Y Block Heat Riser Question
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Senior User
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From: Ridgefield, Washington
Y Block Heat Riser Question
I have not been able to find a functioning heat riser for my 239 engine. I have a set of Rams Horns manifolds that I have been debating about using but find that I can't find a heat riser for them either.
Questions:
1. Does anyone, anywhere, have a heat riser for either my stock exhaust or the Rams Horns?
2. How important is the heat riser? The fellow working on my engine (80 year old man who has been working on Y Blocks since their existence) says they are really crucial for the carburetor to work properly until the engine heats up.
3. What do I do if I can't find a functioning riser for either exhaust?
Nearing the point of putting Floyd's engine back in so really hope you guys can help.
Questions:
1. Does anyone, anywhere, have a heat riser for either my stock exhaust or the Rams Horns?
2. How important is the heat riser? The fellow working on my engine (80 year old man who has been working on Y Blocks since their existence) says they are really crucial for the carburetor to work properly until the engine heats up.
3. What do I do if I can't find a functioning riser for either exhaust?
Nearing the point of putting Floyd's engine back in so really hope you guys can help.
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Are you talking about the choke heat tube that runs from exhaust manifold up to carb to heat up the choke coil? Or are you talking about the heat crossover which runs from the center of each head across the intake manifold to heat up the base of the carburetor and prevent icing?
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From: Ridgefield, Washington
Are you talking about the choke heat tube that runs from exhaust manifold up to carb to heat up the choke coil? Or are you talking about the heat crossover which runs from the center of each head across the intake manifold to heat up the base of the carburetor and prevent icing?
It is a spring actuated butterfly valve that fits in the exhaust manifold and apparently causes a "backup" of exhaust which apparently causes heat to build up on the intake manifold thereby atomizing the fuel.
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From: Ridgefield, Washington
I tend to agree particularly since the engine started and ran fine before I pulled it out. The gentleman working on it said the engine will certainly run without it but what happens is unburned fuel tends to drain down into the cylinders reducing the oil viscosity and resultant wear of the rings.....all his words, not mine, but it seems to make sense.
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From: Rimrock AZ
I tend to agree particularly since the engine started and ran fine before I pulled it out. The gentleman working on it said the engine will certainly run without it but what happens is unburned fuel tends to drain down into the cylinders reducing the oil viscosity and resultant wear of the rings.....all his words, not mine, but it seems to make sense.
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From: NM
I partially blocked my heat riser on my flathead. Even in mild Spring weather, it took about 5 miles of driving to eliminate stumbling. I pulled the blocking shims out and it went away. You definitely need some heat. Those exhaust flapper valves worked poorly IMO even when relatively new, lots of people wired them open. Try running without it, if there's a problem, you should be able to add one later (if you can find one).
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The purpose is to create backpresure to force the engine to warm up faster. Once the exhaust temps come up, the bi-metal spring opens the valve and thus reduces backpressure. Warming the engine up faster means less run time with rich mixture when cold. So yes, less chance of raw fuel getting by rings and mixing with engine oil.
Y-block engines have a valley cover and the intake manifold can get air flow under it. Great for hot fuel engine issues but bad for cold weather warm-up. So the backpressure valve was mean to correct the cold weather concerns by speeding up the warming process. Without it you could get cold weather problems including carb throttle plate icing if you drive a cold engine in cold damp weather.
If you do not drive this engine in winter, forget needing it. It is not needed above 50F and at 50F and above it's only value will be to shorten the choke cycle time. Just let the engine warm up a little before driving and there will be no concern with gas getting by the rings in cold weather.
Y-block engines have a valley cover and the intake manifold can get air flow under it. Great for hot fuel engine issues but bad for cold weather warm-up. So the backpressure valve was mean to correct the cold weather concerns by speeding up the warming process. Without it you could get cold weather problems including carb throttle plate icing if you drive a cold engine in cold damp weather.
If you do not drive this engine in winter, forget needing it. It is not needed above 50F and at 50F and above it's only value will be to shorten the choke cycle time. Just let the engine warm up a little before driving and there will be no concern with gas getting by the rings in cold weather.
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From: Ridgefield, Washington
Thanks to all of you. I am nearly certain I will use the Rams Horns and even though I live in Western Washington (without the frigid winters) I likely will not drive Floyd in anything less than great weather so will take your advice and tolerate the slow warm up.
Fred
Fred
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From: AKRON ohio
Fred, Sometimes when heat risers are installed they cause too much heat at the intake, that's why old timers used to wire them open.
If you have ever noticed how the y block intake burns the paint off in the middle that's from the excessive heat.
I have been running Y's now for 30 years and I NEVER use a riser AND when installing the intake I used thin sheets of Stainless steel to COVER the heat riser ports.
Yes my Y's run extremely cool, but when at operating temp they are great, Also I must say that my Y with a 4V intake gets 20.5 MPG on the highway( this does have some road gears) and my Y with the 2v gest 18 mpg on the highway (this one is in my panel with overdrive)
Never a problem in 90 degree heat. This works for me just saying
If you have ever noticed how the y block intake burns the paint off in the middle that's from the excessive heat.
I have been running Y's now for 30 years and I NEVER use a riser AND when installing the intake I used thin sheets of Stainless steel to COVER the heat riser ports.
Yes my Y's run extremely cool, but when at operating temp they are great, Also I must say that my Y with a 4V intake gets 20.5 MPG on the highway( this does have some road gears) and my Y with the 2v gest 18 mpg on the highway (this one is in my panel with overdrive)
Never a problem in 90 degree heat. This works for me just saying
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From: Ridgefield, Washington
Heat Riser
As I stated earlier, my truck was running very well in all forms of weather and it was only when I pulled the engine that it was discovered the riser didn't work so I guess it really isn't necessary.
I have decided to go with the new Rams Horns manifolds and will not use a riser.
Thanks to everyone for the feedback.
I have decided to go with the new Rams Horns manifolds and will not use a riser.
Thanks to everyone for the feedback.
