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PostPosted: Fri Feb 04, 2022 4:26 pm 
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4 BBL ''Hyper-Pak''

Joined: Tue Jul 13, 2021 6:57 am
Posts: 28
Location: Ontario, Oregon
Car Model: 1977 Dodge D100 Custom
After removing and cleaning up the manifolds because they were not removed from the truck when the head was rebuilt, and a smoker revealed several leaks around the manifold gasket the engine will still not run. During earlier diagnosis I replaced the carburetor with an automatic choke carb, but it was carefully cleaned and carburetor cleaner shot though the passages to confirm they were clear. The tailpipe is cut apart to get it out with the manifolds so there is no back pressure. Just a lot of noise. The vacuum gauge would quickly climb to about 17 inches before it fell off and the engine died. Timing was checked by watching cylinder one valves and the timing mark, as well as a camera in cylinder one to confirm it was at the top of its stroke. Looking into the carb, the acceleration pump is working. I started the engine on starting fluid almost every time because it would not fire on gas. Today after I confirmed fuel was being pumped in when the throttle was pressed, I tried starting it on fuel only. It did not start, but I noticed smoke under the carb and looking closely I can see there is exhaust on the fresh paint on the intake manifold. There is a large leak between the manifolds. When I installed the manifolds the last nut and two bolts I tightened were the three bolts between them. Now I finally know why the engine won't run. What I would like to know, is there any liquid or cream gasket material that I can put on the metal gasket between the two manifolds to make certain these surfaces cannot leak again? Can I get some high temperature gasket material and make a more crushable gasket to go between these two surfaces? Fortunately, all the bolts are free, and I can take it all apart fairly easily now.


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PostPosted: Sat Feb 05, 2022 5:58 am 
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Turbo Slant 6

Joined: Thu Jun 07, 2012 4:29 pm
Posts: 726
Location: Houston
Car Model: 68 Valiant
Not sure what you are exactly doing...but the intake/exhaust leak won't prevent the engine from running. It'll run fine, just be noisy due to the leak.

So...once you get it to start on starting fluid, it dies after a few seconds. What happens when you keep spraying it with starting fluid? Does it stay running then?


It sounds a lot like you are starving for fuel (i.e. gasoline). Spraying carb cleaner through a carb doesn't guarantee it's not faulty.


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PostPosted: Sat Feb 05, 2022 7:44 am 
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EFI Slant 6

Joined: Mon May 26, 2014 4:02 pm
Posts: 340
Location: Vermont
Car Model: Slant Six powered M37
If it runs on ether, then it would suggest a fuel related issue. Was this a recently running and driving truck or are you trying to get it running for the first time in a long time?

I am not understanding why it won't fire or even cough on the fuel that the accelerator pump is contributing... is the fuel old-stale?

Also I have gotten rather concerned by using starting fluid unless absolutely dire necessity. When trying to get rigs running I use chainsaw gas for the slight upper cylinder lubrication it provides.


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PostPosted: Sat Feb 05, 2022 8:56 am 
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Supercharged

Joined: Wed Sep 17, 2008 6:48 pm
Posts: 3564
Location: Indianapolis
Car Model:
An exhaust leak at the joint where the exhaust manifold attaches to the bottom of the intake manifold is not desirable as it will let exhaust fumes into the engine compartment and possibly through the firewall and into the cab, but that will not have an influence on how the engine starts or runs.
Are you sure you don’t have a large vacuum leak at the carb base-gasket or at the intake to cylinder head?
Look into Remflex gaskets, they make a really good intake/exhaust to head gasket and they also have a good heat stove (the joint at the bottom of the intake to the exhaust manifold) gasket.

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PostPosted: Sat Feb 12, 2022 1:42 pm 
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4 BBL ''Hyper-Pak''

Joined: Tue Jul 13, 2021 6:57 am
Posts: 28
Location: Ontario, Oregon
Car Model: 1977 Dodge D100 Custom
I immediately assumed a vacuum leak, which I do have, but after removing the gaskets I found that there was a gap between the manifolds, which means I did not tighten the three bolts tight enough. When I reinstall the manifolds I will tighten the 3 bolts evenly to about 35 Lbs. torque to make sure the gap is closed.

