Don Terrill’s Speed-Talk

jmarkaudio wrote: Strictly an effort to market someone's cam...

I agree that you can not generalize things as much as Vizard may have claimed, but I think he is speaking in regards to street NA engines, which then does bring some credibility to his generalizations.

Even at that I don't see how it is marketing anything except for a few cam grinders who do use narrower LSA's on their shelf stocked cams. BUT those are not the same cams companies that run huge ads in these magazines. Maybe its "anti-marketing"?

Does anyone have a list of cam companies offering BBC cams on such tight LSAs? Or of BBC cams made with such LSAs?
I know at UltraDyne, from 1980 on, two of our most popular BBC cams, the BB288/296F7 and the BB286/300R7, were extremely popular ground on 107 LSAs.
However, they were almost unstreetable, at least for the average guy.....

UDHarold

Hmmmm....

No reply for some time...

Does these mean that EVERY cam company in America has got it wrong?

UDHarold

UDHarold wrote:Does anyone have a list of cam companies offering BBC cams on such tight LSAs? Or of BBC cams made with such LSAs?
I know at UltraDyne, from 1980 on, two of our most popular BBC cams, the BB288/296F7 and the BB286/300R7, were extremely popular ground on 107 LSAs.
However, they were almost unstreetable, at least for the average guy.....

UDHarold

http://www.compcams.com/Cam_Specs/CamDe ... d=417&sb=2

http://www.compcams.com/Cam_Specs/CamDe ... d=418&sb=2

Um... Isky. I know its the obvious reference as they run narrower LSA's on almost all of their stuff though. Even you said that 107's and 108's were ground by companies you had a good part in though.

Those GM engineers who picked the cams for the LS series of motors need to renew their subscription to PHR. Those crazy guys went wide on the LS cams, 114 to 118 LCAs. Hope they read the magazine article and get their act back together with the narrow LCA required to make power.

andyf wrote:Those GM engineers who picked the cams for the LS series of motors need to renew their subscription to PHR. Those crazy guys went wide on the LS cams, 114 to 118 LCAs. Hope they read the magazine article and get their act back together with the narrow LCA required to make power.

Except they need to worry about emissions, fuel consumption, and driveability.

ap72,

Yes, I know.
Crower has been grinding BBC rollers and solids since the 1960s on 107, and I have at UltraDyne since April, 1980.
I use 107, 108, and 109 all the time, as well as 114, 116, and 118 LSAs.
I was curious if ANYONE listed any BBC cams on LESS than a 107, which I consider common enough not to be unusual.
Surely some cam company would hit on this magic number......

UDHarold

I see where you're going now. I thought you were just talking about narower than the typical 110-114 which is too wide in some applications.

i had a solid roller from crane i bought in 86 that was ground on 106. i dont remember the duration but it was 270 or smaller

I still don't understand why plus or minus maybe 5° on duration, which alters valve events far more than 1-2° LCA, doesn't seem to get nearly as much attention...

Too many generalizations. You can't just say 'big blocks like this and small blocks like that' and be accurate. Every engine is different.

I'll say that recently I have installed several BBC Comp Thumper cams that are set up on a 107 with a really wide duration spread and they've all performed better than expected.

It gets back to the four main valve events and the fact that LSA is just a byproduct of those.

Ive read a few of Vizard's articles and I agree with him on a lot of stuff. This one however, I dont think he even believes his own BS. A few years ago he had an article where he built a 418 windsor. The following year a similar article came out where he built the same combo with 425 cubes. Keeping his valve diameter the same for both engines he widened the LSA for the displacement increase. In both articles he claims that the LSA was computer spec'd and right on. Going by his theory he should have gone tighter. Not trying to knock the man, he has been in the game for a while, but I dont think his theory is universal. Just works on some.

MadBill wrote:I still don't understand why plus or minus maybe 5° on duration, which alters valve events far more than 1-2° LCA, doesn't seem to get nearly as much attention...

I find this to be very true, ESPEIALLY on exhaust lobes, you see some people specing a single pattern and others a dual pattern with 10º+ more duration on the exhaust for the exact same heads and exhaust with a relitively identaical intake lobe.

I thik the LSA is brought up so much now because for so long it was not talked about. Everyone just slapped it somewhere between 108-116 and called it good. Many old cam advertisements don't even mention LSA, ICL can be adjusted on installation but since the LSA is ground in you would assume people would include it when trying to sell a cam.

And yes Harold and CamKing, you guys are of the few that always have appreciated the LSA for what it is and never over looked it, but you're the bright and shining exception IMO.

And before people jump on this and start talking about when they were drag racing in the 10's 35 years ago they knew about it- most of the posters on this forum are a little more skilled than the typical person who reads those car magazines, the article needs to cater to the majority of its audience, not the top 20%.

I am allready sick and tired of hearing all this, but I will just say this one more time, if you are wanting the most performance for your engine, you will be better off with tighter centers than wider centers- I am not talking about street drivers, but street racers or drag racers. MANY people get mixed up between street and race- they are NOT the same

JOE SHERMAN RACING ENGINES