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Author Topic:   Sbc Questions
Rookieracer76
Dirt Maniac

Total posts: 182
posted October 13, 2002 02:53 PM
I'm not too good when it comes to motors so i have a few questions.

Are all sbc parts conpatiable ? (like 305,350,383 and 400)

Would putting 400 parts in a 350 block make more power? is it worth it?

what makes a stroker motor ?

Any help is appreticated! Thanks to any help

carscomefirst
Dirt Full Roller

Total posts: 45
posted October 13, 2002 09:45 PM
Rookie, with the right machine work almost every part in SBC's will interchange. Pistons don't swap, dont use 400 rods(5.56") in anything. 305's and 350's use the same stroke(although there might be a ballancing issue when swapping them). 383's & 400's use the same stroke(turn a 400's mains to 350 size and you have a 383 crank). 350's and 305's use the same rods. Heads will interchange on all sbc's, but watch clearances if using large valves on a 305.
Stroking a motor is when you a crank with longer stoke than stock. Such as a 400 crank in a 350 or 305 block. By the same means, you can destroke a motor. Ie a 350 crank in a 400 block. When stroking a motor watch for clearance between the rods and the block, camshaft, oil pan, and bottom of cyls.
I believe that there are 3 differant size mains that came stock on a sbc. 1 (400)2 (350,305,&late 327's)3 (early 327 and 283's). I don't know much about the 262 or 267 ci sbc.
All sbc's EXCEPT 400's and 383's are internally ballanced. The 400 and 383 are Externally ballanced.
I am a firm believer in ballancing all motors for use in racing. It cost a little more to have it done, but I fell it is money well spent. A good machine shop can convert an external ballance motor to a n internal ballance.
While parts interchange from 1 size to another some years are a little different. I think that 69-80's interchange. 81-85 use rh dip stick block.(different oil pan) 1986 is all by its self.(1 pce rear main and early valve covers) 87-95 1 pce rear main, center bolt valve covers, and different intake manifold bolt angles. 96 up vortec heads.
I hope this helps. sorry so long.

Rookieracer76
Dirt Maniac

Total posts: 182
posted October 13, 2002 09:53 PM
carscomefirst, thanks that helped alot. one more question. is it better to stroke or destroke a motor? whats the advantage ? Thanks !

rico 08
Dirt Freak

Total posts: 372
posted October 14, 2002 12:54 PM
STROKED MOTORS WILL HAVE MORE BOTTOM END TORQUE THIS HELPS IN HEAVIER CARS BUT IN LIGHTER CARS THEY CAN BE HARD TO GET OFF THE CORNER WITH SAME CAM-RPM RANGE. DESTROKED MOTOTS ARE JUST THE OPPOSITE AND LIKE MORE RPM AND USUALLY HAVE LESS BOTTOM END AND MORE ON TOP.

Rookieracer76
Dirt Maniac

Total posts: 182
posted October 14, 2002 06:09 PM
so if i put 400 sbc chevy parts in a 350 block would it be a 350 stroker ? Also why arent pistons interchangeable ? Thanks !

[This message has been edited by Rookieracer76 (edited October 14, 2002).]

jhon hollomon
Dirt Maniac

Total posts: 181
posted October 14, 2002 08:53 PM
If you put a 400 crank in a 350 you get a 383 stroker. Bore size restricts interchanging of most pistons.

carscomefirst
Dirt Full Roller

Total posts: 45
posted October 14, 2002 08:57 PM
There are +s and -s for both stroking and destroking a motor. One main factor is cost. To stoke a 350 w/a 400 crank you have the added expence of turning the mains and buying a 400 flywheel(or ballance plate) and ballancer. Destroking a 400 block w/a 350 crank you have to buy special mains or bearing spacers. I have never run a 377.(400 block 350 crank) but have heard good things.
If you us a 400 crank in a .030 350 block it is a 383.
Pistons are not interchangable due to different bore sizes and wrist pin locations.
I prefer to run a sb400, however my best motor is a 385 stroker. I've had good luck with the 3.75 stroke motors but, I only turn about 6000 rpm.
If you are looking for max power pay close attn to the heads that you use. pay attn to the track rules. At the track I run you have to us a "stock head" w no porting or polishing. This allows the use of double humps, vortecs, and BOWTIES. Guess what I use.
Good luck.
#13

Rookieracer76
Dirt Maniac

Total posts: 182
posted October 16, 2002 08:42 PM
If i put a 400 crank in a 350 block with 350 flat top pistons, what rods do i use ? Do i use 350 connecting rods or 400 ? is one better then the other ? Is a longer rod better ? Thanks !

c21
Dirt Freak

Total posts: 346
posted October 17, 2002 11:19 AM
Normally you will select a piston with the correct compression height to work with the rod length/stroke you have chosen.

a 6" rod or longer is a good choice for a 3.75" (400) stroke motor.

to find compression height, multiply the stoke times 1/2 (3.75 x .5 = 1.875) add the length rod you want (6.125" sounds good) and then subtract these two numbers from your deck height (stock is 9.025", -8.000 = 1.025") and you will come up with the "compression height" of the piston you are looking for (+ 0, - up to .025" or so).

clear as mud?

c21

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