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#1 |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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HEI distributor tuning problem
I switched to a HEI dist. About a month or so ago and I can't seem to tune out the tapping at the 50-55ish speed. I have played with different base timing settings. I have tried a different vacuum advance module? and even went to the heaviest springs in the distributor.
I'm thinking maybe the distributor is just bad? The motor (350) does have some kind of performance cam in it, maybe that's effecting it? (Vacuum) Any thoughts? Thanks! Joe Posted via Mobile Device
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Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#2 |
Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,143
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Re: HEI distributor tuning problem
Joe, What does tapping mean? Lee
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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#3 |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
Valves tapping?
I thought I was having some other noise problem but after reading about another member with same symptoms it dawned on me what it was. If I disconnect the vacuum advance and cap the port it doesn't make the noise, it just goes to 5 MPG... Posted via Mobile Device
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Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#4 |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
Compression is 180, give or take a lb or two at all 8 cylinders.
I haven't tried high octane, but if it needed higher octane it would ping a lot more often... I would think anyways... Posted via Mobile Device
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Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#5 |
Registered User
![]() Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: HEI distributor tuning problem
what does it do without vacuum advance connected? Still ping?
Also since it has a performance cam, did it get head work too....compression?
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 |
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#6 |
Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,143
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Re: HEI distributor tuning problem
I'm taking it that it did not do this with the other distributor? Did you do any maint (assure the shaft and weights were free, etc) to the HEI? Is the gear orientated correctly? Is the advanced stop in tact? Is the shaft end play excessive?
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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#7 |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
To be honest I don't know if it did the same thing with the other distributor, because I also changed the exhaust to a quieter one because I couldn't hear crap over the other one. In fact you can barely hear the noise with the quiet exhaust.
The hei is new and seems fine. Shaft fit good, no excessive play. Posted via Mobile Device
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Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#8 |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
Yes I did the initial timing with the advance unplugged and I capped the port.
Yes on the tdc question. Posted via Mobile Device
__________________
Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#9 |
Active Member
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Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: HEI distributor tuning problem
As Lee H mentioned if it was a used HEI.
The last used one I got the grease was so dried out it was preventing the mechanical weights from springing back. They would move but sort of stiff. Check carefully for vacuum leaks and with a "dial back" timing light check regular and total timing. If you don't have one, rent one or borrow one. It's easier to see total timing with one of those. As far as using higher octane, it's more expensive but one tankful would let you know if that's your problem. .
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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#10 |
Registered User
Join Date: Dec 2012
Location: Altoona Iowa
Posts: 481
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Re: HEI distributor tuning problem
I know it may be a redundant question, but before you put the distributor in did you take cylinder one to TDC? It really sounds like you are still out of time a bit something like about 12-16 degrees. I ran into this once.
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#11 |
Registered User
![]() Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: HEI distributor tuning problem
did you verify the initial timing was set properly with the advance disconnected?
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 |
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#12 |
Registered User
![]() Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: HEI distributor tuning problem
If you have a timing light with dial up advance on it, start the truck with timing light connected and vacuum disconnected and plugged.
Bring the RPM up with the light on the timing mark. You should see it moving advanced. If it doesn't check weights and springs. If it does and still only goes 5 MPH, pull the module.
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 |
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#13 |
I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,993
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Re: HEI distributor tuning problem
Just a thought but did you mark the Harmonic Balancer when you brought it to TDC?Occassionally the rubber in a HB will allow the outer ring to slip,giving a false reading of timing.
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The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil" |
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#14 | |||
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
Thanks for all the help!
Quote:
Quote:
Longhorn70, you misread my post on 5 mpg when vacuum advance is disconnected, gas mileage suffers greatly when the advance isn't connected. Quote:
Since I have the heavy springs, which are supposed to hold the advance from fully advancing until 3,200 rpms, maybe its the weights? Because basically its going into full advance too soon, thus causing the tapping? Am I understanding this correctly? Thanks!
