Gas boiling

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cuda67

cuda67

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Took the Barracuda out for it's maiden voyage today, about 70 miles. Some small issues I have to check. After about 35 miles I stopped at my son's house to check things out and to let him have a look see. Right off the bat we noticed that the gas was boiling in the carb.. The car was not running hot. I have a Holley street avenger 80770 on a M1 MP intake. The engine is a 360 magnum/390 horse MP crate engine. I don't think I can get much of a spacer on it, maybe a 1/4 to 1/2 inch. What would make the carb so hot to boil? Temperature was about 84 degrees. Engine temperature 185-190. Besides a spacer what else can I try if that doesn't fix it?
 
Those phenolic spacers do wonders, even a 1/4 would help. Aluminum is worst, Good 'ol wood is best, but check regularly for soaking.
 
pishta said:
Those phenolic spacers do wonders, even a 1/4 would help. Aluminum is worst, Good 'ol wood is best, but check regularly for soaking.
Click to expand...

I will more than likely put the spacer on tomorrow. It has to be better than nothing.

Thanks
 
Also consider installing a "vapor return" system. I did this on my 67 Dart, and it helped a lot. First car I ever saw with one was my '70 440 sixpack RR. On my Dart, I brazed a tube into the front face of the tank, after flooding it with CO2 from my MIG welder bottle. Run a 1/4" tube up front, and plumb in a Wix 33040 (5/16) or 33041 (3/8) fuel filter. These filters have a built in 1/4" return line with an orifice built into the filter

You can mount them vertically or horizontally, just so the 1/4" return is on top

31KUuv21WdL._SL500_AA300_.jpg
 
that crappy gas they sell these days is the problem. i have a 1/4" gasket under my carb to help against that crap. just watch if you go with a thick gasket. its easy to crack a base plate if you don't tighten the carb down slowly and evenly..
 
If the spacer has smooth sides you can cut grooves in the vertical sides to increase the exposed surface area which will improve heat disapation, like a heat sink. Wasn't my idea originally but I thought it was a very good idea.
 
Yeah the gas is more of the problem than engine related but we have to do what we got to do I guess. I bet if it had good gas like the good old days you wouldn't have any trouble.
 
I appreciate all the advise and plan to add the 1/4 inch spacer this week, time is a factor. I need to get the lady cleaned up for the Southeast NSRA show, 14-16 Oct. and I don't want to start something I can't finish. I have this knack to turn a 10 minute project into a week long ordeal. There are a few other small problems that need attention and I think I would rather tackle them at one time rather than piece meal. I was also told that I need to jet the carb down as it is running a little rich. It has 72 in it now and it was sugested I drop a couple of sizes, I am not even sure how or why to do this. But as I stated in the first post, I am mechanically stupid and I seek help from people who know what to do. I need to find on site help and that is getting hard to do. I will keep you updated as I get things done.

Thanks to all of you.
 
I had the same problem with my 66 with a 273 added a 1/2 inch [phenolic] spacer it cured it,but now i'm having issues again the spacer is about 2 1/2 years old could be soaked plus the crappy gas, i'm buying non ethenol high test here tried a small amount last time but this time i'm gonna go for a full tank see what happens.
 
Yep, crap gas is the issues... A 1/2 inch phenolic spacer cured the problem on my 340.
 
lou3500 said:
I had the same problem with my 66 with a 273 added a 1/2 inch [phenolic] spacer it cured it,but now i'm having issues again the spacer is about 2 1/2 years old could be soaked plus the crappy gas, i'm buying non ethenol high test here tried a small amount last time but this time i'm gonna go for a full tank see what happens.
Click to expand...

Robb said:
Yep, crap gas is the issues... A 1/2 inch phenolic spacer cured the problem on my 340.
Click to expand...

lou3500, Let me know how that works out. A buddy of mine told me that there are three (3) places to get non ethenol gas in Hillsborough County.

