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Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: cnicol ()
Date: April 30, 2018 07:09PM

I'm just putting together a 140 for my '66 Sprint and I could use some advice.

I purchased the low-mile Isky 280 cam used from Jonathon Knapp but I adon't have a cam card. All I have are the specs reprinted in Bob Helt's "The Classic Corvair".

Anyone have a cam card for an Isky 280 (221280)?

I'm using the Ray Sedman adjustable cam gear so setting the cam timing is ridiculously easy and I've set it to the .050" lift points from Bob's cam table. All the timing points fit Bob's reprinted data perfectly but I am a little concerned because the cam gear is near the end of it's adjustment. Why would that be if the timing is supposedly "straight up"?

I double-checked and I don't think the cam gear is off a tooth but I suppose that's still possible.

Gotta cam card or advice to lend?

Thanks in advance!smiling smiley

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: MattNall ()
Date: April 30, 2018 07:13PM

Where's Scott V when we need him??? ggg





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: Wagon Master ()
Date: April 30, 2018 07:29PM

Shot in the dark.
140 PG crank gear?

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: cnicol ()
Date: April 30, 2018 08:57PM

Wagon Master Wrote:
-------------------------------------------------------
> Shot in the dark.
> 140 PG crank gear?

That's an interesting thought. Some time ago I (I've had the crank for many years) I paint-marked the crank "STD GEAR". I'll double check that and the tooth alignment.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: Jonathan Knapp ()
Date: May 01, 2018 01:18AM

Hi Craig,

You can see where I had the gear in relation to the hub by the marks the bolts left on the aluminum gear. I think you must be one tooth off. Remember, though, I was running it 4 degrees (or maybe 6, I can't remember for sure) advanced for better low-end torque.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: JimBrandberg ()
Date: May 01, 2018 04:14AM

So for a street 140 are you setting the Intake centerline at about 108 degrees?

Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Date: May 01, 2018 04:32AM

Craig, the 221280 is a current part in the Isky catalog.

Give 'em a call - (310) 217-9232


Dan Davis ~ Pierce County, WA ~ CORSA Western Director + Corvairs NW + North Cascades Corvairs + Corvanatics
1966 Corsa Turbo coupe ~ ~ 1966 140 Corsa ~ ~ 1965 Monza 140/4 'Vert Sierra Tan/Fawn ~ 1964 Monza 'Vert (SOLD) ~ 1960 Monza Ermine White/Red PG ++ ~ 1965 Monza 140/4 Evening Orchid w/ ivory/black interior ~ 1962 Monza Wagon 102/4 ~ 1963 Rampside/Scamper ~ 1963 Red/Greenbrier ~ 1969 Ultra Van #468

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: martyscarr ()
Date: May 01, 2018 08:46AM

Here ya go

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: cnicol ()
Date: May 01, 2018 01:01PM

Thanks for that Marty!smiling smiley The numbers are the same as in "The Classic Corvair" too so "doubly redundant" as I like to say.grinning smiley

As for my initial concern, the cam gear being near the end of it's adjustment, Jonathan Knapp had it right: The gear was off a tooth.

When I assembled the cases I carefully checked with paint-marked timing marks and a square but that apparently wasn't good enough. This morning I rolled the crank 360 to bring the timing mark down to the case parting-line and clear as a bell, it was off a tooth. Separated the cases, clicked the gear over one tooth, and all is well.

Thanks to all!smileys with beer

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: john.jackson ()
Date: May 01, 2018 01:35PM

Craig,

How about a picture of the corrected assembly?

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: MattNall ()
Date: May 01, 2018 02:51PM

Glad you caught it now!





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: cnicol ()
Date: May 01, 2018 10:32PM

Two lessons here:

1) Skip a step and pay the price. Usually, before I bolt the cases together "final", I slap on the rear housing and a pulley just to give me an accurate TDC and then check the alignment of the timing mark with the case seam at the bottom. Nothing left to chance and no guesswork like the suggested crank mark vs. cam mark approach.

2) When something doesn't seem right, stop and investigate. I did that with this concern before proceeding and it paid off.

First and Second picture:

Here's the alignment at the bottom, before and after splitting the cases and moving the gear a tooth. The timing mark (painted yellow) is supposed to align with the seam when the crank in on #1 TDC compression, as shown in the second photo.

Third picture: Adjustable cam gear in the middle of it's travel with the cam installed "straight up". This is what I expected in the first place. Yeah team! smileys with beer

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: Jonathan Knapp ()
Date: May 02, 2018 11:16PM

Hi Craig,

Don't be afraid to advance that cam. Even with my 4-6 degrees of advance, it made great power in the top end and revved willingly to 7,000 rpm. The advance timing gave good bottom and mid-range power. With your last picture, you can see where the cam gear's bolt heads dug into the aluminum gear.

