Don Terrill’s Speed-Talk

cam specs are 110* lobe center,adv dur. is 264 ,210*@ .050. 478* lift. Total timing should be 36*, according to "Babe Erson" Dist. is an electronic one from a '74 nova. with a HI- 6,with adjustable vacuum can, which is not adjusted at all

I don't think 6 cylinder engines had HEI until '75. So, if you could take a close up picture of the advance mechanism under the rotor so the springs and numbers on the weights and the advance cam are visible, it would be possible to offer an opinion. The advance curves in original '72 through '74 Chevy distributors were nearly all very short and would be OK for most engines simply advancing the initial setting over the factory emissions setting. The 73 and 74 distributors in Chevy 350s had 18 degree mechanical advance parts which made it easy to make a radical cam distributor for 18 initial + 18 curve = 36 total, no welding or brazing to shorten the slot required.

It might have been a '75 or 76, it's been about 25 years since I got it.it's the external coil style I replaced the weights and springs with a curve kit,

Any chance you still have the original parts, the weights and the football shaped cam? What numbers are stamped on them, the weights and cam? What is the distributor number?

if you just want to see if a faster curve will make better performance just remove one advance spring and try it. put a "E" snap ring on the post to make sure the weight can not come off

The weights can't go anywhere because the rotor holds them in place.

Not saying you can't try it, but using only one spring will cause excess friction between the rotating pole piece (reluctor) and the shaft which will result in the mechanism not wanting to retard when the speed slows down. The springs in Delco type advance mechanisms should be identical and have the same preload so the rotating pole piece is floating on the film of grease between it and the shaft. Lopsided springs or a single spring will pull the mechanism to one side which will push the grease to the other side, eventually no grease on the tight side will stick. Guaranteed.

Tuner wrote: ↑Sat Mar 03, 2018 9:48 pm The weights can't go anywhere because the rotor holds them in place.

Not saying you can't try it, but using only one spring will cause excess friction between the rotating pole piece (reluctor) and the shaft which will result in the mechanism not wanting to retard when the speed slows down. The springs in Delco type advance mechanisms should be identical and have the same preload so the rotating pole piece is floating on the film of grease between it and the shaft. Lopsided springs or a single spring will pull the mechanism to one side which will push the grease to the other side, eventually no grease on the tight side will stick. Guaranteed.

Gonna suck when the day comes that all this information and the people who have acquired it are gone. Kinda reminds us of that every time we lose someone from the community.

Rest in Peace, Big Joe.

I tried getting pics of under rotor but it said they were too big. I'll try again.

Well, that picture with the part # and date code turned out good. It was made October 16th 1975. Do you have the original parts, weights, springs and advance cam? Do you have any other HEI advance parts? Are the weight pivot pins OK, unworn?

How can I make the picture fit? It keeps saying that the pic is too big

Here it is. The weight pins are in excellent condition.

That looks like it is stuck now and not in the fully retarded position. Do you have the original weights and springs? The 400 cam gives a short curve with the original weights, suitable for your cam timing. I have an HEI in the dist. machine right now so I will look and see if I have one (400 cam) and see how it acts. I think all you need to do with the original parts is set the total for best power and the curve is short enough the idle and low end will be about right. I recall the 6 cyl. distributors advanced quick enough they didn't need softer springs, just the initial timing set more advanced than the smog legal 4 degrees or whatever it was.

You see in the hole in the center of the cam, the shiny circle where the peg in the center of the rotor is in contact with the end of the main shaft. That is a good thing. That peg is supposed to contact the shaft to support the mechanism with minimum friction, sort of like the ballerina's toe. A tiny dab of grease there is advised. Some rotors are not made correctly so that peg doesn't touch and the underside of the rotor rubs on the weights, causing friction. For a while in the late 70s there were some gypo rotors around that would lock up the mechanism, but I haven't seen one of those in 35 years. Some new Chinese rotors in the cheap HEI clones drag on the weights because that peg is too short.

read my mind tuner. once posted about initial jetting on a fresh build Joe was spot on
back on topic..

I don't think that any part is stuck. I had the dist. sideways when I took the picture. Everything seems to move freely. I don't think that I have the stock weights.