Engine: Effects of R1 cam

[5brown1]

I'm trying to sort out some engine/automatic transmission issues and cannot find answers in my web/forum searches. The engine is a recently overhauled 289 which had a R1 camshaft and new valve springs installed. The engine was also bored .060 . The prior owner had the work done. So I have some questions.

1. Will the camshaft require a higher idle speed over the stock 550 RPM? Idle seems rough at that RPM.
2. Will it lower the engine vacuum? Currently vacuum is about 15-16. My other 289s both run at about 20. I can not find any vacuum leaks.
3. Will the valve lash need to be changed from the stock settings? I saw reference to altered settings on a post during my searches.
4. Any other pertinent information?

I believe I have transmission issues but want to eliminate the engine as a cause.
Thank you.

[PackardV8]

I'm trying to sort out some engine/automatic transmission issues and cannot find answers in my web/forum searches. The engine is a recently overhauled 289 which had a R1 camshaft and new valve springs installed. The engine was also bored .060 . The prior owner had the work done. So I have some questions. Life and engine performance require tradeoffs:

1. Will the camshaft require a higher idle speed over the stock 550 RPM? Idle seems rough at that RPM. Yes, the R1 increased duration doesn't idle as low and slow as the stock cam. The R-2 idles at 650 RPMs. Did he also have R1 flattop pistons installed?
2. Will it lower the engine vacuum? Currently vacuum is about 15-16. My other 289s both run at about 20. I can not find any vacuum leaks. Yes, increased duration lowers manifold vacuum.
3. Will the valve lash need to be changed from the stock settings? I saw reference to altered settings on a post during my searches. Yes, setting the valve clearances to the loose end of the allowable range will reduce duration and improve idle and vacuum. Conversely, setting tight will increase duration, rougher idle, lower vacuum and more top end power.
4. Any other pertinent information? Yes, an R1 ignition advance curve in the distributor is required to get maximum performance. A custom curve is still better. Adding a few degrees initial advance and restricting the total to no more than 36 degrees will usually improve idle and vacuum. If the builder did not install flattop pistons, experimentation with the advance curve is required, as he screwed the low end and isn't getting that much more on the top end.

I believe I have transmission issues but want to eliminate the engine as a cause.
Thank you.

jack vines

[5brown1]

Thank you Jack,
I have emailed the builder to see about the pistons. I have a distributor from Dave Thibault (his recent model) so maybe he can help out there after I find out about the pistons
I probably should add the engine is on a 57 Golden Hawk although I don't have the supercharger on it at present while trying to get the mechanical issues fixed.

[PackardV8]

Thank you Jack,
I have emailed the builder to see about the pistons. I have a distributor from Dave Tibault (his recent model) so maybe he can help out there after I find out about the pistons
I probably should add the engine is on a 57 Golden Hawk although I don't have the supercharger on it at present while trying to get the mechanical issues fixed.

If the builder knew engine was to be supercharged, he wouldn't/shouldn't have used flattop pistons without changing to R2/truck heads. If you have standard heads, what we hope you have is the semi-dished pistons and 9:1 compression. That would be ideal with the '57 GH supercharger.

When you get the supercharger up and working, follow the Shop Manual for R2 ignition timing, 24 degrees at 1600 RPMs. That's a pretty cautious curve, but experiment at your own risk.

jack vines

[Ron Dame]

Dave is out of pocket for a few days due to knee replacement.. I hope he doesn't mind me saying so. He called me Sunday night letting me know that Janet was shipping my distributor Monday. when he told me this.

Thank you Jack,
I have emailed the builder to see about the pistons. I have a distributor from Dave Thibault (his recent model) so maybe he can help out there after I find out about the pistons
I probably should add the engine is on a 57 Golden Hawk although I don't have the supercharger on it at present while trying to get the mechanical issues fixed.

[5brown1]

I received word from the builder that he believes he used the "1/2 dished pistons" but is not sure. It has been 12 years but only 2800 miles ago. I know he used the standard SC heads. I will remove a spark plug and check it out.
Is the semi-dished piston a special part or standard 289 piston?

[StudeRich]

Those shallow dish pistons are "Studebaker Vendor" Aftermarket Pistons, not anything like any Factory Piston.

You will be able to measure the small dished area when at TDC, to tell if they are Stock 289 Deep Dish, Avanti Shallow Dish or Avanti stock replacement Flat tops.

[sals54]

Look through the little peep hole under the spark plug with a good flashlight. You should be able to see the piston top fairly well.

[5brown1]

I measured the piston depression which appears to be about 3/16" to 1/4". Is that the shallow one?

[kxet]

Lower idle vacuum will change idle mixture by opening power circuit at idle speeds.

[bensherb]

Lower idle vacuum will change idle mixture by opening power circuit at idle speeds.

That would be some crazy low idle vacuum requiring a lot of overlap in the cam to get down that far.

I don't know what cam is in my GT, but at idle it pulls around 15 inches vacuum, and is REALY lopey if I try to get it to idle much below 850-900 rpm. It pulls very strong and goes like a bat outta hell from a roll on at freeway speed.

[kxet]

Idle mixture means throttle closed, not open. It is open when pulling and at freeway speed. Holley sold power valves that opened at different vacuum signals caused by racey cams. Engines like rich, they are happy with it.

[bensherb]

The power valve opens at low vacuum, such as at wide open throttle, and directs more fuel into the main power circuit. For Holley carbs, when opened, it allows fuel to flow through a calibrated opening in the metering block called the power valve channel restrictor. This restrictor determines the amount of additional fuel delivered to the engine.

I've never seen a power valve that would open above 10.5 inches vacuum, it would typically be used on an engine pulling around 21" vacuum at idle. The Holley type valve is available from 2" to 10.5" vacuum.

Most other carbs have a similar circuit built into them, but they're not usually as easilly changed as the simple screw in unit the Holley, Ford , Autolite carbs use.

How many would you like?

[Jeffry Cassel]

The R1 cam is like super-mild and I have never noticed the it idled any rougher than standard. My 64 has a Delta R3 cam and even that is just a little bit lopey at idle. If it is rough at idle look at carb timeing or vacuum leaks.

[PackardV8]

The R1 cam is like super-mild and I have never noticed the it idled any rougher than standard. My 64 has a Delta R3 cam and even that is just a little bit lopey at idle. If it is rough at idle look at carb timeing or vacuum leaks.

Yes, agree the R1 cam is mild by today's performance standard.

No, it's not without some tradeoffs.

Maybe, follow directions. Studebaker didn't spend a nickle without necessity. The Shop Manual specifies 550 RPM idle for the stock cam and 650 RPMs for the R1 cam and an additional throttle kicker for the AC idle. The Powershift torque converters have a higher stall speed than the standard converters.

jack vines