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Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#15 | |
Active Member
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Location: Centrally located between Houston, Austin and Waco. BCS area.
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Re: HEI distributor tuning problem
Quote:
The tapping descripton is still a little confusing to me. When the engine is too advanced the noise I usually hear sounds like a pinging or rattling chains sound. A tapping sound is normally a loose rocker, piston slap or something not tight.
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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#16 |
Registered User
Join Date: Feb 2003
Location: Santa Ana, CA
Posts: 2,191
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Re: HEI distributor tuning problem
If you have a new HEI, chances are you have an adjustable vacuum advance can. To set the vacuum advance you need a 3/32 inch allen wrench. The adjustment screw is located inside the can, down the vacuum line port. You start by setting the vacuum advance to 0 degrees by turning the screw all the way in until it is lightly seated. Then unsrew it to the desired amount of vacuum advance. On my Accel vacuum can, each turn out equates to something like 2 to 3 degrees of vacuum advance. If your HEI did not come with the vacuum advance curve and adjustment directions, you can go online and find these for the Accel units. By adjusting the vacuum advance, you can possibly remove the detonation without messing with your initial timing or mechanical advance.
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#17 |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
Yep been there done that even tried another vacuum advance just to rule that out.
Posted via Mobile Device
__________________
Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#18 | |
Registered User
![]() Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: HEI distributor tuning problem
Quote:
Another thought, too "hot" a spark plug could do this too. When this happens you will see whitish flakey deposits on the plugs. Or white/grey build up on the center electrode if I remember correctly. For grins, have you tried octane booster to find out if it is ping or detonation?
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 Last edited by Longhorn 70; 03-06-2013 at 04:24 PM. |
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#19 | |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
Quote:
I'm fairly positive on detonation. It actually makes kind of a tic tic tic sound. Another bit of info, once its good and warmed up, as in after driving 20 miles or so, it doesn't seem to make the noise anymore. I thought maybe its a oil issue, as in oil is thick then thins out once hot. HOWEVER, when its making the noise, all I have to do is pull over, unplug the advance, cap the port and away I go with no noise. So it can't be a oil issue.
__________________
Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#20 |
Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,143
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Re: HEI distributor tuning problem
What brand distributor is this?
Posted via Mobile Device
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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#21 |
Registered User
Join Date: Aug 2012
Location: Port Hueneme, CA
Posts: 10
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Re: HEI distributor tuning problem
I have the same exact problem! That tapping noise happens when you are sort of maintaining that 50-55 mph? If you still have the links to where other people had this problem and feel like PMing them to me it would be appreciated it. I haven't tried to fix it since it only happens at that one speed.
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#22 | |
Registered User
Join Date: Oct 2012
Location: Ravenel SC
Posts: 317
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Re: HEI distributor tuning problem
The distributor is from Skip White Performance, the last distributor you'll ever buy! I researched it on here before I bought it. I couldn't find anyone with a bad one. Found post bashing them, because they're so cheap (pricewise) but overall quality looks great, billet shaft, decent parts, etc etc and warranty to, they will swap it, I already talked to them. Just worried the result will be the same since I tried a different advance can and springs.
Quote:
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Toys/projects Many toys, not enough time to play! My youngest son and I picked up a 69 Chevy C-10 on 1/7/22, this is my second 69, it was 10 years ago that I had my other one. So I知 back!!! ![]() |
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#23 |
Registered User
![]() Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: HEI distributor tuning problem
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.
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 |
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#24 |
Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,162
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Re: HEI distributor tuning problem
subscribed!
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1972 Chevy C-10, SWB, Fleet, 350/350, PS, PB, HEI, mostly stock, Survivor. ![]() |
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#25 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: HEI distributor tuning problem
big difference in quality from something like a shippy chinese and a real quality unit like msd pertronix
THE BITTERNESS OF POOR QUALITY REMANINS LONG AFTER THE SWEETNESS OF LOW PRICE IS FERGOTTEN
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71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY |
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