Date: Wed, 24 Sep 1997 20:26:49 -0600 (MDT)
From: (fordtrucks61-79-digest)
Subject: fordtrucks61-79-digest V1 #239

fordtrucks61-79-digest Wednesday, September 24 1997 Volume 01 : Number 239

Ford Truck Enthusiasts - 1961-1979 Trucks Digest
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In this issue:

Stock rim/tire size? [Joe D ]
Amp meters & Shunt []
RE: Amp meters & Shunt [ (Graphics & Research Fabrica]
[Fwd: funding] [Stuart Varner ]
Re: Stock rim/tire size? ["Gary, 78 BBB" ]
RE: 76 Ammeter [Tom Hogan ]
Re: [Fwd: funding] ["Gary, 78 BBB" ]
Re: 351M Cam Timing ["Dave Resch"]
FW: ammeter [Tom Hogan ]
RE: 351M Cam Timing [Tom Hogan ]
(Fwd) 1968 Tran. and Cyl Head questions.... ["KEN DUKE"
Re: FW: ammeter []
Fuel tank coatings []
Re: BTU's 'R' us.. []
Re: Flathead Help (Ignition math..) []
351 M Cam Timing ["Dale and Donna Carmine" ]
Re: Fuel tank coatings [Randy Collins ]



Date: Wed, 24 Sep 1997 07:15:14 -0400
From: Joe D
Subject: Stock rim/tire size?

Anybody know what the boggest tire you can put on a factory 68 steel
rim????Can I get a 31 on it????


Date: Wed, 24 Sep 1997 08:51:39 -0400
Subject: Amp meters & Shunt

What value SHUNT did you use??? The list needs to know. I ,in
particular, need to know. Also what is the composition of the SHUNT?
Wire or carbon or ????????


Date: Wed, 24 Sep 97 09:02:57 EDT
From: (Graphics & Research Fabrication)
Subject: RE: Amp meters & Shunt

Does anyone know if Ford ever issued a TSB on the nonfunctioning ammeters?
The ammeter on my 80 Bronco never worked but I didn't realize that it could
be an entire group that was affected!



Date: Wed, 24 Sep 1997 10:11:18 -0700
From: Stuart Varner
Subject: [Fwd: funding]

Date: Wed, 24 Sep 1997 10:07:02 -0700
From: Stuart Varner
X-Mailer: Mozilla 3.01Gold (Win16; I)
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Subject: funding
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As a former subscriber/donator - now returning from summer break - I
encourage all who have the means to submit a dollar or two. Ken does a
Kick butt job with the list. Few in this world have the consideration
and expertise to do what Ken does. Not only is he a true Ford BLUE gear
head, but he has the abilities to help so many of us through the list he
maintains. In our quest to better our GM/Mopar/Foreign counterparts,
Ken provides this great service at no cost......dig deep. You'll be
giving up one meal at Micky D's for a wealth in return. Enough

Any one know where I can find a really nice set of Custom badges for the
68-72 F-100/250
trucks which go on the bed? Anyone with knowledge of a new gearshift
knob for a 4 speed

1 3

2 4 R pattern?

Also looking for an 82-83 84 Mustang Ford Autolite 2BBL with the LARGER
(tall) power valve on the front of the carb. Core unit will do if in
decent shape. Any help would be appreciated. Private email reply is
great. STU

71 F-100 4x4
89 Grand Marq - Soon to be replaced with a 96 COBRA 4 CAMMER
95 Special Service Crown Victoria
Nuke GM!


Date: Wed, 24 Sep 1997 12:05:21 +0000
From: "Gary, 78 BBB"
Subject: Re: Stock rim/tire size?

> Date: Wed, 24 Sep 1997 07:15:14 -0400
> From: Joe D
> Subject: Stock rim/tire size?

> Anybody know what the boggest tire you can put on a factory 68 steel
> rim????Can I get a 31 on it???? joe +-------------- Ford Truck

It really has to do with the width factor more than height. Stock
rims are probably 6" and will take up to the old "H" width with no
problems. I think that is like a P225 now. If you go to the "sized"
style then treads up to about 8.5" can be used on a stock 6" rim but
that's pushing it. I put 33x12.5x15 wranglers on 6" rims and it was
fun but really balloony and not safe at highway speeds due to bending
the bead away from it's seat in the rim. A 10.5 is supposed to go
on a 7 or 8" rim and a 12.5 can go on either an 8" or 10" rim etc..

