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Member
Posts: 11
| Looking for someone who can answer a question about the mounting of the throttle linkage at the rear of the LH cylinder head.
I had to replace a rubber bushing in the linkage. Removed the linkage from the firewall. Had to unbolt the bracket from the rear of the LH cylinder head.
Two bolts held it on. Discovered two different length bolts. So it seemed somebody had disassembled this before.
Thought it was dumb that the bracket was bolted up and sealed a water passage at the rear of the head. Lost a few quarts of coolant when I removed the bolts. I also couldn't see if there was a gasket between the head and bracket (working blind back there) but figured there had to be or it would leak.
AFTER reassembly, I discovered a cover plate laying on the back of the block that either fell out when I removed the linkage or had fallen off from a previous throttle linkage removal and was not in place when I took it apart.
I immediately recognized that this cover plate is supposed to go between the head and the throttle linkage bracket and that there must have been a gasket between the plate and the head.
In thinking about it, I thought that there was no way that Plymouth would have designed the cover plate so that it had to be removed when the throttle linkage was removed.
I looked in the Shop Manual but the only mention I could find was in troubleshooting coolant leaks, "other" less common leak points included the cover plates at the rear of each cylinder head.
So my question is, was the throttle linkage bracket AND the cover plate really secured to the head by 2 bolts or should there be 2 studs at the rear of the head so that the cover plate can be nutted down and secured and a 2nd set of nuts used on the studs to secure the throttle linkage bracket?
If the latter is true, using bolts instead would cause the linkage to align differently (the 1st set of nuts would offset the bracket by the thickness of the nuts).
And that misalignment might even explain why the bushing at that end broke apart.
Since I have to disassemble it once again to get the cover plate and new gasket installed, I figure now is the time to make it right.
If they really did just use bolts to hold the bracket to the cover plate and the cover plate to the head, I'll put it back together that way but still believe that is a dumb design.
Thanks for any pictures or explanations that help me put it together correctly. |
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Expert 5K+
Posts: 9911
   
Location: Lower Mainland BC | .
I don't know the answer to your question but to open up the field for potential answers, I am pretty sure that the 1955 Plymouth V8 was actually a Dodge poly engine (with curves at the lower edge of the valve cover) rather than the saw tooth edge of the 56 Plymouth "A" engines.
Therefore, those with 55 or 56 Dodge poly V8s might be able to answer your question.
(My 56 Dodge has a double rocker ("hemi") so I can't directly answer your question.)
Good luck.
Edited by 56D500boy 2023-08-21 2:00 PM
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Expert 5K+
Posts: 9681
Location: So. Cal | All early hemi and poly engines that use these plates, attach the linkage with the same bolts - i.e. no studs. I don't have information specifically about the '55 Plymouth application, but this is true for the Dodge & Chrysler cars that I have experience with, so I would expect the same with the '55 Plymouth.
However, there is variation in terms of where the engine sits in the chassis and the condition of your engine mounts etc. So if you are experiencing binding, then by all means, use whatever spacers or shims you need to, to adjust that out of your linkage. |
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Member
Posts: 11
| Okay, thanks. No binding that I'm aware of. I'm working on this for my 88 yo f-i-l. He's owned it about 5 years but no longer drives.
My first driving experience, the throttle response was poor. I was certain that little V8 was more powerful than that. On diagnosis, I saw that about 1/2 the pedal travel was just taking up the slop in the linkage caused by the broken rubber bushing that left an empty hole in the linkage support bracket.
The carb will fully open when manually pulling the carb linkage open but the throttle linkage couldn't do it. I molded a urethane bushing (a reasonable looking facsimile of the original) and I believe it will allow the linkage to work properly now.
Luckily, I spotted the missing cover plate before refilling the radiator. I've now made a new gasket and will disassemble/reassemble soon. Just hesitated to reinstall with the existing bolts because it seems like such a dumb design to me.
If my homemade bushing DOES fail, I'll have to disassemble again and waste more coolant. I was really hoping you were going to tell me it should have studs, haha! But if it was always bolts, putting studs on now might result in misalignment and binding so not looking to modify the factory design.
Again, thanks for the responses. |
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Extreme Veteran
Posts: 446
Location: Beaumont TX | Do you need more information on the throttle linkage. I have the original throttle linkage in my 1955 Plymouth Savoy with a V8 and can take some pictures if you still need help.
Sam |
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'55 Plymouth Throttle Linkage Mounting
