Fast idle from air leak? M135

[Jeff Cal]

I've replaced the intake manifold gasket, and disassembled, cleaned, reassembled the Holly 2bbl. The thick rubber spacer and pair of gaskets under the carb may be leaking air. Can I discard the 1/4" thk spacer?
Thanks in advance, Jeff

 

[badgmc56]

The spacer is there to keep from boiling the fuel in the carb bowl. It raises the carb off and away from manifold heat.

 

[Jeff Cal]

Hi colonel,

Thats a reply that even a jar-head can understand - thanks much.

I can't locate a spacer, but I can get the two gaskets from Memphis Equip.
I'll pull the carb off again and inspect the spacer. Maybe I can make it work.

As soon as it stops snowing I'll clear the hood off (again) and get on with it. I'm so looking forward to firing it up again, after just getting it going before the cold weather set in.

Thanks again, Jeff

 

[jfnemt1ff1]

Might want to check at a hi/po speed type shop they might be able to come up with something.
John

 

[topo]

when you had the intake off the head where the three sleeves that fit in the head and intake there ? with out these rings air can get pulled in there also .

 

[Jeff Cal]

topo,

I looked for those sleeves, couldn't find them. Maybe I can find a length of pipe with the right dimensions and make them.

Anybody have a clue for me where I can get sleeve specs.

Thanks, to all.
Jeff

 

[topo]

Jeff I looked for some sleeves and only found some for a 235 they are to small . the sleeves for the 302 are 1 3/4 outside od and 3/8 to 7/16 wide they are split and springy to hold them in place . I have never made any of these before but you maybe able to use a large stainless hose clamp and cut it to length . just a idea .kenny

 

[rlwm211]

You can locate the air leak in your intake system by starting the truck. Then spray either carb cleaner or wd40 on all the gaskets and all the vacuum connections and any place where there is a gasket such as the carb base, and the intake manifold runner gasket to the head.. When the spray hits the leak the speed and quality of the idle will change.

It is possible you have another issue besides a leak at the base of the carb. A small vacuum leak can cause a high idle, as well as a worn carb body allowing air to enter alongside the shaft for the main butterflies.

As to the rubber spacer, they use all sorts of different materials for spacers on throttle body engines. From a hard heat resistanct plastic material to aluminum. You can make one if need be. It does not have to be rubber.

I would definitely test and make sure it is or is not the carb base as the source of the air leak before going to far into this.

Just my two cents
RL

 

[hippiedude]

I just pick up some carb. rebuild kits from popacom (Bill) send him a PM .if your in need .. Good price too ........ Tim

 

[butch atkins]

put a vacuum gage on the fitting at where the cranckcase ventilator hose is at on the intake manifold ,remove the square headee plug and connect the vacuum gage there ,that will tell you if you do in fact have an air leak,should have 18-21 on vacuum gage with engine at idle,if that is good next up should be to check timing and dwell ,if not check all the rubber lines fro the governor to the carb,and are you sure you reinstalled the carb return spring ,the one that hooks to the bottom of the arm on the carb to the hook on the the bolt that holds intake ex man togetjher,USE VACUUM TEST FIRST,that will eliminate issues of air leaks,keep posting,good luck

 

[butch atkins]

BTW ,if you put intake back on without the alingment sleeves ,your throttle linkage is for sure out of adjustment,check that also,that also means that the rod to the tranny shift control is ALSO out of adjustment,lot of possibilities here to make a lot of mistakes ,DONT FIX IT IF IT AINT BROKE,good luck,do you have a manual? TM 9-8024 is in the resorces section at the top of the page,I cannot stress the importance of the proper tune up procedures for these trucks to run as they should,GET A MANUAL

 

[butch atkins]

yet another post,running up the score,the sleeves are called pilots in the ORD 9 book,just went to garage and measured one,the outside dia is approx 1.755 inches ,the inside dia is approx 1.625 inches and they are.335 wide,these numbers are approx because the pilots have a split in them,so i hope this helps,should be really easy to make them out of 1 3/4 od x 1/16 wall tubing,good luck