BTW, I just read another tire test and guess what 35" Goodyear AT's
and MT's measure? Fully inflated to 30 psi and unladen 32-7/16 and
32-5/8 respectively. Now I know how these guys can run "35's" on
their unmodified broncos! :-) Buyer beware!!! If you are buying
tires to gain ground clearance you better take a tape measure with
you :-)

The swift of foot and slow of wit
have more off road experiences

- -- Gary --


Date: Wed, 24 Sep 1997 09:27:36 -0700
From: Tom Hogan
Subject: RE: 76 Ammeter

I don't know how the '67 circuit is set up. If someone out there has a
schematic maybe they could tell us if it shows a shunt present. The way
I checked mine was to pull the instrumet cluster, followed the ammeter
traces to the wiring harness to find the wires feeding it and then I
checked the resistance across them. Expect a very low reading if there
is any resistance. Ammeters have a low internal resistance and it
doesn't take much reistance in parallel (in the shunt) to direct a
significant current to the meter.

I also connected the hand held ammeter on my DMM to the wires and
started the engine. Read zero amps at the dash. Both of these
measurements together led me to believe that the shunt resistance was
too low to allow any current to flow to the dash.

Date: Tue, 23 Sep 1997 22:50:46 -0400
From: DC Beatty
Subject: RE: 76 Ammeter

I sent this on the new list to see if it works. Thanks for all your hard
work Ken. You are the master!!!

Mine doesn't work either. Could this be the same on the '67??

Thanks, =

DC Beatty
1967 F100 352
1974 Maverick 302

You wrote:

there is an error in the circuit design from Ford. The meter is of a
shunt type design. The current goes through the meter (no loop on the
back of the meter). Ford probably did not want to have to rout all of
the current through the meter on the dash (good idea, prevents shock
hazard, electrical fires and if meter dies so does the charging circuit)
so they put a large shunt across the leads to the meter. This would
work if the shunt has a little resistance in it. Mine was pure copper
wire and the reason the meter did not work is that there was not enough
resistance in the shunt to deflect some current through the meter.>>


Date: Wed, 24 Sep 1997 12:44:19 +0000
From: "Gary, 78 BBB"
Subject: Re: [Fwd: funding]

> Date: Wed, 24 Sep 1997 10:11:18 -0700
> From: Stuart Varner
> Subject: [Fwd: funding]
> Any one know where I can find a really nice set of Custom badges for
> the 68-72 F-100/250 trucks which go on the bed? Anyone with
> knowledge of a new gearshift knob for a 4 speed
> 1 3
> 2 4 R pattern?

Looks like the same as the NP 435 or T-18. Might work eh?

The swift of foot and slow of wit
have more off road experiences

- -- Gary --


Date: Wed, 24 Sep 1997 10:36:41 -0600
From: "Dave Resch"
Subject: Re: 351M Cam Timing

>i am sorry, but you misunderstand. there is a connection between the cam
>and the cam gear, let's call it the cam button. this connection is used
>when machining the cam to grind the lobes relative to crank position
>is relative to cam gear position on a factory cam gear and chain.) the
>factory basically ground the cam with the whole lobe pattern moved.

Ooops! You're right. I misunderstood. Your explanation above is correct.

I believe you are not in this class, sleddog, but some people I've met
would swear that cams are ground with retard or advance built in. When I
was buying a cam at Super Shops about 2 years ago, the counter chimp swore
that Comp Cams grinds a certain amount of advance into their cams. This
was a guy who supposedly raced his own 5.0 Mustang, too! I gave up trying
to explain valve timing events to him and just ordered the cam anyway.

Dave R. (M-block devotee)
1980 F250 4x4 351M


Date: Wed, 24 Sep 1997 09:46:59 -0700
From: Tom Hogan
Subject: FW: ammeter

The shund was located in the wiring harness that connects the
alternator, voltage regulator and battery side of the starter solenoid.
Near the starter solenoid the harness has three other connectors, one
has 1 wire, one has 2 wires and one has 3 wires. The 3 wire connector
has a black, a red and a yellow wire. The black wire is larger than the
other 2. The yellow and the red wire connect to the ammeter in the
dash. If you remove the harness and unwrap it there is a very large
black wire that connects between the red and yellow wire. That is the

The resistance wire that I used had pink insulation it was 60 inches
long and had about 1.5 ohms resistance. This converted to 0.025 ohms
per inch. I had calculated that I needed 0.0128 ohms (I calculated the
internal resistance of the meter to be 0.7ohms). I figured 0.025 ohms
was close enough. Next problem was that the resistance wire was a small
diameter and wouldn't carry the current if the alternator had to go to
max output. I estimated that the resistance wire was 1/6 the diameter
of the shunt so I multiplied the length by 6 and cut 6 sections of wire.
Six 6 inch long resitor wires in parallel have the same resistance as
one 1 inch long resistor wire (Ohm's law for parallel resistors).

