Holleys seen to have more problems than other carbs with heat soak boiling the gas in the float bowls.The only fix that has worked for me is an AFB in the summer. The factory ran tubes from the float bowls to the charcoal canister in the '80s. Does this help? I've tried thick heat insulating carb gaskets and aluminum heat shields.These mods didn't help much.I like Holleys but they don't like summer heat soaks.
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Hard starting after heat soak.
- Thread starter jckkys
- Start date
Must just be a issue with yours I've been running one for 30+ years and have never had a heat soak issue. Even on several different vehicles. To me holley has less chance of heat soak due to the fact that the fuel bowls are pretty much outside the carb so to speak.
The factory lines to the charcoal cannister was only for emissions purposes they didnt want vaoprs emitted into the air.
The factory lines to the charcoal cannister was only for emissions purposes they didnt want vaoprs emitted into the air.
The tube from the air cleaner to the canister seams to serve the same vapor control purpose. The Holleys I've used all seem to start as if flooded after sitting hot for 10-15min. on a hot day. The float bowls are empty after sitting over night in the summer. In cool weather the problem goes away.The AFB works much better in heat soak situations. I'm happy to hear your Holley doesn't have this problem but that knowledge won't help me. Can anyone tell me how to trouble shoot this problem?
I would be surprised to find Ford equipped new vehicles with heat insulating carb gaskets and heat shields for no reason. The bean counters wouldn't allow it.
I would be surprised to find Ford equipped new vehicles with heat insulating carb gaskets and heat shields for no reason. The bean counters wouldn't allow it.
More or less yes the tube from the aircleaner to the canister is the same concept except that that is where the vapors reenter the engine as vacuum sucks any vapers from the cannister into the engine to be burnt off instead of wasted.
From the mid 70's on up its all about emissions one way they reduce emissions is with leaner mixtures which also result in higher temps. early on the factory T stats were like 180 then they jumped up to 190. So thick gaskets are used to help insulate the carb. Those 1980's factory holley carbs are not very good plus they are calibrated for use with emission equipment so they tend to be a little finicky compared to regular holley carbs.
I think your having more a of a issue with overall tuning than the actual carb maybe the AFB is setup richer than your holley and thats why it would start better when sitting.
Pretty much all Im saying is I dont think its brand of carb issue unless your running one of those 80's factory holley's.
From the mid 70's on up its all about emissions one way they reduce emissions is with leaner mixtures which also result in higher temps. early on the factory T stats were like 180 then they jumped up to 190. So thick gaskets are used to help insulate the carb. Those 1980's factory holley carbs are not very good plus they are calibrated for use with emission equipment so they tend to be a little finicky compared to regular holley carbs.
I think your having more a of a issue with overall tuning than the actual carb maybe the AFB is setup richer than your holley and thats why it would start better when sitting.
Pretty much all Im saying is I dont think its brand of carb issue unless your running one of those 80's factory holley's.
The '80s Holleys are model 4180s. The only real change from 4160s is in the idle circuit. Idle mixture can be adjusted at each of the 4 throttles individually. This allowed more precise mixture to the cylinders. They can be set to run as lean or rich as any Holley made for gasoline. Don't see why that makes them" not very good". The 190degree thermostat reduces engine wear and allows a more constant running temp. In hot weather my engine runs hotter than that any way.The vapor in the canister is pulled into the gas tank not into the engine, especially while cranking . The engine won't start because it's already too rich. The gas in the float bowls is boiling because the air under the hood is trapped over a hot engine. If I could move some cool air into the area over the engine that may help. For all I know, you may run with out a hood. For now all I can do is hold the peddle to the metal while cranking until enough fuel-vapor is removed and replaced by air to produce a combustible mixture,like any flooded engine scenario. My original question was to see if getting the vapor out of the bowl at lower point,as vapor is heavier than air, may mean less vapor going into the intake. Or is the amount removed insignificant.
Its still a emissions carb. Basically meaning it was setup to run leaner and with other emission equipment. yes it can be retuned to give better performance but they are still pretty touchy carbs. Sure you can adjust the idle mixture if the plugs are removed and you can actually get to the screws on the base plate real PITA. So really unless your still running all the smog equipment on your engine and its all functioning correctly or have totally retuned the carb its not going to run right.
As for T stats and emissions you might want to read up on that. While yes 190 degree t stats reduce wear but thats a side effect. The 190 t stats really didnt come about until emissions needed to be reduced. The T stat is there to maintain temparture if your running hotter than that then you have cooling system issues or your tuning is off.
Yes sometimes the engine temps may creep up a little higher than normal during stop and go driving but you should still maintain temp during normal driving.
You might think that all the other bronco owners here in AZ are running without hoods or are lying about how there truck runs but I assure you thats not the case. Heck I daily drove my bronco in tucson for 8 years never a issue. believe it or not.
I really doubt its fuel vapor thats causing your issue. vapor is just that vapor it wont flood a engine unless it cools down enough to condense back into a liquid. raw fuel will though. You may have heak soak issues but you need to figure out if its from the carb or fuel line routing? a fuel line maybe heating up to much and the fuel boils sending it past the needle seats and then flooding the engine due to the fuel bowls being to full. Of course the same can be true of the carb itself you might try lowering the fuel level to help prevent the boil over.
