Backfiring

I really do have to thank you all for the help, and i'm still trying to figure this out, to answer ken's question i split the posts on the compression
checks the left side was in a post before the right's here they are together
Right side
1 - 125
3 - 130
5 - 130
7 - 135
Left side
2 - 140
4 - 125
6 - 135
8 - 120
I can always recheck the compression in cylinder 5 as well ?

also to answer jim's question, no i haven't replaced the coil, and I was considering to do that tomorrow as well along with the ignition module ?

Thanks David

--
1974 G-M-C Painted Desert #136
"Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit
the wall, and torque is how far you take the wall with you when you hit it."
 
and i'll regap the plugs to .40 as well then too
--
1974 G-M-C Painted Desert #136
"Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit
the wall, and torque is how far you take the wall with you when you hit it."
 
Given the new info, a couple of thoughts:

A timing issue would effect all cyl. So would a coil issue

The key i think is when you were able to isolate the problem to one cal by removing the wire. [BTW, a faster way is using a grounded test light, peice
the plug wire boot at the distributor and short out that plug temporarily]

My money says you have a mechanical problem there, most likely on the exhaust side either not opening or opening enough. If you are lucky it will only
be an adjustment on that rocker arm, but it could also be a colapsed lifter,a bent pushrod or worse, a wiped cam lobe- but that is usually gradual not
sudden

This wont show up un a compression test at cranking speeds
--
76 Glenbrook
 
Vacuum leak on that port that is on the manifold runner for the #5 cylinder. Plug it and see if that makes a difference.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
Engines do not backfire with the valves closed USUALLY. If you are
experiencing the ignition of air-fuel in the intake manifold, then, you
either have an electrical ignition source (like crossed ignition wires) or,
you have a source that is mechanical, (like a cracked intake valve seat or
an intake valve that is not seating.) Cause can be as simple as rusty valve
guides/ stems, or more complex, like frozen rocker arm pivots or bent
pushrods. So, that is where you look for the cause. If you were grossly out
of time with the distributor, more than one cylinder will be involved.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

Given the new info, a couple of thoughts:

A timing issue would effect all cyl. So would a coil issue

The key i think is when you were able to isolate the problem to one cal by
removing the wire. [BTW, a faster way is using a grounded test light, peice
the plug wire boot at the distributor and short out that plug temporarily]

My money says you have a mechanical problem there, most likely on the
exhaust side either not opening or opening enough. If you are lucky it will
only
be an adjustment on that rocker arm, but it could also be a colapsed
lifter,a bent pushrod or worse, a wiped cam lobe- but that is usually
gradual not
sudden

This wont show up un a compression test at cranking speeds
--
76 Glenbrook

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Old - cheap plug wires + running #5 and #7 side by side can cause crossfire. Separate the wires and see if that helps. A quick and easy check.
--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers
 
Probably already checked but I had spring in distributor fall off caused backfire and another time bottom of distributor got messrd up and backfire....both times nothing had bren changed and happened at end of long drive,ie,Couple hours on hwy.

Sent from my LG Mobile

>Old - cheap plug wires + running #5 and #7 side by side can cause crossfire. Separate the wires and see if that helps. A quick and easy check.
>--
>Patti & Jerry Burt
>73 Gmc 26' Canyon Lands -
>Photos - http://jburt.smugmug.com/GMC-Motorhome
>Lots of upgrades but lots to do to make it ours.
>Members: FMCA - GMCMI - GMCWS - Pacific Cruisers
>
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I can't make it back up to the coach today, it's just simply too late, I'd only have like a hour of daylight and i'm tired.
it will all have to wait till Wednesday but probably Thursday.

My to do list,
plug as many open vacuum ports that i can find
Regap the plugs to .38/.40
Install the new spark wires, and triple check the firing order
and check the ground at distributor and possibly ground it
and i'll test it then ...
if it is still doing it, i plan on
put the engine at tdc and make sure the rotor is pointing towards plug one
check the harmonic balancer for slippage
Removing the valve covers and watching to see if any valves are sticking
also to inspect for any loose rocker arms and bent push-rods, and overall condition

I did buy some mystery oil for the engine, and a new coil, the coil will be the last thing i do.
--
1974 G-M-C Painted Desert #136
"Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit
the wall, and torque is how far you take the wall with you when you hit it."
 
