Ive had gas boil in the carb on my model A in hot weather when ive stopped to gas up.The engine will heat soak & run crappy for a few minutes until it gets the cooler gas from the tank.Years ago,before ethenol this would never happen,even if it was 110* in the shade.
Blocking Off Heat Risers
- Thread starter dullchrome
- Start date
columbia, Two things, 1 you are not pumping the gas it is gravity feed so there is no vapor lock in the pump. 2 the A has an up draft carb and the gas is not flooding the engine when it boils over. You did point out the differance in the old gas not doing this. I never had vapor lock that I was aware of before this new gas came along. This boiling of the new gas does not happen I'm going guess at below out side temperatures of about 75 degrees. Even above 75 and even up in the 90s it may not show as a problem. You can drive in 90 degree temps on the open road and not get into much stop and go traffic, stop the car and get out for an hour or so and it may be slighty harder to start than normal but you would never know you were on the boarder line of vapor lock in the pump and boiling over in the carb. As the weather warms up a NUMBER of people taking laser thermometer readings of the fuel boil of the carb and the fuel pump will define the problem areas. One person like myself providing ALL the info doesn't prove a consistant over all problem. G.M.
dullchrome
Senior Member
Re: Blocking Off heat Risers
Would this be something that happens over an extended period of time or something that could happen on a single freeway run around town?
Would this be something that happens over an extended period of time or something that could happen on a single freeway run around town?
blucar
Well-known member
I received a big dose of modern automotive engineering last week...
I have a '49 Olds 88 that has been sitting under cover for a few years awaiting the time to restore it.. The time has finally came.
I want to keep the car all Old's, however, I want to improve the 60+ year old engine so it will run on modern fuels and be able to cruise the highways like the one I had in '54-55 did..
We all know that the unleaded fuels are not friendly to the valves and seats in the pre 73 engines, so a major rebuild of the heads was going to be in order.. The more I checked into the engine, the more I found that I had a real problem with an out of date antique..
Talking with Old's people I found out that as long as I used an Old's engine and did not increase the HP more than 20%, the car would still be classified as being a stock Old's. This bit of news meant that I could use a more modern 350 CID Old's engine.
I bought a 350 engine and started the rebuilding wheels turning..
In short order I found out that the heads were a problem.. Being emission heads they had some bad features which could be overcome for $1,200. It was then suggested That I consider using aftermarket aluminum heads.. @ $1,400 for the pair complete with valves etc... Why use the aluminum heads?
The aluminum heads are engineered for today's fuels, redesigned chambers and NO HEAT RISERS.. Hmmmm?... It was then explained to me that it has been found that a cooler charge of fuel provides for better combustion... The use of heat risers in the heads caused the center ports to be hot, where-as the end ports where cooler, in other works uneven fuel/air ratios..
It was also explained to me that with good driving habits the engine would give me fuel mileage of 15-18 mpg in the city... 20-25 mpg on the highway with an OD trans and good gearing.. I was hooked.
I would guess that inline engines might be a different story since the carb is hanging out in space.. But maybe not.
I have a '49 Olds 88 that has been sitting under cover for a few years awaiting the time to restore it.. The time has finally came.
I want to keep the car all Old's, however, I want to improve the 60+ year old engine so it will run on modern fuels and be able to cruise the highways like the one I had in '54-55 did..
We all know that the unleaded fuels are not friendly to the valves and seats in the pre 73 engines, so a major rebuild of the heads was going to be in order.. The more I checked into the engine, the more I found that I had a real problem with an out of date antique..
Talking with Old's people I found out that as long as I used an Old's engine and did not increase the HP more than 20%, the car would still be classified as being a stock Old's. This bit of news meant that I could use a more modern 350 CID Old's engine.
I bought a 350 engine and started the rebuilding wheels turning..
In short order I found out that the heads were a problem.. Being emission heads they had some bad features which could be overcome for $1,200. It was then suggested That I consider using aftermarket aluminum heads.. @ $1,400 for the pair complete with valves etc... Why use the aluminum heads?