Robb, I had to add a spacer to the 318 and it solved the problem but with the M1 intake there isn't enough room for a 1/2 inch spacer. I will try a 1/4 inch.
 
cuda67 said:
lou3500, Let me know how that works out. A buddy of mine told me that there are three (3) places to get non ethenol gas in Hillsborough County.

Robb, I had to add a spacer to the 318 and it solved the problem but with the M1 intake there isn't enough room for a 1/2 inch spacer. I will try a 1/4 inch.
Click to expand...

I had the same problem with clearance on my 410 with the air gap I found a "Drop Base " air cleaner allowed me to add the 1" plastic spacer the builder had supplied and got some increase in bottom end tq to boot
 
cuda67 said:
lou3500, Let me know how that works out. A buddy of mine told me that there are three (3) places to get non ethenol gas in Hillsborough County.

Robb, I had to add a spacer to the 318 and it solved the problem but with the M1 intake there isn't enough room for a 1/2 inch spacer. I will try a 1/4 inch.
Click to expand...

I'm thinkin i have some carb issues but i'm trying the gas treatment [lucas] and non ethy gas first i'll let you know when i get my first tank run thru we have two places that i know of here in pinellas close to me.
 
lou3500 said:
I'm thinkin i have some carb issues but i'm trying the gas treatment [lucas] and non ethy gas first i'll let you know when i get my first tank run thru we have two places that i know of here in pinellas close to me.
Click to expand...

I am pretty sure that the problem will be corrected with the spacer. As I mentioned earlier I had this same issue with the 318, Eddy 318/360 Performer with a 650 Holley and the spacer fixed it so I believe a spacer should do the trick. The thing that is confusing me is the M1 intake has air gap of about 2 inches or better so I don't know where the heat is coming from to make the gas boil in the bowl and force it out into the carb. I'll keep trying to get this right. :sad8::sad8: :banghead:
 
This may a stupid question but where does your exhaust exit. I had exhaust exit under the car and it would boil the gas in the tank. I ran it out the side and the problem was solved.
 
cuda67 said:
I am pretty sure that the problem will be corrected with the spacer. As I mentioned earlier I had this same issue with the 318, Eddy 318/360 Performer with a 650 Holley and the spacer fixed it so I believe a spacer should do the trick. The thing that is confusing me is the M1 intake has air gap of about 2 inches or better so I don't know where the heat is coming from to make the gas boil in the bowl and force it out into the carb. I'll keep trying to get this right. :sad8::sad8: :banghead:
Click to expand...

I have a spacer installed but recently she started to run a little funny not horrible just a miss every now and again [but not like it was ignition] i'm thinking i need to rebuild carb the ethy gas has messed up something plus change gas lines,filters ect. The spacer does work but it's been several years since installing it.
 
racerx23 said:
This may a stupid question but where does your exhaust exit. I had exhaust exit under the car and it would boil the gas in the tank. I ran it out the side and the problem was solved.
Click to expand...

My exhaust exits under the car just in front of the axle. I am planning to run the exhaust out the back after the NSRA show. I am a little older now and it is way loud with this 360. I thought the 318 was loud....... I don't think this is heating the gas tank but I will find out step by step. First try will be the spacer. My gas lines are not close to the exhaust, though.
 
My brother dumped his exhaust in front of the axle and it boiled his gas.Be careful taking your gas cap off when the car is hot.
 
cuda67 said:
I appreciate all the advise and plan to add the 1/4 inch spacer this week, time is a factor. I need to get the lady cleaned up for the Southeast NSRA show, 14-16 Oct. and I don't want to start something I can't finish. I have this knack to turn a 10 minute project into a week long ordeal. There are a few other small problems that need attention and I think I would rather tackle them at one time rather than piece meal. I was also told that I need to jet the carb down as it is running a little rich. It has 72 in it now and it was sugested I drop a couple of sizes, I am not even sure how or why to do this. But as I stated in the first post, I am mechanically stupid and I seek help from people who know what to do. I need to find on site help and that is getting hard to do. I will keep you updated as I get things done.