As for T stats and emissions you might want to read up on that. While yes 190 degree t stats reduce wear but thats a side effect. The 190 t stats really didnt come about until emissions needed to be reduced. The T stat is there to maintain temparture if your running hotter than that then you have cooling system issues or your tuning is off.
Yes sometimes the engine temps may creep up a little higher than normal during stop and go driving but you should still maintain temp during normal driving.
You might think that all the other bronco owners here in AZ are running without hoods or are lying about how there truck runs but I assure you thats not the case. Heck I daily drove my bronco in tucson for 8 years never a issue. believe it or not.
I really doubt its fuel vapor thats causing your issue. vapor is just that vapor it wont flood a engine unless it cools down enough to condense back into a liquid. raw fuel will though. You may have heak soak issues but you need to figure out if its from the carb or fuel line routing? a fuel line maybe heating up to much and the fuel boils sending it past the needle seats and then flooding the engine due to the fuel bowls being to full. Of course the same can be true of the carb itself you might try lowering the fuel level to help prevent the boil over.
Last edited:
blubuckaroo
Grease Monkey
I'd try lowering the float level a bit like broncnaz said. Also you could try blocking off the heat riser exhaust port under the carburetor with a piece of .004" stainless shim stock on the intake side of the intake gaskets. That port is there to get the carb up to operating temperature faster in cold weather. Mine doesn't miss it and blocking it has helped keep the carb cool.
NYLES
Bronco Guru
- Joined
- Aug 13, 2004
- Messages
- 9,846
x2 and a phinolic spacer
I use insulating carb gaskets and bake lite spacers for front PVC hose.
I long ago lowered the float level on every carb. used off road. It does help with bump stall and angularity issues. The emission versions of Holleys and Performers (AFB)s are jetted identically to their equal sized non-emission counterparts. Bowl vents are all that makes an AFB "emission". Holley added either a reverse idle circuit or the 4180 idle mixture screws in the throttle body. Some of these used on high GVW trucks have the exposed idle adjustment screws exposed like a 4100 Autolites. I agree the no tamper idle screws are a pain, it's cause the government thinks it knows best . My experience is the emission version is some what richer at idle to compensate for the diluting effect of EGR.
When the timing is overly advanced it kicks back effecting cranking. Mine cranks fine.
The 190degree thermostat works as well as any,when the 351 is dealing 110, long grades,and traffic. I'm working that problem too.
If flooding after heat soak is not common in Holleys, I'll have to look at the internals of this one. Dried out gaskets have caused accelerator pump and float bowl leaks. Maybe the metering block gasket surface is scratched or warped enough to leak when hot.
This can't happen on AFBs,AVSs.or Autolites ;so I never had this problem with them.
I long ago lowered the float level on every carb. used off road. It does help with bump stall and angularity issues. The emission versions of Holleys and Performers (AFB)s are jetted identically to their equal sized non-emission counterparts. Bowl vents are all that makes an AFB "emission". Holley added either a reverse idle circuit or the 4180 idle mixture screws in the throttle body. Some of these used on high GVW trucks have the exposed idle adjustment screws exposed like a 4100 Autolites. I agree the no tamper idle screws are a pain, it's cause the government thinks it knows best . My experience is the emission version is some what richer at idle to compensate for the diluting effect of EGR.
When the timing is overly advanced it kicks back effecting cranking. Mine cranks fine.
The 190degree thermostat works as well as any,when the 351 is dealing 110, long grades,and traffic. I'm working that problem too.
If flooding after heat soak is not common in Holleys, I'll have to look at the internals of this one. Dried out gaskets have caused accelerator pump and float bowl leaks. Maybe the metering block gasket surface is scratched or warped enough to leak when hot.
This can't happen on AFBs,AVSs.or Autolites ;so I never had this problem with them.
Well yes it cranks fine. It just doesn't fire up until the excess fuel is moved out into the exhaust manifold and is replaced by a combustible mixture. The gas in fact seeps out of the throttle shaft after the engine is shut down, so it's hard to miss. Oh, and I've changed the needle and seat even tho the Viton tipped needles have never caused this problem for me.
Not that I ignored the suggestion to block the exhaust cross over in the intake. I did try the intake gaskets that have stainless baffles on a 460 about 30 yrs. ago. It ran like crap till it was warmed up. So I haven't been tempted to do it again.
Having been a firefighter I've seen plenty of car fires and don't want my truck to burn. My fuel line is all steel from the pump to the carb. Worn or cracked rubber fuel hose was the #1 cause I've seen. I also use the rubber distributor cap cover from 5.0 Mustangs and top quality plug wires to remove an ignition source. So gas seeping out of the carb bothers me. Has anyone found Holley gaskets that are better than the blue ones?
NYLES
Bronco Guru
- Joined
- Aug 13, 2004
- Messages
- 9,846
Mine would sit for a few days and be really hard to start come to find out the hard way it sat for a 2 weeks filled crankcase with fuel, drained re oiled and somewhere between trashing the old carb and installing the new.....somebody turned it over...then well spark pooof its on fire......880 gals later they got it put out!
