First Gremlin........New 512 Stroker, can't handle the heat-get out of the kitchen.

[Propwash]

Hey Gent's...

Got my roadrunner on the road after a few years of ditching the wife for the garage, hiring Indiana Jones to find parts and turning my bank account into a funeral pyre. Anyways, driving around yesterday looking for trouble and the car started having some pretty significant vapor lock/fuel issues. Now granted this is a new motor and yesterday was 95F and humid, but she was having a real hard time with the heat. I shut it off and trying to restart was like trying to give CPR to a whale. Once I did get it going, it shaked and shuttered for a while. Even after a hard acceleration she wanted to die (and did once). Didn't matter if it was sitting in traffic or going down the road. Even a big bump or sudden change in pitch you could hear/feel the engine stumble. So, i'm coughing this up as a fuel heat issue, mainly because it runs great when cold and there is no vacuum leaks. Engine temp was running 190-200F.

I do have a trans-dapt 3/8" phenolic spacer under the carb (limited by hood clearance), the braided fuel line has the protective heat barrier on it where it get's within 6" of the headers. Crossovers are blocked just by design of the Indy intake. The engine itself had timing and fuel dialed in on the dyno via EGT sensors, A/F sensor and torque/HP curves and vacuum. So what would you guys recommend as the next step? Bigger spacer with a deeper drop base aircleaner? Wrap all fuel line in the engine compartment? Heat shield/sink for the carb or fuel pump? Bring up the float levels a little higher in the sight glasses (currently set at half)? Is this a matter of a few small variables, and being a new motor with the extreme heat is just adding a lot of fuel to the fire? I appreciate anyone's past experiences with this sort of issue and any remidies.

 

[67 coronet]

if there is anyplace the exhaust gets close to the fuel line you are much better wrapping the exhaust then the fuel line.heat radiates out,so blocking it at the edge or the exhaust pipe is much more effective then at the fuel line.what kind of fuel delivery are you using?mechanical,electric,w/wo presh reg,dead head,or return line?i would hope your spacer is enough for the carb,or that pig is making some monster under hood temps.

 

[krowbar]

I'm having the same problem. Had to put a new radiator in mine. Not enough flow through the once 4 now only a 2 core radiator. It's getting better . I was in the process of testing when I ran into a problem with my primary float full of fuel and flooded me out. Bought a 1/2" phenolic spacer and will put that on too, because the torker 440 intake gets pretty hot. Do you have a vented gas cap? I ha w a fuel cell in back w/ the rollover vent plumbed into the fuel filler neck trunk housing.

 

[Northwest]

Try wrapping the fuel lines to the carb. I had. A similar problem with my 512 and a heat wrap plus always using non ethanol gas has seemed to fix my problem. I think that in my case there was so little clearance between the intake and the fuel line to the carb that the gas was cooking on the way in.

 

[lewtot184]

you don't state what fuel pump your using and there may be something there. i use return lines on both my cars; nothing exotic. i think with the alcohol gas it's even more important to have some kind of return for the vapors and to prevent dead heading the pump. i have absolutely no vapor lock issues and i use mechanical pumps.

 

[Propwash]

Thanks for the replies guys. '67, pump is a Clay Smith Mechanical with a line running up to the fuel log for the carb (filter in between). Backside of the fuel log is a Holley Bypass regulator with a return line running back to the tank. I don't mind running header wrap being the headers are ceramic coated and can hold the corrosion at bay a bit better than paint/raw. If it will work better, i'm all for it. Spacer is just a plain phenolic composite, but like mentioned not very tall. I though about the MR. Gasket heat dissapater with the 4 gaskets and 3 aluminum spacers that total up to 1/2", but I have no experience with those.

Krowbar, I have the stock tank with the two vents in the front upper left corner of the tank. The tank cap is non vented, being it's location down low on the backside of the fuel tank. Radiator is a champion 3 core 26", with a 19" steel fan, jaguar clutch and Mopar shroud.

