HEI distributor tuning problem

[WadmalawJoe]

Originally Posted by Longhorn 70

This is weird....Usually detonation INCREASES with increased engine temp. Yours seems to be going against that.

Most people install colder heat range plugs in mildly built engines is to alleviate detonation caused by increased head temperatures. I have colder plugs in the Olds engine in my truck and that has helped me get rid of ping.

I have a Skip White 6503 on the Olds. I haven't had pinging problems with it either. That distributor has performed well for me.

Could you be running too lean while cold and when it warms up all is good? Like the heat riser isn't there/working or the choke pulls off too soon?

Please post the solution to the issue when you find it.....I gotta know.

Maybe it is to lean when its cold, but my choke is a manual and I probably tend to leave it on longer than I need to, just to help warm up the motor. In the morning especially, I let it run a few minutes before heading out.



[QUOTE=cdowns;5933044]big difference in quality from something like a shippy chinese and a real quality unit like msd pertronix
I hear ya, I was extremely hesitant about buying it, I asked around on here and no one had a problem with theirs. Maybe, I should swap it out for another just to see if its a bad distributor. I will have to say I was surprised at the actual quality of it. Looking it over carefully, it looks pretty good, metal and plastic parts are all pretty solid, not super thin or cheap feeling.



After bouncing PM's back and forth with CB1987, I'm leaning towards a vacuum issue. I need to research my carb and make sure I'm on the right port or maybe switch to a port on the intake manifold or something.
It's been a busy week and I haven't had time to mess with it unfortunately. I drove it almost everyday for two weeks with it making the noise so I'm scared I might have damaged something or that it is damaging it. So I parked it for a few days until I can mess with it more.

[WadmalawJoe]

Well, I finally had a chance to read up on my carb, the edelbrock 1405, I have 3 ports on the front; a ported vacuum, pcv port and full time vacuum port. Well its plugged into the full time vacuum, that's got to be it. It's supposed to be on the ported vacuum. I should have time to try it out tomorrow, so I will let you all know what happens.

[LONGHAIR]

Here we go again with carburetor instructions telling us how to time our engines. Holley instructions do this too, or at least used to.
You can only plug it into the place where the distributor is calibrated to work.
While I am firmly against running ported vacuum, if that's the way the distributor is set up, that's the easiest way.
It's not the best way though, it leaves performance and fuel economy on the table. Setting up your distributor to work with full vacuum will gain you the most.

[tim21391]

did you use the power wire off the other original coil? you should be running it off the fuse panel if you have not i know i had that issue when i converted mine

[WadmalawJoe]

Originally Posted by tim21391

did you use the power wire off the other original coil? you should be running it off the fuse panel if you have not i know i had that issue when i converted mine

nope, ran new wire, 12v feed.

[WadmalawJoe]

ttt
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[JOJABOY]

My buddy and I went round and round with this a few weeks back. We then incorporated the help of an elderly gentleman. Words of wisdom....never under-estimate the knowledge in our elders.

You have to look at all three aspects of your timing. (initial, centrifugal and vacuum). You need to know what your total timing is at 3000+ rpm (all in) and with and with out a load on the engine. You may be at 12* inital and have 18* vacuum advance. But how much is your weights advancing? You need to check it with vac advance unplugged and capped. Use your timing light and get the timing at 3000 rpm. Then....hook a vacuum pump to the vacuum advance can and pump it up to see where it puts you timing will all of the advance added in.

[WadmalawJoe]

Thanks Longhair and JoJaboy.
It's taking a minute for all the timing info to get through my thick skull.
I also really need a tach so I can get a better handle on what rpm's I'm at and so forth. It's been on my list since I bought the truck.
I don't have a vacuum pump either. They can't be to much, I will look into getting one, but I think I can get some readings anyway with out it, just by unplugging the advance vs plugged in advance.
Anyway, I will do my best to figure out where its at and when (timing/rpm) and post my findings.

Thanks again!
Joe

[JOJABOY]

Originally Posted by WadmalawJoe

I don't have a vacuum pump either. They can't be to much, I will look into getting one, but I think I can get some readings anyway with out it, just by unplugging the advance vs plugged in advance.

It's not exactly the same. When you rev your engine in park, the engine isn't under any load. So the vacuum is different. Short of hiding under your hood with a timing light while your wife takes the truck for a drive.....You can get a cheap $5 vacuum pump and pull the vac advance can in. This will simulate the intake creating different vacuum till all in.

Sure beats hanging on to the headers while straddling the fan and wife at the wheel.

