Harmonic balancer size question!
Thread Starter
Drifting
Joined: Aug 2006
Posts: 1,624
Likes: 2
From: Canandaigua New York
Harmonic balancer size question!
Hi, I'm fairly new here and have looked on the forum for anything regarding replacing a 6 3/4 inch harmonic balancer with an 8 inch.
My question is, can it be done without any detrimental effects to the engine.
I bought one fairly cheap from a 79' chevy 350 engine thinking that it was a 6 3/4 inch and it's not returnable so I just wondered if it can be used on my 84' vette.
In case you wonder why I need to replace it, the engine was stuck when I bought the car and my son-in-law welded a plate and bolted it on the balancer with a large nut so we could try to free the engine. Problem is, it already spun over once and stuck again and my son-in-law kept pulling on the bar in the same direction that the engine spins and 'broke' the balancer. Key way and all.
Thanks in advance.
Paul
My question is, can it be done without any detrimental effects to the engine.
I bought one fairly cheap from a 79' chevy 350 engine thinking that it was a 6 3/4 inch and it's not returnable so I just wondered if it can be used on my 84' vette.
In case you wonder why I need to replace it, the engine was stuck when I bought the car and my son-in-law welded a plate and bolted it on the balancer with a large nut so we could try to free the engine. Problem is, it already spun over once and stuck again and my son-in-law kept pulling on the bar in the same direction that the engine spins and 'broke' the balancer. Key way and all.
Thanks in advance.
Paul
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
Hi, I'm fairly new here and have looked on the forum for anything regarding replacing a 6 3/4 inch harmonic balancer with an 8 inch.
My question is, can it be done without any detrimental effects to the engine.
I bought one fairly cheap from a 79' chevy 350 engine thinking that it was a 6 3/4 inch and it's not returnable so I just wondered if it can be used on my 84' vette.
My question is, can it be done without any detrimental effects to the engine.
I bought one fairly cheap from a 79' chevy 350 engine thinking that it was a 6 3/4 inch and it's not returnable so I just wondered if it can be used on my 84' vette.
(ie: my '89 is neutrally balanced) then they can be used interchangeably.
The smaller diameter balancer will be lighter and the reduced inertia
will permit the engine to accelerate faster as if it has more power.
However, Davd Vizard has written that a heavier balancer generates
more measureable power on a dyno.
BUT - regarding fitting an 8" to your C4. Past threads suggest that
the 8" will require modification to a lip/edge on the cross member.
7-1/4" seems to be the upper limit without modifications.
Here is some discussion: Can a 7-1/4" OD Harmonic Damper be used w/o k-member mods?
Notice that Sami85L98 recommends an inexpensive 6-5/8" from
Summit. That is intended for an engine that is externally balanced
like a 400 SBC or a 383 stroker. I do not believe that damper is
appropriate for your internally balanced 350 - the SUM-C4265
might be more suited
Both of the above are SFI approved for racing. You can pay less
for a non-approved damper that will be fine for daily diver usage.
.
Thread Starter
Drifting
Joined: Aug 2006
Posts: 1,624
Likes: 2
From: Canandaigua New York
Thanks for the info and posting the link for me.
Unless I want to modify the crossmember, it looks like I just threw money out the window.
If I were 20 years younger, I probably wouldn't care and just go ahead and modify it. But at my age, crawling around under cars can only go so far before it's time for a break.
Unless I want to modify the crossmember, it looks like I just threw money out the window.
If I were 20 years younger, I probably wouldn't care and just go ahead and modify it. But at my age, crawling around under cars can only go so far before it's time for a break.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
You should be able to recoup most of your money by
reselling the 8" balancer.
They have their place and there will be demand.
Gotta say that if crawling under cars gets old quick,
then a seized '84 may not be the best project for you
and the S-i-L to bond on. Especially if he is prone
to twisting first and thinking after.
.
reselling the 8" balancer.
They have their place and there will be demand.
Gotta say that if crawling under cars gets old quick,
then a seized '84 may not be the best project for you
and the S-i-L to bond on. Especially if he is prone
to twisting first and thinking after.
.
Thread Starter
Drifting
Joined: Aug 2006
Posts: 1,624
Likes: 2
From: Canandaigua New York
You should be able to recoup most of your money by
reselling the 8" balancer.
They have their place and there will be demand.
Gotta say that if crawling under cars gets old quick,
then a seized '84 may not be the best project for you
and the S-i-L to bond on. Especially if he is prone
to twisting first and thinking after.
.
reselling the 8" balancer.
They have their place and there will be demand.
Gotta say that if crawling under cars gets old quick,
then a seized '84 may not be the best project for you
and the S-i-L to bond on. Especially if he is prone
to twisting first and thinking after.
.
The balancer is actually the least of my problems with this car since it spent a little time under water.(fresh not salt).
And as far as my son-in-law goes, he's a good kid, with a good heart, but sometimes thinking first and acting last just seems to elude him.
Finances being what they are, I'll probably see If I can do a trade with my local junk yard for the right one, for now.
Thanks again.
