engine timing dilema

[bhunt31]

Originally Posted by Billla

Making a statement like "pretty good power" suggests that people take this approach without fully understanding what they're doing

Making a decision to do this is part of the overall build process and requires an engine builder that knows what they're doing....

I 100% agree with this statement and realize I shouldn't have gone and put ideas into someone's head that I don't know for sure they know how to degree a cam. I'm just used to having people around me that built engines back when, if you wanted a cam for your engine, you had one ground specifically for that engine, then degreed it in when you got it. Nowadays, there's such a wide variety of cams that's it's pretty much plug and play, that doesn't stop me from getting the dial indicators and degree wheel out to double check things though...I don't like doing things twice, especially when the second time the engine is already in the vehicle. I run all my small blocks at a 107-108 LCA unless it's a 400+cuin engine, then it goes to 105-106 LCA...depending on what kind of engine it is and the duration of the cam.

[Billla]

Originally Posted by bhunt31

Do you see where he said that a cam too retarded will hurt performance? A cam can be installed straight up and be too retarded for the engine...that's what I'm getting at. A cam installed 4-6* advanced won't hurt anything for a street engine when it comes to power, but a cam 4-6* retarded will drop power, throughout the band. I do also remember reading him say that "SBC engines run best with between 4-6* advance in the cam" and that's where I run every one of mine and have never had an issue with expected power. It depends a lot on the LCA of the cam. A cam with a 112 LCA will benefit from having 4* advance to bring the LCA back down to 108* where 383 cubes and under run best at. It varies from cam to cam. The cam I bought had a 112 LCA, so I advanced it to put it back down where it needs to be. If you bought a cam with 106-108 LCA, it wouldn't need advancement, it'd be good straight up.

IMHO, you're taking a lot of pieces out of context and then mixing them together. I've kind of run out of steam here for this discussion; we disagree, I think it's bad advice - it's left to the original poster and other readers to do their own research and make their own decisions.

[bhunt31]

Originally Posted by Billla

IMHO, you're taking a lot of pieces out of context and then mixing them together. I've kind of run out of steam here for this discussion; we disagree, I think it's bad advice - it's left to the original poster and other readers to do their own research and make their own decisions.

which is why I said I think it's more of a misunderstanding of meaning than anything. I'm not saying I disagree with your point, cuz I'm not sure if you understand my point about the LCA topic. It's hard to have a discussion on technical topics without having the misunderstanding and disagreeances over the net, but no harm, no foul, no hard feelings.

[bhunt31]

I'm sure we could agree that a 350's cam should be set on a 108 LCA though, right?

If so, say you bought a cam with a 112 LCA, then for it to be optimum for the engine it should be advanced 4*, right?

This is what I'm saying...putting it in straight up would be like putting the 108 LCA cam in 4* retarded, which I'm sure we'd also agree is a bad idea and would hurt performance. I hope that makes a little more sense.

[Billla]

Originally Posted by bhunt31

which is why I said I think it's more of a misunderstanding of meaning than anything. I'm not saying I disagree with your point, cuz I'm not sure if you understand my point about the LCA topic. It's hard to have a discussion on technical topics without having the misunderstanding and disagreeances over the net, but no harm, no foul, no hard feelings.

No, I understand your perspective on LCA - I just disagree. No hard feelings, and I encourage people to read up on the topic.

[Billla]

Originally Posted by bhunt31

I'm sure we could agree that a 350's cam should be set on a 108 LCA though, right?

If so, say you bought a cam with a 112 LCA, then for it to be optimum for the engine it should be advanced 4*, right?

This is what I'm saying...putting it in straight up would be like putting the 108 LCA cam in 4* retarded, which I'm sure we'd also agree is a bad idea and would hurt performance. I hope that makes a little more sense.

No, I wouldn't agree at all - with any of these points. Can we just drop this?

[jablack]

I just read this so I'll put in my two cents. Whenever I change a cam I always buy a matching timing set. Usually they have the math figured out for simple minded mechanics like myself. You just bolt it all together and go.
I'm not sure what type of heads you have but if they are a vortec type, you have to use the right length spark plugs. I built a vortec head 355 years ago and had a problem timing it. It was real high like 50 degrees. I had ac delco r45ts plugs they just don't go down far enough. When I finally figured it out I dropped in a set of autolite 605's and had to back the timing way down to get it to run.
Make sure you read the directions on how to set the cam. You'll have initial, mechanical, and vacuum to set to get it at the right total advancement from the distributer end.
Then the carb will be the last thing to go through.
Once you think it's right, go through and time it one more time just to make sure..

[bhunt31]

Originally Posted by Billla

No, I wouldn't agree at all - with any of these points. Can we just drop this?

sure...just to show there's no hard feelings...Happy New Year, hope your year goes great for ya. Same to everyone else that may happen to read this!

[Painter D]

either way its running great now!

[bhunt31]

Glad to hear it's running good now, sorry we kinda jacked your thread there for a while.

[hotrod 80]

Glad to here you got it running good , now it's time for some drag radials and a track session .

[Billla]

I'm kinda reluctant to dive back in here after asking that we drop the debate, but there was an article in Chevy High Performance this month where this was addressed too succinctly not to reference. I'm not a big CHP fan, but they had the "big guns" from the major cam manufacturers.

"Almost all our cam experts agree that cams tend to run best with a bit of advance in place, so the 'sticks come ground to deliver this advance when installed in the straight-up position. What happens if you advance or retard the cam? With the fomer, the RPM range is moved down; with the latter, it's shifted upward. Knight (Crane Cams) recommends always starting out at the stright-up position. 'You can refine from there', he says, 'but if you're seeing a benefit from moving more than 8 degrees advanced or an degrees retard from 0, you don't have the right cam.'"

[willis0107]

you could have an air bubble trapped somewhere. you could be running to lean on the carb. there are a lot of things that can cause that to happen.