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10-05-2023, 05:18 PM | #1 |
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Join Date: Dec 2020
Location: Pt. St. Lucie, FL
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Heat/ Exhaust Rise Intake
So I've been reading about the intake block off for the heat/ exhaust into the intake manifold and tried the easy fix with slipping in shims under the intake first. Well that didn't work for me because the exhaust leaked at that point afterwards and it called for removing the intake and doing it the right way. Upon inspection of the intake I saw that both holes for the heat rise were cracked. I decided to make hole plugs out of thin stainless, recessed in the hole and then using the extreme heat JB Weld to seal the holes. I ground the cracks V shaped and filled the cracks at the same time in order to make one piece seal on the complete job. Im waiting on the gasket to reinstall and try this out, hopefully will be driving by Saturday. I'll post the results next week after I put some miles on her.
Last edited by BobR35; 10-06-2023 at 08:43 PM. |
10-05-2023, 05:22 PM | #2 | |
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Re: Heat/ Exhaust Rise Intake
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10-05-2023, 10:52 PM | #3 |
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Re: Heat/ Exhaust Rise Intake
Bob, Your reading about the subject has not sufficiently educated you before you jumped into action. It's not the intake manifold that you block the heat risers on, it's the engine block itself, and the ideal device to block it with is a wheatstalk penny, (one on each side) as the metallurgy of that vintage penny is perfect for the job. It taps right into place in the block and stays put. Nowadays, the consensus seems to favor the drilling of a ⅛" hole in each of those pennies, to allow a trickle of heat through. I hope that whatever damage has been done to the manifold can be repaired, and that an unmodified gasket can correct the leaky situation.
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10-06-2023, 05:44 AM | #4 | |
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Re: Heat/ Exhaust Rise Intake
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10-06-2023, 07:43 AM | #5 |
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Re: Heat/ Exhaust Rise Intake
My 40 had a mercury dime in each of the block passages when we rebuilt it so I just left them as they were. and like said above, you block the deck not the manifold. Tim
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10-06-2023, 12:06 PM | #6 |
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Re: Heat/ Exhaust Rise Intake
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10-06-2023, 12:41 PM | #7 |
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Re: Heat/ Exhaust Rise Intake
Not the same as blocking the block . Your creating the hi heat in the manifold gasket area . if you want positive outcome from your fix , I would seriously consider using the penny in the block . This will stop the heat before the intake , gasket surface . You stand a risk of burning the gasket .
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10-06-2023, 05:52 PM | #8 | |
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Re: Heat/ Exhaust Rise Intake
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10-06-2023, 09:51 PM | #9 |
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Re: Heat/ Exhaust Rise Intake
I don't think BobR35 was asking for advice,
I believe he intended to show everyone his solution for his cracked intake manifold. Bruce
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10-08-2023, 08:25 AM | #10 |
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Re: Heat/ Exhaust Rise Intake
WHY? The heat will evaporate the fuel better and increase performance on the street with the original carburetor.
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10-08-2023, 09:36 AM | #11 |
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Re: Heat/ Exhaust Rise Intake
hey Terry, I'm told that you loose horse power with intake temperature. The need for heat rise here in FL isn't necessary (80*-100*), and any increase in power on this old girl is needed. I drove her about 100 miles yesterday, mostly on the highway at 50 mph and she ran great. The intake plugged didn't make any noticeable difference but I'm happy with the change. The running temp especially in town in traffic did drop a bit.
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10-08-2023, 04:27 PM | #12 |
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Re: Heat/ Exhaust Rise Intake
Hi Bob- I'm curious--how did the oil pressure behave on the hundred miles yesterday?
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10-08-2023, 05:18 PM | #13 |
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Re: Heat/ Exhaust Rise Intake
All said and done the oil pressure was 5lbs above what it was before at idle and at speed. It was a lot higher cold but as it got warmer it declined but still was better. I guessed at the amount of shim to put into the oil pressure relief spring and didn't want to overdo it so I leaned on the conservative side. I'm good with the results knowing it's not a new engine. I don't think that blocking the heat rise has any affect on the oil pressure.
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10-08-2023, 08:17 PM | #14 |
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Re: Heat/ Exhaust Rise Intake
I agree-the heat passage isn't going to raise oil pressure so your increased spring pressure must have caused that relief valve to seal a bit better. That's great!
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"It don't take but country smarts to solve the problem" (Smokey Yunick) '41 Merc Town Sedan / 260" 8CM engine '66 Fairlane four door / "warmed up" 302 |
10-09-2023, 11:53 AM | #15 |
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Re: Heat/ Exhaust Rise Intake
Just what do you expect to gain from this? More horsepower? better fuel economy? We id this back in the 50's because it sounded better. I think??
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10-09-2023, 04:45 PM | #16 |
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Re: Heat/ Exhaust Rise Intake
We did it because it popped when you let off the throttle.
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10-09-2023, 05:52 PM | #17 |
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Re: Heat/ Exhaust Rise Intake
Well Ron, I'm just trying to do every little thing and anything in order for this old girl to run a little longer. I drive her more than most do and with the lower compression and the hot weather here, if it isn't perfect, there's gonna be some issues. I'd love to rebuild the engine but I'm not quite ready for that yet. Besides, I'm not sure I can physically do it and I am not one to farm things out. It's a love affair making things happen!
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10-09-2023, 06:02 PM | #18 |
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Re: Heat/ Exhaust Rise Intake
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