TheSamba.com :: View topic

Wed Feb 08, 2023 5:51 pm

I just bought a vw open frame project powered by vw 1600 dual port. IT has some oddities that I don't quite understand. 1st, 4 into 1 exhaust? It has no heat risers going to the intake. Are the heat risers necessary? Thirdly, it has a weird external oil cooler mounted to the back of the fan schroud. This looks like a small radiator, but twice as big as my other oiler cooler. This cooler has supply and return line plumbed into block. Any thoughts on any of this stuff?

Wed Feb 08, 2023 7:03 pm

Open frame? Like a sand rail type of car?

4 into 1 headers typically don't have the heat riser flanges near the heads on 2 & 4 exhaust ports.
I have ridden in many ACVW powered rail framed car that didn't have heat risers from the exhaust. It might run a little funky when cold, and sometimes hot too.

The oil cooler is an old school type available from yester year. They're still offered today. :shock:
The cooler worked pretty well, especially on an open frame car.
Cusser will post a pic of his. If he hasn't already, while a one finger type this response. :D

Wed Feb 08, 2023 9:15 pm

rcproductions wrote: Thirdly, it has a weird external oil cooler mounted to the back of the fan schroud. This looks like a small radiator, but twice as big as my other oiler cooler. This cooler has supply and return line plumbed into block. Any thoughts on any of this stuff?

Some people would mount a remote oil cooler over the intake hole on the back of the fan shroud to get air flowing over it. That is a collosal mistake as it sucks hot air into the cooling system for the engine. A remote oil cooler is fine, just so long as its not mounted over the intake hole, making it an engine cooker.

Pictures help this kind of opinion gathering. If you post pictures, they will come, and they will have opinions.

Thu Feb 09, 2023 1:41 am

The Volkswagen engineers designed & incorporated the heat risers to help keep the fuel/air mix in an atomized state during its travel from the carburetor thru the runners into the intake manifolds & ultimately the combustion chamber. They serve a purpose & were there for a reason.
Will the engine run without them - yes - but not optimally. "Carb icing" may result.

Have fun with your purchase.

Stay safe ... jinx

Thu Feb 09, 2023 7:25 am

The carburetor causes a pressure drop past the throttle plate, this causes air to cool. Add fuel to that, and the manifold gets even colder as the fuel coating the inside of the manifold evaporates, this causes icing. If you are in a hot/dry environment, this isn’t a big issue…. If you are in a warm/humid environment, you will have problems.

Thu Feb 09, 2023 7:37 am

Buggeee wrote: rcproductions wrote: Thirdly, it has a weird external oil cooler mounted to the back of the fan shroud. This looks like a small radiator, but twice as big as my other oiler cooler. This cooler has supply and return line plumbed into block. Any thoughts on any of this stuff?

Some people would mount a remote oil cooler over the intake hole on the back of the fan shroud to get air flowing over it. That is a collosal mistake as it sucks hot air into the cooling system for the engine.

On the other hand - I've been running such shroud-mounted oil cooler on my 1835cc dual port engine since back in 1976, in the Arizona desert, and haven't had any issues. I did this in 1976 because back then doghouse shrouds/coolers were dealer-only and I started with a 1600cc single port engine that was non-doghouse. It's like that to this day.

I don't know if Buggeee has any first-person/hands-on knowledge/experience with this, but remember folks don't like thin-wall 92mm cylinders either, but that's all that was available back then. My own 1835cc engine hasn't been apart since 1986, but I did renew the oil hoses after they started seeping a few drops of oil after 31 years (I recommend changing those hoses every 25-30 years).

This engine does not have heat risers at all, as the manifold for my single Weber 40DCNF did not have them when I bought that set-up in 1976 (the carburetor has NEVER been off its manifold). Yes, the tins will get painted black next time the engine needs to come out (below).

Now, when I resurrected my 1970 sedan in 2016-2017 using my stock 1971 engine, I did drill and clean out its factory heat risers, and connected those.

Thu Feb 09, 2023 8:16 am

Cusser wrote:
A true unicorn.

Thu Feb 09, 2023 8:22 am

Glenn wrote: Cusser wrote:
A true unicorn.

And I ran the dealer-installed DPD AC system on that 1835cc engine from 1976-1993, my daily driver, was in my 1970 sedan then.

Thu Feb 09, 2023 9:05 am

I guess anything is possible up on Big Rock Candy Mountain 😀
https://www.youtube.com/watch?v=E6F0IhdaaWI

Just kidding around

Thu Feb 09, 2023 9:10 am

No heat risers are needed if you have dual carbs as the intake manifolds ate short and the head heats them quickly a center mounted carb will have the problems outlined above without a heat riser in working condition.

Thu Feb 09, 2023 9:24 am

I figure mounting the oil cooler at the shroud intake basically transfers heat from the oil (bearings) to the heads, once it warms up and reaches stasis.

Depending on your engine setup and condition, this may be a good or a bad thing. Clearly it works for some!

Thu Feb 09, 2023 9:35 am

I will report on what I observed on the stock 1600cc single port engine with stock non-doghouse fan shroud v. the shroud-mounted oil cooler (which I ran 1974-1976 if I remember correctly, before going to the 1835cc engine).

With the stock set-up, the rubber spark plug seals on #3 and #4 got hard and brittle within a few months with the stock inside-shroud non-doghouse oil cooler, huge difference from #1 and #2. After the shroud-mounted oil cooler install, the #3 and #4 rubber spark plug seals no longer became brittle.

Thu Feb 09, 2023 9:45 am

You cannot argue with success, well you can but it won’t really do any good. It’s like trying to piss up a rope. So roll with it.

Thu Feb 09, 2023 10:35 am

Heat risers keep your carburetor from icing up.