This is an area that I've never paid any attention too. As to the GMC. From what I've heard. The distributors used in our GMC's. Is different then those used in cars that use the 403, or 455. That difference has to be in the advance curves. I pulled the distributor out of my 78 403. Because I installed an EFI system with spark control. In the cast of the EFI. Car distributors are fine. A friend wants to put a HEI distributor in his 73 455. I would thing that the advance cures between the 403/455 have to be very close. If not the same. Bob Dunahugh
GMC HEI distributor advance curves
- Thread starter Bob Dunahugh
- Start date
Bob, check with Dick Patterson. He knows these distributors very well. Both
the mechanical and vacuum advances vary between the points distributors and
HEI on 455's as well as the 403's, particularly in California options in 77
vs 78 built coaches. There is a whole bunch of data on them in the main
manuals and supplemental manuals.
Jim Hupy
Salem, Or
> This is an area that I've never paid any attention too. As to the GMC.
> From what I've heard. The distributors used in our GMC's. Is different
> then those used in cars that use the 403, or 455. That difference has to
> be in the advance curves. I pulled the distributor out of my 78 403.
> Because I installed an EFI system with spark control. In the cast of the
> EFI. Car distributors are fine. A friend wants to put a HEI distributor in
> his 73 455. I would thing that the advance cures between the 403/455 have
> to be very close. If not the same. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
the mechanical and vacuum advances vary between the points distributors and
HEI on 455's as well as the 403's, particularly in California options in 77
vs 78 built coaches. There is a whole bunch of data on them in the main
manuals and supplemental manuals.
Jim Hupy
Salem, Or
> This is an area that I've never paid any attention too. As to the GMC.
> From what I've heard. The distributors used in our GMC's. Is different
> then those used in cars that use the 403, or 455. That difference has to
> be in the advance curves. I pulled the distributor out of my 78 403.
> Because I installed an EFI system with spark control. In the cast of the
> EFI. Car distributors are fine. A friend wants to put a HEI distributor in
> his 73 455. I would thing that the advance cures between the 403/455 have
> to be very close. If not the same. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> This is an area that I've never paid any attention too. As to the GMC. From what I've heard. The distributors used in our GMC's. Is different
> then those used in cars that use the 403, or 455. That difference has to be in the advance curves. I pulled the distributor out of my 78 403.
> Because I installed an EFI system with spark control. In the cast of the EFI. Car distributors are fine. A friend wants to put a HEI distributor
> in his 73 455. I would thing that the advance cures between the 403/455 have to be very close. If not the same. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Bob, You might look here
https://www.gmcmi.com/wp-content/uploads/2015/06/Ignition-System_simmons_lamey.pdf
This from GMCMI has curves and specs.
HTH
--
Wally Anderson
Omaha NE
75 Glenbrook
Megasquirt III injection
Bob Stone hydroBOOOOST
Manny reaction arm system
Branscombe Kelsey Hayes park brake
http://wallyandsue.blogspot.com/
> then those used in cars that use the 403, or 455. That difference has to be in the advance curves. I pulled the distributor out of my 78 403.
> Because I installed an EFI system with spark control. In the cast of the EFI. Car distributors are fine. A friend wants to put a HEI distributor
> in his 73 455. I would thing that the advance cures between the 403/455 have to be very close. If not the same. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Bob, You might look here
https://www.gmcmi.com/wp-content/uploads/2015/06/Ignition-System_simmons_lamey.pdf
This from GMCMI has curves and specs.
HTH
--
Wally Anderson
Omaha NE
75 Glenbrook
Megasquirt III injection
Bob Stone hydroBOOOOST
Manny reaction arm system
Branscombe Kelsey Hayes park brake
http://wallyandsue.blogspot.com/
> This is an area that I've never paid any attention too. As to the GMC. From what I've heard. The distributors used in our GMC's. Is different
> then those used in cars that use the 403, or 455. That difference has to be in the advance curves. I pulled the distributor out of my 78 403.
> Because I installed an EFI system with spark control. In the cast of the EFI. Car distributors are fine. A friend wants to put a HEI distributor
> in his 73 455. I would thing that the advance cures between the 403/455 have to be very close. If not the same.
