My Ford 7.5 carburated motor is running rough

[trashman1995]

Originally Posted by Bilito

Got the Carb Kit on order from Holley, should be here Sat or Monday
Turns out I have a #4180 carb and the the Renew Kit Number
is #3-1346 should anyone need to sock that info away

There also a power valve plug kit you can install that would solve the power valve problem. Something to think of as an upgrade. Jmtc
Trashman

[jmerritt]

Here are abbreviations info you asked for hope it helps.

John

A/CL DV - Air Cleaner Diverter Valve
A/CL BI MET - Air Cleaner BiMetallic valve
ACV - Air Control Valve
MAN VAC - Manifold Vacuum
EXH HCV - Exhaust Heat Control Valve
PCV - Positive Crankcase Ventilation
SV CBV - Solenoid Valve Carburetor Bowl Vent
TVV - Thermal Vacuum Valve
LCV - EGR Load Control Valve
VCV - Vacuum Control Valve
VDV - Vacuum Diverter Valve
HICV - Hot Idle Control Valve
IVV - Thermactor Idle Vacuum Valve
TVS - Throttle Valve Solenoid (aka SolePot, Dashpot)
VCV - Vacuum Control Valve
HEAT VLV INT - Heat Valve Intake
TK - Throttle Kicker
VRDV - Distributor Vacuum Retard Delay Valve
AIR BPV - Air ByPass Valve (aka Thermactor Air Bypass = TAB)

BV - Bowl Vent
S - Spark port

[jmerritt]

Also, purge CV is/are the purge control valves for the fuel vapor canister(s). Could be only one but more likely two. Looks like in the diagram that maybe your distributor vacuum advance comes off of direct vacuum but only after going through a Vacuum Control Valve which may be temperature controlled off of engine coolant.

DST - Distributor
VCBV - Valve Carburetor Bowl Vent
V REST - Vacuum Reservoir Storage Tank

[Bilito]

Originally Posted by jmerritt

Also, purge CV is/are the purge control valves for the fuel vapor canister(s). Could be only one but more likely two. Looks like in the diagram that maybe your distributor vacuum advance comes off of direct vacuum but only after going through a Vacuum Control Valve which may be temperature controlled off of engine coolant.

DST - Distributor
VCBV - Valve Carburetor Bowl Vent
V REST - Vacuum Reservoir Storage Tank

You know I pulled the dist vac advance hose off the dist when the motor was all warmed up and it still had no suction on it, I even stuck it on my vacuum gauge to be sure. Three lines come off that temp controlled valve, one to the dist, one to each side of a vac valve assembly bolted on one of the pumps and of all of those only one had suction and it was not the one to the dist....?

[Bilito]

Originally Posted by Bilito

You know I pulled the dist vac advance hose off the dist when the motor was all warmed up and it still had no suction on it, I even stuck it on my vacuum gauge to be sure. Three lines come off that temp controlled valve, one to the dist, one to each side of a vac valve assembly bolted on one of the pumps and of all of those only one had suction and it was not the one to the dist....?

You may not believe this one. I pulled the hose off that temp valve again and there was some suction at the valve itself. I put the hose back on and there was no suction on the end of the hose, I took it off and tried to blow thru the hose and it was plugged????
Got a flashlight to look in the hose and darn, there was a steel ball in there plugging the hose. I thought it might be some sort of check valve, I tried to blow it clear from each end of the tube and nothing. I connected another piece of tubing I had to the valve and the dist and damn, the engine sped up a little and smoothed out. I cut open the hose end with the ball in it and it looks just like a steel BB and it was in there tight. It appears I had both a timing issue and a plugged hose to the vacuum advance

[whem2fish]

Ok someone make sure I am posting right yes there is a 2 digit number say it is 60 you put a decimal inbetween these numbers and this would be 6.0 for him to get the correct valve you need the motor running and in gear then take a vacumn reading then you minus 2 to get the correct one this was a long time ago

[jmerritt]

Sounds like you are on the right track but I am guessing you still have issues with the carb. Try the Lucas in the fuel bowls and see if that doesn't help. Varnish can be troublesome in a carb and the Lucas just might do the trick. Also, not sure why anybody would plug the vacuum advance line but given the engine timing issues it almost sounds like they advanced the motor to offset the vacuum advance and used only centrifugal advance. Really have to wonder what their thinking was.

john

[Bilito]

Originally Posted by jmerritt

Sounds like you are on the right track but I am guessing you still have issues with the carb. Try the Lucas in the fuel bowls and see if that doesn't help. Varnish can be troublesome in a carb and the Lucas just might do the trick. Also, not sure why anybody would plug the vacuum advance line but given the engine timing issues it almost sounds like they advanced the motor to offset the vacuum advance and used only centrifugal advance. Really have to wonder what their thinking was.

john

I was thinking about that same thing. I guessing back when they changed that motor under warranty back in 1999 they accidentally ended up with way too much advance (which we found) and it was so much trouble to take all that stuff off to get to the distributer, time it correctly, and then put it all back on again, they might have figured if they disabled the vacuum advance and it ran ok, they could collect their money, send it on it's way and hope to never see it again. Who ever would have thought that small almost inaccessible line would be plugged like that
The guy I bought the RV from was one of those 10 thumbs guys that could not find his butt with both hands and probably paid someone to do all the maintenance for him. As long as it started and ran he was happy.

This is running so good right now I can hardly wait for the carb kit to arrive so I can finish the job.

[Bilito]

Originally Posted by Bilito

You may not believe this one. I pulled the hose off that temp valve again and there was some suction at the valve itself. I put the hose back on and there was no suction on the end of the hose, I took it off and tried to blow thru the hose and it was plugged????
Got a flashlight to look in the hose and darn, there was a steel ball in there plugging the hose. I thought it might be some sort of check valve, I tried to blow it clear from each end of the tube and nothing. I connected another piece of tubing I had to the valve and the dist and damn, the engine sped up a little and smoothed out. I cut open the hose end with the ball in it and it looks just like a steel BB and it was in there tight. It appears I had both a timing issue and a plugged hose to the vacuum advance

This is what was plugging the vacuum advance tube, I had to dissect the tube to get it out.

[jmerritt]

As someone I think has already suggested there is a two stage power valve available that is not subject to rupture from a backfire through the carb. Also, were you able to find the idle adjustment screws?

John

[Bilito]

Originally Posted by jmerritt

As someone I think has already suggested there is a two stage power valve available that is not subject to rupture from a backfire through the carb. Also, were you able to find the idle adjustment screws?

John

I cannot find the screws there is too much plumbing and hoses in the way, and the carb is almost under the dash, gonna be a job getting it out, at least I can see the four mounting bolts

[Dave78Chief]

You are going to have to be able to adjust the idle adjustment screws to set idle mixture after you rebuild the carb. You might have to look at a few different auto supplies but they do make a screwdriver with a bendable spring shaft that allows you to access them easier. May be hard to locate because carburetors are no longer in vogue.

Dave

[monkey]

Idle mixture screws.... They are probably sealed with lead.... No biggy,, dig it out to get to the screws... Remember (write it down in my case) how many turns they unscrewed... Or do a search to find a base point for rebuilding....

[Dave78Chief]

Here are abbreviations info you asked for hope it helps.

JMerrit - I take it you pulled that information from a Ford Service Manual. Could you please list the noun name and ID number of that manual for future reference? Most ford trucks in the year range (86-91) had already been converted to Fuel Injection so trying to find reference documentation for the 89 460 carburated without a cat is a bit difficult

Thanks - Dave