[Fot] A cam for Rick

[Tony Drews]

I was going to keep out of this one but am not capable of it.  :)

I run Larry's original design cams.  I'm not quite sure who is making 
them now - Ken Knight had some made last go-round.  It's fast but not as 
peaky as the Erson 24 - coming out of a turn at 3000 rpm is fine, 3500 
is better, pulls through 6500 RPM, not sure where it drops off - haven't 
had the courage to rev that high.

Most of the front runners (to my knowledge at least) run the Erson 24.  
I ran a modified one of those (experimental) and hated that one because 
it was even worse at low RPM than the Erson.

We ran an Isky 666 cam early on and it might be more suitable for a less 
highly stressed engine.  It was tractable and pulled through 6000, not 
sure about higher - I suspect going over 6000 won't be worth it.  With a 
built engine, ported head, all the goodies it's not as fast / powerful 
as the Larry or Erson ones.

The Isky would be easier on the valve train.  Larry's profile requires 
full diameter stock lifters - if you've gone with the GT40 lifters 
sleeved down it'll wipe the cam.  One set of lifters I bought from BPNW 
they had put a chamfer around the edge to break the sharp edge and that 
was enough to wipe a cam too.  It's pretty high lift so you need to have 
your ducks in a row for there not to be spring bind, have the seat 
pressures right, and consider valves and springs a replaceable wear 
item.  I suspect the same is true for the Erson 24 grind as well.  I 
believe there's an Erson 23 grind which is less radical that might be an 
option.

I'm trying to point out possible "off the shelf" items that don't 
require you to send a profile to a cam grinder...

The Erson ones are hopefully still available from Brian Howlett / BFE / 
www.BritishFrameandEngine.com.  Not sure who's making the Larry Young 
design ones now.

Cheers, Tony Drews

On 1/22/2023 11:30 AM, Larry Young via Fot wrote:
> The numbers for Erson/BFE #24 mentioned by David and Henry is the last 
> one in my list and has the longest duration. Like Henry said, if you 
> drop below 4,000 your dead.
>
> I got interested in the history of cam design. According the Speedy 
> Bill Smith (Speedway Motors) the real innovators after WWII were Ed 
> Winfield and Collins of Harmon-Collins (see the book "Souping the 
> Stock Engine). He said their designs were heavily copied by the 
> others. I think Kas's cams were designed by someone from Harmon-Collins.
>
> I certainly don't have the experience of many others on this list, but 
> I'll contribute a few comments on what Rick has said. Cams is a 
> subject that is mysterious (Rick said "black art") to many, so it is 
> easy for them to be fooled. There is nothing mysterious about it. I 
> agree that most people put to much emphasis on peak HP rather than the 
> entire range you will operate in.
>  - Larry
>
>
> On 1/22/2023 6:46 AM, David Gott via Fot wrote:
>> Hi FOT,
>>
>> I used Larry Young’s site to learn a lot about cams and their 
>> relative effects on engine performance with some crude engine 
>> modeling software, in the quest to pick the right cam for my wants, 
>> building a strong mid range engine, trying not to spin over 6,000 if 
>> I can help it with a stock based crank.    Does anyone happen to have 
>> the specs on the Gillander’s #24 they could share?  Just curious. 
>>  Maybe it’s at the pointy end of the list below?
>>
>> Rick McCurdy, here’s the cam reference list Larry put together, 
>> below, and I’d sure be curious what Rick Parent’s software would say 
>> I should have done!!!
>>
>> Triumph Cams <https://www.tildentechnologies.com/Cams/TriumphCams.html>
>>
>>
>
>
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