odd ball engine combo

greg fulk · 04-08-2010, 01:01 AM

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.

Mark Yacavone · 04-08-2010, 01:57 AM

346 . In other words, a big bore 327

Tom keedle · 04-08-2010, 07:44 AM

Quote:

Originally Posted by Mark Yacavone

346 . In other words, a big bore 327

or a REALLY big bore 307...

Jeff Lee · 04-08-2010, 06:27 PM

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?

greg fulk · 04-09-2010, 12:27 AM

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)

Tom keedle · 04-09-2010, 04:04 AM

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

Alan Roehrich · 04-09-2010, 07:43 AM

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.

Greg Reimer 7376 · 04-09-2010, 04:00 PM

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.

greg fulk · 04-10-2010, 12:50 AM

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??

Dwight Southerland · 04-10-2010, 09:07 AM

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

04-08-2010, 01:01 AM	#1
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	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. __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

04-08-2010, 01:57 AM	#2
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,821 Likes: 2,912 Liked 5,133 Times in 1,957 Posts	Re: odd ball engine combo 346 . In other words, a big bore 327 __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

04-08-2010, 06:27 PM	#4
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	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? __________________ Jeff Lee 7494 D/S '70 AMX

04-09-2010, 12:27 AM	#5
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	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) __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

04-09-2010, 04:04 AM	#6
Tom keedle Senior Member Join Date: Dec 2008 Location: Berthoud, Coloraduh Posts: 695 Likes: 13 Liked 8 Times in 7 Posts	Re: odd ball engine combo how about this for grins, 400 block/302 crank?

04-09-2010, 07:43 AM	#7
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,124 Likes: 1,581 Liked 1,879 Times in 422 Posts	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. __________________ Alan Roehrich 212A G/S

04-09-2010, 04:00 PM	#8
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,137 Likes: 172 Liked 719 Times in 220 Posts	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.

04-10-2010, 12:50 AM	#9
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	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?? __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

04-10-2010, 09:07 AM	#10
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,002 Likes: 64 Liked 783 Times in 195 Posts	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