Well I plugged all vacuum ports, recapped the plugs and thrilled checked the firing order, I hear it trying to start. But doesn't run now, so I pulled
the value cover and found my original issue

So I'll be towing it home ...

http://s3.photobucket.com/user/DavidLive/media/1974%20GMC%20Motorhome/IMG_20161130_153150795_zpsnz8aqshs.jpg.html

And a picture of the pushrods from that cylinder , the one that's been shaved is the exhaust port I believe

http://s3.photobucket.com/user/DavidLive/media/Mobile%20Uploads/IMG_20161130_161511506_zpso2h21roo.jpg.html

--
1974 G-M-C Painted Desert #136
"Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit
the wall, and torque is how far you take the wall with you when you hit it."
 
Meant triple checked the firing order *
--
1974 G-M-C Painted Desert #136
"Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit
the wall, and torque is how far you take the wall with you when you hit it."
 
Sense a push rod is missing more then 1/4 of a inch means there's metal in the engine

--
1974 G-M-C Painted Desert #136
"Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit
the wall, and torque is how far you take the wall with you when you hit it."
 
Are those aftermarket roller tip rockere??? Pic is blurry when zoom in but don't look stock. If so I'd go back to stock (correct). We know non GM
lifters suck. I assume same for other metallurgy in rest of valve train.
--
John Lebetski
Woodstock, IL
77 Eleganza II
Source America First
 
this is the first time even looking into the engine at what was done by the previous owner, but yeah i would think they are aftermarket roller
rockers.

Thanks david
--
1974 G-M-C Painted Desert #136
"Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit
the wall, and torque is how far you take the wall with you when you hit it."
 
David,

I just returned from Beaver Racing Engines, my friend John's shop, where I
happened to notice a cylinder head with those same roller rockers. It, and
the torn down one I then examined, came from Chuck Boyd, who got them from
a well known rebuilder. I'm not going to go any further with that
description, but believe me, the installation of those studs and rockers
was about the sorriest automotive machine work I've ever seen. So, I
strongly suggest you try to find out the source of those heads, examine
them VERY closely, and talk to Chuck about his experience with his.

Someone suggested you return the rockers to OEM. I'm not sure I'd go that
far, because there may be nothing fundamentally wrong with what you have --
they may have been poorly installed.

JMHO,

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc., etc.
www.gmcwipersetc.com

> Well I plugged all vacuum ports, recapped the plugs and thrilled checked
> the firing order, I hear it trying to start. But doesn't run now, so I
> pulled
> the value cover and found my original issue
>
> So I'll be towing it home ...
>
> http://s3.photobucket.com/user/DavidLive/media/1974%20GMC%20Motorhome/IMG_
> 20161130_153150795_zpsnz8aqshs.jpg.html
>
>
> And a picture of the pushrods from that cylinder , the one that's been
> shaved is the exhaust port I believe
>
> http://s3.photobucket.com/user/DavidLive/media/Mobile%
> 20Uploads/IMG_20161130_161511506_zpso2h21roo.jpg.html
>
> --
>
 
Ken,

I need a further explanation. That stud mounted roller rocker should be a
kit
that is sold by Summit. It is a direct bolt-on that requires no machining.
They are highly recommended by the Olds pass-car guys. IIRC, we used them
on the factory sponsored Olds we drag raced in 1972. LONG time ago!

Gary Kosier
77PB w/500Cad
Newark, Ohio

--------------------------------------------------
From: "Ken Henderson"
Sent: Thursday, December 01, 2016 11:06 AM
To:
Subject: Re: [GMCnet] Backfiring

> David,
>
> I just returned from Beaver Racing Engines, my friend John's shop, where I
> happened to notice a cylinder head with those same roller rockers. It,
> and
> the torn down one I then examined, came from Chuck Boyd, who got them from
> a well known rebuilder. I'm not going to go any further with that
> description, but believe me, the installation of those studs and rockers
> was about the sorriest automotive machine work I've ever seen. So, I
> strongly suggest you try to find out the source of those heads, examine
> them VERY closely, and talk to Chuck about his experience with his.
>
> Someone suggested you return the rockers to OEM. I'm not sure I'd go that
> far, because there may be nothing fundamentally wrong with what you
> have --
> they may have been poorly installed.
>
> JMHO,
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, etc., etc., etc.
> www.gmcwipersetc.com
>
> On Wed, Nov 30, 2016 at 7:24 PM, David Morrison

