<VV> Balancing engine and higher shift point for PG

[Bruce Schug]

On Sep 18, 2006, at 4:23 PM, Edelstein and Payne wrote:

> Folks,
>
>        I have 2 queries:
>
>        1.  Finally getting ready to put the motor together.  We 
> ordered barrels , pistons and rods from Clarks, and I had Clarks 
> install the rods on the pistons.  Talked to my favorite machine shop 
> about having them balance the crank, rods, pistons, etc.  They said 
> that Clarks should have sent a balance card with the pistons and rods, 
> showing reciprocating and rotating weights.  Otherwise, they would 
> have to press off at least one rod and were concerned about distorting 
> the piston.  I e-mailed Clarks and they said they didn't have the 
> weight information and that anyway it wasn't necessary to have the 
> reciprocating assembly balanced becuse of the short stroke of these 
> motors.  What do others think?  I've always balanced motors from other 
> vehicles that I've rebuilt.  Is it really unnecessary with Corvairs?

Others have answered your balancing question. certainly a lot of 
Corvair engines have been built without balancing. They do tend to run 
smooth because of being opposed engines. If you're not going to rev the 
engine you probably can get away with it but if you're trying to build 
this engine right, balance it. You'll be glad you did.


>
>      2.  The car my 17 year old son and I are doing for him is a 65 
> Monza coupe.  It was a 110/powerglide car.  We've bought some 140 
> heads that we've had throughly re-worked, the motor will be .060 over, 
> have an Otto 10 cam, and roller rockers with Isky springs.  I've 
> learned that the governor in the powerglide for the 110 motor has a 
> maximum shift point of only 4060 RPM.  The governor for the 140 
> powerglide only goes up to 4600.  The way we'er building the motor, it 
> would be okay to rev it to 6000 occasionally, and I would sure like a 
> shfit point under full load of at least 5200 rpm to make full uyse of 
> the motor's power band.  Clark's does not even have the 140 governor.  
> Does anyone re-build corvair powerglides and modify the governors for 
> a higher shift point?
>

I wanted to comment on the mixture of components you're using for your 
engine. The most important thing in building an engine is selecting 
compatible components. I question your choices here.

You're putting reworked 140 heads on this engine, which was a 110. I 
don't know what you mean by "reworked" but the heads don't sound 
compatible with an Otto 10 cam. This sounds like a pretty mild cam for 
a set of 140 heads - probably milder than the stock 140 cam. You didn't 
mention it, but I presume you're keeping the 110 crank, which is not a 
Tuftrided crank like a 140 would use. It is also not a 140 Powerglide 
crank which would be more suited to a 140 Powerglide combination.

You've spent the money on roller rockers. This is good, but may be 
wasted at the low shift points you mention. Even 5,200 rpm is pretty 
low for a set of 140 heads - if they have an adequate cam.  Likewise, 
do you really need Isky springs with a cam this mild and with the low 
rpm you're talking about? I would think that unless you're going over 
6,000 the Isky springs aren't necessary.

I don't know much about Powerglides. I wish someone would answer your 
question about the PG governors. I'm copying David Clemens on this 
email. He has some experience with a high-performance engine with a PG 
with a modified stall speed. Maybe he can advise you on the situation 
with your governor.

For your information, my 140 uses a 140 crank, Isky 280 cam with Rhoads 
lifters and stock rockers. The heads were cc'd and the engine balanced. 
It revs as high as I'm comfortable revving it and is still as smooth as 
can be. Typically, I use a 6,600 rpm chip in the MSD 6AL. I have over 
50,000 miles on this engine with no failures. It is a joy to drive 
pulling like crazy over 2,500 rpm. It is a 4-speed car, which makes a 
difference.

Be sure you use a good ignition system. The MSD does make a difference.

Good luck!

Bruce

Bruce W. Schug
CORSA South Carolina
Greenville, SC
bwschug at charter.net

CORSA member since 1981

'67 Monza. "67AC140"