Thing that erks me is how much the car was effected when going down the road. Had plenty of battles in the past with other cars and hot fuel issues with hard starting after shut down, heating up in traffic and fuel boil, but this thing is running on the extreme side of it. I already set in place my book of tricks with a carb spacer, covering the lines, adequate cooling system and blocked crossovers, but the car's heat issue walked all over them.


Thanks lewtot and Northwest.....I have no insulation on the line from the pump to the carb, so I will do that tonight. I also have a roll of wrap I can put on the right header like '67 mentioned. Now where to find Non-Ethenol 93 octane is going to be a treat.

 

[70rr-brian]

Floats adjusted properly?

 

[Propwash]

Fuel in bowls sits half way up the sight glasses on primary and secondary side

 

[lewtot184]

what size is the return and are you regulating the return with some kind of flow orifice?

 

[Northwest]

Th Now where to find Non-Ethenol 93 octane is going to be a treat.

I run non-ethenol 92 octane in mine. 10 to 1 with aluminum heads.

Might just be your accent, but you from Wisconsin?

http://pure-gas.org/index.jsp?stateprov=WI

 

[Propwash]

what size is the return and are you regulating the return with some kind of flow orifice?

Fuel line is 8AN for inlet and return. Bypass Fuel pressure regulator is adjusted to 6.5PSI The pressure going out is the offset from fuel not consumed by the carb. As far as regulating that, I have nothing. I would guess that would wreak havoc with the bypass system if restricting flow against the regulated flow from the bypass regulator. Obviously I could be completely wrong though.

I run non-ethenol 92 octane in mine. 10 to 1 with aluminum heads.

Might just be your accent, but you from Wisconsin?

http://pure-gas.org/index.jsp?stateprov=WI

Pretty much the same set up Northwest 10:1, Aluminum heads....Pretty bad when you can't pick up an accent from reading script...LOL Yes, I'm from WI....eh Thanks for the link!

 

[krowbar]

Fuel in bowls sits half way up the sight glasses on primary and secondary side

I believe the level should be right at the bottom of the sights. Just like when you take the sight plugs out it should just dribble out.

 

[70rr-brian]

I believe the level should be right at the bottom of the sights. Just like when you take the sight plugs out it should just dribble out.

What he said and what is your initial timing?

 

[Hemirunner]

I would venture a guess that the return style fuel system is continually putting heat in the fuel as it's circulating. Insulate everything. Put a cool can in the system and see if the problem goes away. The spacer is good but the heat shields under the holley style carbs help out as well.

 

[Propwash]

Distributor is a mechanical ( No Vac/advance), curved and phased by 4 seconds flat. Very soft spring on the low side, hard spring on the high. Initial is set at 22*, full advance of 34* at 3500 RPM. On the dyno, below 22* the torque and HP curve had a stumble down low and recovered after about 500-600 more RPM. Advanced initial to 22*, negative spike went away. EGT Temps at 20* were hotter by about 150F in lower rpm's than at *22F. Along with peak vacuum, that's how we dialed in initial.

- - - Updated - - -

Where can one get one of these carb heat shields? Summit..folks like that?

 

[krowbar]

Distributor is a mechanical ( No Vac/advance), curved and phased by 4 seconds flat. Very soft spring on the low side, hard spring on the high. Initial is set at 22*, full advance of 34* at 3500 RPM. On the dyno, below 22* the torque and HP curve had a stumble down low and recovered after about 500-600 more RPM. Advanced initial to 22*, negative spike went away. EGT Temps at 20* were hotter by about 150F in lower rpm's than at *22F. Along with peak vacuum, that's how we dialed in initial.

- - - Updated - - -

Where can one get one of these carb heat shields? Summit..folks like that?

summit or jegs.... Local part store might be able to order it if you give them the part number.

 

[Propwash]

summit or kegs

I could go for a Keg right about now...lol Thanks

 

[70rr-brian]

Where is your coil mounted?

 

[Propwash]

Coil is mounted with a Mancini Racing Mount bracket (possibly made by AR Engineering) off the front of the intake, above the valley pan.

Sorry, only pic I could find:

 

[Hemirunner]

http://www.summitracing.com/parts/hly-108-70/overview/

While we're on the subject of ignition, did you eliminate the ballast resistor with that MSD coil?