The new FEL-PRO manifold gasket had leakage around the number 3 exhaust port. I used the mounting board for the drill press jig I made to drill out the 2 broken bolts and mounted the manifolds to it. The number 3 exhaust flange has a gap of 0.023" between the board and manifold flange when all of the other flanges are tight to the board. I am replacing the FEL-PRO gasket with a Victor Reinz gasket when I reassemble the manifolds to the head. The thickest part of the FEL-PRO gasket measures 0.045", while the thinnest part of the Victor Reinz measures 0.066" with 0.074" maximum. When I reassemble the manifolds to the head is there any reason why I cannot use a thin layer of Permatex Red around the exhaust port to be certain there will not be an exhaust leak here again?


Attachments:
File comment: This image shows the gap between the #3 exhaust port and the mounting surface.
exhaust 2 gap-1000.jpg
exhaust 2 gap-1000.jpg [ 192.19 KiB | Viewed 1064 times ]
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PostPosted: Sat Feb 12, 2022 3:00 pm 
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Joined: Thu Oct 31, 2002 5:39 pm
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Location: North America
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k7seh wrote:
The new FEL-PRO manifold gasket


…is junk, in my experience.

Maybe too late, but it is very much worth your while to get the good gaskets for the manifolds-to-head and intake-to-exhaust junctions.

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PostPosted: Sat Feb 12, 2022 4:46 pm 
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3 Deuce Webber

Joined: Sun Apr 12, 2020 6:13 pm
Posts: 53
Car Model: 67 Valiant, 73 Duster
Dan is right.

Did the same job—-used the FelPro gasket—car would not run as the leak was too great. The gasket just didn’t work for me.

Re-did the entire job with the RemFlex gaskets and had no issues at all. No leaks. Ran immediately.

The challenge was getting a remflex shipped that was not damaged. 3 times from Amazon they came destroyed in shipping.


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PostPosted: Sat Feb 12, 2022 7:49 pm 
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Supercharged

Joined: Wed Sep 17, 2008 6:48 pm
Posts: 3564
Location: Indianapolis
Car Model:
k7seh,, are you trying to bolt the intake and exhaust manifold as an assembly to the cylinder head?
I don’t run stock slant six intakes and exhaust manifolds, but I think if you are doing it that way you would need to be sure the flanges of the intake and exhaust manifolds are perfectly aligned.
Maybe some one with more experience than I have with the stock intake and exhaust can chime in but it seems to me the intake and exhaust can be ‘loosely’ together until the flanges are aligned and tightened, then the bolts that hold the intake and exhaust together can be tightened.

Concerning applying a thing coat of red RTV, there were a couple million slants that had the intake - exhaust assembled properly and did not have intake vacuum or exhaust leaks with out the use of red RTV. And if there was much of a gap, the RTV will be a temporary fix as it will burn and blow out.

Lastly, the recommended torque in the flange nuts is something like 12 to 13 ft lbs.
That is for the Fel Pro or the Remflex gaskets. Get the flanges aligned and the flanges will seal.

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PostPosted: Sat Feb 12, 2022 11:53 pm 
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4 BBL ''Hyper-Pak''

Joined: Tue Jul 13, 2021 6:57 am
Posts: 28
Location: Ontario, Oregon
Car Model: 1977 Dodge D100 Custom
The Victor Reinz gasket I am planning to use is almost twice as thick as the FEL-PRO gasket. I am pretty sure it will seal all of the manifold ports, but I am not certain about the #3 exhaust manifold flange. The gap on my test mounting is .023", and the Victor Reinz gasket is about 0.030" thicker than the FEL-PRO. Even the little gasket for the EGR port on the head is a lot thicker than the FEL-PRO. I have researched to fine the Remflex gasket, but even on their site they did not list a gasket for the slant 6. RockAuto had the Victor Reinz gasket and gave the specs on the gasket. I measured it when it arrived, and it is much thicker than advertised. The Permatex Red RTV is rated for 700 degrees and exhaust is one of the applications given, which is why I am considering it as a thin filler. But I am worried a little about the seal not holding and blowing out. Maybe I should just put it all together again and see what happens. I am really getting tired of chasing the problems, and this is the last one.

To answer the question about how I am bolting the manifolds to the head, the 3 bolts tying the manifolds together are very loose when I torque the manifolds to the head. I plan to torque them to about 35 Ft. Pounds when I reassemble things and try to not have an exhaust leak there this time. The gasket shown in the picture was tightened too much and I planned to re=torque them. I think I will go a few Ft. pounds more with the thicker gasket to be safe.


