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Re: Turbo Cam
Posted by: v8vair ()
Date: January 23, 2020 07:39AM

Heres a link to make a cam card.[nitroimage.proboards.com]



Edited 1 time(s). Last edit at 01/23/2020 07:39AM by v8vair.

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Re: Turbo Cam
Posted by: L L Garland ()
Date: January 27, 2020 03:06PM

Attached is the cam specs sheet I received when I bought a TB-20 cam from OTTO in February 1990

Leland L Garland
65 Monza 180 66 4-sp
Phoenix AZ

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Re: Turbo Cam
Posted by: JimBrandberg ()
Date: January 27, 2020 07:47PM

Interesting that Otto cams back in the day had split profiles with more on the intake side for a turbo cam.
Just the opposite with more exhaust for natural aspiration Otto cams I believe.

I think there is little chance the specifications on an Otto 20 T are the same today. They're loosey goosey with the grinds and vague with the specifications to verify as time goes on.
A cam that doesn't come with a cam card makes me very suspicious.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Turbo Cam
Posted by: Wagon Master ()
Date: January 27, 2020 08:08PM

JimBrandberg Wrote:
I think there is little chance the specifications on an Otto 20 T are the same today. They're loosey goosey with the grinds and vague with the specifications to verify as time goes on.
> A cam that doesn't come with a cam card makes me very suspicious.

So you feel the chance of the cam card specs. Clark's now supplies on their website for their Otto cams being accurate are slim to none?

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Re: Turbo Cam
Posted by: REM654DPG ()
Date: January 27, 2020 08:35PM

The one thing I don't care for with the new cams I've seen lately is they all have small base circles just like a re-grind would be - or worse. I think the new castings or cores that are available today must have been made smaller than the old ones.

If you compare these new ones to OEM, old Crower, Sig Erson, Etc. they can be as much as .100 smaller on what is claimed to be a "New" cam.

What are your experiences?

Regan Metcalf
Portland, OR

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Re: Turbo Cam
Posted by: JimBrandberg ()
Date: January 28, 2020 06:22AM

Wagon Master wrote:

"So you feel the chance of the cam card specs. Clark's now supplies on their website for their Otto cams being accurate are slim to none?"

----------------------------------------------------------------------------------

I know it's hearsay but people I trust have checked them and found that to be the case.

The last Otto cam I purchased new and installed was OT-20 about 4 years ago. I would have to dig through my old notes but as I remember it was not dual pattern. The owner considered it too noisy but decided he could live with it and I certainly didn't want to press the point.

I've checked a few Otto cams that I removed from engines that someone else built and did not find them satisfactory. I really can't comment on something that I didn't buy and came to me used for an unknown period.

I printed out the current Otto cam specs. The TB-20 numbers are close to what is reported above from 30 years ago. I'd sure like to hear from someone who has purchased one lately and checked it. Was it indeed dual pattern as claimed?

When I first began to question Otto cams here a year or two ago I received a few PMs with some unsatisfactory results. Since the writers chose to stay private I can't really comment here since it's the hearsay I began with.

I'm trying to find out all I can before purchasing cams. I do have a slip fit gear for checking but by the time I slip the gear on, bolt it in the crankcase and run lifters over it with grease there's bound to be some marks and such rendering them no longer new for return.

Someone above reported checking one and finding some discrepancies, I wish they would follow up with more information. A PM is okay.

I hate to be the one sticking my neck out here, I love the vendor and thoroughly enjoy doing business with them. They are not the ones making the cams and suppliers for our small market might be hard to come by.

I bought 2 280s and 1 270 Isky cams in the last few months hoping for some consistency. I'm leaning towards Isky 260 for a stock turbo engine. The TB-10 or TB-20 looks better on paper...

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Turbo Cam
Posted by: Wagon Master ()
Date: January 28, 2020 06:34AM

If you happen to get a PM on cam accuracy findings, feel free to
pm me that info. Any cam grinder or manufacturer of any thing for that matter can make a mistake, but to consistently deliver a product not as advertised is another issue. I'm cam shopping for a couple winter builds also.

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Re: Turbo Cam
Posted by: JimBrandberg ()
Date: January 29, 2020 04:24AM

To approach this from the other direction, has anyone checked an Otto cam lately and found it correct to specifications? I'd be really happy to hear that they're okay.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Turbo Cam
Posted by: Darrin ()
Date: January 30, 2020 06:07AM

I just put a new TB20 in a block to plstigauge and got interrupted. Will measure lift when I take apart for final cleaning next week.

