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!40 HP Powerglide Cam
Posted by: JimBrandberg ()
Date: March 16, 2018 02:34PM

What do you like for a cam in a 140 PG? Installed at what Intake Centerline measured at the crankshaft?

It's a topic with plenty of opinions but I thought I'd see what people like. The engine is for a gal in a convertible. I don't think she's real sporty but I guess you never know. I think just regular driving in town and on the open road, no competition.

I may be off but I'm thinking the 889 has an Intake centerline around 104 when in a 95 HP and they retard it to around 108 in the 140 PG.
I'm thinking the 891 has an intake centerline around 110 Intake Centerline in 140 Manuals and all 110s. I'm wondering how it would run if installed at 106.
I'm thinking an OT-10, an Isky 260 and Isky 270 are usually around 108 Intake Centerline. What about one of these and installed at what Intake Centerline.
If my numbers above are off I'd like to know. I just never seem to have the time to check cams just for making a data base.

I'd prefer to think in terms of a specific Intake Centerline as measured, not just "4 degrees advanced" or "4 degrees retarded" if that's possible.

Some people seem to really like the 891 in most applications and some people don't like it at all for anything. What's up with that?

I did a search on here and it seems like the topic hasn't come up for a while. The last thread I could find was "Cam Assembly". I know I don't deal with 140 PGs in general very often. It's sort of counter-intuitive for me to put a lesser cam in an engine with better breathing.

In reading up, I discovered I don't have Bob Helt's book "Corvair Secrets". I thought I had them all and I'd better rectify that.

Jim Brandberg
Isanti, MN
CorvairRepair.com

Re: !40 HP Powerglide Cam
Posted by: gnvair ()
Date: March 16, 2018 06:06PM

The 891 cam was the camshaft that the early 65 140/PG's came with. You could always install a high stall torque converter to over come the lack of low end torque.

Lee J

Re: !40 HP Powerglide Cam
Posted by: Brizo ()
Date: March 16, 2018 07:26PM

Jim, Keep it simple. Use the 889 with the intake center retarded to 108 . It will have good cold start and idle,good take-off punch, run on 87 octane, and be easy to get a smooth in-gear idle. Inevitably, she'll be comparing it's drivability to modern cars so you want it to make a good impression. Unless she has owned PG Corvairs before, she probably wouldn't know the difference in power which ever cam you used.

Dan Brizendine,
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

Re: !40 HP Powerglide Cam
Posted by: dryenko ()
Date: March 17, 2018 07:49PM

Jim B ,
Try a 8304 cam with LC set 2 to 4 degrees ahead of straight up.
I built a 110 / PG LM coupe engine one time with this cam and timing, 140 exhaust tubes and manifolds into a big single exhaust.
Used a 330 distributor.
Ran like a bear.
With 140 valves size should be even better.
Fool everybody and use only two 1/8" oversize primary carbs,
No secondaries or linkage complications.
JMO
BC

Bob C aka Dryenko
Dobson, NC 27017



Edited 1 time(s). Last edit at 03/17/2018 07:53PM by dryenko.

Re: !40 HP Powerglide Cam
Posted by: JimBrandberg ()
Date: March 27, 2018 02:22PM

What about a 891 4 degrees advanced from straight up with a 2 degree cam gear key? About 106 Intake center.
GM must have tried that but decided to go with the 889 retarded instead.
I wonder if the 891 advanced 4 degrees just gets wheezy at higher RPMs, like just before it shifts?