The aluminum heads are engineered for today's fuels, redesigned chambers and NO HEAT RISERS.. Hmmmm?... It was then explained to me that it has been found that a cooler charge of fuel provides for better combustion... The use of heat risers in the heads caused the center ports to be hot, where-as the end ports where cooler, in other works uneven fuel/air ratios..
It was also explained to me that with good driving habits the engine would give me fuel mileage of 15-18 mpg in the city... 20-25 mpg on the highway with an OD trans and good gearing.. I was hooked.
I would guess that inline engines might be a different story since the carb is hanging out in space.. But maybe not.
Kirby1374
Senior Member
I never knew you could install a 30 year newer engine and still call your car stock. I think I'll put a 1960 engine with aluminum heads in my A and convince the guys on the Barn that it is still stock
flatjack9
Well-known member
I think a lot of these people doing the explaining need some explaining.
ford38v8
Well-known member
"Con - High speed driving may tend to burn your center cylinder exhaust valves over a long period time."
"Would this be something that happens over an extended period of time or something that could happen on a single freeway run around town?"
Dullchrome, I think this would apply more to high RPM driving than to normal driving. There are aftermarket exhaust dividers that can be installed in the center port to improve flow and help prevent the effect (push-pull) each port has on its twin, but again, this is something that is done on highly modified engines, and wouldn't normally provide an advantage for the street engine.
A compromise has been suggested by GM, to drill a small hole in the heat riser block-off coins, to allow a much reduced volume of hot gas to cross over. With the extremely high volatility of ethanol/gasoline, these old time modifications become much more than making your exhaust sound better. Modern systems having computerized fuel injection can deal with the cruddy gas, but our old tech cars have much difficulty.
"Would this be something that happens over an extended period of time or something that could happen on a single freeway run around town?"
Dullchrome, I think this would apply more to high RPM driving than to normal driving. There are aftermarket exhaust dividers that can be installed in the center port to improve flow and help prevent the effect (push-pull) each port has on its twin, but again, this is something that is done on highly modified engines, and wouldn't normally provide an advantage for the street engine.
A compromise has been suggested by GM, to drill a small hole in the heat riser block-off coins, to allow a much reduced volume of hot gas to cross over. With the extremely high volatility of ethanol/gasoline, these old time modifications become much more than making your exhaust sound better. Modern systems having computerized fuel injection can deal with the cruddy gas, but our old tech cars have much difficulty.
blucar
Well-known member
I never knew you could install a 30 year newer engine and still call your car stock. I think I'll put a 1960 engine with aluminum heads in my A and convince the guys on the Barn that it is still stock
I think what a person has to keep in mind is that comparing a Model A or an Early V8 Ford to a '49 Old's 88 is like comparing apples to banana's..
If the Old's people want to consider a later model Old's engine in an earlier car, to qualify as stock, that is their business... Far be it from me to second guess them..
In the same vane, since it has been documented that Ford stopped using hardened valve seats in the 8BA-8CM engines.... So, if a person updates the engine with hardened seats and stainless valves, the engine is no longer stock.
I guess that the fact that the Early V8 people now recognize the Columbia OD to be a stock application, falls into about the same category...
dullchrome
Senior Member
Well its been some time now. I have tried a couple different materials with short term success. First I trimmed a piece out of a aluminum can which only lasted for a short trip down the freeway before blowing out. The same happened with a piece from and older oil can. Now I am running a piece of 22 gauge stainless that seems to be holding up well.
Last edited:
Henry/Kokomo
Well-known member
I've thought for some time that stainless steel would be the way to go. Thanks for informing us on the results of your tests. Did you use shim stock or, if not, what was the source of the stainless (I want to get some)? Thanks and good luck!
dullchrome
Senior Member
I got mine out of the remnants section of a local metal warehouse, IMS(Industrial Metal Supply), cost me a whopping three dollars.
Bruce Lancaster
Member Emeritus
On the Ford...Southern California is probably best place for blocked risers; you'll never be drowning your car with the choke on an icy morning!
