the old penny trick

[cuzncletus]

I guess the practice of blocking off the water to the intake manifold with a penny in the passage goes back to the dawn of the flathead. Is there any practical value to it?

[richard crow]

the holes are exhaust pasages not water. they were intened to heat the manfold. with todays fuel your better off blocking them. back in the day we blocked them to make the duel exhaust sound better.

[JWL]

If the subject is confined to a car which is regularly street driven, and where efficiency is regarded as important, it is a bad idea to block the manifold heat chamber passages.

[Walt Dupont--Me.]

JWL is right. Poor gas mileage and run ruff in cold climat. I just block them in stock cars and drag cars. Walt

[51 MERC-CT]

Originally Posted by JWL

If the subject is confined to a car which is regularly street driven, and where efficiency is regarded as important, it is a bad idea to block the manifold heat chamber passages.

Originally Posted by Walt Dupont--Me.

JWL is right. Poor gas mileage and run ruff in cold climat. I just block them in stock cars and drag cars. Walt

Find it interesting that many if not all aftermarket multi carb. manifolds do not make use of this feature.

[scooder]

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I found the majority of the available aftermarket manifolds for the flatheads do have the heat chamber open.
Martin.

[Charlie ny]

7 out of 10 in Speedways catalog have heat, at least in the Flathead section.
Charlie ny

[jack orchard]

Edelbrock 1109 3X2 for 8BA manifold has open passages.,...jack

[JM 35 Sedan]

I've seen situations where those "pennies" (speaking U.S. size pennies from mid 1800's to modern day ) have sometimes wound up lodged/stuck/jammed in other areas of the engine causing undesirable results. This would be even more likely to happen if modern U.S. pennies from mid 1982 to present were used, because they are nothing more than Zinc, with a very thin covering of copper, and they often wind up looking like a corroded gray slug after a short time in circulation.

Several of the stock intakes on my '35 Fords had that exhaust flow area so full of carbon crud that there was no warming exhaust circulation happening there anyway.

If you feel you must do this block off trick, use a thin piece of shim stock, larger than the hole diameter, between the block intake surface and intake gasket.

☆Also, to MERC-CT's point, many aftermarket intakes, and I believe many stock FoMoCo intakes for Flathead's after some point in time, did not have those holes for exhaust warming.☆

☆ Edit to my above statement....after checking my collection of stock early Ford V-8 intake manifolds used on the little 60hp engines, and on the '33 to '53 larger V-8 engines, both aluminum and cast iron, I found that all of these Ford intakes have the holes that bring exhaust heat up into the manifold. I believe what I was thinking about was the hole on the carburator mounting area was eliminated on some of the aluminum intake manifolds in the '35 to '39 years of manufacture. Also, two of the aftermarket intakes that I own (Thickstun PM7 2x2 high rise & Eddie Meyers 2x2 high rise, both have the holes for exhaust heating at the base of the intake, but not on the carburator mounting deck.

[51 MERC-CT]

My bad, perhaps should have been more specific when referring to 'feature'.
What I was referring to was the heat to the carb. base coming from the heat chamber on a Merc. manifold.

[Admiral]

I've heard this from multiple sources before, but how does blocking off the heat risers improve the exhaust sound in a flathead? I'd think it would make such a minor difference that it'd be unnoticeable. Is it just the placebo effect?

[Bruce Lancaster]

On a car with dual exhausts the crossover connects the two sides, presumably allowing evening up of pressures. The fewer the cylinders feeding a pipe the more staccato the sound because of separate unopposed spikes of noise...I have heard of Chevy 6 people splitting the exhausts unevenly, like 4 and 2 or even 5 and one, to get a genuinely annoying exhaust.

[Merc Cruzer]

Originally Posted by cuzncletus

I guess the practice of blocking off the water to the intake manifold with a penny in the passage goes back to the dawn of the flathead. Is there any practical value to it?

You might want to review the posting in this chain:

https://www.fordbarn.com/forum/showth...riser+blocking

I recommend the tabs since they are easy to install and easy to remove no need to take the intake off, just loosen the bolts and slide the tabs in or out) in the event you don't like the outcome. I can confirm if the temp is below 60 the car takes awhile to warm up and smooth out but when the temp is above 80 I have less issues with vapor lock.

[Cool Kat with Hot Car]

Genuine Ford penny found in old 40 Merc. hot rod engine. Car was parked in 1953 when taken apart to make it go faster.

[jack orchard]

Once the motor is warmed to operating temperature, how much does blocking the passages affect fuel mileage?,..jack

[Merc Cruzer]

Originally Posted by jack orchard

Once the motor is warmed to operating temperature, how much does blocking the passages affect fuel mileage?,..jack

It has not been noticeable at all for me. But then every time I go Denver (5280 ft) for a cruse or show I have to climb back up to 8300 ft to go home. I mainly did the modification to reduce the "vaporlock" issue. It did change the sound of the exhaust for the better in my situation.

[Mike51Merc]

Offenhauser dual manifold has the passages. They're designed to warm the plenum to keep vaporized fuel from condensing on the cold metal. Condensation = puddles= flooding and rough running.

[richard crow]

i still say with todays fuel you don,t heat the carb. why do you think the carb insulators are so popular. because they work.

[Mike51Merc]

Originally Posted by richard crow

i still say with todays fuel you don,t heat the carb. why do you think the carb insulators are so popular. because they work.

It's not about the carburetor, it's about the manifold. You want a cool carb and a hot manifold, which is another reason why insulators are so popular.

[JSeery]

Originally Posted by Mike51Merc

It's not about the carburetor, it's about the manifold. You want a cool carb and a hot manifold, which is another reason why insulators are so popular.

Yep, cool carb to reduce the chance of vapor lock and hot manifold to insure the fuel/air mixture does not condense in the manifold. For high performance you are interested in keeping the mixture as dense as possible to increase cylinder load which leads to the desire for a cool intake.