i just cant win,, help.....
Thread Starter
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Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
hmm, the stock cam sure does make it run smoother. but I still think it may have a miss.
my vacuum guage reads between 16 and 18 in/lbs at idle,(fluctuation), then goes up with speed.
I played with the plug wires and timing light and they all seemed to be steady.
the cam I pulled out looked fine, no excessive wear or anything.
my vacuum guage reads between 16 and 18 in/lbs at idle,(fluctuation), then goes up with speed.
I played with the plug wires and timing light and they all seemed to be steady.
the cam I pulled out looked fine, no excessive wear or anything.
Thread Starter
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Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
heres another little piece of information,
when I snap the throttle, it revs up fine (accelerator pump is working) but when I try to open it slowly the vaccum falls way down (10 in/lbs) and the engine will not rev up. it will just suck air and die if I hold it like this. is this STILL a carburetor problem or would something else cause this?
I have since solved my fuel line issue and it now is getting plenty of gas (to the carb)
last night I did another compression test after it warmed up. I have good readings of 120-130psi in all cylinders. also checked all 8 spark plugs for spark, theyre all firing.
so I know I have good compression and spark. that leaves fuel. and back to the top^^^
when I snap the throttle, it revs up fine (accelerator pump is working) but when I try to open it slowly the vaccum falls way down (10 in/lbs) and the engine will not rev up. it will just suck air and die if I hold it like this. is this STILL a carburetor problem or would something else cause this?
I have since solved my fuel line issue and it now is getting plenty of gas (to the carb)
last night I did another compression test after it warmed up. I have good readings of 120-130psi in all cylinders. also checked all 8 spark plugs for spark, theyre all firing.
so I know I have good compression and spark. that leaves fuel. and back to the top^^^
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
Sounds like a passage in the carb still plugged to me. Extra fuel from the accel pump is giving it the fuel needed to rev. In a carb there are accel pump, idle,cruise, and power curcuits. So there are passages to get plugged. As I recall you've had issues with the carb for awhile.
Thread Starter
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Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
yes this carb has been giving me fits since the beginning of the whole ordeal of trying to make the truck run. that's been since January.
I have another 2100 laying on the shelf. maybe ill clean it up and give it a try...
I have another 2100 laying on the shelf. maybe ill clean it up and give it a try...
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
Please enlighten me on which carb your have as I'm lazy to go back and read through the whole post to see which carb. Sounds like carb problem to me. Close both air/fuel idle jets if engine keeps running power valve is bad.
Look down in the carb while working the carb linkage from idle to wide open and see if gas is being pumped out the two feed jets. No need for engine to be running if none or a little. Check the Acc pump. It could be the Acc pump check valve. Most are like a little red umbrella under the Acc pump diaphragm. But still could be a (vacuum leak)...orich
Look down in the carb while working the carb linkage from idle to wide open and see if gas is being pumped out the two feed jets. No need for engine to be running if none or a little. Check the Acc pump. It could be the Acc pump check valve. Most are like a little red umbrella under the Acc pump diaphragm. But still could be a (vacuum leak)...orich
Thread Starter
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Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
autolite 2100. I milled off all the choke mounting tabs and BS since the choke was never there anyway. so now its just the two barrels and 2 vaccum inlets. about as plain and simple as it can possibly be.
the accel pump works, and the umbrella is new.
I will close the valves and see if she still runs or not.
I don't think its a vacuum leak since it has ok readings at idle. im thinking the fluctuation is coming from a lean miss, due to this other problem...
the accel pump works, and the umbrella is new.
I will close the valves and see if she still runs or not.
I don't think its a vacuum leak since it has ok readings at idle. im thinking the fluctuation is coming from a lean miss, due to this other problem...
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
If that carb don't work let me know. I still have that Holley 500 CFM Superdeuce.