I cut the shunt in the middle, twisted the 6 resistor wires together and
soldered them into the shunt. I ended up with a lot more resistance
than I wanted but so far it just makes the needle more sensitive. Like
I said, I may try to reduce the resistance later or I may just put a
fuse inline with the meter to protect it from spikes. Under normal
operation it doesn't reach full deflection even with headlights,
airconditioner, radio etc on.

Disclaimer: I don't know how this will work long term or if it will
cause a fire or shock hazard. I am willing to do this to my own truck
because it is my truck. If anyone does try this be VERY careful to
properly insulate all of the connections. I realize that I risked
shorting something out or overheating a harness. If you want to try to
duplicate this consult with someone that knows auto electronics to help

>From: Mike Masse[]
>Sent: Wednesday, September 24, 1997 7:57 AM
>To: Tom Hogan
>Subject: ammeter
> I've been wondering about the ammeter myself. Where is the shunt
>you were refering to, and what is the approximate resistance wire
>you're using?
>Mike Masse
>'78 351M/C6/3"-Lift/33"-BFG's


Date: Wed, 24 Sep 1997 09:56:40 -0700
From: Tom Hogan
Subject: RE: 351M Cam Timing

My last issue of Hot Rod had a pretty good tip for setting cam timing.
In addition to a timing wheel they suggested to us a compression tester
and crank the engine a few turns. Whichever setting yeild the highest
pressure is the best to use. I don't know how this would affect
detonation etc. Just passing it on.

Date: Tue, 23 Sep 1997 17:05:22 -0400
From: Sleddog
Subject: RE: 351M Cam Timing

i am sorry, but you misunderstand. there is a connection between the
and the cam gear, let's call it the cam button. this connection is used
when machining the cam to grind the lobes relative to crank position
is relative to cam gear position on a factory cam gear and chain.) the
factory basically ground the cam with the whole lobe pattern moved.
there is a possibilty, i am not sure, that they made the cam gear
instead, which would mean that replacing the timing chain set with
something like a cloyes double roller chain would then, if installed
straight up, put the cam off of the factory position by the amount they
moved it for emissions purposes.
i am not sure which way they did it. to me it doesn't matter because i
will always put in a new cam-lifters-timing chain on a rebuilt engine.
but, aftermarket cams are straight up when installed with a aftermarket
timing chain with the zero deg. marks lining up. and the cam companies
to install their cams straight up on factory chains too i think, which
leads me to beleive that the cam has the whole pattern moved relative to
the cam button on the end of the cam that engages the cam gear.



Date: Wed, 24 Sep 1997 13:54:13 EST5EDT
From: "KEN DUKE"
Subject: (Fwd) 1968 Tran. and Cyl Head questions....

I have a 1968 F-100 with 3 spd and 352 V-8....

...what type of Auto Transmission would "bolt-up" and is there a
match that would prevent changes to drive shaft, etc.???

...are competition/performance heads available? Any suggestions?

thanks, KD

Ken Duke
Assistant to the Dean Phone: (706)542-1911
College of Pharmacy FAX: (706)542- 5269
The University of Georgia E-Mail: KDUKEMERC.RX.UGA.EDU
Athens, GA 30602


Date: Wed, 24 Sep 1997 14:58:59 -0400 (EDT)
Subject: Re: FW: ammeter

the law of relativity indicates that a fuse will not save your meter needle
in the event of a current spike.....your math was very good, though :-)


Date: Wed, 24 Sep 1997 13:58:07 -0700
Subject: Fuel tank coatings

Well, I've got the bosch heater nearly installed in the truck.
I built a nice little 2 gallon fuel tank for it that lives
alongside the frame rail, but before I bolt it up I wonder if
I should coat the inside of the tank to keep it from rusting?

Any advise on fuel tank coatings? (favorite types, etc?)
Should I even bother?
It's made of clean, rust free 1/8" thick material, is it necessary to
coat it?


