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Holbay camshaft

Bratfink

Donation Time
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.

What rpm does this occur at? Never seen a 140hp version, that would seem like a more reasonable increase from 88hp.

I have presumably only ever played with the 108hp version and it barely seemed worth the effort to swap it in. Ended up doing to a total engine swap for a modern unit making over 200hp. That livened it up!
 

H One-Twenty

Donation Time
1974 Lamborghini Countach LP 400 - 375hp

1985 Lamborghini Countach LP 500S QV - 450hp

Is this a more reasonable 20% increase? ;)
 
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Jay Laifman

Donation Time
What rpm does this occur at? Never seen a 140hp version, that would seem like a more reasonable increase from 88hp.

I have presumably only ever played with the 108hp version and it barely seemed worth the effort to swap it in. Ended up doing to a total engine swap for a modern unit making over 200hp. That livened it up!

Given my experience, I'm going to argue that you simply experienced a bad example. Say for example it was a Holbay head on top of a 1600 engine. That results in almost no compression! And there is nothing that can be done to change that. Who knows what advance curve it had or carb throats, jets, etc. So many things can be done wrong by someone who doesn't realize the specifics.

Jay
 

Jay Laifman

Donation Time
I never did find out which "Holbay" cam I have. As indicated above, I presumably have the traditional H120 cam, but may have the E128 cam. Is there some way I can tell from the installed engine? Lobe open/close? Lift? Some way of telling duration?
 

RootesRacer

Donation Time
A true H120 cam will have a narrow lobe center which increases overlap.
The lobe centers on the H120 is 103 to 105 degrees, the lobe centers on the E128 is 108 or 109.
Also IIRC the E128 yields about .470 lift which is greater than the H120 by a fair margin.

Since the H120 has such narrow lobe centers, I would not expect one could be ground on any non holbay cam blank (I would expect a special cam part# cast into it). The E128 can be ground on a stock SV 1725 cam.
 

Jay Laifman

Donation Time
I bought mine from Rick, and it was in a Chrysler box and marked Holbay cam. I don't remember the other details. I think I might have saved the box end somewhere. Just not sure where - it was 22 years ago.

The cam is in the car. I can take off the valve cover and rotate the engine. But I don't have any special tools. I've never measured lob centers or lift. Any idea how to do it and what I would need?
 

Jay Laifman

Donation Time
Found the invoice, but not the box end:

1991, $137.45, "Camshaft - Holbay Hi Perf" #A1267721

Probably Rick's number.

I recall at the time, he was finding some final stock out of Peugeot/Chrysler. But I know that's not conclusive of what was in the box. I do recall that a Lotus mechanic that I was working with for the machining and stuff measured the cam at the time and thought it was not typical. Don't know if that kind of comment would more likely apply to the H120 or the E128.
 

RootesRacer

Donation Time
I think you and I rehash this topic every 10 years or so...

The E128 was an aftermarket Holbay/Coltec cam, I kind of doubt that Chrysler would have been involved with packaging and selling it.

That said I would bet your (not mine) eye teeth that its going to come up as an H120 cam.

To test it, you will need a degree wheel on the crank and the normal procedure to degree a camshaft on an engine which requires a dial indicator to monitor lift on both sides of the intake and exhaust lobes at the valve retainer.
You find max lift and take .100" off of it and find the degree timing points on each side of the lobe then calculate where the nose would be a+((a-b)/2).
You have to do it this way becuase its impossible to determine the cams nose timing point since the cam rotates a number of degrees without much lift change.
You then take the intake center point and calculate the angle difference and see what that is.


You dont even have to accurately set the timing wheel as its the difference in the lobes you are after, not absolute timing accuracy.
 

Jay Laifman

Donation Time
Ha! Yeah, and the same thing happens probably every time. I figure I'll try to measure it, and I never get around to it. So here's to our chat in 10 years. :)
 

V6 JOSE

Donation Time
Hi Jay,

If you want to know exactly what you have, take it to a cam grinder and they can measure it and tell you exactly what it measures. That way you can stop all the guessing.


Found the invoice, but not the box end:

1991, $137.45, "Camshaft - Holbay Hi Perf" #A1267721

Probably Rick's number.

I recall at the time, he was finding some final stock out of Peugeot/Chrysler. But I know that's not conclusive of what was in the box. I do recall that a Lotus mechanic that I was working with for the machining and stuff measured the cam at the time and thought it was not typical. Don't know if that kind of comment would more likely apply to the H120 or the E128.
 

Jay Laifman

Donation Time
Ha! But then I'd have to stop driving it!

