hei cap orientation

trevor pordage

New member
Jun 10, 2013
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i am trying to get my coach running after sitting for about 4 years. it is idling rough and backfires under load.has hei dist and has been converted
to throttlebody fuel injection. i was going to pull the plugs and do a compression test but noticed that the cap is 180 degrees out. it was obviously
working ok when i bought it and i havnt touched it since getting it here . just would like to know the reason for this. i assume this is because it is
a dist. out of a car and the cap has not been notched to spin 180 degrees. am i correct
--
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project
 
The cap has a notch in it so the cap can only go on one way and seat fully on the distributor. I have seen people actually get those caps installed
wrong and a couple of those spring retainers latched while th cap is not fully seated. If it is really 180 degrees out, then someone in the past
installed the distributor with the rotor in the wrong position and then rotated the distributor body to match the rotor. Or they the wires on the cap
to match.

If it has run correctly in the past and you have not loosened the distributor, I would not mess with it now. It will run just fine the way it is.
There is no reason for it to have changed. I am working on one here right now that someone installed about 30 degrees out. It bugs me when I look at
it, but it is really not a concern to the actual running of the engine. If I end up pulling the distributor for some other reason, then I'll
reinstall the distributor in the correct orientation. Otherwise it will stay just like it is now. I have other more important things to fix.


--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> i am trying to get my coach running after sitting for about 4 years. it is idling rough and backfires under load.has hei dist and has been
> converted to throttlebody fuel injection. i was going to pull the plugs and do a compression test but noticed that the cap is 180 degrees out. it
> was obviously working ok when i bought it and i havnt touched it since getting it here . just would like to know the reason for this. i assume this
> is because it is a dist. out of a car and the cap has not been notched to spin 180 degrees. am i correct

Trevor,

While you are under there, check for a 5-7 cross. This does not have to be wires switched. If 5 and 7 are too close together, this can happen.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Trevor,

After being idle that long, there's a very good chance the centrifugal
weights in the distributor have frozen up with rust. Remove the cap and
check/lubricate them.

Ken H.

On Fri, Jan 19, 2018 at 12:10 AM, Trevor Pordage
wrote:

> i am trying to get my coach running after sitting for about 4 years. it is
> idling rough and backfires under load.has hei dist and has been converted
> to throttlebody fuel injection. i was going to pull the plugs and do a
> compression test but noticed that the cap is 180 degrees out. it was
> obviously
> working ok when i bought it and i havnt touched it since getting it here .
> just would like to know the reason for this. i assume this is because it is
> a dist. out of a car and the cap has not been notched to spin 180 degrees.
> am i correct
> --
>
 
To elaborate on what Ken H said if your dist has not been serviced then the original lube has offgassed and is now glue. They need to be pulled and
disassembled so the stiction can be cleaned off the concentic shafts and relubed. Perfect time to inspect/replace worn parts and reclock correctly. If
you are not running a magcore spiral wire set you need to.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
I also reapply the white heatsink compound under module as that dries and shrinks as well.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Back fire through throttle is mainly a lean condition , so make sure the
MAP sensor and TPS is hooked and the fuel pressure is wher it need o be.

On Fri, Jan 19, 2018 at 7:05 AM, John R. Lebetski
wrote:

> I also reapply the white heatsink compound under module as that dries and
> shrinks as well.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Sounds like bad gas to me. After my coach sat for over a year this happened to me.

>

>> i am trying to get my coach running after sitting for about 4 years. it is idling rough and backfires under load.has hei dist and has been
>> converted to throttlebody fuel injection. i was going to pull the plugs and do a compression test but noticed that the cap is 180 degrees out. it
>> was obviously working ok when i bought it and i havnt touched it since getting it here . just would like to know the reason for this. i assume this
>> is because it is a dist. out of a car and the cap has not been notched to spin 180 degrees. am i correct
>
> Trevor,
>
> While you are under there, check for a 5-7 cross. This does not have to be wires switched. If 5 and 7 are too close together, this can happen.
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
It has run correctly in the past so I am not going to touch the distributor. I just read something about having to file a notch in the cap to get the
orientation correct. It appears that Bobby Moore did not do this as the plug markings on the cap are 180 degrees out I just wanted to confirm this
--
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project
 
I guess I'm not understanding. Is the vacuum advance on the right side (US passenger side) when standing behind the engine? Is the power plug in the
cap also on the right side?