Steve Delanty


Date: Wed, 24 Sep 1997 13:58:03 -0700
Subject: Re: BTU's 'R' us..

Wow! Thanks to all who replied to my quest for more heat in my 71 F100.
You guys gave up a ton of good suggestions!

I wont try to reply to all the posts, but they were all appreciated,
and here's a summary of them and my efforts to get warmer:

* The cooling system is in good order, no leaks, holds pressure, has
recovery tank so the radiator stays full, good working thermostat, etc.

* The heater and bypass hoses are hooked up correctly.
(Not much choice with FE.)

* The heater core, coolant valve and hoses are new.

* The coolant valve is working and opens fully.

* The heater core doesn't have an air pocket in it. This is one I
hadn't thought of yet, so I "burped" it last night.
(with the garden hose, got a good stream thru it for a while, then closed
the heater valve and hooked the hoses back up before any water could
drain out. No air, no difference...

* Coolant is 80% H2O and 20% glycol with a pint of redline water wetter.

* The heater fan works fine, moves lots of air, just not very hot air.

I think that I've run out of good possibilities, altho I will try
Dave's suggestion about restricting the bypass line and see if that
helps. I'll be changing intake manifolds next week, so it's a good
chance to try that.

Maybe I just expect to much from it... perhaps I just need to wear
warmer clothes when I drive.
Getting new door rubber and fixing some of the air leaks into the cab
would probably help a lot.

I thought about installing an electric "booster pump" in the heater
hose, but I already had the bosch heater. (which will be fully
functioning by next week.)

Someone asked if I was worried about monoxide from the Bosch heater..
No. Not really. The bosch heater has a nice stainless heat exchanger,
and exhaust from the combustion chamber exits thru its own 1-1/2" exhaust
pipe and can be routed well away from the fresh air inlet.
Also, now that electronic CO sensors are becoming cheap, I'll probably
get one and put it in the camper shell and wire it into my fuel pump
control circuitry.

Thanks again You guys..

Happy motoring,

Steve Delanty


Date: Wed, 24 Sep 1997 13:57:56 -0700
Subject: Re: Flathead Help (Ignition math..)

>Isn't the condenser supposed to help stop point burn? If there isn't one
>on an old flat head maybe you could add one external on the distributor.
>I agree that most 12 ignition systems use a ballast resistor but a while
>back when I was looking for a stock coil I came upon an interesting
>item. In the parts books there was an entry for coils with "internal or
>external" resister. I assume ( and we all know where that can get us )
>it meant there was an internal resister in the coil so an external one
>would not be needed. Keep in mind I have never seen an older car / truck
>without an external ballast resister and I am not even sure what the
>application was for the internal one.

This thread has lots of stuff about ign systems lately, so I'll jump in
and try and confuse the issues a bit for Ya...

All coil and points type ignition systems (Kettering ignition) should
have a resistor in series with the coil, and a condensor across
the points.

The resistor limits the current through the points and coil which keeps
them from self destructing quickly. (especially the points)
It helps protect the coil in case the ign is left on with the
engine not running and the points closed.
Also it reduces ignition noise that would otherwise have a low impedance
path to the battery + terminal.

The resistor should always be there, whether it is a seperate unit
mounted on fender or firewall, or a "resistor wire" in the feed to the
coil, or an internally ballasted coil.
60's and 70's aircooled VW's used internally balasted coils, so if You
need one for Your application they are available in either 6v or 12v
from bosch. I know other vehicles used 'em also, but can't name any now..

Calculating an external resistor:

Anexternal resistor should be chosen to provide the coil with
aprox 7-8 volts for a 12v coil or about 4 volts on a 6v coil.

If You have a external resistor coil already, measure the resistance
of the primary winding (da 2 little posts..)
The coil in front of me measures, err, let's see... 3.5 ohms.

So, we have 12 volts to work with and we want 8 volts across a 3.5 ohm
resistance. Right? (just nod)
That means that we need to drop 4 volts across the ballast resistor.
( 12-8=4... with me so far?)
So to calculate the ballast resistor we need to know how much current
the coil is gonna draw.
We wanna put 8 volts on it so: 8v / 3.5ohms = 2.29 Amps. (Ohms law)

Now we know that the ballast resistor has to drop 4 volts with a current
of 2.29 amps thru it, so: 4v / 2.29A = 1.75 ohms.

So for this coil You would want a 1.75 ohm resistor.
But wait..! The resistor also has to be sized for wattage so it doesn't
burn up!

