I'm sure this one has been dragged through the coals but here goes..the vendor I bought my repop Fentons for my 216 Chevy says in CA. I will not need the copper tubes/compression fittings/plate that heat up the intake...another vender tells me they are worthless anyway and do nothing because the pressure from each exhaust manifold is equal therefore it cannot circulate and recomends running hot water to the stock 1bbl intake instead....any opinions?...alot of you guys seem to be running the 216/235 with Fentons....Thanks
yeah, you are right - this has been dragged through the coals, but what the hell - its still fun to get the debate going a second or third or 40th time. It does no good, huh??? Tell him to grab the intake manifold after the thing has been running about 10 minutes with the heat to the intake. Make sure he grabs it real close to the center of the intake to get the whole feel. It wont take him long to look at it, I ***ure you. What you are trying to achieve is hot intake/cool carbs. That allows the fuel to better atomize before it hits the combustion chamber. The vendor that says the pressure is equal is correct. But think of the firing order - its 153624 - another way to look at it is which header is supplying the heat and when?? front (1) - back (5) - front (3) - back (6) - front (2) - back (4). It curculates hot air just fine Te debate usually centers around what part of the country you live in - the further south you live the more likely you will hear that you dont need it. it sure made my 235 run better.
I live in NJ and don't run heat, never had, so I don't know what I'm missing? Had an iron intake manifold with fenton exhaust, no heat. It was fine. Now run an Al Offy, no heat. it's fine. This heat thing is an urban myth for the Chevy's in my opinion. I got a Ford 300. When it had an Offy on it it needed hot air to the carb with a heat stove off the exhaust manifold or the carb would ice up, even in the summer. Frank
Ken: You getting your dual carb set up sorted out? I still need to send my 52 to your brother to have the front end done! As to running heat to the manifold, I think there must be something to it or all those high paid automotive engineers who developed heat risers would not have wasted their time coming up with them and profit minded car companies would have stopped installing them if they did not help with how the car ran. Just make your own heat plate, it would be cheap, easy, and would not hurt to try it. Ted
Nah not an urban myth really. I thought the same thing till I piped water to my Tattersfield. It was one of the best things I could have done for my engine. Heating the intake works and there's no doubt about it! Dom
So what is more efficient for atomizing the fuel? hot water or exhaust gas?...remember I am still running the cast iron 1BBL intake until one of you great HAMBers sells me a dual of any brand at a price not compared to the overinflated E-PAY!!! ha-ha
Both work equally well in theory. On the inliners board a month or 2 ago that very question came up. When the day was done, it is a trade off on what you want to use. Exhaust heat is quicker, but the g***es are corrosive to manifolds. It will take a while to corrode them and the high temp/ceramic coatings protedct them the best. I'm old, so i figure I'll be dead long before they corrode so somebody else can worry about my manifolds leaking. Water heat is slower, but more evenly distributed. According to carb expert Jon at the carb shop, there is an ionic exchange with dissimilar metals that all alloy engines face with antifreeze. Of course the newer antifreezes are better with this than the older style glycols, but you still have to change it on a regular basis or use the appropriate additives to keep from dissolving the intake.
With the conditions just right I have had a carb ice up and my truck quit running (early lov truck at 2:00 am on the way home from work) . Never heard of a chev doing that thou. But you never Know. Years ago I ran two and three carbs on a chev six and never seemed to have any real problem but then that car was so suped up it was cranky anyway. I always waited untill it was warmed up to go out on the street
I am kinda leaning toward the ex gas method,sounds simpler being they make a bolt on kit (I was sent the kit when I bought the Fentons but it was for a 235 intake)...and I kind of like the idea of no other place for a coolant leak,Thanks
Tell that to the guy I know that ran tubing headers on a 235 powered truck, and took over an hour to travel 18 miles one cold (25 degrees) morning. He could make it about two miles before the carb would ice up and stall, then sit for 4-5 minutes while the heat rose from the engine and thawed it out.