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PostPosted: Sun Feb 13, 2022 4:59 am 
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Board Sponsor & SL6 Racer

Joined: Wed Oct 23, 2002 7:57 pm
Posts: 7397
Location: Waynesboro, Pa.
Car Model: 65 Valiant 2Dr Post
You could double up on the gaskets if you need too. Is it just # 3 that is warped when you lay a straight edge across the manifolds?

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PostPosted: Sun Feb 13, 2022 5:36 am 
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Supercharged

Joined: Wed Sep 17, 2008 6:48 pm
Posts: 3564
Location: Indianapolis
Car Model:
Remflex slant six manifold gasket set

http://catalog.remflex.com/MOPAR_Header ... p/6008.htm

Remflex slant six manifold gasket set from Amazon

https://www.amazon.com/Remflex-6008-Exh ... B00C5T8YMA

although just like mentioned above by Rodrju the last two Remflex slant six gasket sets were damaged, both in the same place both prior to shipping. They shipped me one and it was damaged, I contacted Amazon and they promptly sent me a second that was damaged identically to the first one. After returning both, Amazon did a refund, that was a couple of months ago, they should have it figured out by now.

Be sure to read the recommended torque stated on the Remflex packageing.

Quote:
The Permatex Red RTV is rated for 700 degrees and exhaust is one of the applications given,


that may work down stream on an exhaust pipe where the exhaust gas has a chance to cool, or at the cylinder head if you only plan to idle the car around at very low speeds as the exhaust gas temperature at the cylinder can easily get to 800 degrees with normal driving and over 1000 when driving for extended times at highway speeds.

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PostPosted: Sun Feb 13, 2022 6:43 am 
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4 BBL ''Hyper-Pak''

Joined: Tue Jul 13, 2021 6:57 am
Posts: 28
Location: Ontario, Oregon
Car Model: 1977 Dodge D100 Custom
I think I am going to forget using RTV around the exhaust manifold port. It seems to leave room for problems, if not at first then down the line. The picture I posted is the best way I have to put a straight edge along the manifold flanges. All of the other flanges are tight to the board with only number 3 exhaust showing a gap. The original gasket I removed the first time I tore things down had two exhaust leaks, but it was assembled to the head without having the three bolts that tie the manifolds together loose so who knows how the manifolds were set up then. They rebuilt the head without removing the manifolds from the header pipe because the bolts would break, which they did for me. I have wondered about two gaskets and will study that. the Victor Reitz gasket has a metallic filler on one side of the gasket thickness, which I will put towards the head and keep the softer side towards the manifolds.


Attachments:
File comment: Here is an edge view of the FEL-PRO and Victor Reitz gaskets. I tried to show the FEL-PRO in an area that was not compressed by the manifolds.
Victor_Reitz_FEL-PRO_edges-600.jpg
Victor_Reitz_FEL-PRO_edges-600.jpg [ 144.35 KiB | Viewed 963 times ]
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PostPosted: Sun Feb 13, 2022 6:48 am 
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Board Sponsor & Moderator
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Joined: Mon Oct 21, 2002 11:08 am
Posts: 15362
Location: Blacksburg, VA
Car Model:
Best thing would be to take the exhaust manifold (and maybe intake too) to the machine shop and have them mill/sand it flat all the way across. Doubling gaskets will help, but they will eventually blow out if the manifold(s) is/are not straight (planar).

Lou

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PostPosted: Sun Feb 13, 2022 7:43 am 
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Turbo Slant 6
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Joined: Sat Sep 13, 2014 8:25 am
Posts: 713
Location: Springtucky OR
Car Model:
Yes. Just have the manifolds machined flat and you'll solve the problem.

The factory torque spec for the manifold nuts is intended to allow the exhaust manifold to 'float' a little as it expands with heat. Over tightening them may eventually lead to a cracked exhaust manifold.

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PostPosted: Sun Feb 13, 2022 4:49 pm 
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Turbo EFI

Joined: Sat Feb 18, 2006 2:19 pm
Posts: 1492
Car Model:
Not Recommended. Finally did get remflex, but time had run out. Measured gap cut fel-pro spare gasket up, glued one small section to exhaust port with big gap. One other port smaller gap, found some thin card board to match the gap, cut to fit exhaust ports glued to port. Glue is for holding while assembling not for sealing. That was three years ago still holding. Remflex still on shelf will use it next time.


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