Vapor lock VS Cool Carb

[jibbers66]

Hey Guys.

72 Cuda 440/727. Vapor
Lock stumble if stuck in traffic. I Live in LA, so it’s unavoidable.

Running a brand new Holley with vapor separator. My plan was to add the cool carb shield under it. Dude from
The company said I must block the Heat exchanger so it won’t melt the plate.

Question I have will this be a Non issue if I install the valley pan with blocks
For exchanger? So cal weather is early below 60 degrees.

Any one else close up the exchanger to help deal with Vaporlock..?
Who likes this approach..


Thanks in advance..
Jib

 

[pschlosser]

Yes, if you can find a valley pan (intake manifold) gasket without the heat-riser cutouts, this will effectively block exhaust from entering the heat riser.

Are you sure the issue is vapor lock? I don't experience this in Orange County with my 1970 440 HP. I removed the vapor separator some years back. Warming up the engine will be less fun without the heat riser, especially with a long-duration camshaft.

In my car, the factory radiator, fan shroud and clutch fan, keep it cool even in the hottest 100F weather in stop-n-go traffic, which is pretty much how the 405 moves most days.

 

[Chryco Psycho]

Blocking the heat crossover is basically a must anyway , you need to be near or below freezing , otherwise it just overheats the intake
Fel Pro 1215 is the part # for the intake gasket

 

[DetMatt1]

Blocking the heat crossover is basically a must anyway , you need to be near or below freezing , otherwise it just overheats the intake
Fel Pro 1215 is the part # for the intake gasket

Agreed. I’m in Michigan and in the beginning and the end of the season it is not uncommon to be running in upper 30 degree temps. Never once have I wished I hadn’t covered the crossover, it’s a must.

 

[540HemiCuda]

Been blocking the cross-over since these cars were almost new. And today's fuel is even more volatile than the fuel was when these cars were designed and built. The best carb insulators are made of wood, believe it or not. That is what I have always used but some of the other materials are more readily available. A blocked cross-over and a good carb insulator are absolute musts for our big blocks.

I would look up some reviews of the product you are considering. The vendor has already warned you about it's limitations. Here is just one thread on it: Anyone Using COOL CARB plates?? - CorvetteForum - Chevrolet Corvette Forum Discussion

.

 

[Xcudame]

OK, I have to put in my plug for my favorite Mopar carburator, buy a good used Thermoquad, rebuild it if necessary and run it!! They don't vapor lock!

Seriously, after 50 years and no one has cleaned them, the heat passages in the cylinder heads are usually block off with carbon and don't allow heat to the intake. That's one area I don't typically clean. Poor man's heat block off!

 

[Cratos]

switched to Aeromotive return fuel setup here in FL, vaper lock sucks ! and non-ethanol fuel!! my sixpack is much happier now!

 

[540HemiCuda]

Thermoquads weren't bad carbs, but had their problems. The gasket UNDER the fuel being at the top of the list. Warped centers also comes to mind. For most guys today who aren't fluent in carbs, the half century old Thermoquads are not the best choice. What if the one they get has the throttle shaft bushings worn, which is quite probable? Just to use one example.

If a thermoquad style carb is desired, the new Street Demons are a good choice. I have used several. They were originally designed by a Carter engineer and work well. And they are available with a polymer center like the old Thermoquads, but there is no gasket under the fuel.

These are the best bolt on carb for stock or near stock engines I know of today.

 

[Xcudame]

@540HemiCuda, true, I was fortunately lucky enough to learn about Thermoquads from the Chrysler Mechanic who tuned the CHP cars in the 70s and 80s. Plus I have a stash of dozens of Thermoquads. Interestingly I've only come across one warped center section, and two needing throttle shaft bushings. Unfortunately, like you said, carburator tuning is becoming a lost art. Hence to switch to throttle body EFI.

And I do like the new Holley Street Demon with the plastic center. I own one.

IMO, money no object, MPI is the way to go. Easy for small blocks and RB (413, 426, 440), but not so easy for low deck Big Blocks (361, 383, 400) due to the lack of intake manifold with injector bungs.

 

[540HemiCuda]

You touch on the FACT that carb tuning is becoming a lost art, then jump to tuning MPI. There are probably even fewer regular car guys that can properly install and tune multi port injection than can tune a carb. They just don't have the equipment let alone the knowledge. Just look at the enormous amount of failures with the current crop of the much simpler "self tuning" retrofit throttle body EFI. Marketplace is full of them for sale.............cheap.

I am not arguing that either the old Thermoquads or MPI are bad. It's just that for guys like the OP, there are simply better, more practical choices.

 

[Xcudame]

Common sense isn't so common anymore, unfortunately. I've worked on everything from Briggs&Stratton lawn mowers to ICBMs so I'm probably uncommon.

 

[540HemiCuda]

May I suggest keeping in mind the OP's level of experience AND abilities in your responses? Offering otherwise excellent advice to someone before you know whether or not they can actually take advantage of it does not necessarily help. And may actually confuse the situation for them. In other words; THEIR abilities (or lack thereof) may be at least as important to solving the problem as yours.

KISS; Keep It Simple.....................Sir.

.

 

[jibbers66]

Yes, if you can find a valley pan (intake manifold) gasket without the heat-riser cutouts, this will effectively block exhaust from entering the heat riser.

Are you sure the issue is vapor lock? I don't experience this in Orange County with my 1970 440 HP. I removed the vapor separator some years back. Warming up the engine will be less fun without the heat riser, especially with a long-duration camshaft.

In my car, the factory radiator, fan shroud and clutch fan, keep it cool even in the hottest 100F weather in stop-n-go traffic, which is pretty much how the 405 moves most days.

Helpful thank you…

Yes, if you can find a valley pan (intake manifold) gasket without the heat-riser cutouts, this will effectively block exhaust from entering the heat riser.

Are you sure the issue is vapor lock? I don't experience this in Orange County with my 1970 440 HP. I removed the vapor separator some years back. Warming up the engine will be less fun without the heat riser, especially with a long-duration camshaft.

In my car, the factory radiator, fan shroud and clutch fan, keep it cool even in the hottest 100F weather in stop-n-go traffic, which is pretty much how the 405 moves most days.

well not sure what else it could be. Runs great all the time. If I get stuck in traffic and the temp gauge rises a bit it gets sloppy until it cools.

Fan, shroud all in place. New radiator and always runs at the same temp until stops and then raises just a bit..
Perhaps a thermostat swap.?


This was in Huntington Beach on the PCH, during the last surf competition. Traffic got nuts for about 15 minutes.
Once I bailed and got it a little
Cool
It was fine….

Thank you…..
Share a pic….?

 

[jibbers66]

Been blocking the cross-over since these cars were almost new. And today's fuel is even more volatile than the fuel was when these cars were designed and built. The best carb insulators are made of wood, believe it or not. That is what I have always used but some of the other materials are more readily available. A blocked cross-over and a good carb insulator are absolute musts for our big blocks.

I would look up some reviews of the product you are considering. The vendor has already warned you about it's limitations. Here is just one thread on it: Anyone Using COOL CARB plates?? - CorvetteForum - Chevrolet Corvette Forum Discussion

.

Great thank you….