BBC 396 to 434 stroker [Archive] - Chevy Nova Forum

: BBC 396 to 434 stroker


68ctnovabb
29th-July-2010, 07:50 PM
Has anyone had any experience with or opinions on stroking a 396 to 434? I've seen 2 kits online (speed-o-motive and wheeler) but not much info about results or tests. I did read an older article where the engine put out some good torque but lower hp than I would have thought. The chevelle sites have some info but I'd love any input from here.

My 396 is tired and ready for a rebuild, but I want to keep the block as unmolested as possible. I'm also not interested in swapping to a 454 even though I know that would save some $ and make more power. My car is a 4sp and would be more of a street machine, so I'd really be looking for good low end torque rather than hi rpm hp.

Thanks!

Chris

levisnteeshirt
30th-July-2010, 12:11 PM
makes a piston for that ,,, i'd do some checking myself before i bought someone elses kit

Bad69Nova511
30th-July-2010, 02:00 PM
If you're looking for torque then there's no substitute for c.i. The 454 will make more low end grunt then the smaller 434. Plus whatever heads you use will flow a lil bit better because of the bigger bore. Have you ever thought of destroking a 454? I know that goes against what I just said but. 4.280 bore x 3.76 = 432.76 or 433 . Just food for thought . If you're interested in destroking a 454 PM me I might be able to help. Good Luck which ever way you go

Gary

68ctnovabb
22nd-August-2010, 05:54 PM
Thanks for the input Gary. I am most likely looking to stick with my 396 block, but havent made any definite plans yet. Just looking into all my options. I see you're in Chicopee. I work in that area and keep wanting to make it to the cruise on thursdays (not sure the name). You been to that one?

Anyway hope to run into you at a show or on the road. Your Nova is a beauty.


Chris

Paul Wright
22nd-August-2010, 06:47 PM
October 2010 Car Craft has an article on a 396 to 461 stroker may be just what you may be looking for. They use a 4.25" crank with small block 4.155" custom ($900) Ross flat top pistons sporting BBC valve notches hung on 6.385" rods.
They guessed 425 hp and 500 lb/ft.

I noodled around with another combination using an off the shelf piston CH (still need to machine the notches for splayed valves).

4.155" pistons with 1.25" CH (3.5" stroke 6" rod), BBC 6.535" rods and a 454 crank (4" stroke) for 434"

You can buy a used 454 engine for about what the custom pistons cost.

68ctnovabb
22nd-August-2010, 07:58 PM
I literally just read that article. :yes: I saw the 396 mention on the cover and had to pick it up. It was an intersting read, but a little different than what I had in mind. I was looking to use aluminum heads and maybe not quite as big of a stroke (4 inches max) and not so much over-boring (4.126) for a total of around 427ci. I'd also like to keep the engine internally balanced. The 461ci in the article I assume has to be externally based on how big they went with things. But the price of squeezing the extra cubes out of my 396 (1966 block) does make me take a hard look at the good old 454.

I'm far from an expert in engine building so I'm learning a lot while researching this idea. It was interesting to read how the small bore of the 396 can be such a restriction to performance. I still have to sit down with my engine shop to see what they think.

Thanks for the input!

Chris

levisnteeshirt
22nd-August-2010, 08:47 PM
here is the link to the " 434 " KB pistons

http://www.jegs.com/i/Richmond+Gear/836/79-0099-1/10002/-1

4.185 works out to 440 ci ,, thats a .090 396 ,, i had a friend that took one .090 and it did fine ,, ,, they list them at 4.125 stock , thats starting out with a 402

68ctnovabb
22nd-August-2010, 09:08 PM
I think if my 396 is untouched it would be 4.094 stock bore. Its good to hear the blocks can handle 0.090 but I probably won't go that far. For my driving I'm sure just a nice 396 would be more than enough. Of course bigger can be more fun. :yes:

levisnteeshirt
22nd-August-2010, 10:26 PM
i tell ya ,,, i've saw some fast 396's , nothing wrong with a 396 at all

look how mild this one is in this video ,, 557 hp ., 500ft lb ,, 9.75 -1 comp

http://www.youtube.com/watch?v=M61ZPqGQovQ

Paul Wright
23rd-August-2010, 10:30 AM
here is the link to the " 434 " KB pistons

http://www.jegs.com/i/Richmond+Gear/836/79-0099-1/10002/-1

4.185 works out to 440 ci ,, thats a .090 396 ,, i had a friend that took one .090 and it did fine ,, ,, they list them at 4.125 stock , thats starting out with a 402

?That looks like a ring and pinon, not a piston and ring

JamesC459
23rd-August-2010, 10:19 PM
You can probably build a cast crank,truck rod hyper piston 496 for less than that 434 and have ample torque down low to mid. CUBIC INCHES MAN.

bigblockbob427
23rd-August-2010, 10:34 PM
How about putting your crank & rods in a 454. Buy what compression ratio pistons you want & keep it all internally balanced. Use your balancer & flywheel(flexplate). I ran a 396/408 for 30 years. I love my 427.

68ctnovabb
24th-August-2010, 12:07 PM
Thats an interesting idea about putting my rotating assembly in a 454 block. Never really thought about that. I suppose I could sell my 396 block, but for some reason I've become attached to it.

My first step really should be checking out the condition of my block before I even make any other plans. I currently have 781 casting heads on it but it really lacks the power I would like. Not completely sure why. I must say that it sounds great the way it is, just wish it backed up that bark a bit more.

What type of heads did you run on your 396/408 bigblockbob?

Did you ever have it dyno'd?

Thanks.

Chris

zman1969
24th-August-2010, 01:46 PM
You can probably build a cast crank,truck rod hyper piston 496 for less than that 434 and have ample torque down low to mid. CUBIC INCHES MAN.

X2 If i decide to build a BB again I'll make it a SS496! :rolleyes:

levisnteeshirt
24th-August-2010, 04:56 PM
?That looks like a ring and pinon, not a piston and ring

twice this has happened ,,

http://www.kb-silvolite.com/kb_car/performance.php?action=details&P_id=110

68ctnovabb
24th-August-2010, 07:40 PM
Using the free (and oversimplified) Camquest6 software from compcams I ran a basic setup using different bore and stroke combos for my 396. Some assumptions are Edelbrock Performer RPM heads and comp cams XR276HR hydraulic roller cam for all combos.

Stock bore and stroke (396ci) gave me 471 ftlbs @4k. I'd be happy with that any day. With the stock stroke I then increased the CI to 402ci and 408ci (bored 0.030 and .060 over) with resulting torques of 477 and 482 both at 4K.

When I increased the stroke to 4.00 inches (421ci, 427, 434) the resulting torque jumped to 491, 497, and 502 repectively all at 4K. Thats a nice little bump.

Then just for kicks I ran it again with a stock 454 block and rotating assembly and torque jumped to 518ftlbs at an even lower 3500 rpms.

I'd be happy with any of those results.

These numbers are far from real world and are probably more useful for relative comparisons only, but I thought I'd share my info. :)