Jim Brandberg
Isanti, MN
CorvairRepair.com

Re: !40 HP Powerglide Cam
Posted by: JimBrandberg ()
Date: October 03, 2019 09:36AM

I'm working on a 140 PG that's a little doggy. The owner built it with help from Larry's Corvair several years ago.
It has a Isky 260 cam. The cam card shows the Intake centerline at 111. Correct me if I'm wrong but if they were going to deviate from their usual 108 Intake center I think they went in the wrong direction.
If the numbers are correct and it's been installed with a 140 PG crankshaft it may be sporting a 115 Intake centerline.
I don't relish the thought of trying to check the cam timing with the engine in the chassis working with the dial indicator on the rocker arm and everything hanging sideways.
I'm nobody or nothing to be arguing with Isky Cam but I think my reasoning is okay.
The Isky 260 is essentially a 95 HP 889 cam which had an Intake centerline of 104 for good low RPM torque. When installed in the 140 PG they retarded it to 108 Intake centerline which surprisingly gave it pretty good low RPM torque for getting underway without getting too wheezy on the top end. I sort of gathered all that from a Bob Helt book.
If I'm not seeing things clearly please let me know.
Perhaps Larry's Corvair took all that into consideration with an offset key.

Jim Brandberg
Isanti, MN
CorvairRepair.com






Edited 1 time(s). Last edit at 10/03/2019 09:40AM by JimBrandberg.

Re: !40 HP Powerglide Cam
Posted by: Wagon Master ()
Date: October 03, 2019 10:20AM

Watching with great interest. I'm building a 140 PG with A/C this winter. Have yet to make my cam choice.

'29 Ford Model A Tudor
'61 700 Lakewood 110 4 speed
'69 Monza Convert. 140 Auto.
'70 Dodge Challenger R/T 440 4 speed

Been aircooled since 1973
Northwest Ohio

Re: !40 HP Powerglide Cam
Posted by: 66vairman ()
Date: October 03, 2019 10:55AM

Good approach Jim.

You probably know GM factory cam specs. are more like machining specs. and not comparable to the aftermarket method of measuring duration. Bob Helt compiled GM cam duration timing charts in "The Classic Corvair" based on the the now accepted 0.050" lifter lift reference point. Most, but not all, camshaft manufacturers now use the 0.050" lifter lift reference point for duration values.

Re: !40 HP Powerglide Cam
Posted by: JimBrandberg ()
Date: October 03, 2019 12:30PM

Yes I always use .050 numbers. I have lifters with bolts epoxied in to stick up out of the bores so the dial indicator can ride easy when building an engine. I like to register at least .050 and .150 to figure the center a couple times along with the max lift. I love that sort of stuff with the clipboard and all.
An assembled engine is a horse of a different color.

Jim Brandberg
Isanti, MN
CorvairRepair.com



Attachments:
Re: !40 HP Powerglide Cam
Posted by: vairmech ()
Date: October 03, 2019 04:08PM

It depends on what crank gear you have as to what cam and cam timing you use. Do you have the PG crank and gear? Are you using a standard crank with a standard gear.

Before anything can really be suggested with any meaning.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Re: !40 HP Powerglide Cam
Posted by: JimBrandberg ()
Date: October 04, 2019 05:44AM

I don't know what they used for a crankshaft which is why I'm merely speculating.
Do people think that Isky went in the wrong direction with a 111 Intake center on a 260 cam compared to 108 on the 270 and 280?

Jim Brandberg
Isanti, MN
CorvairRepair.com



Re: !40 HP Powerglide Cam
Posted by: Brizo ()
Date: October 04, 2019 12:38PM

JimBrandberg Wrote:
-------------------------------------------------------
> I don't know what they used for a crankshaft which is why I'm merely speculating.
> Do people think that Isky went in the wrong direction with a 111 Intake center on a 260 cam compared to 108 on the 270 and 280?

You need to find out exactly what parts your working with Jim, but I think your right. The 889/260 has good torque at lower rpm and a 111 degree intake center would be advanced, where it should have been retarded to like 106-108 to improve the power at higher rpm. ? ?

Dan Brizendine,
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

Re: !40 HP Powerglide Cam
Posted by: JimBrandberg ()
Date: October 04, 2019 01:14PM

I think we're on the same page to a certain extent except in regard to what is advanced and what is retarded. If we start at 108 as a base line:
An advanced cam is for lower RPMs. An advanced cam example would be 104 since 104 comes before 108.
A retarded cam is for higher RPMs. An retarded cam example would be 111 since 111 comes after 108.
The 111 is just an example as it would normally be for some pretty high RPMs. 108 is good and plenty for most of us I think.

