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Manifold Heat?
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Author:  64ragtop [ Sun Oct 21, 2012 7:15 pm ]
Post subject:  Manifold Heat?
Well, it's come up again. As I plan and gather parts for the Accidental Dart improvement project, another contributor mentioned the importance of manifold heat. Over the years it seems that I've seen more mention of finding ways to cool the air-fuel mixture than ways to warm it.

I'm planning on using an Offy 4-barrel manifold and a Weber 32-36 progressive on an adapter. The manifold does have a hot box cast in, as well as three bolt holes to attach it to the stock exhaust manifold. The catch is that plans are for Doc's "Dual Dutra" exhaust. So, there goes the manifold heat that I would keep if I used the back half of the stock manifold like the original Dutra setup. Since I first saw the Dual Duals writeup on this forum some years ago, I've been thinking that was what I wanted on my /6 (if I ever got one).

My thinking has been pretty much that any improvement in exhaust flow (and intake flow as well) would wake the 225 /6 up pretty nicely. And, of course there's the eye candy effect of the parts I intend(ed) to use.

Having said all that, my question is: what effect will free(er) flowing exhaust and lack of manifold heat have on power & economy or should I rely on Chrysler's idea to heat the intake . I'd like to hear upsides, downsides, and personal experiences, please.

For what it's worth, plans are for more compression and head porting with larger valves once my wallet recovers from the manifold project.

ATB

BC
Author:  1974duster kev [ Sun Oct 21, 2012 9:27 pm ]
Post subject: 
Having the head cut for more compression will be the best bang for your buck for sure, as far as the manifold heat I have my heater hoses unhooked from my manifold. I'm not fond of the idea of the 200 degree water running through my intake all the time seems counterproductive to me since my intercooler is supposed to bring the temp down going into my intake. I also live in florida so cold weather isnt much of an issue for me, but who know thats just me i'm sure others have different opinions on heated intakes.

Kev
Author:  SlantSixDan [ Sun Oct 21, 2012 10:26 pm ]
Post subject: 
Intake manifold heat is not a "Gosh, I don't need it 'cuz I live where it's warm and sunny" thing.
Author:  DadTruck [ Mon Oct 22, 2012 5:59 am ]
Post subject: 
these two video's do a nice job of explaining the mixing of air and gas in modern motor car engines and why some heat is a good thing for carbs and on road use.

http://www.youtube.com/watch?v=o6GPi2ELz_M

http://www.youtube.com/watch?v=JZ9BiaU7qkI
Author:  patrickhenryhague [ Mon Oct 22, 2012 9:47 pm ]
Post subject:  Manifold Heat
Yes, by all means use Manifold Heat! Simple explanation: today's gas with the alcohol in it makes engines with carbs do funny things like run stupid when cold and run poorly when hot so heat on the manifold is necessary.
On your engine build the carb. header combination will work well the 32/26 Weber will have to be mounted correctly for it to work properly (primary on the outside towards the fender) and it with the Dutra exhaust should get great mileage. This is really a common sense approach do it!
These engines like lots of exhaust lead so a set of long tube three into one headers with a water heated manifold will work wonders it will also cause, too much noise in the car, under the hood heat, leaky header connections, and messy water plumbing on the intake, in short Iv'e done all this before. Don't do it.
Your idea is a good one a good valve job and 90 thou. off the head and it will run with factory built it. If you change the cam Comp Cams has one 252 duration and .435 lift as the factory 244 duration with .436 lift. These suggestions will work and one can drive it every day kinda like a factory car, every day is important.
Author:  SlantSixDan [ Tue Oct 23, 2012 5:13 am ]
Post subject:  Re: Manifold Heat
Quote:
Yes, by all means use Manifold Heat!
Yeah, what he said.
Quote:
Simple explanation: today's gas with the alcohol in it makes engines with carbs do funny things like run stupid when cold and run poorly when hot so heat on the manifold is necessary.
Manifold heat was just as beneficial with yesterday's gasoline as it is with today's. This 1935 Jam Handy cartoon, "Down the Gasoline Trail", would be a real trip to watch even if it didn't contain a sequence specifically answering this question about the manifold heat (at 5:37).
Quote:
These engines like lots of exhaust lead
What do we mean by "exhaust lead"?
Quote:
so a set of long tube three into one headers with a water heated manifold will work wonders it will also cause, too much noise in the car, under the hood heat, leaky header connections, and messy water plumbing on the intake, in short Iv'e done all this before. Don't do it.
I think whether the water-heated intake creates problems with messy plumbing depends on how it's implemented. It can be done neatly and effectively. But yeah, I am not a fan of headers on a streetmobile. Dutra Duals, on the other hand, are great.
Quote:
If you change the cam Comp Cams has one 252
STRONGLY UNredommend Comp Cams in general and their 252 cam in specific: unreliably poor quality of camshafts in general, lazy use of old Chevrolet lobe profile. Much (much) better than that mediocre mess is one of Doc's RV10-RDP cams, that's grind № 2106R from Oregon Camshaft Grinding.
Author:  patrickhenryhague [ Wed Oct 24, 2012 6:07 am ]
Post subject:  Comp Cam 252
I am surprised to find out that the cam I have been running for the last five years is junk and won't perform or run well I've had good luck with it and it works very well. I was wondering just when you bought and used this cam to find about the poor quality and performance?
Author:  Jeb [ Wed Oct 24, 2012 7:23 am ]
Post subject: 
Comp cams are known to wipe out oil pump gears, that's a proven fact. A lot of them came from the factory with "hobbed" gears that chewed up oil pump drives.
Author:  SlantSixDan [ Wed Oct 24, 2012 9:08 am ]
Post subject: 
I didn't say your car runs poorly. I said someone in the market for a camshaft now, today, can make a much better choice than a Comp in general or a Comp 252 in specific.
Author:  64ragtop [ Wed Oct 24, 2012 3:26 pm ]
Post subject:  Re: Manifold Heat
Quote:
Quote:
Yes, by all means use Manifold Heat!
Yeah, what he said.

Simple explanation: today's gas with the alcohol in it makes engines with carbs do funny things like run stupid when cold and run poorly when hot so heat on the manifold is necessary.

Manifold heat was just as beneficial with yesterday's gasoline as it is with today's. This 1935 Jam Handy cartoon, "Down the Gasoline Trail", would be a real trip to watch even if it didn't contain a sequence specifically answering this question about the manifold heat (at 5:37)..... I am not a fan of headers on a streetmobile. Dutra Duals, on the other hand, are great.
My Dutra "Dual Duals" are ordered and paid for as I write. The 1935 cartoon was indeed a hoot to watch. Kinda reminded me of "Steamboat Willie", which I think was the first incarnation of Mickey Mouse. It really does make the point for manifold heat. My only complaint is all the Chevrolet and GM references. I guess if it works on a shivvy it ought to work on a Mopar! :roll:

Guess I'll have to fab up some kind of heat stove to capture some BTUs and funnel 'rm up to the manifold. Any ideas/examples, anyone?? :? I'm thinking a cardboard mockup and turn it over to a sheet metal worker. 1/8" aluminum stock ought be enough, huh? Last time I did any sheet metal work it took a while for my hands to heal! :cry:
Author:  Aggressive Ted [ Wed Oct 24, 2012 4:21 pm ]
Post subject: 
Yes, the carb heat shield really does help in two ways......keeps the carb and gas cooler and helps keep the intake warmer for better atomization.
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