[WadmalawJoe]

Originally Posted by JOJABOY

It's not exactly the same. When you rev your engine in park, the engine isn't under any load. So the vacuum is different. Short of hiding under your hood with a timing light while your wife takes the truck for a drive.....You can get a cheap $5 vacuum pump and pull the vac advance can in. This will simulate the intake creating different vacuum till all in.

Sure beats hanging on to the headers while straddling the fan and wife at the wheel.

Bo wha'cha talking about?! its under load, the bed is slap full!!

The vacuum pump; just give it a couple pumps? that small advance can can't require to much vacuum?

[JOJABOY]

Originally Posted by WadmalawJoe

Bo wha'cha talking about?! its under load, the bed is slap full!!

Ha Ha Ha Been watchin too much Lizard Lick! Just pump it till it retracts. You can put your mouth on the end of the tube and suck if you don't have a pump. But you will need two people. One to suck and one to use timing light. My wife prefers to suck. LOL

[JOJABOY]

He's at 32*. The 50* is with vacuum advance. Yours will probably register 52* or so with vacuum pump hooked up if your total timing is 36*

[JOJABOY]

you said you dialed vacuum advance can as far back as it would go right? if so, try moving your initial timing back to 9*. you may have to turn your idle up a little to get it where you want it in the end but try 9* and go for a drive.

you need to get your "all in" timing back just a little to stop the pinging

[WadmalawJoe]

So you think I should try the other port again and adjust the timing for that port?
That's the ported one and its going to piss Longhair off.....lol

I wonder if that ported one even has any vacuum since it started pinging as soon as I gave it gas. That tells us that its not advanced enough correct? That port maybe stopped inside since it hasn't been used in a few years. I will check that out and let you know.
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[JOJABOY]

ported vs. non-ported is depending on what your engine like best (in my opinion) put it where is runs best then adjust that 12* initial timing down below 10. i would start about 8*. it's simple addition. base timing plus centrifugal timing equals total timing. total timing doesn't factor in vacuum advance timing. most sbc engines like total timing around 32* and another 15* of vacuum for a grand total or (all -in) around 47*

you are at 50. so back the initial timing back to 8* or so. adjust your idle screw to get your idle where you want it and go driving.

[WadmalawJoe]

Thanks, I will give that a try in the next couple of days and let you know. On one hand I hope its that easy on the other hand it will piss me off that I just didn't try backing the timing down more in the first place.
However, it does have some kind of performance cam in it and that is most likely effecting how the timing needs to be set.

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[WadmalawJoe]

Well, I adjusted timing down to 8 degrees but nope.....still doing it. It is reading 47 degrees at all in at 3,000 rpm, its actually all in well before that.
Here is some more info,
I rigged up my multi-meter/tachometer to reach inside the cab.
The detonation issue happens at 2,500-2,600 rpm (50-55 mph)
I came back, reconnected timing light and noticed its all in (47 degrees) around 2,100-2,200 rpm.

Should I go with a heavier spring so it goes all in later or just back the timing down more?

[JOJABOY]

People say 3000 because it's definitely all in by then. Most curves kick in total advance around 2200 like you mentioned. So that part is good. You just have to figure out why your motor is so finicky. I would check my plug gaps. But I would venture to say change to heavier spring is going to be your next move. Try to get that all in down from 47. It shouldn't take much. Some people put stops in their HEI to keep the weights from fully advancing or a stop in their Vac advance to keep it from fully advancing. You can google "vacuum advance can stop" and see what I am talking about.

I am running two blue springs with my cam set up. My vac advance can was advancing around 18* like yours (which is quite a bit) and I got an adjustable one and dialed it back to 12* of advance.

So my initial timing is 10* plus 16* of mechanical advance (centrifugal) and my vac can advances it another 12* so my all in is at 48*

Yours is 8, 20 and 19 it sounds like to get 47* all in. Will your vacuum advance dial it down any???? 19* vacuum advance is ALOT

[WadmalawJoe]

I went back out and backed timing down to 5°, it got a little better, then I went to tdc and it was almost gone. It would only make the noise around 2,510-2,530. Trying to find the noise and hold the rpms is easier said then done.
So I'm thinking either my tape is incorrect, as in the parts guy gave me the wrong one or the tdc mark is off. I measured my balancer and told him the size, if the tape is supposed to go all the way around, mine doesn't because I cut it shorter to make it easier to put on. Wish I would've thought to check the length.
It ran ok at tdc, just had to tweak the idle up a touch while the advance was disconnected. Soon as you plug in the advance it jumps to 19-20° .
My spark plugs are all gaped at 40 or 45? Whatever your supposed to gap them to with going to hei.
With limiting adjustable advance, you mean that little cam piece? I've seen it in pictures, it must be up under the rotor or something? if I have one I can't see it.
The adjustment screw inside the can controls how fast the vacuum advance kicks in right ?
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[LONGHAIR]

