PatsLs1vette

anybody ever build one of these yet ,ive had a 383 and a 406 but havent tryed one of these http://www.speedomotive.com any oppinions on it ,i have an extra 4 bolt main block sitting around looking to come alive.. the 391 is suposed to be a torque motor i saw a write up in hot rod a couple of years ago but cant remember the outcome of it.

PatsLs1vette

by the way my brother wants my 406 so i might just give it to him and build something else.....nice brother eh? :D

gkull

It's starting to look like I'm the only poster! I have a 393 4340 internal bal. 6 inch rod. with 12.5 ish C/R short block. (not for sale) I would have gone for a 395.7 if i would have been willing to wait. It just the difference of 3 13/16th and 3 7/8th with a .040 over bore.

I have a 3.75 in my car now and i had some concerns about my 2.87 overall gearing in OD.

When the cost of cranks are the same why not get the biggest. My one thought was also a 4.00 stroker and run a 4.040 and then when i go to a 4.125 your all set. I just have to much money in my 4.11 rear to just throw it in the pile of race parts.

They will beat up a 355!


[Modified by gkull, 10:47 PM 8/15/2001]

korvetkeith

Where are you finding these 3.8"+ stroke cranks? Would Speed o Motive sell a crank by itself.

PatsLs1vette

gkull so you think i should go for it and also how much relieving of the 350 block to fit the crank more then the 3.75 stroke?Its only gone to get raced occasionally more of a street motor for daily usuage.and korvetkeith these cranks have been available for some time now give then a call they might sell the crank by itself but other manufacturers sell it too.

Vic'89

Please do your research on this company, I never heard anything good about them.

Vic

vettewally

I have an 85 vette w/a 391stroker and fully ported iron heads,accel intake,siamesed runners and ported plenum. It is basically a 3.835 crank with 350/30 over block. The pistons are then shaved down about 100th of an inch or so.This way they don't hit the heads when they come up. The engine makes a lot of torque and power. Never dyno tested but my rear and trans are the proof. Blew rear dana 3:73,two torque converters and one trans.From what I've heard of Speed O motive it's a desent company they a lot of different hyperformance engine combo's.

gkull

This is my 393 when I was fitting it. The white on the studs is just white grease to add in quick assembly. But anyway it's from Speedomotive 4340 6 inch rod and interally balanced.

If your look close on the passenger side pan rail you can see my grinding for clearancing the rod bolts. It's almost done in that picture. How much your take out depends on the size of the rod bolts. I did take out a little more fore and aft for crank end play. If you didn't already know it, the oil pan rail is not square. It's smaller at the front and opens up on the way back. Also the way the rods and crank are, most of the grinding is all on the passenger side. It's not that big of a job - it's just time comsuming to assemble one piston at a time and rotate it 360 degrees and see how much grinding you have to do - Then clean it and go on to the next all the time worrying about the smallest metal flake dinging your micro polished crank or barrings. I used a Makita 25K rpm die grinder.

I do almost all of my engine work. Because then I know what's done and how it was done. I have a mistrust of some flunky in a machine shop that usually doesn't care. When you start getting $5-10K in a motor it's to much to loose.




[Modified by gkull, 9:32 AM 8/16/2001]

gkull

These are the 393 domed pistons for 12.5 or more C/R and big 6 inch rods that I completed the motor with. The dart heads are just out of the box. Before they got the make over. As shown with 2.08/1.625 and .700 lift roller springs.

The Dude

I have a cast, offset-ground 3.832" stroke crankshaft. It was in my old Speed-O-Motive 415 when it blew up. It's been magged and it checked out OK, so my machinst tells me. A couple fo the rod journals will require a little polishing, however. That's no big deal since you'll have to have the mains turned down, anyway, to fit the 350 block.

I am willing to make any fellow forum members who are interested a very attractive deal.




[Modified by Jack Sweet, 11:34 AM 8/16/2001]

PatsLs1vette

ok guys appreciate the help so far now i just got to decide what to do.....

korvetkeith

If you use 5.7 inch rods could you avoid grinding the tops of the pistons down? What about the 5.95" PM rods and maybe a thicker head gasket?


[Modified by korvetkeith, 11:23 PM 8/17/2001]