Now that I asked the questions I need to go look at mine. From memory I believe mine are both on the right side. Do NOT trust my memory.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Trevor, the numbers on the secondary conductor retainer are usually
included on genuine GM cap components, but not always on aftermarket parts.
What has happened in your case is that the engine was not at top dead
center, compression stroke, when the distributor was installed. So, the
installer rewired the plug wires in the cap instead of removing the
distributor and rotating the engine 360 degrees. If you want the numbers to
agree with the wire placement, the distributor should be removed, the
engine rotated clockwise 360 degrees, and the cap rewired to coincide with
the numbers on the cap. OR, YOU COULD JUST LEAVE IT ALONE, AND IGNORE THE
NUMBERS ON THE CAP. Just make sure that the mechanical and vacuum advance
mechanisms are functional and that basic static timing is set at about 8°
before tdc.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

I guess I'm not understanding. Is the vacuum advance on the right side (US
passenger side) when standing behind the engine? Is the power plug in the
cap also on the right side?

Now that I asked the questions I need to go look at mine. From memory I
believe mine are both on the right side. Do NOT trust my memory.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Thanks James

just to correct a few things i had a better look today and it appears that i am only 90 degrees out
my setup has no vacuum advance as it is running EFI with electronic spark control
i have no knowledge of efi or these hei distributors so i am trying to find out how this all fits together
here is a link to a photo http://www.gmcmhphotos.com/photos/uploads/42104/20180120_140014.jpg
as this was running correctly previously i do not want to touch it but i would like to be able to understand why it is set up this way
i assume by your response below that this dist was installed incorrectly and rather than remove and reinstall the wires were just relocated and
therefore the cap numbers do not match the plug numbers

> Trevor, the numbers on the secondary conductor retainer are usually
> included on genuine GM cap components, but not always on aftermarket parts.
> What has happened in your case is that the engine was not at top dead
> center, compression stroke, when the distributor was installed. So, the
> installer rewired the plug wires in the cap instead of removing the
> distributor and rotating the engine 360 degrees. If you want the numbers to
> agree with the wire placement, the distributor should be removed, the
> engine rotated clockwise 360 degrees, and the cap rewired to coincide with
> the numbers on the cap. OR, YOU COULD JUST LEAVE IT ALONE, AND IGNORE THE
> NUMBERS ON THE CAP. Just make sure that the mechanical and vacuum advance
> mechanisms are functional and that basic static timing is set at about 8°
> before tdc.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>

>
> I guess I'm not understanding. Is the vacuum advance on the right side (US
> passenger side) when standing behind the engine? Is the power plug in the
> cap also on the right side?
>
> Now that I asked the questions I need to go look at mine. From memory I
> believe mine are both on the right side. Do NOT trust my memory.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project
 
Trevor,

Comparing your photo and this photo I agree:

http://www.gmcmhphotos.com/photos/gary-rockwell-aluminum-intake-manifold-installation/p44402-running.html

The power connection on your dizzy is rotated 90 degrees counter clockwise as compared to the dizzy above.

However, if the plug wires are connected to the correct plug as per the maintenance manual I don't think it makes a difference?

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Trevor Pordage
Sent: Saturday, January 20, 2018 4:55 PM
To: gmclist
Subject: Re: [GMCnet] hei cap orientation

Thanks James

just to correct a few things i had a better look today and it appears that i am only 90 degrees out
my setup has no vacuum advance as it is running EFI with electronic spark control
i have no knowledge of efi or these hei distributors so i am trying to find out how this all fits together
here is a link to a photo http://www.gmcmhphotos.com/photos/uploads/42104/20180120_140014.jpg
as this was running correctly previously i do not want to touch it but i would like to be able to understand why it is set up this way i assume by your response below that this dist was installed incorrectly and rather than remove and reinstall the wires were just relocated and therefore the cap numbers do not match the plug numbers
 
