Home » Public Forums » GMCnet » [GMCnet] GMC HEI distributor advance curves
| [GMCnet] GMC HEI distributor advance curves [message #340304] |
Wed, 23 January 2019 23:55  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
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Senior Member |
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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
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| Re: [GMCnet] GMC HEI distributor advance curves [message #340313 is a reply to message #340310] |
Thu, 24 January 2019 12:12  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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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.
On Thu, Jan 24, 2019 at 6:03 AM Matt Colie wrote:
> BobDunahugh wrote on Thu, 24 January 2019 00:55
>> 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@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] GMC HEI distributor advance curves [message #340314 is a reply to message #340313] |
Thu, 24 January 2019 12:30 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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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
On Thu, Jan 24, 2019, 10:13 AM Jim Kanomata Bob,[/color]
> 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.
>
> On Thu, Jan 24, 2019 at 6:03 AM Matt Colie wrote:
>
>> BobDunahugh wrote on Thu, 24 January 2019 00:55
>>> 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@appliedairfilters.com
> 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
>
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