fuel atomizing is endothermic. that means it takes energy (heat) for your fuel to mix with the air, so heated intake just makes sense, the heats gotta come from somewhere, according to my offy intake instructions....(paraphrased a little) without heat fuel stays in liquid form and that liquid coats the walls of your intake, wilth all the fuel hangin out in the intake, much less makes it to your cylinders. leans out and motor runs ****ty. when the walls of the intake get too much fuel, you start getting way more much to the cylinders, rich mixture and motor runs ****ty. this cycles back and forth, obviously different motors are affected differently, but intake heat is not going to hurt. water or exhaust? if you hook up the hoses to the thermostat byp*** and your thermostat works, you wont be waiting too long for it to warm up, and 200 deg. (operating temp.) isnt to hot. exhaust is more corrosive, and needs to be regulated because its so hot, but works instantly more or less. no idea how the chevy motors regulate the exhaust but my flatty had a ****erfly valve, heat activated, the springs can wear out, and it doesnt flow as well
Am I not understanding what this thread is, or has everyone forgotten what a heat-riser is? The heating p***age under the manifold is simply for helping the car's drivability during warm up. It is correct that the exh flow inside the p***age is almost nothing because both sides are just about equal in pressure,.. when the engine is WARM. One ONE SIDE exhaust pipe, right at the exit of one exh manifold, there is supposed to be a ****erfly valve with a bi-metallic coil on it's shaft. When cold, the HEAT RISER valve restricts the exhaust on one side so a very large part of the exh flow is forced thru the p***age under the carb, heating the manifold floor, vaporizing the cold fuel and improving the fuel/air mix. That is why a car that is warming up will usually look like the exhaust is coming from only one side (the heat riser valve is closed, forcing the exhaust to cross over to the other side, heating the intake along the way), then as it warms up you will see the steamy exhaust coming from both pipes.. When the engine starts to warm up, the heat riser valve opens and quits forcing heat to the heating pad in the intake manifold. Both exhausts should then have roughly equal flow. It was also very common to simply remove the valve and discard it the first time it stuck shut (overheating the intake and carb) and made the engine run poorly. Often never replaced because the car ran better without it (except during start-up). Too much heat is very bad. It needs to be reduced as the engine warms up or other problems arise such as carb boiling, reduced power, etc. In fact, a good performance trick has been to install a metal shield under the intake manifold to keep it from absorbing the heat from the engine. People used to block off the heat riser p***ages completely and get a power boost from a cooler intake. When I lived in Florida, we used to remove any heat riser valve, and block off the heat riser p***ages completely to make the cars run faster in the warm weather. A cooler intake charge always gave more power. Never needed them in the winter because the engines warmed up quickly. After I moved north to Illinois, I discovered that although it wasn't necessary to have a working heat riser most of the time, it sure did help in the winter for the first 2 or 3 miles of driving. After the engine warmed up a little, it didn't matter whether or not you used the heat p***ages. In the summer with the engine warm it hurt performance a good bit if you didn't block them off and keep the intake cool. But back in those days we didn't have computers to override our tuning efforts, or fuel injection, or sensors everywhere that would persuade the computer to go into a different "mode". What I described above was for the pre-smog carbureted cars. They loved cool air when the engine was warm, loved warm air when the engine was cool. I had never seen the water-heated versions until the smog days started, when the EPA got involved and the new carbs were jetted so lean that the cars wouldn't run very well at all until the air was well-heated even in warm weather. The water-heated versions stayed hot all the time. Those cars never ran as well as the earlier versions, but they met the EPA specs at the time. There may be a few exceptions, but that's the way it was. OR- did I completely misunderstand the question?
- On the dyno, on a 500 Caddy, blocking the heat crossover p***ages is worth about 15 HP on a mild (450 HP) engine. - Growing up in Kansas (below freezing for weeks in the winter and triple digits in the summer), you had better have a regulated heat supply - if the EFE valve (the flapper in the exhaust on one side) didn't work automatically, you had to wire it open in the summer and closed in the winter, to keep the car drivable. Alcohol is worse. Knowing how hard it is to start the race cars on a cool summer day (70s), I'm wondering what the E85 guys do in the winter? I'm not sure if the factory full time hot water thing is an EPA deal or just a brilliant Ford idea. It really should be thermostatically controlled one way or another.
I agree. For those not familiar with Heat Riser Valves (EFE you call it? new term to me. what does it stand for?), OPENING the valve will let the two exhaust pipes flow freeley, and does NOT force any hot g***es to heat up the intake. Wiring the valve OPEN keeps the intake cooler for summer use, just like he said. When the Heat Riser Valve (EFE??) is closed either by the heat coil or by wiring it CLOSED, it will then force hot g***es to go thru the p***age under the intake in order to exit out the "other" exhaust pipe. That makes the intake HOT. So the term OPEN actually means that NO g***es are forced thru the manifold p***age, and the term CLOSED means that hot g***es ARE being pushed thru the intake making it hotter. I didn't want anyone getting the terms mixed up since it could sound like it works the other way.
