odd ball engine combo
 

Ok guys here's what I have...I have a 71 virgin 400 4-bolt main sb chevy. I also have a 68 Lg journal 3.25 stroke crank. What will this make? I know a 3.50 stroke in a 400 block will make a 377 & they run pretty good but have any of you went this way ? I'm just thinking out-loud here.

Re: odd ball engine combo
 

346 . In other words, a big bore 327

Re: odd ball engine combo
 

or a REALLY big bore 307...

Re: odd ball engine combo
 

I've always been impressed with the 377, not so with the 383. A 346 like this sounds intriquing...Anything on the down side, other than cubes?

Re: odd ball engine combo
 

The only thing I can think of is I think it would like RPM. But I would build it with 6" rods so that wouldn't be a big deal. ( not to upset my S/SS buddies but I'm thinking of this as a 10.90 engine ....something that could leave the line @ like 5800 & shift @ like 8000)

Re: odd ball engine combo
 

how about this for grins, 400 block/302 crank?

Re: odd ball engine combo
 

Use a 6.125" or 6.250" rod, and as good a set of heads as you can get. It will want plenty of compression. Only two problems you have are the 4 bolt main 400 is weaker than the two bolt main, and most large journal 327 cranks are cast, not steel, neither of which is great for high RPM, which is what a big bore short stroke engine does best. Just don't put it in a heavy car, especially not with a tall gear.

Re: odd ball engine combo
 

That's not so odd ball.It's been done. The 4.125 inch bore by 3.250 stroke acftually makes a 348 inch motor.The old 348 inch W motor had a 4.125 x 3.250 configuration as well. Three motors in the Chevrolet camp had a 4.125" bore- the 348 W motor, the small block 400, and the 402 big block. One thing- the mains on the 400 sbc were larger diameter than the large journal 327 or 350,so some sort of space saver bearing is necessary. The six inch rod is a great idea, as well as making as much compression as possible.I heard of a repair shop that came up with a 307 short block,.030" over from a rebuilder, then the customer opted for a GM Goodwrench crate engine. The crank in the 307 turned out to be a 327 steel large journal piece, so out it came to be used in something else, leaving the block, pistons, and rods. One of the guys in the shop figured out that a 3.480"stroke stock 350 crank in that 307 with a 400 sbc stock length rod would go together very well, making a 328 cu.inch motor that went into a Nova for a street driver. Wonder what the next guy that tried to rebuild it must have thought.

Re: odd ball engine combo
 

you know that's funny because the crank I have is steel & it's out of a 68 307! A guy gave the engine to dad & said it was a "truck" motor...thing is it had a 4bbl intake on it...the #'s on the intake are that of a 69 350 255??

Re: odd ball engine combo
 

Hot Rod magazine had an article back in the '90s about an engine based on that combination titled "The 350 Engine Chevrolet Should Have Built". The guy in the article used 6.2" rods, small port AFR heads, a 215 degree hyd roller cam, 11:1 compression, Edelbrock Perormer intake and carb. The engine made over 400 ft lbs of torque between 2800 and 5200 rpm and it ran on 87 octane gas. Worthy investment of time to read the article.

http://www.purplesagetradingpost.com...%20engine.html

Re: odd ball engine combo
 

Inteesting.68 327 pickup truck engines, the 300 horse Corvette 327, and the rather elusive 325 horse Chevelle motor had large journal steel cranks. This 307 from this rebuilt engine house had one,probably because that's what they had on hand when they assembled it.It's possible,even probable that the steel cranks came in 307 truck engines,as well. The Q-jet intake had to have been added later,however.307's were all two barrels as I remember.

Re: odd ball engine combo
 

http://classracer.com/classforum/showthread.php?t=19467

PLease let me know. I'm curious.

And I think the magazines are full of ***** because I ran across an article about a 307 +.030 that made over 400 HP with a tunnel ram and roller cam. Just doesn't sound right to me.