metalmonkey47 Posted October 18, 2011 Report Share Posted October 18, 2011 Just parked the truck. I have no power above idle. Just put on an accelerator pump, new condenser, ign coil, points, etc. Popped the hood and the sightglass in the carb is bubbling :/ Quote Link to comment
datzenmike Posted October 18, 2011 Report Share Posted October 18, 2011 Like boiling? Engine is running too hot. Have you set the timing??? Too retarded will have no power and the exhaust will get glowing hot. This will heat up the carb too. Try turning the dizzy clockwise while idling. The idle speed will increase if you are going the right way. Quote Link to comment
banzai510(hainz) Posted October 18, 2011 Report Share Posted October 18, 2011 Is carb really HOT or is it just air bubbles. Now you said this was fixed? so It was running OK the last day or so? Need to be specfic as it will help trouble shoot. I dont know what a 76 has for a intake exhaust set up as I know one usued a mated intake and exhaust which used a heat plate. if its getting hot then it should work Ok when cold. Then when hot goes bad then you know its the proplem.Its a funky heat plate system to warn the intake manifold. I hate em!!!!!!! I LIKE THE HOT WATER LINE SYSTEMS otherwise maybe the stock car get a few bubbles in there. you said this was timmed Ok right? I cant remeber all the posts Quote Link to comment
metalmonkey47 Posted October 18, 2011 Author Report Share Posted October 18, 2011 (edited) This is with it off on the side of the road. Click for video Seems like it may be pulling in air. I set the timing, and I think this is not going to be related to spark here. I do not have a good mist of fuel in the carb. It's kinda..... crappy is the easy way to put it. Inconsistent if you want the technical term. Gonna pull the carb when it cools off. Good thing I got a rebuild kit! Edited October 18, 2011 by metalmonkey47 Quote Link to comment
Guest 510kamikazifreak Posted October 18, 2011 Report Share Posted October 18, 2011 Hows the filter. Quote Link to comment
datzenmike Posted October 18, 2011 Report Share Posted October 18, 2011 MM yours is a '76 so it has the L20B wih the co-joined intake and exhaust (unless you changed it) Under the intake below the throttle cable, on the exhaust manifold is a spring loaded valve, called a heat riser. It should easily turn by hand and is closed when cold and as the spring warms up and expands, closes. When cold, and open, hot exhaust is directed up onto the underside of the cold intake to warm it. When the motor is warmed up the valve should close this off. If the valve is stuck open it will overheat the carb. In the picture below there is a rod sticking out of the exhaust manifold on the right side. There is a spring coiled around it and a small weight attached with a screw. This rod should easily rotate by hand, and works a valve to direct exhaust upward. Here you can see the two manifolds bolted together.... This thin little plate is sandwiched between the manifolds and gets very hot from exhaust on one side and warms the cold intake air on the other. If the valve were to stick open with the enging warmed up it would over heat the air and probably the intake and the carb on it. (those holes are where the carb sits on the intake looking up from underneath) . Quote Link to comment
banzai510(hainz) Posted October 18, 2011 Report Share Posted October 18, 2011 Like I said earlier is it really getting HOT???? Touch the glass. going by the vid I hear motor reving up . Really it look like gas is filling in the bowl . maybe its sucking air in thru the glass gasket area. Dont matter it idles so you know it has enough vaccum dont be in a Rush yet to pull a stock carb apart!!!!!!!!!!!!!!!!! timming is set? is it in the middle of the timming plate or cranked over to one side to ge the timming? Are you still running the .8 ohm ballast in there or you put the stock ballast resisitor BACK in there???? To much current could be saturationg the points /condensor I would let it cool off then run it but I have a feeling the carb is just bubbles and not BOILING Quote Link to comment
hogboy52 Posted October 18, 2011 Report Share Posted October 18, 2011 The float bowl is normally vented to the outside air but this one is sealed with a brass fitting and line to the manifold vacuum to draw off gas fumes. I can see it at the 2 o'clock position. The bubbles are air drawn in through the bottom of the accelerator pump which may be why the pump doesn't work well. The fuel level looks to be too high but I can't see where the line is. The float also looks like it has sunk some. It's brass and might have leaked some fuel inside. I would take the line off the bowl fitting and plug the manifold end. Quote Link to comment
datzenmike Posted October 18, 2011 Report Share Posted October 18, 2011 The float bowl is normally vented to the outside air but this one is sealed with a brass fitting and line to the manifold vacuum to draw off gas fumes. I can see it at the 2 o'clock position. The bubbles are air drawn in through the bottom of the accelerator pump which may be why the pump doesn't work well. The fuel level looks to be too high but I can't see where the line is. The float also looks like it has sunk some. It's brass and might have leaked some fuel inside. I would take the line off the bowl fitting and plug the manifold end. If there is a vent on the fuel bowl (some later ones and California ones had it) it goes to the charcoal canister which stores fumes until the motor starts. When running fumes are drawn into the carb to be burnt. The fuel bowl is not normally under any vacuum from the intake. Not seeing anything out of the ordinary in the picture at 2 o'clock. Quote Link to comment