Dont think there is anything much better than the blue gaskets I've also had good luck with the red ones.
Out on a limb here but you said your 4180 is jetted equal to a non emissions version? Have you checked your spark plugs to see if its jetted correctly for the engine? The same jetting as a perfromance version doesnt mean it will react the same way as its a different carb with differently metering. It may be jetted wrong as even the perfromance versions usually require some tuning to whatever engine you install it on to get things right. Yes they may seem to run fine out of the box but a little tuning can go a long way.
Yes it could very well be a warped metering block could even be a wrong gasket since the 4180's have a little different metering block and metering plate than normal holleys so gaskets must be correct or issues arise.
I still think its a tuning or a cooling issue. Holley's are no more inherent to boiling over or heat soak than any other carb. Something has to be worng with the tuning with that carb thats making the engine run hotter or maybe somethings just jacked up with the carb itself.
For awhile when in tucson I had some radiator issues I was running 220+ for "normal" temps still didnt have heat soak issues with mine.
Out on a limb here but you said your 4180 is jetted equal to a non emissions version? Have you checked your spark plugs to see if its jetted correctly for the engine? The same jetting as a perfromance version doesnt mean it will react the same way as its a different carb with differently metering. It may be jetted wrong as even the perfromance versions usually require some tuning to whatever engine you install it on to get things right. Yes they may seem to run fine out of the box but a little tuning can go a long way.
Yes it could very well be a warped metering block could even be a wrong gasket since the 4180's have a little different metering block and metering plate than normal holleys so gaskets must be correct or issues arise.
I still think its a tuning or a cooling issue. Holley's are no more inherent to boiling over or heat soak than any other carb. Something has to be worng with the tuning with that carb thats making the engine run hotter or maybe somethings just jacked up with the carb itself.
For awhile when in tucson I had some radiator issues I was running 220+ for "normal" temps still didnt have heat soak issues with mine.
My experience with a 4180 was not on a Bronco. It was a 78' 460PI . I was forced to reinstall all the emission crap in the early '80s when Pima Co. and Maricopa Co. fell under the Az. emission law. The 4180 needed smaller primary jets, much larger secondary jets,and a much smaller vacuum secondary spring. Then the 4180 ran as well as the list 1850 it replaced. The Bronco is now running a 500cfm AFB while I fix the 1849 550cfm Holley. Both carbs are dialed in and run equally strong. The 1849 gives better mileage and less bump stall so I would like to use it. The 1848,1849,and 1850 Holleys were original equipment in the late 50's and early 60's. They aren't performance carbs just pre-emission. I never assume a new or original equipment carb is tuned correctly I've found they are at best close. The radiator shops here in Tucson all tell me an EB with a 351 can't be expected to maintain the temp where the thermostat is set, on hot days. You must be very fortunate. I've abandoned the boiling fuel theory and am looking into leaky gaskets or a bad metering block. Only an idiot would use a 4180 metering block gasket on a 4150 or.4160. They don't even look similar and the accelerator pump wouldn't work at all because the 4180 uses a transfer tube. There were many articles in the 80's dealing with the tuning of 4180s in 5.0 Mustangs racing in stock classes that required retention of the stock carb. Some oddly recommended replacing the annular discharge booster venturis. Otherwise they did what I did and got similar results. The Holley doesn't run hotter than the AFB it just leeks, and several hot rod shops and engine builders told me the large float bowls boil the gas more than other carbs. They also say new fuel blends are hard on gaskets.
A lot of the older 4160 carbs also had fuel transfer tubes so its not a 4180 only item just that the 4180 has different metering blocks and plates altogether than a 4150/60. I just mention it becuase I've seen people use the wrong gaskets had a fellow member in tucson that couldnt get his bronco to lean out at idle. Tried the forum diagnosis but nothing was changing. finally went over to meet him and figure out was was wrong took me about 5mins to determine a possible cause and 10 minutes later it was purring like it should. All due to a wrong metering block gasket.
There are a lot of people running 351's and larger strokers that have no issues running in AZ. Yes the bronco cooling system is small and needs to be in good shape but it can handle a 351.
I fully understand there is all kinds of info on the 4180 but its still not the best carb to run. I also know why they would remove the annular boosters. But again its a emissions carb. Mods are needed to make it run like the pre emissions carbs if your not runniong any emissions equipment.
There are a lot of people running 351's and larger strokers that have no issues running in AZ. Yes the bronco cooling system is small and needs to be in good shape but it can handle a 351.
I fully understand there is all kinds of info on the 4180 but its still not the best carb to run. I also know why they would remove the annular boosters. But again its a emissions carb. Mods are needed to make it run like the pre emissions carbs if your not runniong any emissions equipment.
74bob
Full Member
I used to get heat soak with my Edelbrock carb until I installed a Derale auto trans cooler with integral fan. I have the cooler mounted on top of the drivers fenderwell. The fan runs even when the key is off (how I have it wired) and it moves the hot air out from under the hood. This cooler has a temperature switch that turns on or off the built in fan. It's surprising how much air this moves and cools the under hood temps. No more heat soak.
