[F-BIRD'88]

Originally Posted by 1932bantam

thing about the 400 you got to run that big heavy crankhub for ex balanced that and pulleys for alt etc. puts alot of strain on the end of the crank. As far as quench no need to worry about it on a blown engine. We just had a crank hub twist off, bent end of crank on 383 idling was running a spacer behind blower pulley, not a good setup

I would never use a "383 crank" in a 6-71 8-71 blower motor.
Any 383 crank. But especially any off shore crank.

And a lot for just these reasons, and more.
The stroker crank just does not pay off in a blower motor.

If I was going to build using a 4.125" bore block I would just use a 3.48" stroke 350 crank or the stock GM 400 crankshaft.

The 355 engine base is the way to go.
If you must have more than what this will deliver, jump to a big block engine.

If you are starting from scratch and don't have a 350 engine core the GM ZZ4 350 short block is a great base-start point for the build.

[vinniekq2]

Many reputable crate engine builders will build 383/406/434 turn key blower engines.They use a callies crank.Just dont try to build powerful and cheap,leave that for the low horse power guys

[1932bantam]

yes i agree . he already had engine , so we tried it

[cobalt327]

Originally Posted by techinspector1

Read this from Blower Drive Service...

"Flat tappet and roller cams are recommended for high performance applications especially where the engine will see high RPM's.

I'm thinking they left out Solid lifter, as in "Solid lifter flat tappet and roller cams are recommended for high performance applications especially where the engine will see high RPM's."

As long as the crank is good quality, there's not a thing inherently "wrong" w/using a longer stroke.

[F-BIRD'88]

The stroke length it self is not the issue. There is more to it than that.

[cobalt327]

That's my point. A 383 crank is not inherently bad. There are good and bad "383" cranks just like there are good/bad cranks of any stroke for any engine.

[F-BIRD'88]

A 383 crank has a inherently bad design characteristic. I won't use them in a 6-71 or 8-71 roots blown
motor, specificly, because of this. I'll build a 355 (thats just as powerfull and more reliable) or a 4.125" bore 400 block based 377 or a 406. Or go 427-454 BBC based.

I'd trust a stock cast GM 350 crank more than a 383 stroker crank in a roots blown application.

Engine builders will sell you what ever you want, cause thats what you want.
If they don't or won't, the next shop down the street will...so...

But....

If someone comes to me and wants me to build them a 383 stroker motor for a roots supercharger, I will pass on it. No thankyou.. I'll offer to build a equally power full 355 based roots blown sbc motor or a roots blown BBC or not at all.

[vinniekq2]

Originally Posted by F-BIRD'88

A 383 crank has a inherently bad design characteristic. I won't use them in a 6-71 or 8-71 roots blown
motor, specificly, because of this. I'll build a 355 (thats just as powerfull and more reliable) or a 4.125" bore 400 block based 377 or a 406. Or go 427-454 BBC based.

I'd trust a stock cast GM 350 crank more than a 383 stroker crank in a roots blown application.

Engine builders will sell you what ever you want, cause thats what you want.
If they don't or won't, the next shop down the street will...so...

But....

If someone comes to me and wants me to build them a 383 stroker motor for a roots supercharger, I will pass on it. No thankyou.. I'll offer to build a equally power full 355 based roots blown sbc motor or a roots blown BBC or not at all.

first question, "why"?

second question: how do "you" build a 355 equal in power to a larger 383?

[496CHEVY3100]

Normaly the crank is not the weak link, the bolts and caps usually give up and crank gets blamed ,i agree with F bird on 383 ,mine is a two bolt big block ,but i have arp studs not bolts also billett caps knife edged crank,lightned and balanced with mallory I dont anticapet any problems with 7.9 cr alum heads and pump gas, Streetdriver, if you see this on trailor report it stolen.

[strokin]

I do have a mid 70's block 4 bolt never been bored that I can use for this build, but just thought when buying a $2000 rotating assembly is another 1500 for a block to protect it all that much? Will a mid 70's 4 bolt take 650 hp? I would think so but always that hint of doubt. Also u mention 8-71 on sbc, is that not to big for sbc? This is all going in 87 monte ss 9" 3.89 spool, coilovers, 8 point cage, notched frame, 3" exhaust with 1 3/4 hooker headers. This car is mainly for show and street but does hit the track a few times a year. Only drive it 2 times a month if I'm lucky.

[496CHEVY3100]

A Properly machined and preped 4 bolt with aftermarket caps or straps,ARP studs in mains ,arp cap screw in good prepared forged rods ,something like C&A bearings ,high quality pistons ,good solid roller cam with maching springs & kit will live at that level.when i say Live engine producing this much horsepower has a SHORTER life than say 400 hp Also i think a $1500 assembly will not cut it.

[1932bantam]

way to much mass out front blower is already puttn a strain on the end without that damn big counter weight on the end of the crankhub then adding pulleys to turn other things really puts it out there. externally balanced I stay away from. blown or not

[F-BIRD'88]

No the 8-71 is not too big. Strokin: how much horsepower is enough....