VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 math problem

"If you double the size of a pipe you increase the volume four times"

I've got (2) 3/8"od tubing going to the heat stove. The engine runs like it's a little cold, even after warm up.I wonder if going to 1/2"od tubing would make a difference. The tubing is red hot. I drove about 20 miles and it still acted a little cold at mid range.

OR

Maybe I need to adjust the carb now that I've changed to twice as much exhaust flow with the split exhaust manifold.

I've got a vacuum gauge that I used to set the max. vacuum but it was before changing the intake breather and exhaust manifold. Is it time to set it again?

Bet ya didn't see that coming...lol

The balance tube between headers is fine...What you've done with the increased flow is that your engine can now accept more fuel...Were you still thinking of adding a different intake with dual carbs...? You can certainly make adjustments with the carb you've got...Done with the metering rod or even a larger reverse flow jet...In fact I'd recommend it, to get the most out of the work you've already put in to it...

So nothing can be done by tinkering with the carb adjustment screws?

You'd be tinkering with the idle...

I guess I'll just live with it until I change out the intake someday. It's not that bad, I'm just picky. Thanks

Your car is green...How picky can you be...?

Sorry, I had to get that one in there...

Steve...You may want to think about the obvious...copper conducts heat better than steel...Sooo maybe the copper tubing is sucking up all the heat, and dispersing it before it can get to the "heat stove" Just a though >>ED

By design your engine is going to be a bit cold blooded with the Fenton's. The original manifold had the heat riser with the thermostatic spring that would control the flap. Now you are heating the carb all the time. It is much less heat when cold using the small diameter tubing vs. the flap being closed. I'd keep an eye on the copper tubing. I'm not sure how long it will last getting red hot before it blows a hole in it. You maybe can tweek the carburetor some with the exhaust flowing more than with the single exhaust, its up to you how much you want to do. Maybe change the main jet a size or two.

Don's correct...Fenton's are notorious for running cool...This is what happens when you mess with Chevrolet's long-lasting smooth running stovebolt design...( Insert open palm slap to the forehead here )

I think steel lines probably would have been a better idea, mostly due to eventual heat oxidation problems...

The other option could have been run a line from the radiator and let it do the job instead of the exhaust. (like the heater inside the car). I saw instructions about that on the heat riser kit. I think I'll just live with it until I change to a Tattersfield dual intake someday.Thanks for the replies.

BTW..My forehead still hurts...

Like this

The heat riser kit came with the tubing and fittings and they were copper and brass. I didn't like the route they chose so I ran it my way, but it is still copper. This will be okay for now. The only difference I can tell in the way it runs is now it will idle really low and it seems a tiny bit better in the wide open postion (maybe). Other than that,it's just a waste of time and money. Not having the intake sleeve/rings was the problem with it not idling correctly. I did fix that.

Fenton made the same exhaust manifold that I have but it has the stove/heat box made into it. They are rare. $1000 manifold. It will bolt up to the orginal intake or a fenton intake made to accept that design. A little rich for my blood.

http://www.restorodstogo.com/2011/01/235-261-chevrolet-split-dual-exhaust.html

It looks like this manifold but made by Fenton.

Just for an experiment, Could you wrap the copper lines in heat wrap to see if it makes a difference? Might not work but who knows?

That's a thought.
The problem with the GM design manifold is that it serves the purpose UNTIL it locks up and the heat flapper won't move. There is no way to lube the flapper. The only way to make sure the spring is working the flapper is to move it by hand every once in a while to check if it has stop moving. I bet 90% of the old chevys are locked up. Mine was until I researched everything about how it works. I soaked it in Marvel Mystrey oil and finally got it to brake free.

The heat flappers on my 37 and 52 never lock up or ever did. Most of these old cars and motors set outside or in a junk pile for years. Thats how they rust up. If a car is driven or stored in a dry place, no lube is needed.

Steve,

I agree with Kevin47. Once you start improving on a basic design, especially when done one part at a time, you still have to make adjustments to the original parts that are left.

The "cold running" could be a lean condition brought on by a free flowing exhaust. Be careful at highway speeds, and watch for engine temp increases.

I agree....When as a Young guy ( Early 1950's) I worked in a very busy garage...We did Nothing but repair..No grease jobs or gas sold there.....I will venture to say that 90% of the Chevy's we worked on had the heat riser valve stuck. It was a standing joke and we all wondered why GM would make something like that. Why would they install something that would be such a problem???....The only conclusion we could come too was...TO MAKE MONEY & keep them coming back>>>>>>ED

When I put the Fentons on my 37 I had to increase the jet size to get it to run better,I had no heat kit until last year and the heat kit helped but it does not run the best until it gets completely to operating temp. I am going to keep watch for a 53/54 corvette exhaust manifold since it has the heat riser like the original manifold,those manifolds get expensive and will have to save up for awhile.

You could always get a 53 - 54 Corvette exhaust manifold. Free flowing split exhaust and a heat riser so your carb warms up.
You could really go for the bling and put the Corvette 3 side draft set up on. Might be a tight fit by the firewall.

This is what one of the previous owners did to mine...Chopped up another exhaust manifold to make it a dually...Along with real cherry bombs folks say it sounds cool...To rod-ish for me...

I wish some one would have made a 2 bbl intake for the 235,the dual single bbl intakes are nice but I like the simplicity of a single 2 bbl. A single 2 bbl carb would help with tuning when dual exhaust is installed on these motors and look period correct.

The closest thing to that I can think of is a 6=8 Clifford Research 4-Barrel w/2-Barrel adapter plate...

Steve, In your manifold picture, I see 2 copper lines reduced to only one line going into the stove. That way the hot air can go from one exhaust manifold straight across into the other manifold and back & forth. Might be better with 2 lines into the stove.

Like in this 1954 ad:

This is true...Really no way for heat to flow in to the "stove", just passes between the headers.