| Best thermostat [message #317366] |
Wed, 10 May 2017 20:34  |
 |
pjburt
Messages: 436
Registered: February 2016
Location: Fresno, California
Karma: 1
|
Senior Member |
|
|
What is the current best thermostat to put in our 73 - 455?
I was looking for a Robert Shaw based on what I have read on the forum. The only place I found them was at Summit and Speedway. NAPA has the re-branded Mr. Gasket. All are now made in China.
I was reading a couple of Vette forums and it seems the Chinese thermostats' quality has fallen off.
Any suggestions?
While on the T'stat subject, the bolts on the t'stat housing are metric. Is this correct for 73? They are the only metric bolts I've run across so far.
Thanks.
Jerry Burt Fresno, CA.
73 Gmc 26' Canyon Lands
Members: FMCA - GMCMI - GMCWS
A truly happy person is one who can enjoy the scenery on a detour.
|
|
|
|
| Re: Best thermostat [message #317375 is a reply to message #317366] |
Wed, 10 May 2017 23:34  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
|
Senior Member |
|
|
I got my Robert shaw clone from summit it is the same thermostat for most GM and some other mfgs of the era. I am pretty sure all 73 to 78 are SAE and not metric in the original thermostat housing bolts.
Roy Keen
Minden,NV
76 X Glenbrook
|
|
|
|
|
|
| Re: Best thermostat [message #317421 is a reply to message #317384] |
Fri, 12 May 2017 00:14 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
|
Senior Member |
|
|
I had a factory replacement 455 block I thought the casting number was on the rear of the block and yes it is a totally different number. Other then that the block is identical to the original.The thermostat mounting holes are on the intake manifold not the block. If the intake is aftermarket I suppose it could be metric but why would they do that? I believe all the Motorhome engines were GM blue but some earlier car engines were also red I believe like an earlier 425?
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Fri, 12 May 2017 00:19] Report message to a moderator |
|
|
|
|
|
| Re: [GMCnet] Best thermostat [message #317444 is a reply to message #317443] |
Fri, 12 May 2017 11:27 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
This thing is not an all matching numbers concours show quality vehicle. It
is more akin to a manure spreader. A useful vehicle to be sure, but, it is
still a pig no matter how much lipstick you put on it. It is assembled from
parts scrounged from other vehicle assembly lines, at the lowest cost
possible. For the most part, they used Oldsmobile pieces. Some were
modified in later years as they proved not to be robust enough for the
weight and forces applied to them by motor home use.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On May 12, 2017 9:11 AM, "Jerry Burt" wrote:
> The mechanicals seem to be a Frankenstenian combination of parts. I'm not
> interested in doing a numbers matching build. I'm just trying to get some
> sense of what I've got. The intake is cast iron with the proper casting
> numbers. I will re-thread the t-stat bolt holes to Am/std. Could this be off
> of an industrial engine?
>
> The later blocks (Fa) did have the casting numbers in the back. The
> casting number on my block is on the front,center next to the oil fill tube
> and is
> an F block cast in 72. The engine serial number is on the oil fill tube as
> it should be according to the GMC manual. This shows it is a 73. Since the
> tube can be re-installed on a different block, it doesn't help with
> whether the block is original or not. On cars, the vehicle VIN is supposed
> to be
> stamped on the front, left side of the block. I was wondering if that was
> the case with our coaches.
>
> roy1 wrote on Thu, 11 May 2017 22:14
>> I had a factory replacement 455 block I thought the casting number was
> on the rear of the block and yes it is a totally different number. Other
>> then that the block is identical to the original.The thermostat mounting
> holes are on the intake manifold not the block. If the intake is
>> aftermarket I suppose it could be metric but why would they do that? I
> believe all the Motorhome engines were GM blue but some earlier car engines
>> were also red I believe like an earlier 425?
>
>
> --
> Patti & Jerry Burt
> 73 Gmc 26' Canyon Lands -
> Photos - http://jburt.smugmug.com/GMC-Motorhome
> Quad bags w/disc brakes - Alcoas w/ Michelins lots of interior updates.
