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Username Post: 400 cu. in Flywheel question        (Topic#343576)
1980 MALIBU 406 CU. IN. 
Forum Newbie
Posts: 11

Reg: 03-26-17
03-26-17 06:48 PM - Post#2683541    

I have a 406 cu. in. small block chevy in my Malibu.
The motor was built with a 350 crank so I believe it is now an internally balanced motor?
The harmonic balancer is smooth on both sides with no weight or different size cut outs on it.

I have an aluminum Flywheel that was for the 400 cu. in. Externally balanced engine.

My question is, Can I remove the counter weight that is bolted on the back side of this flywheel with 2 bolts and use it on my internally balanced small block engines?




 




grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17104
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
03-26-17 07:20 PM - Post#2683547    
    In response to 1980 MALIBU 406 CU. IN.

you may be able too, but the issue of how the flywheel is balanced does differ between manufactures, (no I don,t have a list) on some the weights can be removed to get neutral balance, on some the external weights NOT the only difference in the flywheel balance
personally ID call the flywheel manufacture and ask... and yeah! you might need to have the assembly balance and use the flywheel. but a good machine shop that does engine balancing should be easily able to test and get that flywheel to meet the factory balance specs.
obviously it would help if you know or have the balance sheet and know the bob-weights the 350 crank,rods,pistons,rings, bearing and piston pins have, that were used



http://garage.grumpysperformance.com/index.php?thr...


http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 03-26-17 07:38 PM. Reason for edit: No reason given.

 
raycow 
Honored Member
Posts: 26932
raycow
Loc: San Francisco, CA
Reg: 11-26-02
03-27-17 10:08 AM - Post#2683636    
    In response to 1980 MALIBU 406 CU. IN.

How were you able to build a 406 cu in engine with a 350 crank? That would need about a 4.31" bore.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17104
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
03-27-17 01:39 PM - Post#2683668    
    In response to raycow

(thats a good point) and he should have made that clearer,
I was assuming he meant the engine he has was a 350 crank, being used with main bearing spacers in a 400 block (377) (a common engine build for performance)

Chevy V8 bore & stroke chart

CID BORE STROKE
262 = 3.671" x 3.10" (Gen. I, 5.7" rod)
265 = 3.750" x 3.00" ('55-'57 Gen.I, 5.7" rod)
265 = 3.750" x 3.00" ('94-'96 Gen.II, 4.3 liter V-8 "L99", 5.94" rod)
267 = 3.500" x 3.48" (Gen.I, 5.7" rod)
283 = 3.875" x 3.00" (Gen.I, 5.7" rod)
293 = 3.779" x 3.27" ('99-later, Gen.III, "LR4" 4.8 Liter Vortec, 6.278" rod)
302 = 4.000" x 3.00" (Gen.I, 5.7" rod)
305 = 3.736" x 3.48" (Gen.I, 5.7" rod)
307 = 3.875" x 3.25" (Gen.I, 5.7" rod)
325 = 3.779" x 3.622" ('99-later, Gen.III, "LM7", "LS4 front wheel drive V-8" 5.3 Liter Vortec, 6.098" rod)
327 = 4.000" x 3.25" (Gen.I, 5.7" rod)
345 = 3.893" x 3.622" ('97-later, Gen.III, "LS1", 6.098" rod)
350 = 4.000" x 3.48" (Gen.I, 5.7" rod)
350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
364 = 4.000" x 3.622" ('99-later, Gen.III, "LS2", "LQ4" 6.0 Liter Vortec, 6.098" rod)
376 = 4.065" x 3.622" (2007-later, Gen. IV, "L92", Cadillac Escalade, GMC Yukon)
383 = 4.000" x 3.80" ('00, "HT 383", Gen.I truck crate motor, 5.7" rod)
400 = 4.125" x 3.75" (Gen.I, 5.565" rod)
427 = 4.125" x 4.00" (2006 Gen.IV, LS7 SBC, titanium rods)

Two common, non-factory smallblock combinations:

377 = 4.155" x 3.48" (5.7" or 6.00" rod)
400 block and a 350 crank with "spacer" main bearings
383 = 4.030" x 3.75" (5.565" or 5.7" or 6.0" rod)
350 block and a 400 crank, main bearing crank journals
cut to 350 size

ALL production big blocks used a 6.135" length rod.
CHEVY BIG BLOCK V-8 BORE AND STROKE


366T = 3.935" x 3.76"
396 = 4.096" x 3.76"
402 = 4.125" x 3.76"
427 = 4.250" x 3.76"
427T = 4.250" x 3.76"
454 = 4.250" x 4.00"
477= 4.5" bore x 3.76" stroke
496 = 4.250" x 4.37" (2001 Vortec 8100, 8.1 liter)
502 = 4.466" x 4.00"
557T= 4.5 bore 4.375" stroke
572T = 4.560" x 4.375" (2003 "ZZ572" crate motors)

T = Tall Deck

ALL production big blocks used a 6.135" length rod.