> Bob Dunahugh
Bob,
Tell him to not bother unless he is also going to go the EFI with knock controlled spark.
If he gets a Pertronix 1181LS, it will do as well.
If he thinks he wants more spark power, put in anybody's real CDI and good wires.
This way, he won't have to hammer the air filter housing or find another that fits.
I did this 70K and 14 years ago and the only trouble I have had was with the MSD CDI that failed. So now I am using a 1974 Delta MarkX and it has been
flawless. I run an 0.060 gap - just don't mess with the wires.
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
> then those used in cars that use the 403, or 455. That difference has to be in the advance curves. I pulled the distributor out of my 78 403.
> Because I installed an EFI system with spark control. In the cast of the EFI. Car distributors are fine. A friend wants to put a HEI distributor
> in his 73 455. I would thing that the advance cures between the 403/455 have to be very close. If not the same.
> Bob Dunahugh
Bob,
Tell him to not bother unless he is also going to go the EFI with knock controlled spark.
If he gets a Pertronix 1181LS, it will do as well.
If he thinks he wants more spark power, put in anybody's real CDI and good wires.
This way, he won't have to hammer the air filter housing or find another that fits.
I did this 70K and 14 years ago and the only trouble I have had was with the MSD CDI that failed. So now I am using a 1974 Delta MarkX and it has been
flawless. I run an 0.060 gap - just don't mess with the wires.
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
Bob,
Since your runing the Howell base with the EBL Flash ECM, the program will
out perform any standard HEI in terms of mecanical and vac timing. That iis
why you will gain fuel milage with the EBL that the other so call EFI
cannot deliver.
Your HEI distributor runs a 7 pin module that is signaled by the ECM with
the EBL so the Vac and Mech advance is not used.
> > This is an area that I've never paid any attention too. As to the GMC.
> From what I've heard. The distributors used in our GMC's. Is different
> > then those used in cars that use the 403, or 455. That difference has
> to be in the advance curves. I pulled the distributor out of my 78 403.
> > Because I installed an EFI system with spark control. In the cast of
> the EFI. Car distributors are fine. A friend wants to put a HEI distributor
> > in his 73 455. I would thing that the advance cures between the 403/455
> have to be very close. If not the same.
> > Bob Dunahugh
>
> Bob,
>
> Tell him to not bother unless he is also going to go the EFI with knock
> controlled spark.
> If he gets a Pertronix 1181LS, it will do as well.
> If he thinks he wants more spark power, put in anybody's real CDI and good
> wires.
> This way, he won't have to hammer the air filter housing or find another
> that fits.
> I did this 70K and 14 years ago and the only trouble I have had was with
> the MSD CDI that failed. So now I am using a 1974 Delta MarkX and it has
> been
> flawless. I run an 0.060 gap - just don't mess with the wires.
>
> 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
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
Since your runing the Howell base with the EBL Flash ECM, the program will
out perform any standard HEI in terms of mecanical and vac timing. That iis
why you will gain fuel milage with the EBL that the other so call EFI
cannot deliver.
Your HEI distributor runs a 7 pin module that is signaled by the ECM with
the EBL so the Vac and Mech advance is not used.
> > This is an area that I've never paid any attention too. As to the GMC.
> From what I've heard. The distributors used in our GMC's. Is different
> > then those used in cars that use the 403, or 455. That difference has
> to be in the advance curves. I pulled the distributor out of my 78 403.
> > Because I installed an EFI system with spark control. In the cast of
> the EFI. Car distributors are fine. A friend wants to put a HEI distributor
> > in his 73 455. I would thing that the advance cures between the 403/455
> have to be very close. If not the same.
> > Bob Dunahugh
>
> Bob,
>
> Tell him to not bother unless he is also going to go the EFI with knock
> controlled spark.
> If he gets a Pertronix 1181LS, it will do as well.
> If he thinks he wants more spark power, put in anybody's real CDI and good
> wires.
> This way, he won't have to hammer the air filter housing or find another
> that fits.
> I did this 70K and 14 years ago and the only trouble I have had was with
> the MSD CDI that failed. So now I am using a 1974 Delta MarkX and it has
> been
> flawless. I run an 0.060 gap - just don't mess with the wires.
