Remflex vs copper exhaust gaskets

https://www.gmcrvparts.com/product-p/gm12-030.2.htm

On Sat, Sep 21, 2019 at 7:12 PM Bruce Hislop via Gmclist <

> Ken, That's good to hear because my 3/8" torque wrench is rated for specs
> between 20 and 150ft-lbs... so I'm good with that.
>
> John, would the one for headers have the center piece for the dual port
> center position? Mine is open there.
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.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
>
> _______________________________________________
> 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
 
Both Remflex gaskets states 20 ft. lbs.

> https://www.gmcrvparts.com/product-p/gm12-030.2.htm
>
> On Sat, Sep 21, 2019 at 7:12 PM Bruce Hislop via Gmclist <

>
>> Ken, That's good to hear because my 3/8" torque wrench is rated for specs
>> between 20 and 150ft-lbs... so I'm good with that.
>>
>> John, would the one for headers have the center piece for the dual port
>> center position? Mine is open there.
>>
>> --
>> Bruce Hislop
>> ON Canada
>> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.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
>>
>> _______________________________________________
>> 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
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
> The sticker on my Remflex package says 14-18ft-lbs, but I've had them for a few years.
>
> Matt, is there any issue with using the grade 8 bolts? I have them re-installed, but only finger tight. I have some plated 3/8" bolts.. with the
> 3 bars on top so they are grade 5 I believe.. TSC stores up here have switched to black phosphate bolts in their bins.
>
> We are registered for Mansfield. I have a Chemo treatment on Tuesday so hopefully I'll be bright-eyed and bushy-tailed in about a week after
> that.

Bruce,

Yes, there is a problem with Gr8 bolts in exhaust applications and there are actually two issues. Well three if you try to use them at Gr8 loads.
That last one is that as they are heat treated, they will actually unload (creep) at near normalization temperatures (~900°F). This is a time and
temperature problem that may take a while to show up.
The next problem is that the alloy of Gr8 fasteners is much more likely to cause transfer (aka gall) in a hot application. This is something you
really don't need.
A third issue is related to the first, but can get you even if they are not tensioned to Gr8 stress. As they are heat treated and with heat, they
will loose that temper, the frequently develop cracks at the thread root and so are prone to failure when any attempt to remove them is made.

I hope the Chemo does you well.

Hope to see you both at Mansfield.

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
 
Manifold Update,

I installed the driver's side exhaust manifold today. Some choice words were used as I eventually managed to get my torque wrench around the
obstacles.

The coach is much quieter, so now I can hear I likely have leaks on the passenger side too!

I have EFI and since the O2 sensor is on the driver's side, I suspect air was leaking into the exhaust as well. I hooked my computer up before
starting the engine. As soon as the closed loop mode was entered, the EBL was pulling fuel from the mixture and the engine was running much smoother.
I took it for a VE learn and every cell hit was removing -3 to -6.

Thanks everyone for their input!


--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.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
 
Now that your "experienced" your can do mine....lol. :d Just kidding of course and good to hear it worked well.
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
Bruce,

Congratulations on getting the job done. I can feel for you having
recently had to do the same job on my Cad500, which is even tighter in the
hole. On top of that, as sort of a warning to others, I had another
problem: During the previous installation I replaced the manifold bolts
with studs and double brass nuts. That wasn't such a bad idea because the
brass nuts came off easily. But the fact that I left some of the studs too
long was BAD. It meant I couldn't get the manifold off without removing
the studs. Despite liberal nickle anti-seize, most of them wouldn't budge
with reasonable torque. My final solution was to leave the manifold
hanging from the studs and modify the Remflex. It was easy to clean the
old Remflex residue from between the head and manifold. Then I extended
the Remflex's bolt holes downward so I could drop it into the head-manifold
gap. Cutting the gasket was something of a surprise because that was the
first time I realized they contained the metal screen reinforcement. Good
aviation snips made the task simple. The installation trick worked
amazingly well and I've had no sign of adverse effects -- yet.

Ken H.