Darrin Hartzler
Bethesda, MD/Catlett, VA

Northern Virginia Corvairs & Group Corvair

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Re: Turbo Cam
Posted by: JimBrandberg ()
Date: January 30, 2020 06:27AM

I'm especially interested in durations and lobe centers and overlap.
Also very interested if the intake and exhaust lobe patterns are different or the same. Lift might tell us a little about that if you're not going to check it with a degree wheel, dial indicator and all that.

Thanks for any info you come up with, I would really like to see good news.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Turbo Cam
Posted by: Wagon Master ()
Date: January 30, 2020 07:59AM

Here's the message I sent to Clark's tech. support dept. concerning their Otto cam.

I'm a little concerned about some of the quality issues I've been hearing about the recent Otto brand camshafts. What is your return policy, if I would happen to purchase one of these cams and it doesn't spec. out to what the cam card says they are?/size]

'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

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Re: Turbo Cam
Posted by: Brizo ()
Date: January 30, 2020 09:26AM

JimBrandberg Wrote:
-------------------------------------------------------
> I'm especially interested in durations and lobe centers and overlap.
> Also very interested if the intake and exhaust lobe patterns are different or the same. Lift might tell us a little about that if you're not going to check it with a degree wheel, dial indicator and all that.
>
> Thanks for any info you come up with, I would really like to see good news.

Please include me on the PM list for test results. The problem is, its very easy to make mistakes when measuring and recording cam specs, which may account for some of the discrepancies being seen ?

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

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Re: Turbo Cam
Posted by: 4carbcorvair ()
Date: January 30, 2020 09:37AM

joelsplace Wrote:
-------------------------------------------------------
> I thought some of the OT20 cams were ground incorrectly and they made noise.

I have one in my 140, installed around 2005. It's clacky and frankly, sometimes a bit embarrassing pulling into car shows. Back in 2012 at the convention in MA, I heard a Corvair pull in that sounded just like mine. Turned out that owner had the Otto cam also. I've lived with it as I haven't wanted to pull the engine and split the case. Or had the $$ to throw at a new cam. Heads, valves, pushrods, etc have all been replaced after I had dropped a seat and replaced the heads. And the noise continues.

--------------------------------
Ronnie
Southern Maine.
www.dirigocorvairs.net
66 Corsa Convertible, 140, 4sp.
65 Monza Convertible, 110, PG.




It doesn't leak, it's marking it's territory.

A mirror is a reflection of the miles travelled.

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Re: Turbo Cam
Posted by: dryenko ()
Date: January 30, 2020 04:01PM

Jim
I dial indicator by itself won't give the proper cam duration, a same face diameter lifter or disk on a dial indicator must be used.
I seem to remember your said you check your cams in a case with a lifter.
So this may be for the general audience.
I made the pictured tool so I don't have to build up a engine to check duration and lift , over lap etc
It does most any cam if it fits lengthwise, and uses a degree wheel and a pointer on the far end.
VW SOHC cam shown , but I have done a number of Corvair cams.
I check all Corvair cams now, ever since I got a 260 cam from Clark's that had a small bump on the #5/6 exhaust lobe base circle that made the lifters bleed down when running and not hold a adjustment.
A costly problem !!

Bob C aka Dryenko
Dobson, NC 27017

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Re: Turbo Cam
Posted by: Wagon Master ()
Date: January 30, 2020 05:29PM

My response from Clark's on substandard cam spec. return policy.

All of our cams are made from brand new billets except the ones clearly
listed as reground and they are all ground to spec by our supplier. We have
been using the same cam grinder for many years and we have had minimal
issues with any of the cams they grind for us. We sell a lot of camshafts of
various grinds and it is rare that we hear a complaint. We have not heard
any complaints about the quality of our camshafts. If for some reason you
did receive a defective cam we stand behind our products so we would replace
the defective part or issue a refund when the part was returned for
inspection. It is extremely difficult to get accurate readings from a cam
without the proper equipment and experience. Different people also measure
cams differently so depending on how it is measured the readings may vary
from one person to the next. The cam grinder we use has made high quality
Corvair cams for us for many years as well as cams for many other
applications with excellent reviews.

47 years serving the Corvair enthusiast

So in a nutshell, buy with confidence from Clark's and if the parts prove to be defective, they'll make it right.

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Re: Turbo Cam
Posted by: JimBrandberg ()
Date: January 30, 2020 06:31PM

Bob you said degree wheel on the other end. How do you find Zero? Do you have a picture of the degree wheel end? Thanks.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Turbo Cam
Posted by: Jonathan Knapp ()
Date: January 30, 2020 09:25PM

Wow! Less exhaust duration and lift on a dual pattern cam! That seems crazy to me, even for a turbo application. Corvairs need a lot of help on the exhaust side compared to the intake side. This TB-20 really keeps the overlap down, but maybe to the point of overkill. 7 degrees of "non-overlap" (underlap?) at .050" lift. With a few more degrees of lobe separation and more exhaust duration, you could still have minimal or no overlap, more lift, and more ability to move the exhaust charge out past a very restrictive exhaust valve and port.

