Exhaust Manifold Conclusions

[pflaming]

The heat riser thread became a manifold thread which was not a pure hi-jack. From that thread for my needs I concluded the following:

1. How the exhaust gases are routed out and away from the engine aids the engine. Whether by single, dual, or tuned exhausts is secondary and in some cases cosmetic, which is ok.

2. A single port on the manifold means cylinder #6 gases get preference thus cylinder #1 must then run under more exhaust pressure then #6. A split manifold into a 3" exhaust pipe and a freer flowing muffler wouild be a reasonable, less expensive, and system for most. (my choice for my 53 convertible).

3. The heat riser is a cold whether assist. If one lets the engine warm up then the riser is not needed, possibly should block off the eddy under the carb by welding in a plate or , as Plymouthy informed me, by putting in a plate between the carb and the manifold.

4. The length(s) of dual exhaust pipes should be the same, and it goes withought saying, the mufflers should as well.

5. Smoothing out the interior of the exhaust manifold by the use of a dremmel or something similiar, also aids the escape of the gases.

6. The same holds true for the intake manifoldl, smooth it out and the air can draw into the combustion cylinders faster. (one reason for more carbs)j.

7. Carburators are part of the manifold system. Most of what applies to the exhaust system applies to the intake. Multiple Carbs distribute air and fuel faster and more efficiently but may double or quadruple the maintance. For my use a good single carb with a good air filter will do.

8. So I conclude that for me dual carbs and exhaust PIPES are bing and money. I prefer the simplicity of the single systems for my use but truly enjoy the beauty of the mulltiple carbs and imagintive headers.

So once again, thanks to all who have contributed and are contributing to my growing knowledge.

[aside] The New England geography is beautiful. I'm now in Maine, looking out the window at the Eastern River which is my son's back yard and is a half a mile wide at this point. It's great to watch the eagles fly by.

[Plymouthy Adams]

I still suggest that if you entertain adding another dump for the forward three cylinder and still maintain the single log look that it be blocked on the inside giving you a true split exhaust...and with the less heat and no riser..the less chance of percolation in the summer time..the suggested plate was a band aid for the removed heat riser in your truck

 

contact Olddaddy I believe he is still doing this work for folks...some of the manifolds that are offered are  bit pricey..but you still have to pay to play unless you got the skill to do this yourself.  With the flattie, the induction/exhaust if a good place to dress up, add a tad of performance and enhance the tone of the exhaust. 

[Don Coatney]

In case you have not had a look at the inside of the manifolds here is what you are dealing with. In these pictures you should note that the heat riser flapper plate in my manifold has been welded to block off the front 3 exhaust ports and give a true seporation from the back 3 exhaust ports. There are two exhaust manifold dumps one for the front 3 and one for the rear 3. You will also note that there is now access for the rear three cylinders to pass gas into the area where the carbuerator used to be. But on my engine there is no longer a carburetor there so added heat in that area has no effect on my intake manifold.

 

 

 

 

[greg g]

I welded my plate in the opposite position from Don's.  Don's is that way because it blocks the mix of exhaust for his dual out let system.  I chose to stay with single outlet, and welded mine in the horizontal position to insure direct flow out of the rear of the manifold.  I did change all my exit plumbing to 2 in ID tubing with a low restriction turbo style muffler.  I am happy with my choice of dual carbs, single exhaust and increased compression through decking the block and milling the head.  I have driven my car in several instances of below freezing temperatures with no noticeable drive-ability problems.  I do have my return heater hose attached to the side of the intake manifold.  Whether it contributes anything to cold weather driving is up for debate.

 

Lots of choices.  Like my dad said, make a plan and carry it through. If it doesn't work like you hoped, make the best use of the lesson and move on.

[cheap chad]

A friend of mine has a 52' coupe with a 230 and overdrive unit, he spent the better part of a year chasing the "percolation" thing nothing seemed to work, (this guy is no dummy ether) ended up separating the manifolds by removing as much material as possible were they bolt together and making block off plates to "cap" them and put some insulating material in between the two caps,I would not have noticed the mod except for the insulation, worked out just fine. He's been driving the coupe for about 30 years did the mod 20 years ago. That's some nice work Don!!!       

[Plymouthy Adams]

an assuming that the chap was running a single carb center mounted on the log?  percolation is an easily overlooked cause of fuel problems especially in summer time conditions

[Young Ed]

an assuming that the chap was running a single carb center mounted on the log?  percolation is an easily overlooked cause of fuel problems especially in summer time conditions

 

I noticed it many times during back to the 50s when restarting after a short period. You could tell there was a flooded condition for the first 10-20 seconds after the restart. I have found running the no ethanol gas helps with this but I didn't have it in the car for this w/e.

[greg g]

Lower your float level a couple 32nd's.   Today's fuel cocktail expands more, and more quickly than the gas of the 50's, causing percolation at lower temps.  Although percolation may not be the correct term, as it refers for a liquid's flow downward through a material, like a ground layer or filter.  Thermal expansion is probably a better term.

[Plymouthy Adams]

dual meaning word....in the "perc " test they do measure absorption but in the case of fuel percolation the term is correct as it imitates the action of the old time coffee pots...heat related expansion and displacement.....as the car is running this is often not apparent but when the car is hot and turned off..the block becomes further saturated with the heat that is no longer being carried off by the coolant..this is a quick heat up also...most folks see this at the gas pump...top fuel up temp mornal..as they sit for the few minutes of the fueling process the block temperatures continues to rise..

Edited June 25, 2013 by Plymouthy Adams