Hi, I just joined. Hope someone can help me. I don't actually have a truck but a 1979 Ford Thunderbird Heritage with the 351M and 2bbl 2150 carb. I can't seem to get any help (no activity or maybe lack of knowledge?) on T-bird forums so knowing the setup should be quite similar between the truck and car, I came here hoping for some help.
I bought this over the past summer and had to do quite a few things to get it OK to drive (even though it did run and drive...it had a cool leak, dryrot tires,etc) but I can't seem to get it to run right. I rebuilt the carb, repl spark plug wires, cap, rotor, fuel filter, fuel pump, air filter, breather, radiator, t-stat, etc. Seems Ok when it's cold but after it warms up or I take it on a short drive, the idle is terrible. It has stalled on me a couple times and was a bear to restart, too. If I sit there at idle I can watch the tach go up and down erratically. I think it was between 500-800 RPM but not 100% sure. If I'm driving on the hiway it's pretty much fine and has lots of power although I swear I can feel a slight surge sometimes. I have checked for a vacuum leak and have not found any (using brake cleaner spray). Took the carb back off (I seem to think it's carb related, but could be wrong. Carbs are not my strong point) and checked the gaskets and even went to NAPA and had them see what they call for and what they should look like (the shop manual was no help). Everything seems good. I checked the vacuum and had about 17-18in, steady.
I took some pics of what I have as a set-up. I had to cut a hole in the gasket that sits on the manifold to match the one that came off. Just seems to me, looking at all the channels, etc; that there should be more passages in the gaskets? Although I can't really see the purpose of many of the pockets/channels, as they are blocked by the gaskets.
As you can see, I have the manifold, then a paper gasket (yes I noticed I had it flipped but it didn't seem to fit wrong. I have a spare one of those from the kit), then the aluminum spacer (I see no issues with the spacer. I have heard some are problematic), then a thick plate/gasket, then the carb.
Anybody a carb/351M/Ford whiz here that can help me out? Also I live in the Phoenix Valley if anyone may be local and can help me out in person.

Thanks,
Rich

 

Check the vacuum tree behind the carb. Notorious for rotten/leaking hoses. Also try plugging the hose to the booster, known to cause same problem when diaphram is ruptured

 

I've been giving that thing the evil eye, actually. Haha. Some of the hoses to it are hard but didnt seem to be leaking. I'm kind of afraid to touch it (might be brittle and break) but I was seriously considering just replacing all those hoses anyway. I'm pretty sure I tried the booster trick already but I don;t think I tried it while it was hot.

Plus this thing has like a bajillion vac hoses on it

 

It's a vacuum leak somewhere. Have you checked that worthless EGR? Have seen them hang open

 

You know what? I only checked to see if it was moving (stuck) and the pintle works. I didnt think the check to see if it is actually not seated all the way.
I thought about that while looking at the spacer today and realizing it's self contained in that spacer plate setup (no tube connected to the exhaust manifold) but not 100% sure how to see if its leaking. I actually dont even need it since I'm running under classic insurance and no emissions required on it but not sure how to bypass it (or if I should). You think that could act up mainly hot?

 

Fashion a block-off plate

 

Do you think if I just use a new gasket at the manifold but dont cut out the egr hole in it...would that work(at least long enough to determine if thats the issue?)
I'm still gonna replace all those vac hoses at the tree anyway.

 

Not a chance

 

on my 400, I had the motorcraft 2150 carb with the EGR stuff. I replaced the carb with a Holley 2300 model 500 cfm 2 barrel carb(not cheap, but got me what I needed/wanted). I took the EGR plate off and put a thick gasket under it, to block off the EGR, the the plate(used as a spacer now) then a thin gasket, then the carb. The Motorcraft is good enough for regular use, but if you want a little more response the Holley is recommended.
For the stalling. Uh oh... check vacuum lines, you should have one going to the power brakes, transmission modulator valve(***if you have an automatic tranny), and one going to the heater/ac selector in the dash(depends if yours has it). If the lines are ok, idle it up. If it is still stalling, your brake booster might be pulling too much vacuum or your motor is losing compression in one or more cylinders.