Marty's card says 280 degrees at .020" lift. At .050" it measured out to 224 degrees. The total lift was, surprisingly, more than .440" however. They all measured out in the .450-.455" range (Yes, I measured the duration, lift, and piston to intake valve clearance on every valve!)

With flat topped pistons, the advanced cam timing, the big 140 intake valves, .032" head gaskets and no cylinder base gaskets, I had between .090" and .100" clearance between the piston and the intake valves at their closest points.


Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: JimBrandberg ()
Date: May 05, 2018 05:04AM

I'm curious what Intake Centerline you decided to set it at?

\ Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: v8vair ()
Date: May 06, 2018 06:20AM

[nitroimage.proboards.com] I dont trust the cam cards any more from what ive seen. This makes figuring out what you have easy. Just remember when you advance the cam the intake valve gets closer to the piston. Not a problem on most street motors. And yes i would advance the cam atleast 2 degrees. Mike



Edited 1 time(s). Last edit at 05/06/2018 06:23AM by v8vair.

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: cnicol ()
Date: May 06, 2018 07:31AM

Thanks for posting that, Mike. I'm going to print it and put it into the permanent reference file.

Reading it and attempting to answer Jim's question, I'm starting to get confused. (This is my first time to advance or retard a cam)

There's a bunch of measuring, adding and subtracting "needed" to come up with the intake centerline. A lot of the confusion for me comes from the scales on the the degree wheel.

Are all degree wheels 0-90-0-90-0-90? It's hard to keep track when a valve event crosses those corners so the numbers are ascending and descending several times for a given event. You almost have to ignore the scale numbers and count out loud with a pointer.

BIG QUESTION: Wouldn't you just verify .050" I/O event timing vs the cam card (mine verified) and then advance the .050 lift timing point by the desired cam timing advance?

In my case, I want to advance the cam 4-deg so the .050" intake lift event so I moved the event from 4 BTC to 8 BTC. Is that not the way to do it?

If the cam's designed intake centerline is 108, I would think advancing the cam 4-degrees would move it to 104. Do I have that right?

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: v8vair ()
Date: May 06, 2018 09:03AM

read this [www.webcamshafts.com]



Edited 2 time(s). Last edit at 05/06/2018 09:08AM by v8vair.

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: cnicol ()
Date: May 06, 2018 06:07PM

v8vair Wrote:
-------------------------------------------------------
> read this
> [www.webcamshafts.com]


Perfect! Thanks Mike. My googling around for some kind of "how-to" yielded only "Hot Rod Magazine" type articles that didn't really hesplain things; more of an overview.

I'm pretty sure I'm on the right track now but it might be fun to doublecheck using the procedure you linked.

Thanks again, Craig

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: JimBrandberg ()
Date: May 07, 2018 04:38AM

When doing the Intake measuring I generally don't think in terms of before or after Bottom Dead Center, in other words 20 ABDC is 200.
If Jonathan talked about running it with 4 degrees of advance, I believe he would be talking in the 104 Intake Center neighborhood.
I believe the stock 891 cam is about 108.
I believe the stock 889 cam in a 95 HP is about 104.
I believe the stock 889 cam in a 140 HP PG is about 108.
I believe the Isky 280 installed with a regular key is about 108.

I don't know all about it which is why I was asking what you decided.
I got used to speaking in terms of Intake Centerline several years ago with my race engines and talking to folks. I suppose it's only one piece of the information but it's what I'm used to.
In checking cams recently, I found one I'm sure is incorrect. It will be a good one to research and learn about lobe separation angles.

I still can't wrap my brain around using a lesser cam in a 140 PG but I'm going off topic. I don't understand why they didn't take the 891 cam and advance it 4 degrees for better low end power. Instead they took the 889 cam and retarded it 4 degrees for better high end power. I suppose the limitation and wide power band of only having 2 gears and what happens at the shift point.
Then factor in ignition timing...

Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Isky 280 cam: Got specs? Adjustable timing gear advice?
Posted by: Jonathan Knapp ()
Date: May 13, 2018 12:05AM

Hi Craig,

Sorry to get back to this thread late. The answer to yourBIG QUESTION is Yes! If you know where your .050" intake lift event is "supposed to be" according to the manufacturer, then simply make that happen 4 degrees earlier. Voila, your cam is timed. This is the genius of the adjustable cam gear! No need to split the cases, remove the cam gear, put in an off-set key and reassemble with a new cam gear (which may still be off from your target because it is a different gear). All you do is loosen the six Torx-headed screws, turn the hub slightly to advance and then retighten the screws. Why couldn't Chevrolet thought of this!

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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