Worked on the 500 a bit today...

[rockhog]

Well my motor seemed to run out of steam at about 3200 to 3300 rpm or so. It has a mild MT 5 cam in it so it should pull to 4000 easy. So since it has been 6 years since the last tune up I figure it was time... :lol: .

First, Checked the initail timing. It was 10 deg. Cool. next checked total timing . Only getting 25 toal ...hmm. The weights/springs looked pretty crusty. So I went out and picked up a new cap,rotor, spark plugs,fuel filt,weights and springs for mech advance. Pulled the plugs and looks like the motor is running lean. The tips look brownish white.

Still need to get it back together today so I will keep you guys posted it it was ignition related issue.

One question.....can you get 34 to 35 deg's total advance out of these HEI's with having a ton of initail timing?? Oh yeah....also checked my vacum advance and it was not working as well.....gotta get a new one of those as well!

[Andy V]

might be tough, depending what year it is.....mine is out of a 76 I think. With 18 initial I can get 34 total. For everyday driving I put it around 10-12 and run the vacuum advance.

You can take a dremel and open up the slots in the plate to allow more advance. Kind of a trial and error job (start small) unless you have a distributor curve machine on hand to check it.

If you go too far you can weld the slot back up and dremel it back to shape.

Also, not sure I would worry too much about the plugs..with today's unleaded gas I'm not sure you can rely as much on the look of the plugs...at least that's what I'm finding on mine.

[rockhog]

Thanks for the reply Andy! Sucks that these HEI's cant get 34-36 timing without a ton of initail. Noone had the vaccum advance in stock so I had to order it today. Should be here on the 27th. I will set the initail at 12 deg and se where the total ends up at. On the new platium plugs I got recommends .060 gap! Thats way big compared to the .035 on the regular ones. Once it gets back to gether I will post how it responds.

How much power am I leaving on the table if I end up running like 30 deg total??

[Andy V]

it should be fine with 30-32 degrees timing without the vacuum advance hooked up. You'll have over 45 or so with the vacuum for part throttle cruising.

And the factory plug gap for the HEI system was .060". They run fine with that, most of the time I bump down a little to like .050"-.055" though. I just run the cheapy Autolite plugs, 646 is pregapped at .060 and a little over $1 something a piece.

[rockhog]

If I went to like 68-72 early motor(472 or 500) would those HEI's factory weights and springs allow for more mech advance?? I figure they limit the advance becuase its from the 76 smog dog era??

[STDog]

If I went to like 68-72 early motor(472 or 500) would those HEI's factory weights and springs allow for more mech advance?? I figure they limit the advance becuase its from the 76 smog dog era??

You can change the weights and the cam in the HEI to get a different curve. The early/late motor doesn't matter. Just get a different dist, or modify the one you have. You might find a different year HEI with more total, but it'd be easier/cheaper/faster to modify the curent one.
And after market dist would also be easy and fast, but not cheap.

Oh, and the earlier engines didn't have HEI, and the weights/cam in the points dist are different.

[rockhog]

Thanks ST

[Andy V]

HEI's didn't exist till '74 for the caddy, so any earlier distributor will be points.

What are you getting now for total with your 12 deg. initial?
And which year motor you running (and comp. ratio) as I don't recall if you listed that info?

One other thing of note, I put a set of the new weights in mine before, Proform or whatever el-cheapo stuff. The sides of the weights are so rough from the amount of shear in the stamping process, that they would not open all the way or freely. That could be your problem as well.
I took the weights back off and polished all the roughness out of the edges on the weights and the center piece with a bench grinder and polishing wheel. Then lubed up and it seems to open consistently and freely now.

[rockhog]

Its a 76 500 with stock 8.5 to 1's. Yeah I picked up a cheap advance curve kit from Mr gasket I think and the weights were junk. I just keep my stock ones and polished them up. I did use the silver springs from the kit. Seems to work very smoothly now. What are you guys using to lube the weights/springs up??

I got it all put back together today. Fired right up! I set the initail at 12 degs and seem to be getting about 31 degs total but not till almost 4000 rpm. The new vaccum advance now works and get about 42 degs at part throttle 2000-2500 rpm or so. I have not got a chance to drive it yet so need to see how it acts. I might try one gold springs and one silver to get a bit more total out of it. I saw on CB7 that a few guys said that was the set up to get 35 total with 10 inital on the stock HEI.

I will keep you guys posted on how the test ride is............ :twisted:

[Andy V]

You won't really get any more advance with the spring change, just will bring it in quicker. I'd go lighter on the springs, try to get it in close to 3000rpm.

If you got the adjustable vacuum advance, the set screw will adjust the rate of vacuum advance as well. They usually come with a limiter type plate you put under the back screw, to limit the total amount of vac adv you get. If you have 42 or so total at cruise I think you'll be fine, no need to limit that. I'd almost expect you'd have a little more, like 50 total with vac.

For lubing the weights, I either use a spray on graphite lubricant, or the spray on white lithium grease. Something that will stay on there for awhile.

[rockhog]

Thanks Andy for the reply,


Took the Jeep out for a cruise today and it feels great! Part throttle seemed much better and now pulls strong to 4000 rpm were the shift light comes on. Another thing the motor runs much cooler than before. Before it used to run 210 to 215 consistant. Didnt matter hot or cold outside. Now even after hammering on it 5 or 6 times ran 190 to 195 the whole time. Must be the vaccum advance helping it out. Either way I am happy as a clam.

[Nashalac]

Don't you just love it when a plan comes together?? Good job!!

[rockhog]

Thanks man! I am ready for a wheelin trip now.......... :D