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Thread Starter
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Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
get ready, here it comes, guess what? YEP! another problem! WHOOOO HOOOO! if this thing ever starts running right I wont know what to do! haha.
anyway, my 7 & 8 cylinders are dead. they have spark at the wires, new plugs. good compression. I cant imagine why I wouldn't have fuel.... so... now what?
the good news is it runs great on the other 6 cylinders...
anyway, my 7 & 8 cylinders are dead. they have spark at the wires, new plugs. good compression. I cant imagine why I wouldn't have fuel.... so... now what?
the good news is it runs great on the other 6 cylinders...
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
get ready, here it comes, guess what? YEP! another problem! WHOOOO HOOOO! if this thing ever starts running right I wont know what to do! haha.
anyway, my 7 & 8 cylinders are dead. they have spark at the wires, new plugs. good compression. I cant imagine why I wouldn't have fuel.... so... now what?
the good news is it runs great on the other 6 cylinders...
anyway, my 7 & 8 cylinders are dead. they have spark at the wires, new plugs. good compression. I cant imagine why I wouldn't have fuel.... so... now what?
the good news is it runs great on the other 6 cylinders...
Thread Starter
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Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
no nipples right there, they are fed from different planes in the intake. there are no leaks from the outside of the gaskets, I was spraying some starting fluid around and nothing jumped up.
would a internal vacuum leak between those two intake ports cause this?
7 & 8 do not fire at all. I can pull both wires off at the same time and the engine does not run any differently. they are DEAD
would a internal vacuum leak between those two intake ports cause this?
7 & 8 do not fire at all. I can pull both wires off at the same time and the engine does not run any differently. they are DEAD
Senior User
Joined: Jul 2006
Posts: 409
Likes: 1
heres another little piece of information,
when I snap the throttle, it revs up fine (accelerator pump is working) but when I try to open it slowly the vaccum falls way down (10 in/lbs) and the engine will not rev up. it will just suck air and die if I hold it like this. is this STILL a carburetor problem or would something else cause this?
I have since solved my fuel line issue and it now is getting plenty of gas (to the carb)
last night I did another compression test after it warmed up. I have good readings of 120-130psi in all cylinders. also checked all 8 spark plugs for spark, theyre all firing.
so I know I have good compression and spark. that leaves fuel. and back to the top^^^
when I snap the throttle, it revs up fine (accelerator pump is working) but when I try to open it slowly the vaccum falls way down (10 in/lbs) and the engine will not rev up. it will just suck air and die if I hold it like this. is this STILL a carburetor problem or would something else cause this?
I have since solved my fuel line issue and it now is getting plenty of gas (to the carb)
last night I did another compression test after it warmed up. I have good readings of 120-130psi in all cylinders. also checked all 8 spark plugs for spark, theyre all firing.
so I know I have good compression and spark. that leaves fuel. and back to the top^^^
1) bent valves
2) cam timing not right
3) crack in the intake manifold
4) improper gap on points
A bent exhaust valve may close in time for you to get good compression, but not in time to prevent a total loss of vacuum to draw fresh fuel in on the intake stroke.
If you dont set the cam timing up with #1 piston at TDC, and the timing marks pointing at each other, you will get the same symptoms.
crack in the intake manifold will cause a loss of vacuum during the intake stroke.
Set your points and DWEL for this engine, not the engine that it came off of......
Thread Starter
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Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
7 and 8 wires have fire, I got jolted good a few times,
this morning I took the intake manifold off and it seemed like it was sealed up fine, no cracks that I can see.
the HEI unit has solved my revving problems, I just have two dead cylinders now.
since I know I have spark and compression, im thinking I must have a valve problem on those two cylinders.
before I pull the head and trash a $30 gasket, how plausible is it that I have burned, bent, or otherwise goofed up valves on the 2 adjacent cylinders?
this morning I took the intake manifold off and it seemed like it was sealed up fine, no cracks that I can see.
the HEI unit has solved my revving problems, I just have two dead cylinders now.
since I know I have spark and compression, im thinking I must have a valve problem on those two cylinders.
before I pull the head and trash a $30 gasket, how plausible is it that I have burned, bent, or otherwise goofed up valves on the 2 adjacent cylinders?