Thanks to all of you.
Click to expand...

Get yourself some 70 jets, they are small threaded brass pill looking things with a metered hole in the middle, about 7 bucks nowadays at a speed shop, fewer bucks on line. They have a screw driver relief in them so you can screw 'em in like a threaded insert. Get yourself a small bowl to catch some gas in. Remove the front bowl of the cold carb, lower corner screw first, itll be the hole that all the gas runs out of, just put your bowl under there (whatever side has more clearance) and unscrew the bowl bolt, The bowl is about 1/2 filled with gas so lots will pour out. remove the rest and catch the smallll bit of gas thats left when you break the bowl seal. The jets will be screwed into the plate between the bowl and the body. the block may try and come off too so hold it against the body when you break the bowl seal, you ll save yourself a gasket. Youll see the 2 brass jets right there on the lower 1/4 of the metering block. Unscrew them and screw the 70's in. If bowl gasket came off clean in one piece, your lucky. If it tore, clean off and get yourself a new one. Most chain parts stores have them in blue, (bring the remains of your old one to match up, there are about 4 different bowl gaskets that Holley used) they are the good ones anyway. Put bowl back on, but remember to put the Acc. pump lever under the spring loaded pump actuator, EZ to forget. They sell bowls that have access ports to make jet changing EZ-r but All they seem to do is make you buy the special jet driver and save you a 1 doller gasket.
 
68383GTS said:
Make sure your gas lines are away from the headers and anything else that gets hot.
Click to expand...

I agree.

And post a current picture of what your gas lines/routing look like that go from your fuel pump to carb.

I insulated my fuel line with Themosleeve covering from fuel pump to carb connection. I also ran Themosleeve on the hard line that parallels the header on the passenger side front frame rail. Also notice we routed the fuel line around the alternator instead of in the small space between the alternator and motor block. And it can get catch airflow to help cool it.

Also notice the fuel lines comming into and out of the fuel pump are straight and no 90 degree connectors. Our thinking/theory was that fuel making sharp turns created turbulance and could vapor lock quicker and reduce flow.

I've driven on two 80 mile each way trips in 90-100 degree weather. I cruised at around 3800-4000 rpm and them some (running late!). Then drove the piss out of it on a short autocross track and second trip on a road course. About 4-5 hours of on and off racing. Then drove home. No fuel boiling. I've got a MP M-1 intake too.
 

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pishta said:
Get yourself some 70 jets, they are small threaded brass pill looking things with a metered hole in the middle, about 7 bucks nowadays at a speed shop, fewer bucks on line. They have a screw driver relief in them so you can screw 'em in like a threaded insert. Get yourself a small bowl to catch some gas in. Remove the front bowl of the cold carb, lower corner screw first, itll be the hole that all the gas runs out of, just put your bowl under there (whatever side has more clearance) and unscrew the bowl bolt, The bowl is about 1/2 filled with gas so lots will pour out. remove the rest and catch the smallll bit of gas thats left when you break the bowl seal. The jets will be screwed into the plate between the bowl and the body. the block may try and come off too so hold it against the body when you break the bowl seal, you ll save yourself a gasket. Youll see the 2 brass jets right there on the lower 1/4 of the metering block. Unscrew them and screw the 70's in. If bowl gasket came off clean in one piece, your lucky. If it tore, clean off and get yourself a new one. Most chain parts stores have them in blue, (bring the remains of your old one to match up, there are about 4 different bowl gaskets that Holley used) they are the good ones anyway. Put bowl back on, but remember to put the Acc. pump lever under the spring loaded pump actuator, EZ to forget. They sell bowls that have access ports to make jet changing EZ-r but All they seem to do is make you buy the special jet driver and save you a 1 doller gasket.
Click to expand...

I will do that this week. Do you think 70 is what I need? I was leaning that way myself. Thanks for the great info. I bought the blue gaskets gotta get the jets. I have 65, 68 and 69 but no 70.
 
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