All effects, good and potential bad, will be considerably less with a stock iron manifold than with aluminum.
Partial blockage...on later carbureted SBC's, some had iron and some aluminum manifolds. Heat was used for waring manifold, of course, but also served a stove for choke tube on some. Gasket sets for aluminum came with shim stock partial blockoffs...I think exhaust hole on these was circa 1/4" from memory.
Olds guy...you are being sold a CROCK. Your engine will run fine completely stock on unleaded with any random modern oil you find, though I would think about the oil issues IF putting a new cam and lifters in there.
Your problem areas, if you have any, will be limited to rubber carb parts (Try adapting accel pump cap from a late Rochester or such...there are specialists to help!) and fuel pump diaphragm, MAYBE. On the fuel pump IF you have probs, throw in an electric modern one and forgetaboutit.
New engine, hardened valve seats, oil no good for old engines, gotta have super-duper heads: CROCK. Put your wallet back in your pocket and RUN from that mechanic!
All effects, good and potential bad, will be considerably less with a stock iron manifold than with aluminum.
Partial blockage...on later carbureted SBC's, some had iron and some aluminum manifolds. Heat was used for waring manifold, of course, but also served a stove for choke tube on some. Gasket sets for aluminum came with shim stock partial blockoffs...I think exhaust hole on these was circa 1/4" from memory.
Olds guy...you are being sold a CROCK. Your engine will run fine completely stock on unleaded with any random modern oil you find, though I would think about the oil issues IF putting a new cam and lifters in there.
Your problem areas, if you have any, will be limited to rubber carb parts (Try adapting accel pump cap from a late Rochester or such...there are specialists to help!) and fuel pump diaphragm, MAYBE. On the fuel pump IF you have probs, throw in an electric modern one and forgetaboutit.
New engine, hardened valve seats, oil no good for old engines, gotta have super-duper heads: CROCK. Put your wallet back in your pocket and RUN from that mechanic!
Bruce Lancaster
Member Emeritus
Old Henry...don't see pictures, but I think you are are talking about a heat valve on the crossover pipe on a 59A?? These took two forms, one with a coil and counterweight visible right below L exhaust manifold, the other a crazy duckbill one that hid inside the pipe. These block the crossover that connects bot manifolds to the muffler and so force exhaust to flow through the intake manifold crossover until exhaust heats up. It is rare to find them intact and functional on '46-8 Fords.
Shadetree
Well-known member
I have a lifter starting to get loud in my `51 F1. It probably doesn't have 300 miles on the rebuild. Not sure if I'll use Red Locktite or stake the threads, but rest assured when the intake manifold comes off I'll be two wheat straws poorer when it goes back on. The Smithy's are just too quiet. My 2 cents worth.
blucar
Well-known member
The '49 olds V8 was a great engine in it's day.. In an 88 chassis car it would run off and hide from anything on the road, Chrysler Hemi's included.. The key words to my statement are "IN It's Day")... The engineering that went into the Rocket engines is now over sixty years old...
It is very true that there are hot-shot mechanics out there that will tell you they can buildup the old engines to handle unleaded, etc., the one thing they can't do is improve the metalurgy and lower the weight issues that the old engine/transmissions have.
The difference between a '49/50 Olds 303 V8 with a Hydromatic trans and a 350/403 Olds V8 w/TH350/200R4 trans is 550 lbs... A significant weight savings in my book.. Adding in the modern engineering/metalurgy, and the engine swap is a no brainer...
Merc Cruzer
Well-known member
![$(KGrHqN,!rcE88g9dOHYBPc0Ll0SD!~~60_35[1].jpg](/data/attachments/104/104225-e354da5c58910c803b4afac98ebf3a5c.jpg?hash=NzwaMSLrmi)
ford38v8
Well-known member
Yep, those are them, and seeing your manifold pic reminds me of a friend's '36 with aluminum manifold: His manifold passageway (riser) burned through, scrapping an otherwise show condition manifold.
"How hot was it, Mabel?"
Merc Cruzer
Well-known member
Pennies go in the intake or the block?