And where did Otto Parts get the idea that Corvair rocker arms had a 1.56:1 ratio? The written specs at the time were 1.58:1 but everyone pretty much agrees that they were 1.5:1. That would only be .428" lift on the exhaust side.

If I were building a flat-tappet turbo motor today and that version of the TB-20 were available, I don't think I would use it. Dick Griffin's, 13-second turbo car in 1966 ran a 280 Isky single pattern cam: 224 degrees at .050" lift, .440 lift, 8 degrees of overlap at .050" lift. (BTW, Isky understood that Corvair rockers were 1.5:1) See the cam card here: [corvaircenter.com]

That car ran strong.

Jonathan Knapp
Wheeling, WV
'66 Corsa Autocrosser

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Re: Turbo Cam
Posted by: 63turbo ()
Date: January 31, 2020 06:08PM

Jonathan Knapp Wrote:
-------------------------------------------------------
> Wow! Less exhaust duration and lift on a dual pattern cam! That seems crazy to me, even for a turbo application. Corvairs need a lot of help on the exhaust side compared to the intake side. This TB-20 really keeps the overlap down, but maybe to the point of overkill. 7 degrees of "non-overlap" (underlap?) at .050" lift. With a few more degrees of lobe separation and more exhaust duration, you could still have minimal or no overlap, more lift, and more ability to move the exhaust charge out past a very restrictive exhaust valve and port.
>
> And where did Otto Parts get the idea that Corvair rocker arms had a 1.56:1 ratio? The written specs at the time were 1.58:1 but everyone pretty much agrees that they were 1.5:1. That would only be .428" lift on the exhaust side.
>
> If I were building a flat-tappet turbo motor today and that version of the TB-20 were available, I don't think I would use it. Dick Griffin's, 13-second turbo car in 1966 ran a 280 Isky single pattern cam: 224 degrees at .050" lift, .440 lift, 8 degrees of overlap at .050" lift. (BTW, Isky understood that Corvair rockers were 1.5:1) See the cam card here: [corvaircenter.com]
>
> That car ran strong.

Jon- all of the TB series cams are a HUGE improvement over any of the stock cams for Corvairs. I ran both the stock 63 "turbo" cam and the "62-66" Turbo cam replacement and both were way worse than the OTTO TB-10 I had, and Ray's OTTO TB-20 "tribute" cam kicks the TB-10's butt big time! All turbo cams that are intended for "old school" turbos used a bit of negative overlap because there is more back pressure from the exhaust than there is from the intake.
Also, the rocker arm ratio's used on the Otto cam cards are "theoretical", if you measure the actual lobe lift it does correspond to the change in lift from stock. Using a 1.5 rocker ratio for a .3 lobe lift gives .450" lift, using 1.56 rocker ratio for the same .3 lobe lift gives .468" and a whopping .018" change from the rocker ratio difference wouldn't seem to make a hill of beans worth of difference, compared to using a E-flow turbo, water injection, and a huge carb and extra compression like Dick Griffin ran to go as fast as he did.
Here's more on why old school turbo cams are different than now, and what is important...

[www.hotrod.com]

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Turbo Cam
Posted by: Darrin ()
Date: February 04, 2020 05:27AM

Ok, finished fitting bearings and measured the brand-new-from-Clarks TB20 camshaft. I measured lift on both intake and exhaust in a thoroughly inexpert manner and got the following:

Intake: lift measured 0.302 (x1.57 = 0.474, x1.56 = 0.471)

Cam card on Clark’s site says 0.300 or x1.57 = 0.470

Exhaust: lift measured 0.286 (x1.57 = 0.449, x1.56 = 0.0446)

Cam card says 0.290 (1.57 = 0.455)

These strike me as being pretty darn close to the card.

Darrin Hartzler
Bethesda, MD/Catlett, VA

Northern Virginia Corvairs & Group Corvair



Edited 1 time(s). Last edit at 02/04/2020 05:28AM by Darrin.

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Re: Turbo Cam
Posted by: dryenko ()
Date: February 04, 2020 08:00AM

Jim, I will discuss via email, easier for me that way.
I do have to drill and tap the end of the Corvair cam for a Allen style head screw to hold the degree wheel on a custom spacer.
BC

Bob C aka Dryenko
Dobson, NC 27017

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