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12-31-2023, 09:05 AM | #1 |
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Blocking Hear Riser
Engine is a 59A in a 1940 Coupe. 276" with Fenton headers, Harman-Collins Cam and Magneto, Ford of Canada aluminum heads, Offy intake with 2-97's by Uncle Max.
I recently had the intake off and decided to block the two heat risers in the block with some steel 3/4 inch freeze plugs. Everything went well and the plugs tapped in firmly just just below the block surface. The strange thing is that since doing this it seems that the exhaust noise at the tail pipes is much louder than it was before. I wouldn't think that this would be the case but has anyone experienced this before? |
12-31-2023, 10:06 AM | #2 |
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Re: Blocking Hear Riser
Isn't that the reason that is done, to make the exhaust sound different?
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12-31-2023, 11:24 AM | #3 |
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Re: Blocking Hear Riser
You are correct.
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12-31-2023, 12:24 PM | #4 |
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Re: Blocking Hear Riser
Yup, that is one of the effects of blocking the heat risers. I think , tradition has it, you were supposed to use the "year of the car penny" to block them.
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12-31-2023, 01:03 PM | #5 |
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Re: Blocking Hear Riser
If you are familiar with the mechanics of a muffler providing Noise Cancelation, that was what was happening with the heat risers before you blocked them. Now, with no crossover to cancel each other, your exhaust has a crisper sound to it. Let the good times roll!
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12-31-2023, 01:35 PM | #6 |
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Re: Blocking Hear Riser
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12-31-2023, 01:37 PM | #7 |
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Re: Blocking Hear Riser
I did tha when I was younger 60 years ago. but I don't do that anymoew because I can't find the right pennys.
Gramps |
12-31-2023, 02:48 PM | #8 |
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Re: Blocking Hear Riser
Thanks to all for the replies. I knew that blocking the hear risers in the block would allow for a denser charge of the mixture in the intake manifold but did not realize that the exhaust tone would change. Also I did not have any 1940 steel pennies to use.
Last edited by topfuel724; 12-31-2023 at 03:07 PM. |
12-31-2023, 05:08 PM | #9 |
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Re: Blocking Hear Riser
Could be because there were no 40 steel pennies. Use copper.
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12-31-2023, 06:06 PM | #10 |
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Re: Blocking Hear Riser
Only 43. OT My Grandfather said that later on the bars downtown hated the steel pennies and would throw them over the back of the old bars to keep them from coming back. Said they looked like nickels after dark.
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01-01-2024, 12:32 PM | #11 |
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Re: Blocking Hear Riser
I didn’t know either it would change the sound of the exhaust either. Nor the year of the car penny “requirement". Will start looking for 1946 pennies.
-Conrad
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01-02-2024, 11:49 PM | #12 |
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Re: Blocking Hear Riser
brass welch plugs do the job if you dont get snow good idea if you do i wouldnt do it as its use is to heat the inlet manifold [a double edge sword ] helps heaps when baby its cold outside but can cause endless issues when its hot with todays fuels
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01-03-2024, 12:27 AM | #13 |
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Re: Blocking Hear Riser
For this reason, the best compromise is to drill a ⅛" hole through each of the two plugs. Copper pennies of the year of manufacture do the job very well, as the metallurgy is compatible as well as the year.
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01-03-2024, 03:24 AM | #14 |
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Re: Blocking Hear Riser
I can remember about 45yrs back a fellow club member had a Ford Pilot with sixpences in the heat risers and straight pipes with no mufflers. On a winding road coming down from the hills you could hear him coming from miles away. Accelerating on the straights and backing off on the down hill.
No other car in existance could ever have that sound. Geoff Kiwi |
01-03-2024, 05:38 AM | #15 |
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Re: Blocking Hear Riser
During the early to mid 1950's, blocking the hear risers on a flat head Ford was a common event if you wanted two rattle the neighbors windows and have the law after you.
I don't know where the penny thing came from, probably from the same guys that used large washers in lieu of thermostats, or cut every other blade off of the water pump impeller. All of these tricks made the engine run faster due to less drag in the cooling system... Ya sure. In my world we cut a strip of shim stock, .030/040, about 3/4" wide, loosened the intake and slid the shim material between the block and the gasket at the heat riser, tightened the bolts up and let the good times roll. Then when we had all the fun we could and every beat cop in town was looking for us we would stop the car, get out the roll of steel wool, a couple of sixteen penny nails, stuff the pipes with steel wool slid the nail into the pre-drilled hole in the tail pipe and went our merry way to the local stroll or drive-in burger joint. Oh The Good Ole Days, Almost Brings Tears To My Eyes. After we had our fun for the night we would pull the nails out of the pipes and head home, within a few mile the steel wool would burn out. Next morning a few minutes work would have the shims stock out and the manifold snugged down... Everything was quiet on the western front. Time to go to school...
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01-03-2024, 10:05 AM | #16 |
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Re: Blocking Hear Riser
I had to block off the risers in my 46 Cadillac flathead and now I seem to own a hotrod instead of a cruiser. the pipes are a lot cracklier. All the kids want me to rap them off. As said above, If you don't like it a balance tube is a option. Tim
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01-03-2024, 10:35 AM | #17 |
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Re: Blocking Hear Riser
Like blucar described in his post, I used the strips of metal to block off my heat rises on both sides.
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01-03-2024, 12:50 PM | #18 | |
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Re: Blocking Hear Riser
Quote:
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The only thing nice about being imperfect is the joy it brings to others.... "Silver rings, your butt! Them's washers!" "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0 |
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01-03-2024, 02:16 PM | #19 |
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Re: Blocking Hear Riser
And then there are guys like myself who could care less about period correct pennies or a "cool factor". We block off the majority of the passage to cut down on the heat soak on the carburetor while sustaining the cold startup drivability.
Luckily, I grew up with guys that weren't concerned with "being cool" and focused on actually improving horsepower and drivability. |
01-03-2024, 03:12 PM | #20 | |
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Re: Blocking Hear Riser
Quote:
The exact reason I blocked mine off was too cut off the heat going to the carburetor, I did the metal tabs with the edge bent up, rather than the penny's, so I could install and remove them with needle nose pliers, after just loosening the bolts. Just in case I didn't like it. 13 years later and they are still in. Here is the before and after blocking off the heat riser, at the same location. Last edited by Merc Cruzer; 01-03-2024 at 03:27 PM. |
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