I recently changed jobs and the new job is close to home. So I'm happy to be commuting in it again. Also probably why I've shown up here more lately. I was admittedly spending more time on the board for the other car I was commuting in.
 

Jay Laifman

Donation Time
FWIW, I was just searching and found some of those old posts I did. Looks like I put together a decent chart of the possible cams. To summarize my long post below, it looks like there is a "stock" H120 cam and an H120 cam from Sunbeam Specialties (as measured by Cal Cams for Sunbeam Specialties). That Sunbeam Specialties H120 cam appears to be more like the E128 cam in opening/closing, but with a lower lift. My cam seems to be this Sunbeam Specialties H120 cam:

BTDC IN / ABDC IN / BBDC EX / ATDC EX

Holbay H120 -
Intake: 44 / 51​
Exhaust: 69 / 26 Lift .436​
Holbay (SS) (as measured by Sunbeam Specialties) -
Intake: 27 / 60​
Exhaust: 62 / 25 Lift .47​
Overlap: 52.1​
Lob Center Sep: 107​
Intake Duration: 268.5 crank deg​
Intake Lobe Area: 26.49​
Exhaust Duration: 266.5​
Exhaust Lobe Area: 26.45​
Holbay E128 -
Intake: 35 / 60​
Exhaust: 60 / 30 Lift .465​
WSM Chrysler -
Intake: 58 / 66​
Exhaust: 84 / 40 Lift N/A​
Elgin #6708 -
Intake: 23 / 65​
Exhaust: 65 / 23 Lift .433​
Delta L2 grind -
Intake: 22 / 63​
Exhaust: 63 / 22 Lift .438​
Isky SB-2 -
Intake: 22 / 62​
Exhaust: 62 / 22 Lift .430​
Stock
Intake: 29 / 63​
Exhaust: 69 / 23​


I also found my own old notes where I tried to measure when the valve started to move and stopped moving - just from marking the crank and visually watching the drivetrain. The opening numbers fell within the range of the others - closest to the "Holbay (SS)" that Jan measured. But the final closing spots were longer than all the others:

Intake open/close: 25 / 84
Exhaust open/close: 62 / 40

I also noted the mid point that the valve was fully open: Intake 87.5 ATDC, Exhaust 11.75 BTDC.

I have obviously no faith in the accuracy of any of these numbers! I'm looking at my calculations to convert from where the crank pulley was to the ABDC and the ATDC for the valves closing. I'm thinking that I converted the opening spots right, but must have flipped something on the closing spots. I don't know if I can resurrect the results from my notes and fix it. But next time I adjust the valves, I'll try to measure the closing spots again. But if that mistake is true, that does more strongly suggest the Jan Sunbeam Specialties H120 cam measurement, which is closer to the E128 cam than the "stock" H120 cam, with less lift - don't know about the peak/duration.
 
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RootesRacer

Donation Time
I have never heard of this "Holbay SS" cam.

IMO the easiest way to determine if its an E128 or an H120 is to straight up measure the valve lift and this can be done on the engine by doing nothing other than removing the valve cover and measuring the lift delta.
 

Jay Laifman

Donation Time
Sorry, I kept editing the post above.

My notes indicate that I read an article where Jan bought a cam from Sunbeam Specialties that was supposed to be an NOS H120 cam. He measured it or had it measured and provided the data I put in above.

Is he still on this board to answer to it?

I will try to measure the lift this weekend - for my sake!
 

RootesRacer

Donation Time
The "SS" cam has nearly the same lobe centers as the E128 and stock.

The H120 is well known to have a lot of overlap, the "SS" cam and all the rest do not.

We will probably never know the details on that cam, but its not even close to being an H120. Perhaps its a profile duplicate of an H120 cam ground on lobe centers compatible with stock 1725 cams but what would be the point of that?

Jan pops in here now and then, message him and you may well grace us with his knowledge.
 

jumpinjan

Bronze Level Sponsor
My notes indicate that I read an article where Jan bought a cam from Sunbeam Specialties that was supposed to be an NOS H120 cam. He measured it or had it measured and provided the data I put in above.
Jay,
I don't remember the H120 cam, maybe I did. I do remember having a Lemans cam and I sent that to Delta for profiling. I'm pretty sure the Lemans cam was the only one to have profiled.
Jan
 

Jay Laifman

Donation Time
I'm looking for my source. My notes say that it was in "an article" by Jan. Did you ever write an "article" either on this site, in the SAOC Horn, or some other publication?
 

husky drvr

Platinum Level Sponsor
Jay,

"Alpine Marque", issue #7, page 30.

couldn't get the link to copy and work - check header at top of page "SAOCA Info" > "Alpine Marque"

HTH
 
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