Jim Brandberg
Isanti, MN
CorvairRepair.com



Re: !40 HP Powerglide Cam
Posted by: Brizo ()
Date: October 04, 2019 06:50PM

Correct Jim. I'm easily confused on this issue, especially comparing graph type timing charts compared to circular style. I often need to think more before I type.

Dan Brizendine,
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

Re: !40 HP Powerglide Cam
Posted by: vairmech ()
Date: October 04, 2019 07:32PM

You can easily look at the crank gear and determine what gear is on the crank. You either have the standard gear or the retarded one. This is explained in the Corvair Primer and with pictures.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Re: !40 HP Powerglide Cam
Posted by: 66vairman ()
Date: October 04, 2019 07:44PM

Jim - Take a look at the Isky 260 with the standard crank gear. Seems to be close to the 889 (95HP) with the PG crank gear, but the Isky 260 has a little more duration and lift. It's a nice torque cam.

I run the Isky 260 in my 140HP four speed car and I like the strong low end and it pulls well to 5,000RPM due to the larger valves in the 140HP heads. If you want revs up to 6,000RPM then a more aggressive cam is suggested, but you'll lose some low end torque.

Re: !40 HP Powerglide Cam
Posted by: vairmech ()
Date: October 05, 2019 05:38AM

To answer some of the questions of why -

The 140 does not have good low end torque, the powerglide requires good low end torque. That is why a standard 140 engine in a PG is a dog off the line but then will pick up after a few RPM's are gained.

What did GM do for the 140 engine to make it work with a PG?
They used a low end torque cam from the 95hp engine but the engine would run out of steam on the upper RPM's. That is the reason for the crank gear change, they retarded the cam timing to advance the power curve so the engine would pull to 5000 rpm. but they did that by retarding the crank NOT the cam!

So what do we do using a standard crank?
The 889, 260 or my FC cam is a good choice for the 140 engine but you do need to use a key in the cam to retard the cam timing to gain back some of the upper end. Case in point, I have driven my FC cam and when it hits around 4500 +- it falls flat on it's face! to cure that you change the cam/crank timing.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Re: !40 HP Powerglide Cam
Posted by: Wagon Master ()
Date: October 06, 2019 08:31PM

Would I be correct in my thinking that a 4° retarded crank gear on a 140 PG only regards the cam 2°? So if using a standard crank, a 2° offset key in the retarded position on the cam gear achieves the same effect?

Re: !40 HP Powerglide Cam
Posted by: vairmech ()
Date: October 07, 2019 04:02AM

Actually I think I wrote the above wrong. The crank is advanced, not retarded.

If I remember correctly without looking it up I think the crank degrees is 8 so the cam degrees would be 4. Before I would actually commit I would run it in my Dyno program for comparison.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Re: !40 HP Powerglide Cam
Posted by: JimBrandberg ()
Date: October 07, 2019 04:26AM

I believe the stock 140 PG retards the 889 cam 4 degrees at the crankshaft which would be 2 degrees at the camshaft since it turns twice.

For my project at hand I'm done. I've got it running better by reaching WOT and the transmission TV in adjustment.
The 260 cam was supplied by Larry Shapiro and the cam gear could be installed with everything properly in mind. I've not been hired to get into a whole big thing at this time. I would have done more if it was still doggy but it's come around.

As an aside, it has a 330 140 HP Manual distributor rather than a 339 140 HP PG distributor. When comparing they both have initial timing of 18 degrees and 18 degrees of mechanical advance but the PG begins advancing at a higher RPM and is all in at a higher RPM. All in is at much lower RPM than 319 110 HP distributor. It's not pinging and I don't have a 339 distributor that doesn't need a bushing so I'll leave ths as is too.

It has a torque convertor with a higher stall speed as well so lot's of things to consider.

The owner rebuilt the entire car and is very competent to carry on. It's a black '65 4-door Monza with a brown interior and quite fetching. He would like to find a bench seat as they are a family of 6.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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