So, Watt's law says: Watts = Volts times Amps.
So the voltage across the resistor is 4 and the Amps is 2.29 = 9.17 watts.

Also, Watts = Amps (squared) times resistance,
So: 2.29 * 2.29 * 1.75 = 9.17 watts. Hey, I got the same answer both
ways! Wow, math does work!

In order to have our resistor live a cool, long, healthy life it should
be rated for twice the wattage You are gonna use it at.
A 1.75 ohm, 20 Watt resistor would be a nice choice for this example.

Yeow, enough resistor math, eh?
If I had a 6v coil to measure, we could do it for 6v. (-:

Are Y'all still reading? Wow, You MUST be bored!

The condensor (capacitor) also must be in the circuit.
It acts as an electrical "shock absorber", preventing current from
arcing across the points when they open.
It also gives the secondary winding a low impedance path to ground for
that nasty voltage spike. (The end that doesn't go to the spark plug)
A coil run without a condensor will have a VERY weak spark, and very
short points life.

The math for calculating the optimum capacitance involves coil impedance,
current, RPM, and more, and I AIN"T gonna do it here.. (so relax)
In practice, traditional values are usually .22 - .47 microfarads.

You can tell if Your condensor is too big or too small by watching the
points at tune-up time...

"Metal migration" can be a sign of improper condensor size.
If Your points build up a little "tit" on one contact, and a matching
"crater" on the other, then You may have a condensor problem.

If the "tit" is on the moving contact (+ side), then the capacitor is
too small. If the tit is on the stationary (ground) side, than the
cap is too big.

If the points just wear out without excess migration, then Yer O.K.

Well' that's all the ign theory for today. It's probably more than
anyone wants, my fingers are tired, and I want a beer...

Happy motoring,

Steve Delanty


Date: Wed, 24 Sep 1997 20:58:25 -0500
From: "Dale and Donna Carmine"
Subject: 351 M Cam Timing

I sent this message last night, think it went to the wrong list with the
changeover and all, if it is a duplicate I apologize.

Thanks to all who responded to my questions about the 351M cam timing
History is interesting, but I think Gary found the bottom line when he

>I looked at cam specs for stock engines over the late
>60 to late 70 era and almost every year the spec changed on some
>engines so it could make a difference but why buy stock spec when
>there are so many good after market grinds out there now anyway?

I guess it's time to start saving for a new cam, timing set, lifters,
springs, etc.

Thanks again,

dale c


Date: Wed, 24 Sep 1997 20:23:18 -0700
From: Randy Collins
Subject: Re: Fuel tank coatings

Any advise on fuel tank coatings? (favorite types, etc?)
Should I even bother?
It's made of clean, rust free 1/8" thick material, is it necessary to coat
Steve Delanty

If the fuel tank would only be required to contain fuel it wouldn't be
necessary to coat it. Unfortunately, the tank will also contain moisture
that will settle on the bottom. You need to protect the tank from the
moisture or the 1/8" steel thickness will soon become less...on the bottom

Manufactures protect their tanks by galvanizing. If you aren't familiar
with galvanizing it is a process that leaves a layer of zinc on the surface
of the steel. The whole zinc corrosion concept is beyond the scope of the
note but you should be aware of it's presence and it's function. On large
gasoline storage tanks (the ones you see in the tank farms) the coat only
the bottom of the tank and up the wall about 4 feet. Of course the
function of the coating is to protect the tank from the moisture settled on
the bottom. Then they simply monitor the moisture content.

I am not sure if coating only the bottom of a mobile fuel storage tank
would be sufficient. I am not certain how fast the moisture will settle
back to the bottom of the tank. Maybe some of the chemistry folks could

More bad news:
I have no faith in the readily available single component gas tank coatings
I often see advertised. I believe that the sell quite a lot of these
coatings and have few complaints simply because no one bothers to monitor
the condition of the coating. Unfortunately a great deal of this goes on
in the coating industry.

Other than having you tank zinc coated the only reliable method to coat the
tank is to have the surface sandblasted and coated with an epoxy designed
to withstand both the contact of the fuel and the water. If you need
recommendations on specific products send me a note and I will give you
names and phone numbers for their purchase.

Did you know that rust expands to 13 times the size of the steel? That
ought to really plug up fuel filers!

Randy Collins > "the dork"
Boise, Idaho

1975 Ford F250 4WD Supercab "Muscle Truck"
Soon to have the following Randy installed options:
460 C-6


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