Cam design

[Quickstop [UK]]

I've read a couple of people have gone off and made custom grinds and then followed with some impressive dyno/track numbers.

I also am led to believe that turbo cams are very different from n/a cams.

Where do people get their info? Please can you point me to some links or ideas where I can learn about cam choice?

I'm googling as well as browsing the site.

Happy Thanksgiving!

 

[midnightbluS10]

Re: Cam design

WindedV6 just made an awesome post regarding cams.

edit: http://www.syty.net/forums/showthread.php?t=86361&highlight=lsa

 

[bezerk]

Re: Cam design

with turbo and cams you can do some freaky stuff. you can let the boost blow away all of the left bad gasses in the chamber, like a super 4-tact. with overlap.

 

[Icarus-54]

Re: Cam design

Contact Mark Campbell @Campbell Automotive,on this site.He'll hook you up with a custom grind

 

[Quickstop [UK]]

Re: Cam design

Thanks guys.

I'm more interested in reading about how to do it rather than having someone make me something, more knowledge gathering than research for a specific reason.

If anyone has some other links or recommended reading, I'd enjoy reading it and maybe someone else might too.

I asked Harmon about his trucks and he said that the cams were night and day so I just want to understand the science for a turboed cam a bit better.

:tup:

 

[qbnkiller]

Re: Cam design

Hey Mark...John's posts on this topic are good. Cam design (selection) is a closely guarded secret for the top guys. It is very simple to tell someone to just throw in a 420 cam and retard it 4*, but there is definitely LOTS of power to be had with a well-designed cam. Lots of things must come into play when selecting a cam. I found a LOT of power with the cam I ran in my V6. The specs were not anything crazy, but the power it made (as well as for how large the power band was) was amazing.

Good luck Mark!!

 

[MRKING]

Re: Cam design

I will take a 54.5mm ford sized babbit solid roller as well . When can i pick it up ? LOL .

 

[Quickstop [UK]]

Re: Cam design

Thanks for those numbers Dave.

Point to note - these seem different from the specs for 229-1902 which Clevite advertise for our trucks.

So having read through that, looks like the stock cam is .009 230/243 and at .05 195/179
with an LSA of 109. 979 which gives overlap of 16.5* at .009 and -33 at .050

My main interest was to compare overlap with a 415:

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=171&sb=2

Using the same calculation, I get overlaps of 56 and 4 at .006 and .050 respectively.

56:16.5 and 4:-33. at .009 and .050
respectively giving the answers of 40 degrees at .009 and 37 degrees at .05

Basically, 40 degrees at both ends...

Next question - what does this mean in terms of power wasted/ gained. Any gurus care to comment?

turbo cam info

 

[Quickstop [UK]]

Re: Cam design

I had two cams profiled. Each cam came from a known-original LD SyTy engine. Both sets of specs were the same. I don't know what Clevite's cam is, but these specs are from original-equipment cams that came out of SyTy engines.

What I meant is that the Clevite are recommended by some as replacement but that they are different from the stock cams - thanks for certifying the authenticity of yours.

The Clevite thing might be irrelevant. I've mentioned the PN# in a previous post though.

:tup:

 

[ziembic]

Re: Cam design

Thanks for going to the time and trouble to do this Dave. This is a valuable piece of information to have.

 

[Beavis]

Re: Cam design

Not all 4.3 cams are the same. I remember a thread about cams and the differences between the years and vehicles they were in. If I remember right, the 4.3 astro van had the biggest and best general specs from factory. May not be the best for us, but if you look around you might find it and compare it to what the clevite one is.....

 

[dgoodhue]

Re: Cam design

The SyTy cam is unique to SyTy's. it's slightly more aggressive than a stock LB4 cam.

 

[Beavis]

Re: Cam design

http://www.syty.net/forums/showthread.php?t=15850&highlight=camshaft+spreadsheet

Found it.....

 

[DaveP]

Re: Cam design

That old thread shows the LB4 and the SyTy cam as being the same grind. This is incorrect. Yes, for years, it was thought that the two were the same. I believe this comes from specs in the 92 Typhoon Helms manual supplement that incorrectly lists the LB4 specs for the Typhoon.

I have a stock 91 LB4 cam. Maybe someday I'll take it to Isky and have it profiled too.

 

[Beavis]

Re: Cam design

Dave, since I don't know how to read and understand the data on the one you had profiled, what does it translate too in specs we would commonly see and recognize?

 

[SY2455]

Re: Cam design

The old book from our 1991 Astro van with the H/O motor list the lobe lift of the LB4 at .234 for the intake and lobe lift at .257 for the exhaust. The book list the lobe lift for the H/O motor at .269 for the intake and .276 for the exhaust. If I find a H/O van at a bone yard I may pull the cam to get it check out to find out what is so bad about it. Our van ran really well and alot of people used to ask my wife if we put a V8 in it. NOTE: IT also said that these spec are +/- .002 on each.