The vacuum advance seems to be the issue here. But, you never have stated (or I missed it) what you actual vacuum reading is at idle? Also, what amount of vacuum it takes to make the canister advance?
You see, the thing that screws up most people is the term "vacuum advance". It's really backward. The thing is actually releasing the advance that it holds as you accelerate.
This is why you must remove and plug the line when setting the base timing with the light. Because as soon as you plug it back in, you get all of the advance it has to give...at idle, when the vacuum is highest.
So, as you accelerate, the vacuum advance starts to "go away", while the mechanical (centrifugal) advance is "coming in". The only time they are both all-in would be if you suddenly took you foot off of the throttle at highway speed...not much pinging there.

So my thinking at this point is that your engine makes pretty good vacuum and the canister that you have will not release early enough. You really need a vacuum reading at your 2500 rpm pinging point. That, and the vacuum rating of you canister will tell us a lot.

[LONGHAIR]

Dupe.

[WadmalawJoe]

I was reading up on the vacuum advance stops or limiters and came across this explanation its pretty good and with good pictures imho
http://temp.corvetteforum.net/c3/joe..._Recurve.shtml

I think I need to pick up a kit that comes with the stop and install it. Instead of backing my timing down until it the highway tapping goes away, I just need to limit the advance to maybe 10 instead of the full 20 degree jump.
Which is basically what JoJaboy and others have been saying all along and what I have been reading. I guess I just have been trying to make what I have work, but my motor is just real finicky.

Longhair to answer your question on the current advance can, it starts to work with very little vacuum at all, maybe 3-4 inches of vacuum, its at full advance by 10 inches for sure.

[LONGHAIR]

Originally Posted by WadmalawJoe

Longhair to answer your question on the current advance can, it starts to work with very little vacuum at all, maybe 3-4 inches of vacuum, its at full advance by 10 inches for sure.

How much vacuum does your engine make? At idle? At the pinging point?
It seems like there is still too much vacuum advance at that rpm.


This is the screwy thing about a distributor set-up for "ported vacuum". Since there is no vacuum to the distributor at idle, it has more initial advance and less vacuum advance to keep the total similar.
Which is why you can't just change which place where the hose is plugged, bad things can happen.....
Many older trucks are converted to HEI, with "unknown" distributors. They really should be calibrated to match the points-type distributor that came out. The conversion is not done because the timing curve itself is wrong.

The carburetor companies have no idea what is going on, how could they?
Maybe for a few "specific applications" where is was that way in the first place, but how many of those are there? That is certainly not the case with the more universal-fit models.

[formikaus]

Sorry to hear all the problems you are having. When i put my Accel billiet HEI with a supercoil cap in, I did not use the vacuum advance. I just left it capped off out of the box. I did still have some pinging at the same speed range ONCE THEY STARTED ADDING ETHANOL!!!!! I started putting in 93 and it quit. With it capped off I did still get around 18 mpg's, but I am running a stock cam, 700R4, and 308 gears. Like I have said before, I feel for you. A engine noise is as bad as door glass without weatherstripping....it will drive you crazy! Lol.

[WadmalawJoe]

[quote=LONGHAIR;5950317]How much vacuum does your engine make? At idle? At the pinging point?
It seems like there is still too much vacuum advance at that rpm.

I have a vacuum pump, but not a vacuum gauge.... its on the list...
I might could use the gauge on the vacuum pump somehow, I will look into that.

Originally Posted by formikaus

Sorry to hear all the problems you are having. When i put my Accel billiet HEI with a supercoil cap in, I did not use the vacuum advance. I just left it capped off out of the box. I did still have some pinging at the same speed range ONCE THEY STARTED ADDING ETHANOL!!!!! I started putting in 93 and it quit. With it capped off I did still get around 18 mpg's, but I am running a stock cam, 700R4, and 308 gears. Like I have said before, I feel for you. A engine noise is as bad as door glass without weatherstripping....it will drive you crazy! Lol.

18 mpg!!!! nice, this isn't downhill is it? ...lol


Nobody in town has a adjustable vacuum can with a limiter plate, so I would either have to order one or take it out of the mechanical advance.
I read some about making one, I have three vacuum cans to use, so I might try that.

Thank you everyone and I will update with more info asap.