Holbay camshaft

[bing]

Anyone out there familiar with these? I'm trying to find out what the valve lash should be on a 1725 engine. I assume it's different that a stock setup.

 

[alpine_64]

What Holbay camshaft have you got? There were cams used in the Rapier H120 and Hunter GLS engines.. then there were after market cams Holbay did for rootes 1725 that were wilder than the stock Holbay motor ones.. E128 i think was the hot after market one.. do you know where your cam is from?

 

[RootesRich]

The lash is different for the two Holbay cams produced.

The H120/ GLS cam had a hot lash spec of .013 inlet and exhaust.

The E128 cam had a hot lash spec of .009 inlet and .011 exhaust.

 

[bing]

I didn't know that there was more than one. I will have to ask the prior owner.

 

[RootesRacer]

I didn't know that there was more than one. I will have to ask the prior owner.

That usually doesnt pan out becuase most folks hear holbay and that is that.

Actually there were other holbay cams less talked about.

There was a 120hp cam similar to the E128, they also ground holbay H120 cams on stock cam blanks with narrower lobe centers, not sure you would call that except for a mess.

Best to analyze the cam timing to figure what you have.
This would be done with a degree wheel and a dial indicator on each valve on a single cyl.

 

[johnd]

Interesting thread - my Alpine's PO said that he installed a Holbay cam but there was no record of it in the paperwork he gave me. Since he seems to have "misspoken" about a number of other things, he may have "misspoken" about the cam as well. It could, however, explain why the car has so much valve clatter.

 

[bing]

Given that it rumbles and shakes at idle wouldn't that make it the hot aftermarket one? The rest of the engine is stock.

 

[alpine_64]

Given that it rumbles and shakes at idle wouldn't that make it the hot aftermarket one? The rest of the engine is stock.

Well.. it might be.. or the motor may not be set-up correctly.. what distributor are you running? what carbs?

If you had the cam out of an H120 you have a cam designed for a motor with different compression ratio, smaller intake ports different carbs and different distributor with different curve....

If you had an aftermarket cam from Holbay.. maybe it still requires some recurving of the distributor...

 

[RootesRich]

Given that it rumbles and shakes at idle wouldn't that make it the hot aftermarket one? The rest of the engine is stock.

No, both the H120/GLS and E128 can produce a lopey idle depending on how the engine is setup.
If the previous owner can't provide a record of what cam it is (I wouldn't rely on verbal) you need to pull it to check for an ID (assuming it was stamped) or better yet, do as Jarrid suggested and figure out the cam timing.

May I ask what carb(s) you are running as you state the engine is otherwise stock?

 

[bing]

It has a Weber dgv carb.

 

[Rootes 66]

Production Holbay cams were marked with a dash of green paint (difficult to find when used, due to oil and heat) but can be identified by measuring with a micrometer the rise of one of the lobes which should be 0.320"
Pete

 

[Bratfink]

Given that it rumbles and shakes at idle wouldn't that make it the hot aftermarket one? The rest of the engine is stock.

I could make your engine rumble and shake in about 2 mins with a couple of simple screwdriver adjustments of the carb, still doesn't make it a Holbay!

From experience, I have found the Holbay to be of limited performance use, more of a marketing exercise.

The Holbay engines only made marginally more power than the stock engines, there was only so much they could do with the poor engine geometry they inherited from the Rootes engines. They couldn't increase the cam much since increasing lift simply pushes the torque curve further up the rpm range and the long stroke design of the engine didn't really allow for much more rpm. Most of the modifincations that Holbay engines had seem to suggest they were trying to increase low and mid range torque rather than all out power. Thus making the engine more driveable and increasing throttle response.

Am I right in thinking the Holbay cam actually had less lift than the stock cam but had more duration and overlap? It's been a while since I saw one.