Trevor, as there are numerous fuel injection systems out there, I cannot be
too specific, BUT, in the case of the Howell system with the Embedded
Locker Circuit or EBL, there is a 7 pin electronic module in the
distributor, and all advance changes take place within the computer, and
NOT the distributor. So, what I cautioned you about vacuum and mechanical
advance doesn't apply to your situation. Base timing IS critical, however,
as the computer needs a starting point to work from. Some BIN files use 0°
base timing, and some use 8°-10° base timing. I don't know exactly what you
have, so I cannot be certain. If your plug wires are on the correct plugs
and corresponding cap connections, it matters very little what the
distributor orientation is. Pretty much, if the primary wiring harness fits
the cap connections, it should work well where you have it now.
The only distributor that I ever saw that mattered where it was
oriented was the old air cooled VW with the upright fan housing. The number
3 plug wire was retarded 9° from the other plugs to compensate for the heat
from the oil cooler that flowed over the number 3 cylinder. The cam that
opened the points was ground with a 9° retard. If you put the distributor
in wrong, number 3 would run hot. Many people who worked on air cooled VW's
did not know that. VW eventually moved the oil cooler and supplied it with
a different source of cooling air to correct that on the bus engines with
upright fan housings. The pancake engines used remote oil coolers, so they
did not retard number 3.
Jim Hupy
Salem, Or

> Trevor,
>
> Comparing your photo and this photo I agree:
>
> http://www.gmcmhphotos.com/photos/gary-rockwell-aluminum-
> intake-manifold-installation/p44402-running.html
>
> The power connection on your dizzy is rotated 90 degrees counter clockwise
> as compared to the dizzy above.
>
> However, if the plug wires are connected to the correct plug as per the
> maintenance manual I don't think it makes a difference?
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces] On Behalf Of
> Trevor Pordage
> Sent: Saturday, January 20, 2018 4:55 PM
> To: gmclist
> Subject: Re: [GMCnet] hei cap orientation
>
> Thanks James
>
> just to correct a few things i had a better look today and it appears
> that i am only 90 degrees out
> my setup has no vacuum advance as it is running EFI with electronic spark
> control
> i have no knowledge of efi or these hei distributors so i am trying to
> find out how this all fits together
> here is a link to a photo http://www.gmcmhphotos.com/
> photos/uploads/42104/20180120_140014.jpg
> as this was running correctly previously i do not want to touch it but i
> would like to be able to understand why it is set up this way i assume by
> your response below that this dist was installed incorrectly and rather
> than remove and reinstall the wires were just relocated and therefore the
> cap numbers do not match the plug numbers
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I haven't seen that snap on top on the distributor cap used for years. Looking closely at it I see that it is snapped on 180 degrees out of position.
Looking at the wires it appears that they were installed to match the numbers on that snap on piece. (180 out)

To fix it I see five steps that need to be done:

1. Start the engine. With the vacuum hose disconnected and plugged, look at the current ignition timing with a timing light. (I always paint the
mark with white out to make it easy to see.) Record or mentally note the exact position. Depending on the distributor installed it should be
somewhere between 8 and 12 BTDC. Most are 8.

2. With engine off, rotate the engine until it is at TDC. Remove cap and verify that the rotor is pointing at #1. If it isn't, rotate the engine one
complete turn to TDC again and the rotor should now be pointing at #1.

3. Remove the distributor and reinstall it with the rotor pointing to the lower left approximately 280 degrees CCW where #1 should be and rotate the
distributor frame approximately 80 degrees CW do the power plug is on the US passenger side.

4. Remove the that cap snap on lid and start moving wires. All wires should be re-plugged 180 degrees from where they are now.

5. Start the engine and set the timing with a light to where it was before you started this project in step #1. Tighten the distributor hold down
bolt.

OR

LEAVE IT ALONE AND IT WILL RUN JUST FINE the way it is.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
You mentioned you have fuel injection and it has been sitting for 4 years. So another cause of the rough idle and maybe the backfiring could be
sticking fuel injectors. I had a one of the injectors on an Ebay purchased Rochester TBI that would stick closed causing the engine to run on 1/2 the
cylinders. The local injector guy tried 3 times to get it going, but each time it would stick closed, so I finally bought a couple of Standard
Products injectors.

