Going to Elkhart In last fall. I found that the distributor was loose. Was running fine. Didn't have a timing light with my. So I just tightened the bolt to hold whatever I had. Decided Tuesday to check the timing. As I wanted to test run the Mercedes Benz fan clutch that I just installed. Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't hardly pull itself. And popping back at the TB. Advanced the timing to 12 degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't moved. I confirmed that. ) And since I have the Howell EFI that controls the distributor. Plus the knock sensor. It's just interesting that 8 degrees should be fine. As a note. The cams not original. So I'm thinking that the cam profile is causing this. 78 Royale 403
EFI, and ignition timing.
- Thread starter Bob Dunahugh
- Start date
Bob, too many variables in there to account for. Timing pointers are
notorious for being inaccurate. Things like the blank the aftermarket cam
was ground on, come into play, crank keyway location, sprocket keyway
location, and on and on. Generally speaking, 403's like 4° more advance
than 455's do. But, if it does not have high knock counts at 12°, then
bump it up until you see that change. Then back off a couple to account for
all that weight you tow and oddball gasoline you might encounter along the
way. Just what I would do.
Jim Hupy
Salem, Or
> Going to Elkhart In last fall. I found that the distributor was loose. Was
> running fine. Didn't have a timing light with my. So I just tightened the
> bolt to hold whatever I had. Decided Tuesday to check the timing. As I
> wanted to test run the Mercedes Benz fan clutch that I just installed.
> Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't
> hardly pull itself. And popping back at the TB. Advanced the timing to 12
> degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't
> moved. I confirmed that. ) And since I have the Howell EFI that controls
> the distributor. Plus the knock sensor. It's just interesting that 8
> degrees should be fine. As a note. The cams not original. So I'm thinking
> that the cam profile is causing this. 78 Royale 403
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
notorious for being inaccurate. Things like the blank the aftermarket cam
was ground on, come into play, crank keyway location, sprocket keyway
location, and on and on. Generally speaking, 403's like 4° more advance
than 455's do. But, if it does not have high knock counts at 12°, then
bump it up until you see that change. Then back off a couple to account for
all that weight you tow and oddball gasoline you might encounter along the
way. Just what I would do.
Jim Hupy
Salem, Or
> Going to Elkhart In last fall. I found that the distributor was loose. Was
> running fine. Didn't have a timing light with my. So I just tightened the
> bolt to hold whatever I had. Decided Tuesday to check the timing. As I
> wanted to test run the Mercedes Benz fan clutch that I just installed.
> Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't
> hardly pull itself. And popping back at the TB. Advanced the timing to 12
> degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't
> moved. I confirmed that. ) And since I have the Howell EFI that controls
> the distributor. Plus the knock sensor. It's just interesting that 8
> degrees should be fine. As a note. The cams not original. So I'm thinking
> that the cam profile is causing this. 78 Royale 403
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
Bob,
Did you disable the computers spark control?
I know you usually have to when setting the base timing on a FI system, but I'm not sure how, or if, to do that on the howell
________________________________
From: Gmclist on behalf of James Hupy
Sent: Thursday, March 29, 2018 11:09 AM
To: gmclist
Subject: Re: [GMCnet] EFI, and ignition timing.
Bob, too many variables in there to account for. Timing pointers are
notorious for being inaccurate. Things like the blank the aftermarket cam
was ground on, come into play, crank keyway location, sprocket keyway
location, and on and on. Generally speaking, 403's like 4° more advance
than 455's do. But, if it does not have high knock counts at 12°, then
bump it up until you see that change. Then back off a couple to account for
all that weight you tow and oddball gasoline you might encounter along the
way. Just what I would do.
Jim Hupy
Salem, Or
> Going to Elkhart In last fall. I found that the distributor was loose. Was
> running fine. Didn't have a timing light with my. So I just tightened the
> bolt to hold whatever I had. Decided Tuesday to check the timing. As I
> wanted to test run the Mercedes Benz fan clutch that I just installed.
> Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't
> hardly pull itself. And popping back at the TB. Advanced the timing to 12
> degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't
> moved. I confirmed that. ) And since I have the Howell EFI that controls
> the distributor. Plus the knock sensor. It's just interesting that 8
> degrees should be fine. As a note. The cams not original. So I'm thinking
> that the cam profile is causing this. 78 Royale 403
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
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http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Did you disable the computers spark control?
I know you usually have to when setting the base timing on a FI system, but I'm not sure how, or if, to do that on the howell
________________________________
From: Gmclist on behalf of James Hupy
Sent: Thursday, March 29, 2018 11:09 AM
To: gmclist
Subject: Re: [GMCnet] EFI, and ignition timing.
Bob, too many variables in there to account for. Timing pointers are
notorious for being inaccurate. Things like the blank the aftermarket cam
was ground on, come into play, crank keyway location, sprocket keyway
location, and on and on. Generally speaking, 403's like 4° more advance
than 455's do. But, if it does not have high knock counts at 12°, then
bump it up until you see that change. Then back off a couple to account for
all that weight you tow and oddball gasoline you might encounter along the
way. Just what I would do.
Jim Hupy
Salem, Or
> Going to Elkhart In last fall. I found that the distributor was loose. Was
> running fine. Didn't have a timing light with my. So I just tightened the
> bolt to hold whatever I had. Decided Tuesday to check the timing. As I
> wanted to test run the Mercedes Benz fan clutch that I just installed.
> Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't
> hardly pull itself. And popping back at the TB. Advanced the timing to 12
> degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't
> moved. I confirmed that. ) And since I have the Howell EFI that controls
> the distributor. Plus the knock sensor. It's just interesting that 8
> degrees should be fine. As a note. The cams not original. So I'm thinking
> that the cam profile is causing this. 78 Royale 403
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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There are two small wires connected together. Usually located at the top of the motor box drivers side rear.
It is necessary to unplug the connector when setting the timing with the Howell system.
Emery Stora
>
> Bob,
> Did you disable the computers spark control?
> I know you usually have to when setting the base timing on a FI system, but I'm not sure how, or if, to do that on the howell
>
> ________________________________
> From: Gmclist on behalf of James Hupy
> Sent: Thursday, March 29, 2018 11:09 AM
> To: gmclist
> Subject: Re: [GMCnet] EFI, and ignition timing.
>
> Bob, too many variables in there to account for. Timing pointers are
> notorious for being inaccurate. Things like the blank the aftermarket cam
> was ground on, come into play, crank keyway location, sprocket keyway
> location, and on and on. Generally speaking, 403's like 4° more advance
> than 455's do. But, if it does not have high knock counts at 12°, then
> bump it up until you see that change. Then back off a couple to account for
> all that weight you tow and oddball gasoline you might encounter along the
> way. Just what I would do.
> Jim Hupy
> Salem, Or
>
>>
>> Going to Elkhart In last fall. I found that the distributor was loose. Was
>> running fine. Didn't have a timing light with my. So I just tightened the
>> bolt to hold whatever I had. Decided Tuesday to check the timing. As I
>> wanted to test run the Mercedes Benz fan clutch that I just installed.
>> Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't
>> hardly pull itself. And popping back at the TB. Advanced the timing to 12
>> degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't
>> moved. I confirmed that. ) And since I have the Howell EFI that controls
>> the distributor. Plus the knock sensor. It's just interesting that 8
>> degrees should be fine. As a note. The cams not original. So I'm thinking
>> that the cam profile is causing this. 78 Royale 403
>> _______________________________________________
>> 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
> _______________________________________________
> GMCnet mailing list
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> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
It is necessary to unplug the connector when setting the timing with the Howell system.
Emery Stora
>
> Bob,
> Did you disable the computers spark control?
> I know you usually have to when setting the base timing on a FI system, but I'm not sure how, or if, to do that on the howell
>
> ________________________________
> From: Gmclist on behalf of James Hupy
> Sent: Thursday, March 29, 2018 11:09 AM
> To: gmclist
> Subject: Re: [GMCnet] EFI, and ignition timing.
>
> Bob, too many variables in there to account for. Timing pointers are
> notorious for being inaccurate. Things like the blank the aftermarket cam
> was ground on, come into play, crank keyway location, sprocket keyway
> location, and on and on. Generally speaking, 403's like 4° more advance
> than 455's do. But, if it does not have high knock counts at 12°, then
> bump it up until you see that change. Then back off a couple to account for
> all that weight you tow and oddball gasoline you might encounter along the
> way. Just what I would do.
> Jim Hupy
> Salem, Or
>
>>
>> Going to Elkhart In last fall. I found that the distributor was loose. Was
>> running fine. Didn't have a timing light with my. So I just tightened the
>> bolt to hold whatever I had. Decided Tuesday to check the timing. As I
>> wanted to test run the Mercedes Benz fan clutch that I just installed.
>> Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't
>> hardly pull itself. And popping back at the TB. Advanced the timing to 12
>> degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't
>> moved. I confirmed that. ) And since I have the Howell EFI that controls
>> the distributor. Plus the knock sensor. It's just interesting that 8
>> degrees should be fine. As a note. The cams not original. So I'm thinking
>> that the cam profile is causing this. 78 Royale 403
>> _______________________________________________
>> 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
> _______________________________________________
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I messed up on the timing process. You need to disconnect a wire before you can set the timing. I knew about that plug in the wire. And Emery was kind enough to remind me of my error. Timing is now set. Run great. Thanks Emery Bob Dunahugh
________________________________
From: Bob Dunahugh
Sent: Thursday, March 29, 2018 10:57 AM
To: gmclist
Subject: EFI, and ignition timing.
Going to Elkhart In last fall. I found that the distributor was loose. Was running fine. Didn't have a timing light with my. So I just tightened the bolt to hold whatever I had. Decided Tuesday to check the timing. As I wanted to test run the Mercedes Benz fan clutch that I just installed. Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't hardly pull itself. And popping back at the TB. Advanced the timing to 12 degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't moved. I confirmed that. ) And since I have the Howell EFI that controls the distributor. Plus the knock sensor. It's just interesting that 8 degrees should be fine. As a note. The cams not original. So I'm thinking that the cam profile is causing this. 78 Royale 403
________________________________
From: Bob Dunahugh
Sent: Thursday, March 29, 2018 10:57 AM
To: gmclist
Subject: EFI, and ignition timing.
Going to Elkhart In last fall. I found that the distributor was loose. Was running fine. Didn't have a timing light with my. So I just tightened the bolt to hold whatever I had. Decided Tuesday to check the timing. As I wanted to test run the Mercedes Benz fan clutch that I just installed. Moved the GMC out on the driveway. Set the timing to 8 degrees. It couldn't hardly pull itself. And popping back at the TB. Advanced the timing to 12 degrees. Ran perfect. ( And no. The timing mark on the pamper hasn't moved. I confirmed that. ) And since I have the Howell EFI that controls the distributor. Plus the knock sensor. It's just interesting that 8 degrees should be fine. As a note. The cams not original. So I'm thinking that the cam profile is causing this. 78 Royale 403