On Sun, Sep 22, 2019 at 9:33 PM Bruce Hislop via Gmclist <

> Manifold Update,
>
> I installed the driver's side exhaust manifold today. Some choice words
> were used as I eventually managed to get my torque wrench around the
> obstacles.
>
> The coach is much quieter, so now I can hear I likely have leaks on the
> passenger side too!
>
> I have EFI and since the O2 sensor is on the driver's side, I suspect air
> was leaking into the exhaust as well. I hooked my computer up before
> starting the engine. As soon as the closed loop mode was entered, the EBL
> was pulling fuel from the mixture and the engine was running much smoother.
> I took it for a VE learn and every cell hit was removing -3 to -6.
>
> Thanks everyone for their input!
>
>
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> Bruce,
>
> Congratulations on getting the job done. I can feel for you having recently had to do the same job on my Cad500, which is even tighter in the
> hole. On top of that, as sort of a warning to others, I had another problem: During the previous installation I replaced the manifold bolts with
> studs and double brass nuts. That wasn't such a bad idea because the brass nuts came off easily. But the fact that I left some of the studs too
> long was BAD. It meant I couldn't get the manifold off without removing the studs. Despite liberal nickle anti-seize, most of them wouldn't budge
> with reasonable torque. My final solution was to leave the manifold hanging from the studs and modify the Remflex. It was easy to clean the old
> Remflex residue from between the head and manifold. Then I extended the Remflex's bolt holes downward so I could drop it into the head-manifold
> gap. Cutting the gasket was something of a surprise because that was the first time I realized they contained the metal screen reinforcement. Good
> aviation snips made the task simple. The installation trick worked amazingly well and I've had no sign of adverse effects -- yet.
>
> Ken H.

Ken,

I appreciate this information. The only time I saw a Remflex, I thought it was a metal clad graphite part. Now I know that at the very least some
are perforated core with flexible graphite surface.

If you think of it and it is REAL convenient and you are coming to Mansfield, could you save and bring along the little pieces you cut out?

Thanks again for being a valuable source of information.

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
 
Matt,

I've already disposed of the material from the Remflex. However, Remflexes
are among the very few spares I carry, so if you'll remind me at Mansfield,
I'll drag them out for you to examine. I, too, was surprised to find the
"screen wire" inside those gaskets. I'm not at all sure that the earlier
ones had that reinforcement; IIRC, they were considerably more fragile than
the current ones.

Ken H.

On Sun, Sep 22, 2019 at 10:27 PM Matt Colie via Gmclist <

> > Bruce,
> >
> > Congratulations on getting the job done. I can feel for you having
> recently had to do the same job on my Cad500, which is even tighter in the
> > hole. On top of that, as sort of a warning to others, I had another
> problem: During the previous installation I replaced the manifold bolts
> with
> > studs and double brass nuts. That wasn't such a bad idea because the
> brass nuts came off easily. But the fact that I left some of the studs too
> > long was BAD. It meant I couldn't get the manifold off without removing
> the studs. Despite liberal nickle anti-seize, most of them wouldn't budge
> > with reasonable torque. My final solution was to leave the manifold
> hanging from the studs and modify the Remflex. It was easy to clean the old
> > Remflex residue from between the head and manifold. Then I extended the
> Remflex's bolt holes downward so I could drop it into the head-manifold
> > gap. Cutting the gasket was something of a surprise because that was
> the first time I realized they contained the metal screen reinforcement.
> Good
> > aviation snips made the task simple. The installation trick worked
> amazingly well and I've had no sign of adverse effects -- yet.
> >
> > Ken H.
>
> Ken,
>
> I appreciate this information. The only time I saw a Remflex, I thought
> it was a metal clad graphite part. Now I know that at the very least some
> are perforated core with flexible graphite surface.
>
> If you think of it and it is REAL convenient and you are coming to
> Mansfield, could you save and bring along the little pieces you cut out?
>
> Thanks again for being a valuable source of information.
>
> 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
>
 
Without resurfacing the manifold?

Let us know how that works out. 0.015" out of flat is a lot to ask any gasket to seal.

Also, since the heat transfer to the head is what keeps the manifold from heating up too much and warping, that extra layer of insulation is going to
make it heat up, warp and crack even faster.

Keep us posted either way!

> Manifold Update,
>
> I installed the driver's side exhaust manifold today. Some choice words were used as I eventually managed to get my torque wrench around the
> obstacles.
>
> The coach is much quieter, so now I can hear I likely have leaks on the passenger side too!
>
> I have EFI and since the O2 sensor is on the driver's side, I suspect air was leaking into the exhaust as well. I hooked my computer up before
> starting the engine. As soon as the closed loop mode was entered, the EBL was pulling fuel from the mixture and the engine was running much
> smoother. I took it for a VE learn and every cell hit was removing -3 to -6.
>
> Thanks everyone for their input!

--
Todd Snyder, Buffalo NY
1976 Eleganza II
 
Actually I was using a straight edge and the high spot was near the center. I can't justify the $$$ for the actual equipment to measure this so I was
eyeballing it against my digital calipers. Since I was looking at the end of the straight edge, the actual high point would be closer to 1/2 that
amount so maybe 0.008 - 0.010".

I had the manifolds and heads planed flat when the engine was rebuilt, then used DaveL's copper gaskets. The manifold cracked anyway with about 25K
miles. Actually its been this way for a few years now.

Just trying to put off the inevitable cost of header's.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.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
 
> Actually I was using a straight edge and the high spot was near the center. I can't justify the $$$ for the actual equipment to measure this so I
> was eyeballing it against my digital calipers. Since I was looking at the end of the straight edge, the actual high point would be closer to 1/2
> that amount so maybe 0.008 - 0.010".
>
> I had the manifolds and heads planed flat when the engine was rebuilt, then used DaveL's copper gaskets. The manifold cracked anyway with about
> 25K miles. Actually its been this way for a few years now.
>
> Just trying to put off the inevitable cost of header's.

