400 Crank Question

I was going to do that with my 360ci mopar this year but found out there is a lot of things that would need to be modified or changed. In my case being the motor is externally balanced I pretty much had to start from scratch (I have 360ci/320hp now, built right) new pistons, rods, crank. If I would have done it in the first place it would have been worth it. As for a upgrade to a already good motor was to me a waist of money. In my research I found a lot of web pages on how to build a stroker you may want to read a few and see what kind of performance you will get out of it in a boat (no high end RPM’s) and what changes yopu will need to do. If you are still interested on doing it check out northernautoparts.com I see they have a master (“everything” you need to make a 383 including the crank, piston, oil pump, cam at your specs, timing chain, bearings, gaskets ect) stroker kit for a 350/383 for $656.91 and it is a Scat crank. I found these guys from a friend a few years ago and have used there (name brand) parts many times with no problems. <br />P.S. I am no sure but with mine I would have needed new pistons also not just crank and rod. Check it out and good luck.

 

[Sydmoe]

Re: Scat SB 400 Crank Question

Bluewater, you bring up a good point! I remember back when I was 18 and spent every penny I could make rebuilding and hopping up the 440 ci motor i had in my '69 Dodge Charger. After spending $5000 on the motor and nothing on the driveline I seem to be blowing trannys and u-joints every weekend! it was a fast car that spent most of the summer on jack stands in the garage!<br /><br />I will make sure I don't get too crazy with the boat motor.......

 

[Sydmoe]

Re: Scat SB 400 Crank Question

f_inscreenname, I have been reading Dennis Moore's "Small-Block Chevy Marine Performance" which is an excellent book for those wishing to gain some knowledge and map out what performance enhancements can be done to SBC marine engines. I will check out the link you gave me and I appreciate the input. I did plan on changing more than just the crank and rods to go into this thing the right way.

 

[bluewater19]

Re: Scat SB 400 Crank Question

I think a stroker is a great way to go if your out drive can handle it. I would gather all my parts for the bottom end and then have a local machine shop that specializes in hi-po chevies clearance the block and balance the whole thing. You won't have any problems with sustaned high rpm use that way.I would talk with crane or comp cams about which cam to use with your stroker. I built a LT-1 based stroker for my RX-7 and used comp cams magnum roller rockers. I would use those on your marine motor. keep us informed and let us know how it turns out!

 

[rodbolt]

Re: Scat SB 400 Crank Question

hello<br /> I have not had much time to check and cross check part numbers but the new 6.9 sb chebby looks like a 383 stroker from the factory. the hard part about this is to make sure you use the correct balancer and flywhell. the 400 sb manual shift flywhell is getting scarce and some had the wrong diameter ring gear for a boat and some had a different pitch on the ring gear teeth. thats why I dont modify them. if ya gotta go faster buy a bigger rig. the guy with the 8.1 and a bravo III is gonna blow right past. instead of going after modest hp gains I would first sink my money on a DP drive. volvo makes a killer lightweight DP drive that works very well. its like bolt on horse power with no engine mods and the resultant problems.<br /> good luck and keep posting<br /> PS alpha drives become very short lived at the 300 hp mark. if ya dont belive me watch an alpha with a 330 7.4 do a hangrenade impression.