Hot Rod Forum banner
1 - 20 of 41 Posts

·
Registered
Joined
·
83 Posts
Discussion Starter · #1 · (Edited)
Please Help Tonite!!

ok guys so i have a 66 427 that im taking to the machine shop tomoro and i need help deciding wether i should bore it .030 over and stoke it .25 or wether i should keep stock bore/stroke? if i do bore and stoke it will i need to get new heads? if so what ones?

thanks
jacob
 

·
Registered
Joined
·
3,518 Posts
The machine shop will tell you how much it needs to be bored, it may already be .030 or even .060 right now. You won't know till they mic the block. As for buying a stroker crank...sure you can but you're 17, just build a good reliable performance engine without going crazy. Also, you should buy a book like "How to Hot Rod a Big Block Chevy" gives you all kinds of good info.
 

·
More for Less Racer
Joined
·
20,926 Posts
Changing to .250" longer rods doesn't change a thing as far as cubic inches goes, just the rod-to-stroke ratio is changed. The pistons compression height is shorter to compensate, usually making the pistons lighter.

The .060" overbore makes a 438.85 cubic inch engine using the stock 427 crank.

Formula for a 8 cylinder engine is: Bore x Bore x Stroke x 6.2832 = cubic inches.
 

·
Registered
Joined
·
83 Posts
Discussion Starter · #6 ·
ok so i would have to get a new crank to stroke it .25 than right? if so what else would i need?

so about what compresion would that be if a ran stock height pistons and open chamber heads, if that makes a dif?
sorry if im askin dumb questions just new to this stuff

thanks
jacob
 

·
More for Less Racer
Joined
·
20,926 Posts
Yes you would need a new crank to stroke it .250",...a 454 crank. The 427 has a stroke of 3.76", the 454 has a stroke of 4.0". Because the 454 and 427 share a block(same factory bore size), all you would be doing is turning it into a .060" overbored 454 if you stroke it .250", which makes it a 468. If you are going to buy a crank to stroke it, buy a 4.25" crank, this will make a 496 out of your 427 block. All you have to do is buy pistons that match the bore size, stroke, and rod length, and are cofigured on the crown(dome, flat, or dish) to give the compression ratio you want.

There are too many different "stock" piston crown types and open chamber head true sizes to give you a # for the compression ratio, You have to do the math once you pic a parts combo for the crank, rods, and heads in order to know what piston will give you what you need.
 

·
More for Less Racer
Joined
·
20,926 Posts
Can't recommend a piston until you know what head you are using(so that you know chamber size) and what compression ratio you are seeking. You will also need to know what rod length is needed for the crank you are using(some stroker cranks allow the use of stock length rods, some need longer rods to clear the bigger counterweights).
 

·
More for Less Racer
Joined
·
20,926 Posts
56chev100 said:
http://www.summitracing.com/parts/LUN-BP425IN/ and with this crank

and what length rods should i use cause the crankshaft is clearanced for 5.7 in. but the shortest ones on summit are 6.135??
Because i know what I am looking at, I can tell you that that is an obvious misprint. There are no BBC rods shorter than 6.135", the 5.7" rods are Small Block rods. Don't rely on Summit for information, their web catalog has lots of these info misprints. Take the part # and description and look it up directly from Lunati for the correct info.
 

·
Registered
Joined
·
286 Posts
unlimited supply of money? 427 rebuilt would be a blast if the crank is
re-useable, 454 would have more torque. 496 would have even more torque.
Short rod 454/496 will havebettertorque and less chance of detonation.
Long rod will generally rev higher.
Unlimited supply of money? Some great rotating assembly kits on the web with pricing less expensive than having a machine shop rebuild your original stuff. You have to know what you have and what you want to end up with before making the choice!
 

·
Registered
Joined
·
286 Posts
that would do it for me! Mine is just a cast external balanced rotating assy however it came balanced and flexplate and harmonic balancer. All depends how crazy you want to go, how far you want to push it. Mine is pulling just under 500hp at 5000RPM @ 2300' asl. rPM Limited by propeller load. The one I built is pretty much this one: I sure wouldn't mind the one you pointed out.
http://www.cnc-motorsports.com/product.asp?ProdID=20550&CtgID=20548
 
1 - 20 of 41 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top