The camshaft is a comp 6329 solid 252@.050 about .580 lift with a 1.6 rocker.
What is the down side to locking out the distributor?
My distributor adds 24* of mechancial advance, so the motor likes at least 20 degrees at idle so that was pushing me over 40, so we made the decision to just lock it out.
So the plug heat range seems ok to everyone and i just need to come down on the timing?
As I stated above, all ignition boxes retard with RPM. All of them. They don’t all retard at the same RPM or the same amount but they all do it.
Let’s say your box starts retarding at 4K and it’s losing 2 degrees. By 5k, it loses another degree and at 6k 2 more degrees. That’s a total of 5 degrees. Most engines don’t like a 5 degree change in ignition timing.
As lewtot said above a locked out distributor is mostly done because guys don’t know how to get the correct curve or maybe they don’t care. But mostly I think guys just don’t know. I know I didn’t. And I was locking out distributors for 25 years. And because of THIS forum and the one guy on here who said all ignition boxes retard (and he wasn’t wrong) I went out and bought a distributor machine so I could test what he said. And like I said, he was right on the money and I was DEAD wrong.
His name is William Baldwin. A very smart man.
I was appalled when I found out how much some of these boxes retard.
If you are getting 24 degrees of mechanical advance at the crank, it means your distributor has 12 degrees in it. You double whats in the distributor to get what you see at the crank.
With the correct curve and a proper tune up, those factory iron heads will want about 38-40 degrees total. BTW, keep in mind that a timing light is electronic, that it has a slew rate (speed of the electronic switches which is what retards the timing in the boxes) and that they don’t all read the same either. But as a general rule, you should be at 38-40 total with those heads. Your light could be off a degree or two, or maybe even more. So always use the same timing light and look at your plugs and let them tell you what your timing should be.
So...for what you have and to get 20 initial and let’s just say 38 total you only need 18 degrees of mechanical advance in the distributor. Which means you only need 9 degrees in that advance in distributor degrees. Right now, if you have 24 on the crank (mechanical advance) you have 12 degrees in the distributor. You need take 3-4 degree out. I would shoot for 8 degrees in the distributor and let it run at 21 initial.
Then for the curve I’d need more information. But I’d delay the curve starting until 2000-2200 and get it all in by 3800 or so. That may change a bit if you have vacuum advance.
Just my .02 cents. BTW, on pump gas the total timing Mark can be right at the shell.