>
>> Well I plugged all vacuum ports, recapped the plugs and thrilled checked
>> the firing order, I hear it trying to start. But doesn't run now, so I
>> pulled
>> the value cover and found my original issue
>>
>> So I'll be towing it home ...
>>
>> http://s3.photobucket.com/user/DavidLive/media/1974%20GMC%20Motorhome/IMG_
>> 20161130_153150795_zpsnz8aqshs.jpg.html
>>
>>
>> And a picture of the pushrods from that cylinder , the one that's been
>> shaved is the exhaust port I believe
>>
>> http://s3.photobucket.com/user/DavidLive/media/Mobile%
>> 20Uploads/IMG_20161130_161511506_zpso2h21roo.jpg.html
>>
>> --
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
My engine is being rebuilt right now and the builder is going to put in the Comp Cams 1442-16 kit called Magnum Roller Rocker Arms and also the Comp
Cams pushrods for the 455.. I believe that is the one that Summit sells.

Have people had problems with these? I know of a couple of GMCers that are using them and they haven’t had problems.

Emery Stora
77 Kingsley
Frederick, CO

>
> Ken,
>
> I need a further explanation. That stud mounted roller rocker should be a kit
> that is sold by Summit. It is a direct bolt-on that requires no machining.
> They are highly recommended by the Olds pass-car guys. IIRC, we used them
> on the factory sponsored Olds we drag raced in 1972. LONG time ago!
>
> Gary Kosier
> 77PB w/500Cad
> Newark, Ohio
>
> --------------------------------------------------
> From: "Ken Henderson"
> Sent: Thursday, December 01, 2016 11:06 AM
> To:
> Subject: Re: [GMCnet] Backfiring
>
>> David,
>>
>> I just returned from Beaver Racing Engines, my friend John's shop, where I
>> happened to notice a cylinder head with those same roller rockers. It, and
>> the torn down one I then examined, came from Chuck Boyd, who got them from
>> a well known rebuilder. I'm not going to go any further with that
>> description, but believe me, the installation of those studs and rockers
>> was about the sorriest automotive machine work I've ever seen. So, I
>> strongly suggest you try to find out the source of those heads, examine
>> them VERY closely, and talk to Chuck about his experience with his.
>>
>> Someone suggested you return the rockers to OEM. I'm not sure I'd go that
>> far, because there may be nothing fundamentally wrong with what you have --
>> they may have been poorly installed.
>>
>> JMHO,
>>
>> Ken H.
>> Americus, GA
>> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
>> Manny Brakes & 1-Ton, etc., etc., etc.
>> www.gmcwipersetc.com
>>

>>
>>> Well I plugged all vacuum ports, recapped the plugs and thrilled checked
>>> the firing order, I hear it trying to start. But doesn't run now, so I
>>> pulled
>>> the value cover and found my original issue
>>>
>>> So I'll be towing it home ...
>>>
>>> http://s3.photobucket.com/user/DavidLive/media/1974%20GMC%20Motorhome/IMG_
>>> 20161130_153150795_zpsnz8aqshs.jpg.html
>>>
>>>
>>> And a picture of the pushrods from that cylinder , the one that's been
>>> shaved is the exhaust port I believe
>>>
>>> http://s3.photobucket.com/user/DavidLive/media/Mobile%
>>> 20Uploads/IMG_20161130_161511506_zpso2h21roo.jpg.html
>>>
>>> --
>>>
>> _______________________________________________
>> 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
 
Emery,

Dick Patterson doesn't use roller rockers or roller cams in the blueprinted and balanced engines he builds.

Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
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 Emery Stora
Sent: Saturday, December 03, 2016 2:59 AM
To: gmclist
Subject: Re: [GMCnet] Backfiring

My engine is being rebuilt right now and the builder is going to put in the Comp Cams 1442-16 kit called Magnum Roller Rocker Arms
and also the Comp
Cams pushrods for the 455.. I believe that is the one that Summit sells.

Have people had problems with these? I know of a couple of GMCers that are using them and they haven't had problems.