 

Yeah, a simple fix is likely out of the question. Looks like I have more stuff to check. I am definitely going to replace all the vacuum hoses and try blocking off the booster again to eliminate those possibilities.
So am I reading this right? Sounds like you basically swapped the thin gasket (under the egr spacer) with the thick gasket (on top of the egr spacer) to plug up the manifold port for the egr??

 

Just for grins check your timing chain. Pull the cap off the distributor. Rotate the engine until you see the rotor move. The, reverse the engine and note how many degrees of crankshaft rotation you get before the rotor moves. Some say over 5 degrees it's time for a new timing set. (and you can get one that will run your cam at 0 degrees, instead of the 4 degrees retarded in might be at now. Free power.)

Just a thought, as the idle change can be the result of wandering timing.

Good luck with it.

Check out this forum regarding the 400 builds. You think you have power? How would you like 400 hp?

 

yes. you are correct FoMo. I use a thick carb gasket between the EGR plate and the intake manifold. Another way to block it off is to weld it with a mig or tig welder on a low heat setting.( it is aluminum, it will melt.) I don't think there is any other way to get "rid" of EGR without switching to a 4 barrel intake manifold. If it helps you're concerns about sealing it even more, you can use Form a gasket or black oil resistant form a gasket and make a small bead outlining the EGR hole(s).

 

the aluminum plates can burn through causing a vacuum leak from the exhaust side to the intake. gasket material will also eventually burn through and EGR operation will be restored whether you want it or not, including the vacuum leak if there is a burn through in the aluminum. it's easy enough to make a metal plate and gasket each side but the carb is calibrated for EGR, disabling it will cause air fuel ratio problems

the gasket between the manifold and the plate needs to be made of good quality material to withstand exhaust exposure, basically it's an exhaust gasket on the intake manifold... regular carb gaskets may not last long

have you checked the mechanical advance in the distributor to make sure it's not stuck?

sounds like it could be a vaccum line problem too, is there a vacuum doohicky on the waterpump?
they use a temp operated switch to control vacuum to the distributor, maybe the hose that is supposed to work when the engine is warm has a crack in it

i'd replace all the vacuum hoses (one at a time)

 

OK, so it sounds like swapping the gaskets isn't a great idea. As far as I can tell the spacer is in really nice condition. I don;t see any evidence of melting or damage. Where do they usually go bad? I have never pulled the egr off the end of it and looked there.
I tried checking the timing but I already had the engine hot and couldnt see the marks and didnt feel like crawling under and looking for them at that time. I'll have to try the manual manipulation and see how play is in the rotor.
I was told by someone to check for play inside the distributor (side to side?) but didn't find anything (if I was checking it correctly). As far as the ported vacuum switch goes..yes...there is one at/near the water pump (I'd have to go look to see the exact location) but there are no hoses attached to it and nothing loose in the engine bay. The hose for the distributor vac advance is coming from somewhere else but had no vacuum when I checked it so not sure when (or if) it's ever getting any vacuum.
Sorry if I sound like a dummy but when it comes to carbs and old-school stuff I'm not as proficient as with the newer stuff. We barely touched on them in training and being drenched in emissions crap makes it worse.
How can I check the vacuum advance and see if it's working right?
Believe it or not...having the shop manuals doesn't always help. Every time I look something up it either never specifically details the area I need to know about or is too vague (like you should already know).
I appreciate all your help and hopefully can figure this out. It's nearly come to the point where I was ready to just sell it and concentrate on my 64 except I promised the old guy I would keep it and restore it and that's the only reason he sold it to me. It was his deceased wife's car and he cried when the tow truck took it away.
BTW...here's a pic of it.

 

Right now I'll just be content to get it running so I can actually drive it in traffic without having to give it gas at stoplights so it doesn't stall!!!!!