This one bolts to a V8 exh manifold. Most people throw them away and then run without the first time it sticks shut. If you can't move the weight on the lever, get it out of there right away. The other shows a six cyl version. The six uses a flapper valve to direct the hot g***es either upward to heat the bottom of the six cyl intake, or channels the g***es straight downward directly to the exh pipe.
With the Fenton headers ther are no provisions for the ****erfly valve,only 2 ports that run copper tubing to a plate under under the intake where the OEM exhaust mounted up,thats what we are talking about
stock intake/exhaust combos were heated....and it was done so for a reason. the heat plate stuff is to compenstate for the split exhaust manifold....since its no longer connected to the intake...no heat any more. it is needed no matter what climate you live in. does it mean your ride won't start without...? NO, but it will sure start/run better with it. i've got water heat for my 292 in my '53 chevy.
Sorry - they were called heat riser valves pre-WWII. By the 70s they were called EFE valves, which is what I deal with at work all day. EFE = Early Fuel Evaporation (kinda makes sense) Closed = exhaust goes through intake p***ages to heat the intake (and promote fuel atomization on cold starts), as the valve (when closed) blocks the exhaust pipe on that side of the engine. Open = exhaust goes out each separate exhaust pipe. The big Caddy have a vacuum controlled ****erfly, vacuum is regulated by a coolant temp switch which applies vacuum to close the valve if coolant temp is below a certain point. I don't know about the water heated carb spacer being an EPA thing - my '68 Ford (FE engine) has one. I don't think it's going back in, even if the FE engine stays, but it has one
Hey Frank, SO just to be clear you didnt run any heat with the iron intake and headers? Ive got a 300 I am installing some hedman headers, but wasn't sure weather to block off my intake heater, or if I needed to run a heater plate. Any insight would be awesome!
I'm thinking a heater tube from the exhaust to the air cleaner (like the factory did) would do a better job of heating the air and keeping the carb from icing up. I wonder if anyone has told Edelbrock that their Air Gap intakes don't work?
bluemustang21, Chevy with iron intake or aluminum intake and cast iron headers never a problem. Ford with Aluminum intake and tubing headers was a problem .
When digesting all of the information in this thread, it is well to consider that MOST V-8's have the carburetor(s) sitting in the center of the engine; and most inline engines have the carburetor(s) away from the engine. Also consider the three variables most responsible for atomizing fuel are A/F density, air velocity, and temperature. One can sometimes reduce or eliminate one of the variables while significantly increasing the other two. Also, some individuals have a higher tolerance for lousy fuel economy and/or questionable low RPM throttle response than others. If there was one correct answer, everyone would be doing it.....boring. Jon.
So how well do the heat tubes on Fentons work? I know my '51 is hard to start on even cool mornings without intake heat. I put a rochester bc on the 235 and now use my choke cable to control the heat valve. I'm thinking about getting Fentons but I'm afraid they won't provide enough heat in the dead of winter (low teens) since the tubes are so small, and provide too much heat in the dead of summer (high 90s) since there's no way to stop the exhaust.
I live at 4000 ft. al***ude in CA and have triple digit summers and low teens winters at the extreme ends. Got Fentons and 2x1 cast aluminum intakes on both my drivers. I have the direct heat riser early vintage Fentons on my 261 where one exhaust header heats the 2x1 carb intake directly by being bolted to it. And I have the tubes and heat plate for the other 2x1 intake on my 235. I prefer exhaust heat because it is quicker to heat the intake and not just in the winter. No vapor lock or too hot intake in the summers even after long freeways trips and I don't even use carb spacers on the cast aluminum intakes. Should the intake corrode from the exhaust one day, I get another one. I just read in your first post you were told the exhaust does not flow inside the tubes between the headers. The exhaust pulse in each header follows the other, so there is just enough back and forth flow. Doesn't take much and apparently enough and better than no heat in any case. I remember touching the tubes right after cold-start one day and they get very hot in seconds....ouch!
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