Emery Stora
77 Kingsley
Frederick, CO
 
I visited John Beaver again today and we took a closer look at one of the
damaged heads. Supposedly, the pivot studs are to be screwed directly into
the 5/16" OEM holes. These studs had 3/8" threads. Reportedly, after the
engine acted up during a very brief test drive, the studs were found to not
be perpendicular to the head. The adverse loading that led to caused the
damage I saw and reported. The only way we can figure the studs could have
been so improperly installed is that they re-drilled (or didn't) and
threaded to 3/8" without the benefit of a mill or even a drill press -- in
other words, freehand.

Fortunately, Chuck provided John with new studs which came with threaded
adapters which John will properly install in the heads. The studs then
screw into those adapters.

Installed properly from the beginning, those are probably good reliable
components. If our hypothesis is correct, someone was very
careless/ignorant in their procedures.

Ken H.

> My engine is being rebuilt right now and the builder is going to put in
> the Comp Cams 1442-16 kit called Magnum Roller Rocker Arms and also the Comp
> Cams pushrods for the 455.. I believe that is the one that Summit sells.
>
> Have people had problems with these? I know of a couple of GMCers that
> are using them and they haven’t had problems.
>
> Emery Stora
> 77 Kingsley
> Frederick, CO
>

> >
> > Ken,
> >
> > I need a further explanation. That stud mounted roller rocker should be
> a kit
> > that is sold by Summit. It is a direct bolt-on that requires no
> machining.
> > They are highly recommended by the Olds pass-car guys. IIRC, we used
> them
> > on the factory sponsored Olds we drag raced in 1972. LONG time ago!
> >
> > Gary Kosier
> > 77PB w/500Cad
> > Newark, Ohio
> >
> > --------------------------------------------------
> > From: "Ken Henderson"
> > Sent: Thursday, December 01, 2016 11:06 AM
> > To:
> > Subject: Re: [GMCnet] Backfiring
> >
> >> David,
> >>
> >> I just returned from Beaver Racing Engines, my friend John's shop,
> where I
> >> happened to notice a cylinder head with those same roller rockers. It,
> and
> >> the torn down one I then examined, came from Chuck Boyd, who got them
> from
> >> a well known rebuilder. I'm not going to go any further with that
> >> description, but believe me, the installation of those studs and rockers
> >> was about the sorriest automotive machine work I've ever seen. So, I
> >> strongly suggest you try to find out the source of those heads, examine
> >> them VERY closely, and talk to Chuck about his experience with his.
> >>
> >> Someone suggested you return the rockers to OEM. I'm not sure I'd go
> that
> >> far, because there may be nothing fundamentally wrong with what you
> have --
> >> they may have been poorly installed.
> >>
> >> JMHO,
> >>
> >> Ken H.
> >> Americus, GA
> >> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> >> Manny Brakes & 1-Ton, etc., etc., etc.
> >> www.gmcwipersetc.com
> >>
> >> On Wed, Nov 30, 2016 at 7:24 PM, David Morrison

> >>
> >>> Well I plugged all vacuum ports, recapped the plugs and thrilled
> checked
> >>> the firing order, I hear it trying to start. But doesn't run now, so I
> >>> pulled
> >>> the value cover and found my original issue
> >>>
> >>> So I'll be towing it home ...
> >>>
> >>> http://s3.photobucket.com/user/DavidLive/media/1974%
> 20GMC%20Motorhome/IMG_
> >>> 20161130_153150795_zpsnz8aqshs.jpg.html
> >>>
> >>>
> >>> And a picture of the pushrods from that cylinder , the one that's been
> >>> shaved is the exhaust port I believe
> >>>
> >>> http://s3.photobucket.com/user/DavidLive/media/Mobile%
> >>> 20Uploads/IMG_20161130_161511506_zpso2h21roo.jpg.html
> >>>
> >>> --
> >>>
> >> _______________________________________________
> >> 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
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I guess is your cad engine?