> Members: FMCA - GMCMI - GMCWS - Pacific Cruisers - 49ers
>
> _______________________________________________
> 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
|
|
|
|
| Re: Best thermostat [message #317446 is a reply to message #317443] |
Fri, 12 May 2017 11:46 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
|
Senior Member |
|
|
Why mess with the bolts? If it works now with metric bolts and has no leaks, leave it that way. It is not like these bolts are something you will be playing with frequently.
Note: those holes go all the way into the coolant passage. If re-threaded coolant could migrate up the threads and leak.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
|
|
|
|
| Re: Best thermostat [message #317447 is a reply to message #317366] |
Fri, 12 May 2017 11:48 |
|
pjburt
Messages: 436
Registered: February 2016
Location: Fresno, California
Karma: 1
|
Senior Member |
|
|
Thanks Roy and Jim. I'll just wait for the heads from JimK and put it together. Off to do more cleaning.
Jerry Burt Fresno, CA.
73 Gmc 26' Canyon Lands
Members: FMCA - GMCMI - GMCWS
A truly happy person is one who can enjoy the scenery on a detour.
[Updated on: Fri, 12 May 2017 11:48] Report message to a moderator |
|
|
|
| Re: [GMCnet] Best thermostat [message #317459 is a reply to message #317443] |
Fri, 12 May 2017 13:41 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
|
Senior Member |
|
|
I would be willing to bet that they are metric because they were rethreaded
to be metric at some point, for reasons lost to history.
In any case, I stud these fasteners instead of using bolts. That way, I
know how much depth of thread is in the manifold, and I don't have to break
the seal on those threads to replace the thermostat. Granted, I started
doing this when I switched to the Rockwell aluminum manifold, where these
holes are not drilled and threaded all the way into the water jacket, and I
wanted to make use of every single thread available to avoid stripping
them. But it's a good idea for the iron manifold, too, and it means you can
use a robust sealer on those threads without fear of being unable to
extract them in the future.
Rick "who would leave them metric and paint the bolt heads or nuts blue as
GM once did with metric fasteners" Denney
On Fri, May 12, 2017 at 12:10 PM, Jerry Burt wrote:
> The mechanicals seem to be a Frankenstenian combination of parts. I'm not
> interested in doing a numbers matching build. I'm just trying to get some
> sense of what I've got. The intake is cast iron with the proper casting
> numbers. I will re-thread the t-stat bolt holes to Am/std. Could this be off
> of an industrial engine?
>
> The later blocks (Fa) did have the casting numbers in the back. The
> casting number on my block is on the front,center next to the oil fill tube
> and is
> an F block cast in 72. The engine serial number is on the oil fill tube as
> it should be according to the GMC manual. This shows it is a 73. Since the
> tube can be re-installed on a different block, it doesn't help with
> whether the block is original or not. On cars, the vehicle VIN is supposed
> to be
> stamped on the front, left side of the block. I was wondering if that was
> the case with our coaches.
>
> roy1 wrote on Thu, 11 May 2017 22:14
>> I had a factory replacement 455 block I thought the casting number was
> on the rear of the block and yes it is a totally different number. Other
>> then that the block is identical to the original.The thermostat mounting
> holes are on the intake manifold not the block. If the intake is
>> aftermarket I suppose it could be metric but why would they do that? I
> believe all the Motorhome engines were GM blue but some earlier car engines
>> were also red I believe like an earlier 425?
>
>
> --
> Patti & Jerry Burt
> 73 Gmc 26' Canyon Lands -
> Photos - http://jburt.smugmug.com/GMC-Motorhome
> Quad bags w/disc brakes - Alcoas w/ Michelins lots of interior updates.
> Members: FMCA - GMCMI - GMCWS - Pacific Cruisers - 49ers
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
'73 230 "Jaws"
Northern Virginia
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