 

[H One-Twenty]

Sorry, had to chime in here

The engine developed by Holbay for production H120 Rapiers produced 20% more power than standard (108 vs. 88). The original prototypes produced around 120 bhp but were deemed too peaky for everyday driving conditions; for production versions the inlet ports were revised (smaller) and the camshaft was modified (lower lift) in an effort to boost torque and improve drivability. These modifications worked; my bone-stock H120 has lots of torque and is very flexible to drive for a car with dual DCOE’s (will still occasionally ‘oil the plugs’ though, if you are in stop-start traffic for hours)

I agree that the Rootes/Holbay venture was a marketing exercise, as are most 'performance' models from main-stream manufacturers. However the cars weren’t all fur coat and no knickers: 108 bhp and 0-60 in 11 seconds matched the contemporary Lotus Cortina.

 

[RootesRich]

The Holbay engines only made marginally more power than the stock engines, there was only so much they could do with the poor engine geometry they inherited from the Rootes engines. They couldn't increase the cam much since increasing lift simply pushes the torque curve further up the rpm range and the long stroke design of the engine didn't really allow for much more rpm. Most of the modifincations that Holbay engines had seem to suggest they were trying to increase low and mid range torque rather than all out power. Thus making the engine more driveable and increasing throttle response.

As the owner of an 1840cc Holbay engine, I can not disagree with your statements more.
In addition to the famed H120 engine, Holbay also produced a 140HP version. I'd hardly call that increase in power "marginal" over Rootes stock engine.

 

[Jay Laifman]

Ditto. I have an NOS Holbay head and cam, new Webers, custom pistons and a distributor recurved to match. The car goes like stink. The old Alpine wasn't even close. I feel strongly that if all Alpines ran like this, there never would have been a Tiger.

That said, I do not know specifically what Holbay cam I have. It was new, in a Chrysler box and said H120 on it. I bought it from Sunbeam Specialties when Rick got it with a bunch of stuff back around 1990.

 

[RootesRich]

That said, I do not know specifically what Holbay cam I have. It was new, in a Chrysler box and said H120 on it. I bought it from Sunbeam Specialties when Rick got it with a bunch of stuff back around 1990.

I'd say chances are fairly high that you purchased a NOS Holbay H120/ GLS cam. I have two of these, one being in my Holbay motor, the other sitting on my parts shelf.

 

[DanR]

How are these Cams identified?

As a curiosity, just how do you identify a "Holby Cam"??

Are stock Cams similary marked? How do you determine which "Cam" these numbers: 1981080 and MC24239N 8 are associated with?

 

[SIVAllan]

Ditto. I have an NOS Holbay head and cam, new Webers, custom pistons and a distributor recurved to match. The car goes like stink. The old Alpine wasn't even close. I feel strongly that if all Alpines ran like this, there never would have been a Tiger.

That said, I do not know specifically what Holbay cam I have. It was new, in a Chrysler box and said H120 on it. I bought it from Sunbeam Specialties when Rick got it with a bunch of stuff back around 1990.

Chrysler box may indicate Coltec's Holbay grind "E128."

See E128 at:

http://www.coltecracing.com/camshafts.html#various

Chrysler 1725 E128 35/60 60/30 .465 .330 275/270

I considered this grind before finding a used H120 cam from a Rapier.

 

[RootesRacer]

Chrysler box may indicate Coltec's Holbay grind "E128."

See E128 at:

http://www.coltecracing.com/camshafts.html#various

Chrysler 1725 E128 35/60 60/30 .465 .330 275/270

I considered this grind before finding a used H120 cam from a Rapier.

The E128 cam is more aggressive than the H120.
It was closer to the cam originally developed by Holbey for Rootes, having more power up top and a loss in lower end torque.

The E128 cam can be ground from a stock SV cam blank. The H120 however cannot since its lobe centers are too narrow (103 vs 109 degrees).

 

[Bratfink]

The engine developed by Holbay for production H120 Rapiers produced 20% more power than standard (108 vs. 88). The original prototypes produced around 120 bhp but were deemed too peaky for everyday driving conditions; for production versions the inlet ports were revised (smaller) and the camshaft was modified (lower lift) in an effort to boost torque and improve drivability. These modifications worked; my bone-stock H120 has lots of torque and is very flexible to drive for a car with dual DCOE’s.

Isn't that more or less what I said?