metalmonkey47 Posted October 18, 2011 Author Report Share Posted October 18, 2011 Gonna reply to you guys in detail later since I'm off to work, but for now I'll let you know what I see. Pulled the carb and rebuilt it. All jets were clear, but I had some garbage in the float bowl and in the accelerator pump thingy. I got it on now and it's running even worse. When you put your hand over the top of the carb running, theres a ton of bubbles pulled into the float bowl. ECK Quote Link to comment
hogboy52 Posted October 18, 2011 Report Share Posted October 18, 2011 The right side of the lid I see now is the fuel inlet but on the left side it looks like a hose going somewhere. It looks too cluttered for a '76 model carb. Those are air bubbles and are coming from what would normally be the fuel inlet to the accelerator pump. It seems that also air must be being drawn out. The small BB at the bottom of the pump that acts as a one-way valve may be missing. In any case it could hardly have any fuel in it to be pumped into the carb. Quote Link to comment
banzai510(hainz) Posted October 18, 2011 Report Share Posted October 18, 2011 weber carb time. I could never rebuild a stock carb. Quote Link to comment
datzenmike Posted October 18, 2011 Report Share Posted October 18, 2011 The right side of the lid I see now is the fuel inlet but on the left side it looks like a hose going somewhere. It looks too cluttered for a '76 model carb. Those are air bubbles and are coming from what would normally be the fuel inlet to the accelerator pump. It seems that also air must be being drawn out. The small BB at the bottom of the pump that acts as a one-way valve may be missing. In any case it could hardly have any fuel in it to be pumped into the carb. Maybe the gas is just boiling? Quote Link to comment
Boaty Posted October 19, 2011 Report Share Posted October 19, 2011 If you block off the intake of the carb, you're presenting a lot of vacuum into that float chamber. Either you have a bum gasket, or you have a crack somewhere in that float chamber. My guess is that the reason it is running like crap, is a nice little vacuum leak. I vote for a Weber. Quote Link to comment
Boaty Posted October 19, 2011 Report Share Posted October 19, 2011 FWIW Hainz, I'll never even attempt to rebuild a stock carb again. I'm with you on the Weber idea! Quote Link to comment
metalmonkey47 Posted October 19, 2011 Author Report Share Posted October 19, 2011 (edited) Stock carb went to shit. Got a Weber from Hitch this morning. Just finished a basic cleaning (all jets, passages cleared) Can't wait to hear it run again! Mike, the carb was cold when it was bubbling. I'm sure it was just a vacuum leak. Also, I don't have that manifold on the truck. Someone has swapped it, but I do have the stock U67 manifold if I ever decide to go back to it. Edited October 19, 2011 by metalmonkey47 Quote Link to comment
banzai510(hainz) Posted October 19, 2011 Report Share Posted October 19, 2011 you have a adapter and assioated stuff to go with it.??? As you knwo the weber is wider and needs a adapter. There are at least 3/4 types out there. and gaskets might be needed. People say they are a direct install but they are not . theres lettle things that need to be planed out. Return spring cable set up(if comes wiht he weber cable holder or you adapt the one you have. I could never fix a stock carb. To me it was like a Rubix Cube. I said Fuck it, a used 100 weber was ezer to install. Quote Link to comment
metalmonkey47 Posted October 20, 2011 Author Report Share Posted October 20, 2011 you have a adapter and assioated stuff to go with it.??? As you knwo the weber is wider and needs a adapter. There are at least 3/4 types out there. and gaskets might be needed. People say they are a direct install but they are not . theres lettle things that need to be planed out. Return spring cable set up(if comes wiht he weber cable holder or you adapt the one you have. I could never fix a stock carb. To me it was like a Rubix Cube. I said Fuck it, a used 100 weber was ezer to install. Yup, got the adapter with the weber. it's a tall one, but it fits great. Made some gaskets out of some Fel-Pro material I got at work. Temprarilly hooked the return spring at the front of the carb just long enough to drive it. Weber runs great! Other then a slight leak @ the accelerator pump, it's awesome. I'm waiting for the replacement in the mail before I drive it. Quote Link to comment
banzai510(hainz) Posted October 20, 2011 Report Share Posted October 20, 2011 good to hear. get a better ignition/dizzy set when possible. Pertronix or matchbox. Seen soem guys on here with l16 pertronix conversion dizzys for sale for 50$. or matchbox up to 75 would be a good deal. Quote Link to comment
metalmonkey47 Posted October 20, 2011 Author Report Share Posted October 20, 2011 I got a non-matchbox electric dizzy to go on when i got the carby. I'm gonna get a cheap MSD ign for the control module. Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.