I am new to the forum. A guy gave me this truck after it had been sitting for 5 years in his driveway. He said he thought it had carb problems. I have rebuilt the carb, sealed the tanks, replaced fuel filter, etc. The truck idles good, but when approaching 2000+ rpm it starts sputtering and coughing with no power. Timing is good, and I have installed new plugs, wires, rotor button and distrib cap. I have replaced the hot air choke with electric, and sealed the intake where the hot air originated. My thought is that there is a vac system problem. The distrib vac line was hooked to the egr valve, and nothing is connected to the vac reservoir cannister. There is no vac amplifier under the hood, and I am certain other small components are missing. I have read several vac problem threads, and have become familiar with terms like tvv, vcv, etc. My dilemma is that I do not know what belongs under the hood.

Where can I get the factory correct diagram for this truck?

I have pics, but have not figured out how to post them on the forum. Any help is greatly appreciated.

 

Welcome to FTE !

These are for manual trans but the auto trans should use the same calibration I believe ..

1977


1978

 

Thanks for the reply. Any idea where to source the following parts:

spark delay valve
EGR vacuum amplifier
vacuum restrictor
fuel separator
cold lockout PVS

I think that there is a smog pump on the diagram above. My truck doesn't have one on it. Also, I have seen some diagrams that do not have an amplifier. Is it possible that mine did not ever have one? I want to fix this thing right. Thanks for the input.

 

for 77-78 light trucks the calibrations for the 351M were as follows



The calibration would have been determined by the sticker on the valve cover if it is still there and the vacuum diagram would be determined by that calibration number .. As far as the parts and their part numbers I don;t have that information ..

 

You might find the parts numbers your looking for in this thread
Also here and here

 

I read all of those. Very helpful indeed. I will look for the calibration code tomorrow when I go to my shop. Can the dealer tell me the calibration code from the VIN if I cannot find it?

I have been thinking about two issues.
1.) Did my truck ever have the vac amplifier and smog pump? With it being an HD truck, I know the smog requirements were less strict for 1978.

2.) If it did have them and since they are now gone, is there a way to route the vacuum to more or less work adequately without those components?

My primary problem is the vac advance and egr is not functioning.

 

The emissions equipment was based on GVWR and final destination of the vehicle .. Once you get the calibration numbers you can locate a new EGR and spark delay valve to match your OEM distributor .. Getting this working properly with new gaskets is half the battle .. Post back with progress or questions

 

Fortunately, I have the EGR installed with new gaskets. It is just not hooked up. My choke pull off is not hooked up either. Where do they usually get vacuum?

I will look for the code. The engine is a year 2000 Jasper rebuild. Maybe the code will be there. I have my doubts.

 

 

I looked at the truck this morning. Nothing is on the PS valve cover. On the DS I found a chart with idle speeds, etc. It says "Non-Catalyst" and the bottom of the chart there are these numbers: D-006 and D8TE9C485-VA. Nothing else.

I looked closer at the intake and the there is a capped nipple between the distr and carb. At the back of the intake and just above the oil sending unit, there is a vac port with 4 small nipples and 1 large nipple - 2 nipples capped, one hose going back into the firewall (I am guessing for A/C-Heat controls??), one hose going to another cannister on the DS fender (that has no outlet, not sure what the function is), and the brake booster is connected to the large nipple.

I looked at the chart, and I think the only rational calibration that would fit my truck is the 7-72-R11. The truck was owned locally since 1982 and has an engine heater and apparently, a transmission heater, also (there are two 110 plugs up front.) I would think that the truck was originally shipped someplace cold and not CA.

Given, this information, does it sound like the truck originally came with a smog pump and vacuum amplifier?

I posted some pics of my equipment in my album. The forum would not let me post them on the thread, yet.

 

From the same vacuum tree that the power brake booster is connected you should have a line going back to the vacuum modulator Passenger side of auto trans .. Yeah I would say there was no Air pump ..

This should be a vacuum reservoir .. gives you added vacuum volume so you don't run out @ low idle in critical braking scenarios i.e. foot off the gas going down hill ..

Is there a 3 port vacuum switch (temperature activated) anywhere ?

 

There is a 4 port swith on the T-stat housing. 2 nipples are capped off, one goes to the PS top of carb and one is laying there loose. Not sure where it goes. When I got the truck the distr vac line was connected to the EGR valve.

 

Your particular calibration had one maybe two ported vacuum switches (PVS) with more than likely a spark delay inline .. The 4 port PVS you have noted has a color and with that it will open and close ports at certain temps .. To determine if it's functioning and which ports open and close when is probably your next step ..

A PVS is set up to advance the timing of a cold engine, and possibly of a very hot engine like (230*F) depending on the calibration .. There are two vacuum sources supplied to the PVS, manifold vacuum and ported vacuum .. When the engine is cold, manifold vacuum is routed to the distributor vacuum advance canister .. Once the engine comes up to operating temp, the PVS will switch over to ported vacuum ..

The challenge here is to figure out what is still left of the original equipment and the calibration it was used in so as an end result that the current distributor curve is in harmony with the PVS/PVSes and the EGR installed .. Having this all functioning properly will mean added fuel economy without sacrificing performance ..

I'm sorry but I don't have any more time to spend on this today .. I'll check back tomorrow .. In the mean time here is some reading for you

 

That was an informative read. I didnt realize what exactly egr did and why.

It looks like I need an operable PVS that is connected to the, carb, distributor, and to the egr. I dont have the EGR control valve. Is it required?

If I knew what temperature was needed, I would replace the PVS as a starting point and work my way back. It would be great to find someone with it all hooked up and take a peak under the hood...Anyhow, thanks for the input. I am learning a lot.

 

https://www.ford-trucks.com/forums/8...questions.html

This guy has the same code on the DS valve cover, and apparently the same calibration, I think, that I have - 7-72-R11.

He found a yellow PVS. I am thinking that is what I need to get started.

What do you think about this? Get a 3 prong yellow PVS, connect the right end to the Carb (S port), the middle to the Distributor, and the left end (closest to the sensor) to the intake manifold nipple that I have which is currently plugged? The manifold nipple is between the carb and the distributor. I could put a spark delay valve between the distr and the PVS?

Then, how would I connect the EGR to a thermal vacuum switch?

If I understand what is needed here correctly, I need to have ported and thermal controlled vacuum advance on the distributor and I need to have thermal controlled vacuum to the EGR so that it will only open when the engine is warm. Can I get all of this in a 4 prong?

The EGR needs an on/off vacuum switch, and the Dizzy needs a switch between ported carb and intake manifold vacuum. Right?