The actual thermal conductivity of flexible graphite is pretty good, not like copper but way better the any of the other post-asbestos things that
have been sold.

The easy way for a typical person to measure flatness or straightness is with a set of thickness (feeler) gauges and a table saw. Most decent table
saws have a cast and ground table that came out of the box very flat.

Bruce, if you got that manifold back with the center high, that guy really screwed it up. I have never seen an exhaust manifold curl that way.

Matt - Break is over, back on the creeper.
--
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
 
Matt,
To clarify, I did not get this one planed, although it looks like it has been gone over because the facings were shinny and same with the 2 casting
blocks. It had some pitting of the face as well, but just surface and maybe a couple thou deep.

It was in pretty good shape otherwise.

Thanks,

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.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
 
I just talked with Remflex. They suggested my still leaking Remflex gaskets might benefit from a little more torque than the specified 20 LB FT - perhaps 25 LB FT? I'll have to try that next spring...

I also asked about the earlier, lower torque specs. They mentioned the earlier gasket formulation was a fibreglass (?) core and the later gaskets had a steel core and could handle more pressure.

Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath

>

>> My recent Remflex gaskets stated: "Suggested Torque 20 LB FT".
>>
>> Rob
>> Victoria, BC
>> 76 Royale - Rear Twins/Dry Bath
>
> Good on both of you, I don't know where I remembered the 7-1/5 from, but it is way below Dave's 25 and many retorques.
>
> 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
 
AhHa! I thought there was something different about the later Remflexes --
less fragile.

Thanks for posting that.

Ken H.

On Mon, Sep 23, 2019 at 5:10 PM Rob via Gmclist
wrote:

> I just talked with Remflex. They suggested my still leaking Remflex
> gaskets might benefit from a little more torque than the specified 20 LB FT
> - perhaps 25 LB FT? I'll have to try that next spring...
>
> I also asked about the earlier, lower torque specs. They mentioned the
> earlier gasket formulation was a fibreglass (?) core and the later gaskets
> had a steel core and could handle more pressure.
>
> Rob
> Victoria, BC
> 76 Royale - Rear Twins/Dry Bath
>
> > On Sep 21, 2019, at 2:16 PM, Matt Colie via Gmclist <

> >

> >> My recent Remflex gaskets stated: "Suggested Torque 20 LB FT".
> >>
> >> Rob
> >> Victoria, BC
> >> 76 Royale - Rear Twins/Dry Bath
> >
> > Good on both of you, I don't know where I remembered the 7-1/5 from, but
> it is way below Dave's 25 and many retorques.
> >
> > 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
>
 
The parts diagram and maintenance manual don't show any gasket. GM didn't want one there apparently.

I would think that the heat transfer between one clean, flat, piece of iron clamped to another piece of clean flat iron is much better than anything
with 0.015" gap


--
Todd Snyder, Buffalo NY
1976 Eleganza II
 
> The parts diagram and maintenance manual don't show any gasket. GM didn't want one there apparently.
>
> I would think that the heat transfer between one clean, flat, piece of iron clamped to another piece of clean flat iron is much better than
> anything with 0.015" gap
>
>
>
> >

Very true but things have changed since the 70's from fuel perspective etc.....todays fuel has different additive etc so my opinion, not founded in
fact just visual, is the modern fuels burn hotter. (Cleaner combustion chambers = better fuel economy)

GM or Olds never wanted these things to run 40 years plus...they only had to make it till the end of waranty.

--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
> Very true but things have changed since the 70's from fuel perspective etc.....todays fuel has different additive etc so my opinion, not founded
> in fact just visual, is the modern fuels burn hotter. (Cleaner combustion chambers = better fuel economy)
>
> GM or Olds never wanted these things to run 40 years plus...they only had to make it till the end of waranty.

Rich,

Two things here:
Modern fuels really do not burn any "cleaner" than that of 40+ years ago. But even this is a little tough and this is comparing what was good fuel
then to most fuel now. The big thing is the removal of tetra-ethyl lead. Available octanes really have not changed much, but the marketing has. The
fact that combustion is cleaner is really a result of changing engines for emissions.

Maybe GM didn't want engines to last 40 years, but the Olds family sure did. This is why you never saw BB Chevs in industrial and pump service, but
Olds? They were a benchmark and only recently supplanted by diesels. If you talked to any of the first tier suppliers of the past, they will tell
you that Olds wanted the good stuff. The very best seals and bearings and if it didn't pass their validation, you would hear about it....

Matt - The refugee from Dyno-Land
--
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
 
You must log in or register to reply here.
Get your shine on at www.cruzingear.co
GMCMI Fall 2026 Rally

Share this page

Share this page
Top Bottom
Back