To test them, run the engine for 20 seconds or so that there is fuel in the TBI and shut the engine down. Then pull the power plug from the coil so
the engine can't start and pull the air cleaner off so you can look down the throttle. Turn the key and you should hear the fuel pump start for a few
seconds to build pressure then look down the TBI. You should not see any fuel leaking from the injectors as they should be closed. Then crank the
engine for a few seconds and you should see an equal amount of fuel squirt on the throttle plates of both barrels. If so, the injectors passed this
simple test. Shut off the key and plug the power connector back into the distributor cap.

If you got a leaky injector or the amount of fuel sprayed is not in balance, remove the injectors and get them cleaned, or replace them.

An injector cleaning place can test them to be sure they are flowing an equal amount of fuel. Remember the narrowband O2 sensor only measures the
fuel mixture on one bank of cylinders, so they can be out of balance leaving one bank rich or lean. A wideband sensor is generally installed after
the exhaust Y connection and so measures both sides.

Just my farmboy mechanic way of seeing things.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
thanks jim i have a turbo city EFI system which is no lunger supported i do have a little bit of documentation from the PO but not much. it does say
in one part that there is an ignition module but this only has 4 wires but i assume it controls all the timing.

interesting about the VW distributor

Rob and Ken Thanks also the wires are infact in the same orientation and match up with the firing order i will leave it the way it is i just need to
make note not to follow the numbers on the retaining ring

thanks bruce that is the kind of diagnosis advice i need today i will try and do that and maybe drain the tanks and put in new fuel

--
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project
 
If it has a 4 pin module, there is NO distributor timig control by the ECM.

On Sat, Jan 20, 2018 at 2:08 PM, Trevor Pordage
wrote:

> thanks jim i have a turbo city EFI system which is no lunger supported i
> do have a little bit of documentation from the PO but not much. it does say
> in one part that there is an ignition module but this only has 4 wires but
> i assume it controls all the timing.
>
> interesting about the VW distributor
>
> Rob and Ken Thanks also the wires are infact in the same orientation and
> match up with the firing order i will leave it the way it is i just need to
> make note not to follow the numbers on the retaining ring
>
> thanks bruce that is the kind of diagnosis advice i need today i will try
> and do that and maybe drain the tanks and put in new fuel
>
>
> --
> Trevor
> Brisbane Australia
> Siesta Koala 76 Edgemont (old Bobby Moores)
> 71 Cadillac Eldo Convert
> 58 Cadillac Eldorado Brougham Project
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
hi jim this is a turbo city EFI setup i have attached links below relating to the documentation i have got
unfortunatly turbo city have stopped support so i am trying to work out what i have got and how it works

http://www.gmcmhphotos.com/photos/showfull.php?photo=64478

http://www.gmcmhphotos.com/photos/showfull.php?photo=64477

> If it has a 4 pin module, there is NO distributor timig control by the ECM.
>
>
> On Sat, Jan 20, 2018 at 2:08 PM, Trevor Pordage

>
> > thanks jim i have a turbo city EFI system which is no lunger supported i
> > do have a little bit of documentation from the PO but not much. it does say
> > in one part that there is an ignition module but this only has 4 wires but
> > i assume it controls all the timing.
> >
> > interesting about the VW distributor
> >
> > Rob and Ken Thanks also the wires are infact in the same orientation and
> > match up with the firing order i will leave it the way it is i just need to
> > make note not to follow the numbers on the retaining ring
> >
> > thanks bruce that is the kind of diagnosis advice i need today i will try
> > and do that and maybe drain the tanks and put in new fuel
> >
> >
> > --
> > Trevor
> > Brisbane Australia
> > Siesta Koala 76 Edgemont (old Bobby Moores)
> > 71 Cadillac Eldo Convert
> > 58 Cadillac Eldorado Brougham Project
> >
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project
 
the documentation is loose pages of printed matter in a folder that is in a very unorganized state i have just found some more pages relating to the
wirng diagram which shows a 7pin ignition module that goes in the distributor the 4 pin ESC module is attached to the firewall so it appears my spark
is controlled by the computer

thanks everone for your help i will continue with the puzzle

--
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project