[hbj069]

Ok dodge guys here ya go,
225 slant six, no start
New,, carb rebuild, plugs,wires,cap,points, condenser,coil,starter.

I hot wired the coil to the battery via a toggle switch and remote starter, the truck has fair compression and timing has been checked and is correct. the problem is that it still will not run, cranks over and tries but will not take off on its own. Any suggestions please??

 

[Bob Lincoln]

Check the ballast resistor - common failure.

 

[hbj069]

I would but I am bypassing the entire (Key) ignition system, Checked with timing light and its firing at 5 degrees before tdc.

 

[Bob Lincoln]

Exactly what is the history leading up to this failure? Was it running before, for you? Or a new, never-running acquisition.

If you have a timing light firing, you have spark. 5 BTDC is good. So look for fuel, compression, valve timing. Are you getting fuel into the carb's venturi?

 

[hbj069]

A friends dream truck,
History is the truck served air force for many years I am sure (still has markings) was sold locally and set for many years again. when delivered I was told it used to run but ran hot. First was a carb rebuild of the old 1 bbl, I have had real good success with my carb rebuilding over the last 30 years. Second was a complete tune up as the fire was weak, after that I found the wiring in the truck was also weak delivering around 7volts off the ballast resister, so I decided to "hot-wire" it as I have done on many vehicles in the past. I havent run compression on all the cylinders but they do feel fairly strong using the ole finger/spark plug hole check. TDC was checked against TDC mark on balancer and they matched.

 

[Bob Lincoln]

So, was it running at all before the carb rebuild and tuneup?

Bypassing the ballast resistor can only be done for short amounts of time, as it will destroy the coil fairly quickly.

 

[hbj069]

He nor I have ever heard the truck run, With the amount of residue in the carb and the overall condition of the truck it appears to have been several years since it has movered itself,, Yes very brief moments of direct voltage to the coil.

 

[KOG]

5 BTDC is NOT good. That's not why it won't start, but set it to exactly 2.5 BTDC after you get it running. More and you'll destroy a 225 with knock under load.

 

[68RT]

1) What do the plugs look like now? Wet / Dry
2) Do you get a good spark?
3) How much slack in the timing chain. (Use socket on front pulley nut back and forth. Slack portion is easy to move until chain slack is taken up and it tries to move the camshaft) (degrees of slack)
4) How fresh is the gas going into the engine?

 

[hbj069]

1) What do the plugs look like now? Wet / Dry A, Both, can pump it up good enough to wet the plugs still no start.
2) Do you get a good spark? A, Yes
3) How much slack in the timing chain. (Use socket on front pulley nut back and forth. Slack portion is easy to move until chain slack is taken up and it tries to move the camshaft) (degrees of slack) A, pulled the cover and t/c is in excellent shape and on the money.
4) How fresh is the gas going into the engine? A, new

Ran compression check and it only has 75 lbs of compression?

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5 BTDC is NOT good. That's not why it won't start, but set it to exactly 2.5 BTDC after you get it running. More and you'll destroy a 225 with knock under load.

I understand.

 

[KOG]

75 psi is plenty for it to run well. A new one will go around 150, but I've had one with 60psi running fine, using no oil. And that one had .017 bore wear with no ill effects running.
Something basic is wrong with timing, carburetion, etc. Whatever it is is so basic as to be idiotic. Once you find it. But finding it can drive you nuts.

 

[hbj069]

Thanks Kog,
I have been working on beaters for about 35 years and the basics just dont seem to be working on this one. Heck I have started plenty of motors sitting on the ground with a battery, jumper cables and a jug of fuel.. It just isnt making any sense.

 

[Bob Lincoln]

5 BTDC is NOT good. That's not why it won't start, but set it to exactly 2.5 BTDC after you get it running. More and you'll destroy a 225 with knock under load.

Not at all accurate. I ran my slant sixes at 10 BTDC for many tens of thousands of miles with no ill effects. I had lighweight advance springs for even more advance. Five won't hurt at all. It sure won't prevent it from starting.

1) What do the plugs look like now? Wet / Dry A, Both, can pump it up good enough to wet the plugs still no start.
2) Do you get a good spark? A, Yes
3) How much slack in the timing chain. (Use socket on front pulley nut back and forth. Slack portion is easy to move until chain slack is taken up and it tries to move the camshaft) (degrees of slack) A, pulled the cover and t/c is in excellent shape and on the money.
4) How fresh is the gas going into the engine? A, new

Ran compression check and it only has 75 lbs of compression?

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I understand.

75 psi is very bad. These engines run around 120 psi, so 75 will give it great difficulty starting, if at all. It may be that the valve lash was turned in way too far. That lowers the effective compression. Does it sort of 'sigh' when you are trying to start it and you stop cranking?
Spec is .010 inches intake and .020 inches exhaust, hot and running. You can approximate to get it started if you find it really far off.

 

[hbj069]

No sir and finger checked the the valves and none appear to be tight with the corresponding cyl at tdc.

 

[Bob Lincoln]

I'm not sure what you mean by finger checked.

Valve lash is checked with a set of feeler gauges, with the valve cover off and the engine hot and idling. Since it won't run, you can set the lash a few thousandths higher to approximate the thermal expansion. This raises the effective compression and may allow it to start, if this is the issue.

 

[David Eidell]

I assume you full choked the engine in your testing. Jam the choke plate closed for a few engine cranking revolutions. I've had a few old engines not want to start no matter what I did. I full choked them and they lit off.

 

[chuzz]

Check your bulk head connector for corrosion. On a vehicle that old, it wouldn't surprise me if every connector has the dreaded green corrosion on it.

 

[KOG]

I've had several /6s which would knock under load if advanced at 4 degrees or less. Now, these were running 1973 electronic ignition distributors with stock advance which would not match the advance curve of some hearlier models. But I have seen people damage piston pins with more advance. And I have seen rods through the block as well. Not easy to hurt a /6, but it can be done.

No question that 75psi is low compression, but as noted, I seen them running well at less than that. Don't ask me why they'd run well that low, makes no sense to me, but I've seen it.

 

[hbj069]

I'm not sure what you mean by finger checked.

Valve lash is checked with a set of feeler gauges, with the valve cover off and the engine hot and idling. Since it won't run, you can set the lash a few thousandths higher to approximate the thermal expansion. This raises the effective compression and may allow it to start, if this is the issue.

yes sir I have set a few set of valves on engines, enough to know about where they should be cold. thanks but I dont think thats it.

I assume you full choked the engine in your testing. Jam the choke plate closed for a few engine cranking revolutions. I've had a few old engines not want to start no matter what I did. I full choked them and they lit off.

Its definitely getting fuel

Check your bulk head connector for corrosion. On a vehicle that old, it wouldn't surprise me if every connector has the dreaded green corrosion on it.

hot wired, all that is by passed.

 

[68RT]

One old trick for hard to start engines with point sets was to take each plug wire and put it into the
coil and with the points open, short the points to ground several times (fire off the coil) until you get a reaction from that cylinder which could be anything from a backfire to slight movement of the cengine to a firing out the exhaust to make sure each cylinder was cleared out. Then put everything back in place and try it. Be sure you are clear of everything. Also, make sure that the coil primary wires are not switched. Makes a big difference.