SB64

Okay car is or was a 350/300 bored 30 over with a mild cam(do not know lift or duration. I purchased a new damper and I ordered for a 350/300. The left is what was on the car the right is new one.


The reason for new was because the one on the left has a speedy seal (never heard of that ) Thinking new would be better. The larger goes to a 350/350 hi perf. Thought maybe because of the 30 over and cam that someone went with a HP damper. Boy am I confused and wonder if damper on left is ok to use. ANYONE PLEASE HELP ME
R

74modified

The sleeve on the old balancer is for repairing any scoring to prevent leaking from the front cover seal. If it is not leaking it is OK. The balancers are two piece with a rubber bond in the center. If the rubber is not in good shape, the outer ring could move or separate --- otherwise not much to go wrong.

Cavu2u

If you use the one on the left, and your timing cover is built for the balancer on the right, the left balancer will not fit because of the timing tab that's attached to the cover. The larger HB will hit it as you try to put it on the crank.

Steve

Cavu2u

Like this (Old on top--New on bottom):

c69vete

Either one will work as long as they both are for a 350 engine.
On the original one, if the outer ring has slipped, it will throw the balance off, and will not time with the marks.
Going to the smaller one would require you to buy the bolt on timing tab to use the smaller one.

SB64

I did have to replace the timing cover because bubba messed up the tin inside with a screw driver where the seal sits. That's probably why there was a lot of oil on the front of the engine. I got the timing cover with the welded timing chain will the smaller one work???? So I could stick with the orig, and clear the timing mark.

CaseyJones

You need to use the balancer that matches the timing cover. There are 6 inch and an 8 inch balancers so the cover needs to accommodate the balancer it was built for. Don't use a six inch balancer if your cover is for an eight inch one. The distance from the crank centerline to the timing tab should be slightly more than half the balancer diameter.

REELAV8R

According to David Vizard up to 6000 rpm your best damper for power and valve train control is the heaviest one available.
Use the one on the left.

SB64

I have reordered the one on the left and will get it next week
Thank you everyone for your major help. GO FORUM

persuader

I just checked mine and its a 6 1/2. I thought that it was suppose to have an 8 inch. Does anyone here have the definitive answer?

SB64

what engine???

SB64

Timing cover exactly like the damaged one, therefore I will go with the larger unit that came off the car, like you are suggesting.

Cavu2u

High Performance and trucks, like the C10 during the 70's, had the bigger one.

gcusmano74

Well, correct me if I'm wrong, but I always thought the large balancers went on the forged crankshafts, and the small one was used on a cast crank.

persuader

My car is a 77 w/ Sbc.

cardo0

For any '69 & later 350 dampner i get a 6.75" dampner with the timing mark 10 degrees before the crank keyway and has part #6272221 - $50. Also new part #12551537 - $75.

While all the Hi Perf 350" '70-'74 had 8" dampner with the timing mark 10 degrees before the crank keyway and has part number #6272224 - used on ebay. This is verified in my Chevy Power Book and would be the first choice but no longer available.

Also verified in my Chev Pwr Bk is the Heavy Duty off road 8" dampner with timing mark 10 degrees before crank keyway and has part #364709 - copied by professional products $75. This was the better product when built by GM. PPs ???

Dont use the #6272225 which is external balanced for the 400" blocks.

Make sure your timing mark is 10* before the crank keyway (2* is the wrong location unless u have a '68 or earlier).

Hope this helps,
cardo0

chstitans42

Are these two balancers for sbc or bbc engines? Just curious the difference besides the size

REELAV8R

8" is what I pulled off my stock 77 motor.

Cavu2u

These are the smaller balancers, made for the standard, or base, small block (350).

gcusmano74

'77s all had 350 engines. The base engine (L48) probably had a cast crank, and the high performance (L82) was supplied with a forged crank.
If you can ever look at the parting line on the crank, a cast crank has a very thin parting line, maybe 1/16", where the edges of the mold were.
A forged crank has a much thicker parting line, perhaps 1/4" wide, sometimes with grinding marks on it.
For a street engine at typical RPM ranges, a cast crank is perfectly adequate.