>
> 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
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
As far as how much voltage is required to ignite the air/fuel mixture in
the cylinders, it is somewhere near 5,000 to 7,000 volts. A properly
functioning stock HEI will produce between 35,000 and 50,000 volts to the
plugs. Aftermarket coils or modules just are not required. Save your money
for good whiskey or some such.
Jim K is right about the EBL option. The distributor used with it has
no mechanical or vacuum advance. Those curves are provided by the CPU, and
can be tailored to your specific needs,
(towing weight, final drive ratio, cam, headers, heads, compression ratio,
etc)
Jim Hupy
> Bob,
> Since your runing the Howell base with the EBL Flash ECM, the program will
> out perform any standard HEI in terms of mecanical and vac timing. That iis
> why you will gain fuel milage with the EBL that the other so call EFI
> cannot deliver.
> Your HEI distributor runs a 7 pin module that is signaled by the ECM with
> the EBL so the Vac and Mech advance is not used.
>
>
> > > This is an area that I've never paid any attention too. As to the GMC.
> > From what I've heard. The distributors used in our GMC's. Is different
> > > then those used in cars that use the 403, or 455. That difference has
> > to be in the advance curves. I pulled the distributor out of my 78 403.
> > > Because I installed an EFI system with spark control. In the cast of
> > the EFI. Car distributors are fine. A friend wants to put a HEI
> distributor
> > > in his 73 455. I would thing that the advance cures between the 403/455
> > have to be very close. If not the same.
> > > Bob Dunahugh
> >
> > Bob,
> >
> > Tell him to not bother unless he is also going to go the EFI with knock
> > controlled spark.
> > If he gets a Pertronix 1181LS, it will do as well.
> > If he thinks he wants more spark power, put in anybody's real CDI and
> good
> > wires.
> > This way, he won't have to hammer the air filter housing or find another
> > that fits.
> > I did this 70K and 14 years ago and the only trouble I have had was with
> > the MSD CDI that failed. So now I am using a 1974 Delta MarkX and it has
> > been
> > flawless. I run an 0.060 gap - just don't mess with the wires.
> >
> > 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
> >
>
>
> --
> 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
>
the cylinders, it is somewhere near 5,000 to 7,000 volts. A properly
functioning stock HEI will produce between 35,000 and 50,000 volts to the
plugs. Aftermarket coils or modules just are not required. Save your money
for good whiskey or some such.
Jim K is right about the EBL option. The distributor used with it has
no mechanical or vacuum advance. Those curves are provided by the CPU, and
can be tailored to your specific needs,
(towing weight, final drive ratio, cam, headers, heads, compression ratio,
etc)
Jim Hupy
> Bob,
> Since your runing the Howell base with the EBL Flash ECM, the program will
> out perform any standard HEI in terms of mecanical and vac timing. That iis
> why you will gain fuel milage with the EBL that the other so call EFI
> cannot deliver.
> Your HEI distributor runs a 7 pin module that is signaled by the ECM with
> the EBL so the Vac and Mech advance is not used.
>
>
> > > This is an area that I've never paid any attention too. As to the GMC.
> > From what I've heard. The distributors used in our GMC's. Is different
> > > then those used in cars that use the 403, or 455. That difference has
> > to be in the advance curves. I pulled the distributor out of my 78 403.
> > > Because I installed an EFI system with spark control. In the cast of
> > the EFI. Car distributors are fine. A friend wants to put a HEI
> distributor
> > > in his 73 455. I would thing that the advance cures between the 403/455
> > have to be very close. If not the same.
> > > Bob Dunahugh
> >
> > Bob,
> >
> > Tell him to not bother unless he is also going to go the EFI with knock
> > controlled spark.
> > If he gets a Pertronix 1181LS, it will do as well.
> > If he thinks he wants more spark power, put in anybody's real CDI and
> good
> > wires.
> > This way, he won't have to hammer the air filter housing or find another
> > that fits.
> > I did this 70K and 14 years ago and the only trouble I have had was with
> > the MSD CDI that failed. So now I am using a 1974 Delta MarkX and it has
> > been
> > flawless. I run an 0.060 gap - just don't mess with the wires.
> >
> > 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
> >
>
>
> --
> 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
>