> I visited John Beaver again today and we took a closer look at one of the
> damaged heads. Supposedly, the pivot studs are to be screwed directly into
> the 5/16" OEM holes. These studs had 3/8" threads. Reportedly, after the
> engine acted up during a very brief test drive, the studs were found to not
> be perpendicular to the head. The adverse loading that led to caused the
> damage I saw and reported. The only way we can figure the studs could have
> been so improperly installed is that they re-drilled (or didn't) and
> threaded to 3/8" without the benefit of a mill or even a drill press -- in
> other words, freehand.
>
> Fortunately, Chuck provided John with new studs which came with threaded
> adapters which John will properly install in the heads. The studs then
> screw into those adapters.
>
> Installed properly from the beginning, those are probably good reliable
> components. If our hypothesis is correct, someone was very
> careless/ignorant in their procedures.
>
> Ken H.
>
>

>
> > My engine is being rebuilt right now and the builder is going to put in
> > the Comp Cams 1442-16 kit called Magnum Roller Rocker Arms and also the
> Comp
> > Cams pushrods for the 455.. I believe that is the one that Summit sells.
> >
> > Have people had problems with these? I know of a couple of GMCers that
> > are using them and they haven’t had problems.
> >
> > Emery Stora
> > 77 Kingsley
> > Frederick, CO
> >
> > > On Dec 1, 2016, at 10:36 AM, Gary Kosier

> > >
> > > Ken,
> > >
> > > I need a further explanation. That stud mounted roller rocker should
> be
> > a kit
> > > that is sold by Summit. It is a direct bolt-on that requires no
> > machining.
> > > They are highly recommended by the Olds pass-car guys. IIRC, we used
> > them
> > > on the factory sponsored Olds we drag raced in 1972. LONG time ago!
> > >
> > > Gary Kosier
> > > 77PB w/500Cad
> > > Newark, Ohio
> > >
> > > --------------------------------------------------
> > > From: "Ken Henderson"
> > > Sent: Thursday, December 01, 2016 11:06 AM
> > > To:
> > > Subject: Re: [GMCnet] Backfiring
> > >
> > >> David,
> > >>
> > >> I just returned from Beaver Racing Engines, my friend John's shop,
> > where I
> > >> happened to notice a cylinder head with those same roller rockers.
> It,
> > and
> > >> the torn down one I then examined, came from Chuck Boyd, who got them
> > from
> > >> a well known rebuilder. I'm not going to go any further with that
> > >> description, but believe me, the installation of those studs and
> rockers
> > >> was about the sorriest automotive machine work I've ever seen. So, I
> > >> strongly suggest you try to find out the source of those heads,
> examine
> > >> them VERY closely, and talk to Chuck about his experience with his.
> > >>
> > >> Someone suggested you return the rockers to OEM. I'm not sure I'd go
> > that
> > >> far, because there may be nothing fundamentally wrong with what you
> > have --
> > >> they may have been poorly installed.
> > >>
> > >> JMHO,
> > >>
> > >> Ken H.
> > >> Americus, GA
> > >> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> > >> Manny Brakes & 1-Ton, etc., etc., etc.
> > >> www.gmcwipersetc.com
> > >>
> > >> On Wed, Nov 30, 2016 at 7:24 PM, David Morrison

> > >>
> > >>> Well I plugged all vacuum ports, recapped the plugs and thrilled
> > checked
> > >>> the firing order, I hear it trying to start. But doesn't run now, so
> I
> > >>> pulled
> > >>> the value cover and found my original issue
> > >>>
> > >>> So I'll be towing it home ...
> > >>>
> > >>> http://s3.photobucket.com/user/DavidLive/media/1974%
> > 20GMC%20Motorhome/IMG_
> > >>> 20161130_153150795_zpsnz8aqshs.jpg.html
> > >>>
> > >>>
> > >>> And a picture of the pushrods from that cylinder , the one that's
> been
> > >>> shaved is the exhaust port I believe
> > >>>
> > >>> http://s3.photobucket.com/user/DavidLive/media/Mobile%
> > >>> 20Uploads/IMG_20161130_161511506_zpso2h21roo.jpg.html
> > >>>
> > >>> --
> > >>>
> > >> _______________________________________________
> > >> 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
> > 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
>
 
No, no, that is a fresh 455 rebuild.

Ken H.

