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Wed May 21, 2025 8:15 pm

I searched wrapping the heat risers and didn't find anything about it. If your engine is running hot would it help to wrap the heat risers with a fiberglass header tape to keep the heat inside them and not heat the engine compartment air? Would this cool the air blowing onto the heads? This might help heat the intake in the winter also. Thoughts?

Thu May 22, 2025 5:41 am

IMO, wrapping the heat riser pipes would be of negligible help w/ overheating issues — they’re pretty small, and don’t add all that much extra heat to the engine compartment. Recommend looking elsewhere for potential causes and solutions, if you’re having overheating problems.

Thu May 22, 2025 6:30 am

Are all of your engine tins in place, including the rubber engine to body seals?

Thu May 22, 2025 7:02 am

Well one issue I have is I've got a 1970 with two slots in the deck lid and a 1973 1600 with the doghouse fan shroud. So I might not be getting enough air flow. All my tins are in place and seals but I do have an issue with the engine seal having a gap. I think the prior owner did not put the pans in correctly or did not put the body on correctly. My timing should be on. Set at 28. I'm going to pull a plug and see how the air fuel mixture looks. I have a 127.5 as a main and 55 idle jet.
At 65 mph for about about 30 minutes on a 90° day The oil temperature through the dipstick tube read 226F when I parked it.

Thu May 22, 2025 7:20 am

1600man wrote: At 65 mph for about about 30 minutes on a 90° day The oil temperature through the dipstick tube read 226F when I parked it.
You know, an engine oil temp of around 225° F on warm days after highway driving doesn't seem all that bad to me. On my car I've got one of those "save my bug" dipstick temp sensors, and on hot day freeway trips, I'll usually see the sensor's little arm sitting maybe halfway between the "boiling water test" position (approx. 210° F), and the grounding screw (which I measured at about 235° - 240° F) -- so somewhere in the 220° F to 230° F range, I figure (?). Anyway, has never seemed to be an issue for me so far.

For a quick check on if you're getting enough cooling air into the engine compartment, you can always prop the lid open with a tennis ball or similar, to see if that makes a significant difference or not.

Thu May 22, 2025 9:12 am

I will try the tennis ball trick.

Thu May 22, 2025 9:33 am

220F is not a high temp at all. Its the ideal temp for boiling out condensation in the case. That snotty white stuff that clogs up breather tubes is eliminated when oil reaches 210F.

There should be a foam strip between the dog house shroud and cooler. Is that missing?

Thu May 22, 2025 10:27 am

unless you have a stock muffler, chances are the heat risers aren't working as intended anyway.

Thu May 22, 2025 10:45 am

The foam is there for the oil cooler. It's sealed pretty good.

I have the GT exhaust I think. With a glass pack. It's loud and larger sized chrome pipes than stock.
https://www.jbugs.com/product/3418.html

Thu May 22, 2025 1:25 pm

runamoc wrote: unless you have a stock muffler, chances are the heat risers aren't working as intended anyway.

Agreed. I had to drill out the ports on my Tri-mil pipes. The riser ports were there but not drilled out.

Thu May 22, 2025 1:57 pm

Schepp wrote: runamoc wrote: unless you have a stock muffler, chances are the heat risers aren't working as intended anyway.

Agreed. I had to drill out the ports on my Tri-mil pipes. The riser ports were there but not drilled out.

On a stock muffler, one of the heat riser connections is a pipe that goes into the front of the muffler then out one of the exhaust ports where the pea shooters go. This creates a pressure differential and causing a flow thru the heat riser. Those two heat riser gaskets have different size 'holes' to regulate the flow.

Fri May 23, 2025 5:04 am

runamoc wrote: Those two heat riser gaskets have different size 'holes' to regulate the flow.
Note that the heat riser gaskets w/ different-sized holes only seem to apply to earlier engines, the 1200’s and maybe 1300’s (I think - ?).

As far as I can tell (from old VW parts catalogs, etc), all 1500 and 1600 engines use the gasket w/ the larger hole at both the left and right sides of the heat riser connections — probably for increased exhaust flow and heat transfer, to support the larger carbs and fuel-air charge for those increased displacement engines.

Fri May 23, 2025 6:51 am

runamoc wrote: Schepp wrote: runamoc wrote: unless you have a stock muffler, chances are the heat risers aren't working as intended anyway.

Agreed. I had to drill out the ports on my Tri-mil pipes. The riser ports were there but not drilled out.

On a stock muffler, one of the heat riser connections is a pipe that goes into the front of the muffler then out one of the exhaust ports where the pea shooters go. This creates a pressure differential and causing a flow thru the heat riser. Those two heat riser gaskets have different size 'holes' to regulate the flow.

On my tri-mil's I did this modification. The exit hole is angled at 45* slightly more downstream. Made a huge difference hot air flow through the intake. My intake temps went from around 80-90*F to 140ish.

Not enough attention is put into the preheat system when performance exhausts are installed. I bet most people bolt up the preheat tubes and never drill out the holes to make the system functional again.

Fri May 23, 2025 8:31 am

Wrapping headers, exhaust, & or heater pipes will have one big result ...
RUST.
The wrap holds moisture and MANY people have bad experience with it. Similar to frunk bras - they look cool & start conversations but reality is not pleasant.

Wrong timing & wrong carburetor tuning contribute to overheating.
Put a light under your sump pump at night. Open decklid.
ANY light you see from above NEEDS to be addressed, even the area between the fresh air tubes & the breastplate tin.

My '71 came with a non-vented decklid. My timing & carburetor settings have always been spot on. After a commute it would crackle, pop, & complain as I walked away. My oil temps were hot but not danger hot. I drive my car in a spirited manner thus having to replace those tennis balls. (I'll show that Camry who's boss. Lol). The tennis ball trick truly worked but this last early spring I FINALLY put a slotted decklid on. Mentally it's like a new to me car as I had gotten used to the look of it with the smooth lid.

Don't try to reinvent the wheel, just make sure yours is as round as it can be.

Good luck ... stay safe

jinx

Sat May 24, 2025 8:11 am

I've heard that wrap causes rust but Ive had my headers wrapped on my big block Oldsmobile for 15 years and my daughter's small block Oldsmobile for 10. We've never had rust issues. Wouldn't the heat from the header evaporate any moisture?