'49 flat head six valve job

[CoupeBoy]

Are there any special procedures I need to be aware of before I take this motor in to get a valve job done on it? I've never owned a flat head 6 (and still dont, this is a work truck). The owner of our company has this truck as an advertising tool and needs to have this work done.

Any estimate on price to pay? When I have the head off I assume I should measure everything and make sure the CR is decent after re-assembly. Any suggestions on maximum CR?

thanks
-ron

 

[addo]

Just racking my brains for my mate Lyle's comments on Ford flathead fours. I think he was taking an old-school view; reseating the valves lowered them so you had to shorten the valve stem afterwards.

An older commercial flat six's CR? I'd hazard a guess at 7½:1, maximum.

 

[CoupeBoy]

I just talked to the owner and in the future he would like to convert this truck to 12V and elenctronic ignition. He said that he would like to keep it as original looking as possible, anybody got suggestions?

This truck has left fellow employees stranded at least 3 times that I know of, and each time it has been a battery/charging related problem and it has been jumpstarted (the truck is 6V) with cables from a 12V. I told the owner it was just a matter of time before they burn something out on the truck if he doesn't either get the charging system fixed or upgrade it. The truck was bought last year and the exterior was refinished (no pics at this time). But when the thing has your company name on it I really dont want to see it being towed anywere.

-ron

 

[Anonymous]

You don't need to rewire it-the wires for the six volt will take all the amps that 12 volts have, you need to change the light bulbs - all the bulbs, dash, headlight, turnsigs, brake, tail, etc. also install voltage drops ( google " runtz voltage drops") for the gages and the heater fan
Either add a resistor inline to the coil, or get a 12 volt coil. I would suggest switching to a alternator, but you can put a 12 volt generator on in place of your 6 volt unit.
The starter doesn't need to be changed, it'll just spin the motor faster.
That's about it. all the bulbs are available at any auto parts store-just compare the 6 with the 12's 'til you find a match. The points are the same #, or if you switch to electronic, call Pertronix for the correct module.
Piece of cake.

 

[Lazy JW]

I just talked to the owner and in the future he would like to convert this truck to 12V and elenctronic ignition. He said that he would like to keep it as original looking as possible, anybody got suggestions?...

This would be an ideal application for an MSD ignition. Use the original distributor to trigger the MSD box, which you will carefully hide under the dash.

Any competent generator repair shop can fix you right up witha 12v generator.

Be very careful to not shave any more than needed from the head and block, you can run into valve interference pretty quickly. DEFINITELY put in new cam bearings.
Joe

 

[Fred]

To convert to 12 V: take a 12 V generator off a later Ford product (56 or newer), remove the pulley, front plate, and back plate. Put the pulley, front plate, and back plate from the 6 V generator on the 12 V armature and barrel. You now have a 12 V generator that looks completely stock. Change the voltage regulator, swat the battery leads to negative ground, and make the other changes.

* start rant * But why bother? A good six volt system works fine. Make sure the battery is set with POSITIVE GROUND. I have lost count of the number of flathead Fords I have seen with burned up charging systems because people put the battery in backward. If you have a good generator, good regulator, and good starter and the wiring is in decent shape there is no problem with six volts. Changing to 12 volts is usually done to make up for poor parts somewhere in the system. * rant over *

Adjusting the valves is not hard. The lifters are adjustable in this motor. It is easier to adjust them when the motor is out of the truck. There is a removeable panel on the passenger side inner fender panel to allow access to adjust the valves in the vehicle. If I remember correctly the clearances are: .017 intake and .019 exhaust.

 

[flatford6]

Having a valve job done inplies burnt valves. A good plan on all old Ford engines is to check the vacuum advance diaphragm on the distributor by applying vacuum to the fitting end of the diaphragm can where the line fitting screws in. My experience is that well over half of old Ford engines have diaphragms that leak and won't hold vacuum. This causes a no advance condition and since there is no centriifugal advance in these distributors you are left with only the initial advance. This late ignition timing at speed causes the exhaust valves to run much hotter than normal and they burn. When you get the engine running again, check that you have advance with a timing lite. This is because the lines or vacuum ports in the distributor could be plugged with dirt or carbon. Or in some cases, the pivot point on the breaker point can be stuffed with dirt or rusted leaving it unable to rotate. A bad diaphragm allows the vacuum to enter the distributor and it sucks in dust through the joint between the housing and cap. Having the proper amount of advance in these old engines really peps them up, campared to no advance. New Ford advance disphragms are available at parts stores. Good luck

 

[CoupeBoy]

Fred,
I agree, a working condition 6v system is perfectly acceptable, but if they dont get it fixed, and keep jumpstarting it with a 12v system eventually they will have a problem, and that is my worry.

I think I need to get my hands on the truck and do some investigating before it gets sent off to the shop for repair. Since this is not my vehicle and I have only seen it twice, I feel sort of weird asking to drive it. Kind of like asking Dad for the keys the first time.

To be perfectly honest I have no idea who told him the valves needed to be reground, and if that person had first hand knowledge of the system why didnt they suggest a repair facility. I highly doubt that any diagnostics have been done on the truck to ensure that is the problem, it could easily be a vacuum leak or improper valve lash.. I just wanted to know what to expect so that I could pass along that information to my boss so that he could make an informed repair.

When I get my hands on the truck I'll take some pictures

thanks for the tips so far,
-ron