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 03-27-17 01:55 PM. Reason for edit: No reason given.

 
1980 MALIBU 406 CU. IN. 
Forum Newbie
Posts: 11

Reg: 03-26-17
03-29-17 02:23 PM - Post#2684056    
    In response to grumpyvette

The 406 cu. in. in my Malibu was built by a shop near my house.
I am not sure if he used the crank spacers or not, but I do know now that it is "Internally" balanced.
It is a 400 block and was bored .030 over.
I ordered a new Aluminum 11" flywheel for it (American Powertrain Part# FWCV-20002) from Summit for a (400 cu. in. Externally Balanced engine)to replace the old, cast Iron one not realizing that the 400 he built for me was internally balanced.
After the swap, it vibrated like crazy!
I took the trany back out and then realized it was a "Bolt-on" counter weight.
The new clutch that I ordered with it was a Center Force "Dual-Friction" DF148552 Part #183-DF148552.
Maybe I should have bought a Center Force Aluminum Flywheel($650.00)to match the Center force dual friction clutch but now that I have this one, they want $120.00 re-stocking fee (and that is only if it shows no signs of wear and not used) It was bolted to the engine and started in my garage so I know there are some bolt marks on it.
I am hoping that I can just remove this counter weight and have a Neutral balance flywheel and use it on this 406. cu. in. internally balanced engine. This motor put out 510 HP. on his engine dyno.
Is there a specific amount of weight added to all manufactures flywheels that are used to balanced the 400 cu. in. chevy mouse motors? or does this vary from motor to motor or flywheel manufacture to manufacturer?
If I know this, I can weigh the counter weight and screws that I just removed from this flywheel to see if it adds up?



 
raycow 
Honored Member
Posts: 26932
raycow
Loc: San Francisco, CA
Reg: 11-26-02
03-31-17 07:19 PM - Post#2684437    
    In response to 1980 MALIBU 406 CU. IN.

All flywheel weights for a factory 400 crank should be the same. If your weight is a separate piece, just put the flywheel back on without it and bolt everything together.

To avoid this problem when you buy parts in the future, just tell the vendor you have a 377 engine (which you do) and NOT a 406. Whoever told you that you have a 406 should not be allowed anywhere near your car with tools.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
1980 MALIBU 406 CU. IN. 
Forum Newbie
Posts: 11

Reg: 03-26-17
04-04-17 02:52 PM - Post#2685006    
    In response to raycow

This is a 400 Block bored .030 over with a stroked 350 crank.
It is a 406 cu. in. but internally balanced motor.
All is good now that I have removed the counter weight off the flywheel.
Ye! Hawaaa!
Thanks for everyones input!



 
raycow 
Honored Member
Posts: 26932
raycow
Loc: San Francisco, CA
Reg: 11-26-02
04-05-17 09:56 AM - Post#2685116    
    In response to 1980 MALIBU 406 CU. IN.

Ahhh, a stroker crank. That explains a lot.

I'm glad to hear that removing the weight was all it needed. Thank you for the feedback.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
bobb 
Super Senior Member
Posts: 5317
bobb
Loc: paradise
Reg: 09-05-03
06-20-17 08:22 PM - Post#2696857    
    In response to raycow

is it possible to stroke a 350 crank that far out???

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
raycow 
Honored Member
Posts: 26932
raycow
Loc: San Francisco, CA
Reg: 11-26-02
06-24-17 12:06 AM - Post#2697268    
    In response to bobb

Possibly, but I can't see why anyone would want to stroke a 350 crank if it were to be used in a 400 block. The stroke would need to be about 3.74, which is almost the same as a stock 400 crank, and if you use a 400 crank instead, you won't need to deal with the main bearings. To put it another way, if you bore a 400 block .030, you get a 406 with the stock crank.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 




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