Glutton for punishment Bringing 8n back

[skylarkguy]

So as if i didn't have enough projects of my own i offered to get a friends 8n running again, ("sure i said, bring it over, no problem").

So the thing is mostly suffering from neglect. Nothing has been cleaned or changed in well...a long time. It is a 1948 based on the serial number, still has the 6 volt system that seems largely intact, the foot switch has been replaced with a push button in the dash. It cranks ok. It wasn't sparking at first, but after some testing and cleaning the points it makes a spark. It's a weak yellow little spark not a nice blue one. I'm considering replacing the coil.

Here is the problem: the owner doesn't want to spend a lot of money on parts etc if I can't get it running. So given that, what order would you proceed in determining the basic health of the tractor so he can decide if it is a lost cause or to go ahead. Next I intend to check the compression...but after that?

Thanks

[weldermike]

So as if i didn't have enough projects of my own i offered to get a friends 8n running again, ("sure i said, bring it over, no problem").

So the thing is mostly suffering from neglect. Nothing has been cleaned or changed in well...a long time. It is a 1948 based on the serial number, still has the 6 volt system that seems largely intact, the foot switch has been replaced with a push button in the dash. It cranks ok. It wasn't sparking at first, but after some testing and cleaning the points it makes a spark. It's a weak yellow little spark not a nice blue one. I'm considering replacing the coil.

Here is the problem: the owner doesn't want to spend a lot of money on parts etc if I can't get it running. So given that, what order would you proceed in determining the basic health of the tractor so he can decide if it is a lost cause or to go ahead. Next I intend to check the compression...but after that?

Thanks

I hate when people want your help, but dont wanna spend any money. I happen to love 8ns, if its a descent machine and its not gonna bother the guy if it runs or not, maybe offer some money and just buy it off of him and put a couple bucks into it for yourself.

[Soundguy]

before you get the 'parts shotgun' out and just start shooting expensive new parts into it.

actually diagnose the problem(s)

1, points need to be clean and gapped at .015 on a front mount. not arced, pitted or burned.

gap needs to be consistant on all 4 lobes.. if it isn't... check the dizzy bushings

next.. is the coil.. not much to check their YET

next is the wireing and connections from the coil to the 3 terminal dash resistor mount, that has the oem ballast resistor across the top 2 terminals, key switch is tied in there, and bat hot on the bottom post.

make sure ALL those conenctions are clean and tight.

rust don't conduct good.

make sure the bat terminals and cable ends are good.. 6v need 1/0 cables.. not wimpy 4ga automotive 12v cables...

in doubt about a connection.. jumper it out from the battery.. IE.. hotwire coil temporarilly.

remember.. this is a positive ground system.. thus negative is the 'hot' here.

warm, the coil should be seeing about 3-4v on the top terminal. less than that and bad spark.. mor ethan that and the coil and points will suffer..

soundguy

[skylarkguy]

Thanks, I've done some of these things but not all. I'll continue with the trouble shooting and report back.

[Soundguy]

postback yer observations or results.

we'll get er' runnin'

[flusher]

Do the usual dry/wet compression check with the pressure gauge and cranking with the starter. If lower than 100 psi wet in one, several or all cylinders, do a pressure leakdown test on each cylinder to spot the location of the leakage problem (rings, valves, head gasket).

[Soundguy]

100 might be a tad optimistic.. ford spec'd 90 as an operational minimum.

I know of many running on less..but as with most things.. more is better..

I've seen 120 to 135 on new pistons, rings, jugs and valves..

soundguy

[flusher]

100 might be a tad optimistic.. ford spec'd 90 as an operational minimum.

I know of many running on less..but as with most things.. more is better..

I've seen 120 to 135 on new pistons, rings, jugs and valves..

soundguy

Yep, that's what you'd expect for a rebuilt engine with ~ 8:1 compression ratio. Sounded to me like the owner of that 8N has a tight grip on the wallet and might decide to live with a few minor compression leaks .

[Soundguy]

for situations wher emoney is tight and labor is free, and compression is in the 65-80 range... I like to go with a hand lap on the valves, honing the cyl, reaming hte ridge, new rings, and new main and rod bearings of the same size it had.. you know they will fit that way.. so no need to pull the crank..

usually picks up 20 psi compression on the du=ynamic side, and a few psi oil pressure.

soundguy

[skylarkguy]

Well just finished the compression tests...Here are the results

CYL Dry Wet
1 90 100
2 40 60
3 25 30
4 60 65

The lack of balance between them is a bit worrisome, especially between cylinders 1 and 3.

Things I know it needs are a new water pump, which is leaking at the bearing, and for sure the fluids and filters need changing.

Still to work out are stronger ignition and the status of the carb...

So given the compression status, should I try to get it gimping along on what amounts to 3ish cylinders, or tell him it's a lost cause...