What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

4x4high...give me direction

blazin_blazer

blazin_blazer

1/2 ton status
Joined
Aug 2, 2005
Posts
4,040
Reaction score
1
Location
central arkansas
I've read about using a 400sbc block & crank to make a 427 cid sbc

basically, you turn down the 400 rod journals to 2'' sj size ..removing material only on inside of the throw..like this











427sbc.jpg


then use sj rods(nascar rods 1.88''), so should be ok at 2'' and a .040 or .060 overbore block, can't remember which.. supposed to be 427(whats the math to figure cid w/bore&stroke)....

but I'm curious as to what piston to use, the build up i read used off the shelf pistons but don't know which(and i can't find the article)

and i need to find a machine shop that understands what I'm talking about! would the rods &/or oil pan rail need to be clearanced for this? i have everything to do this, except pistons...can it be done? what kinda cash are we talking since i already have 400 and a set of sj rods? shouldn't be to terribly much more than just machine work ...would it? i just need some1 who knows whats going on!
 
small block f*rds have a combo that makes a 427ci windsor. the ford combo involves using a 400m crank (4.00 stroke) with a 351 windsor block. the 400m crank is ground to increase the stroke to 4.125in, i think the term is offset ground. combined with a .060 overbore, the engine displaces 427ci. i would assume that the chevy version would be much the same, might have slightly different dimensions. any competent automotive machinist should know what you are talking about.
 
big bucks to do it right, plan on $3k+ to have it done right so you can shove it in and never worry about it. That is just for machining thought. Good friend of mine just freshened up his motor which meant rechecking and fluxing every surface of the block to the tune of $2500. But the guy that did it builds alcohol dragsters for a living sooo.... Anywho, his combo is a 434 ci sbc running 600+fwhp, with a 100 shot on it, backed by a stage 4 bto 700r4 and a built 8.5" 10 bolt rear, all in a sweet little 71 camaro ss clone that has had a ground up resto. Let me see if I can find a vid. Oh yeah I say do it, bad-a motors fo sho.

http://www.brazosvalleystreetbeasts.com/albums/displayimage.php?album=random&cat=0&pos=-361
here it is, couldnt find a good pic, but it gives a good idea of the quality of this car..oh yeah sorry for my ugly mug in the way....drool. most people dont believe this is a 10.1-1/4mile car (without the nitrous) until they see it run.

Remington
 
Last edited:
yes, it is called offset grinding, but none of my local machine shops have ever heard of doing it!

btw, thats a beautiful car...70 1/2 my 2nd fav car(i love the split bumper look) #1 69 camaro
 
Math for displacement (for a V8, all dimensions in inches)

Cid = 2*3.1415*(Bore^2)*Stroke

So 2*3.1415*(4.185^2)*3.85 = 424 cid

(4.185 bore is a 0.60 over 400 block)

BTW, if you take 0.100 of the crank by offset grinding, you can't quite get a 0.100 stroke increase. Some of that is needed for cleanup, you might get a 0.080 stroke increase.

You would have to select pistons for the correct bore (shouldn't be too hard) and with the correct compression height with the rods you use (might be tougher).
 
Ok, let me first give you the formula to figure out cubic inch displacement.

Bore x Bore x Stroke x .7854 x number of cylinders = cubic inches

Here is a nice calculator that figures it out for you with a few inputs. http://kb-silvolite.com/calc.php?action=disp

Now, onto the question at hand. You can only offset grind a SBC 400 crank enough to gain about .080" of stroke and that's using .040" undersize rod bearings. If you offset grind the journals to standard size you can only gain .040-.045" extra stroke. With a 400 block bored to a max of .060" overbore and offset grinding the crank using a .040" rod bearing you will only end up with a 421 CI engine and no room for future crank grinding or for a rebore. You will also have to use a special piston since the 5.7" length rod is going to push the piston upward an extra .215" and to be honest i don't think you can even do that so that means a special rod will be needed along with a special piston to come up with the correct combination to get the piston to the top of the cylinder without going beyond the deck.
 
can the 5.5 400 rods big end be resized to the sj 2''? just a thought for ideas...the link in post #3 tells of rods and pistons that may work
 
You cannot make a large hole smaller. :haha:

Also the 400 rods are 5.565" in length
 
i thought if you surfaced the cap enuff, that it may could be bored or honed to 2'', or would it take off to much

i knew 5.565 i was being lazy and knew you would know what i was talking 'bout
 
"Clipping" the cap will change the ID bore diameter by a few thousanths of an inch. It is impossible to remove enough material to make a 2.225" diameter hole 2.125"
 
I wouldn't even bother with using a stock cast 400 crank , and paying for machine work .... not in todays world . For the cost of all the machining ( plus or minus ) to get your old stock stuff there , you can buy a complete kit with forged stuff :D

I found a good 400 crank , I think I am keeping it to say I have one :wink1:
 
Get an aftermarket block from World products. Their 'smallblock' supports a 4.250" bore and 4.000" stroke...454 cid.

Rene
 
You must log in or register to reply here.

Latest Posts

Top Bottom