> I guess is your cad engine?
>
> On Fri, Dec 2, 2016 at 3:50 PM Ken Henderson

>
> > I visited John Beaver again today and we took a closer look at one of the
> > damaged heads. Supposedly, the pivot studs are to be screwed directly
> into
> > the 5/16" OEM holes. These studs had 3/8" threads. Reportedly, after
> the
> > engine acted up during a very brief test drive, the studs were found to
> not
> > be perpendicular to the head. The adverse loading that led to caused the
> > damage I saw and reported. The only way we can figure the studs could
> have
> > been so improperly installed is that they re-drilled (or didn't) and
> > threaded to 3/8" without the benefit of a mill or even a drill press --
> in
> > other words, freehand.
> >
> > Fortunately, Chuck provided John with new studs which came with threaded
> > adapters which John will properly install in the heads. The studs then
> > screw into those adapters.
> >
> > Installed properly from the beginning, those are probably good reliable
> > components. If our hypothesis is correct, someone was very
> > careless/ignorant in their procedures.
> >
> > Ken H.
> >
> >

> >
> > > My engine is being rebuilt right now and the builder is going to put in
> > > the Comp Cams 1442-16 kit called Magnum Roller Rocker Arms and also the
> > Comp
> > > Cams pushrods for the 455.. I believe that is the one that Summit
> sells.
> > >
> > > Have people had problems with these? I know of a couple of GMCers that
> > > are using them and they haven’t had problems.
> > >
> > > Emery Stora
> > > 77 Kingsley
> > > Frederick, CO
> > >
> > > > On Dec 1, 2016, at 10:36 AM, Gary Kosier

> > > >
> > > > Ken,
> > > >
> > > > I need a further explanation. That stud mounted roller rocker should
> > be
> > > a kit
> > > > that is sold by Summit. It is a direct bolt-on that requires no
> > > machining.
> > > > They are highly recommended by the Olds pass-car guys. IIRC, we used
> > > them
> > > > on the factory sponsored Olds we drag raced in 1972. LONG time ago!
> > > >
> > > > Gary Kosier
> > > > 77PB w/500Cad
> > > > Newark, Ohio
> > > >
> > > > --------------------------------------------------
> > > > From: "Ken Henderson"
> > > > Sent: Thursday, December 01, 2016 11:06 AM
> > > > To:
> > > > Subject: Re: [GMCnet] Backfiring
> > > >
> > > >> David,
> > > >>
> > > >> I just returned from Beaver Racing Engines, my friend John's shop,
> > > where I
> > > >> happened to notice a cylinder head with those same roller rockers.
> > It,
> > > and
> > > >> the torn down one I then examined, came from Chuck Boyd, who got
> them
> > > from
> > > >> a well known rebuilder. I'm not going to go any further with that
> > > >> description, but believe me, the installation of those studs and
> > rockers
> > > >> was about the sorriest automotive machine work I've ever seen. So,
> I
> > > >> strongly suggest you try to find out the source of those heads,
> > examine
> > > >> them VERY closely, and talk to Chuck about his experience with his.
> > > >>
> > > >> Someone suggested you return the rockers to OEM. I'm not sure I'd
> go
> > > that
> > > >> far, because there may be nothing fundamentally wrong with what you
> > > have --
> > > >> they may have been poorly installed.
> > > >>
> > > >> JMHO,
> > > >>
> > > >> Ken H.
> > > >> Americus, GA
> > > >> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> > > >> Manny Brakes & 1-Ton, etc., etc., etc.
> > > >> www.gmcwipersetc.com
> > > >>
> > > >> On Wed, Nov 30, 2016 at 7:24 PM, David Morrison <
> davidlive>

> > > >>
> > > >>> Well I plugged all vacuum ports, recapped the plugs and thrilled
> > > checked
> > > >>> the firing order, I hear it trying to start. But doesn't run now,
> so
> > I
> > > >>> pulled
> > > >>> the value cover and found my original issue
> > > >>>
> > > >>> So I'll be towing it home ...
> > > >>>
> > > >>> http://s3.photobucket.com/user/DavidLive/media/1974%
> > > 20GMC%20Motorhome/IMG_
> > > >>> 20161130_153150795_zpsnz8aqshs.jpg.html
> > > >>>
> > > >>>
> > > >>> And a picture of the pushrods from that cylinder , the one that's
> > been
> > > >>> shaved is the exhaust port I believe
> > > >>>
> > > >>> http://s3.photobucket.com/user/DavidLive/media/Mobile%
> > > >>> 20Uploads/IMG_20161130_161511506_zpso2h21roo.jpg.html
> > > >>>
> > > >>> --
> > > >>>
> > > >> _______________________________________________
> > > >> GMCnet mailing list
> > > >> Unsubscribe or Change List Options:
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> > > >
> > > >
> > > > _______________________________________________
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> > >
> > >
> > > _______________________________________________
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> > > Unsubscribe or Change List Options:
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> > >
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