Argh....

socalplanedoc

socalplanedoc

Senior Member
Spent the whole weekend working on the Fordor.. new water pump (Yay! no problems there) new 3X plugs, rebuilt the carb (91-99/8BA hybrid)

now it starts super easy and idles all day without a problem - it has never idled the whole time I have had it..

but now it's gutless. argh... in the shop when you mash the accelerator it'll zoom right up.. on the road anything faster than idle it acts like it can't breath (there no filter on it yet) it had jets drilled out to .069 when I got it but all the plugs were real sooty so I went down to .045, then tried .050, and now they're at .055 there's *maybe* a little improvement but it's still not right.
Maybe I'll clean the original plugs and put them back in.. 3 different kinds but heck, they worked :)
I should know better than to change more thing than one at a time...
This time I also noticed the crank pully wobbling and it looks like 1/8" end play in the crank when it's running..
And I thought antique planes were a lot of trouble :)
 
Was it running at speed before you did this? If not something else to consider is valve timing.
 
Check ignition timing. What kind of carb? Doesn't sound like a stocker??? If it is a Stromberg 97, .045 is the stock main jet and should be very close to what you need. You may be making changes that are too big?
 
thanks guys, a little moral support goes a long way :)

"One of the jets plugged? Points closed down? Crud in the tank?"

jets are open, I've been using one old set soldering and drilling to experiment. Lots of good quality 100 octane alcohol-free aviation fuel fed by a pump/regulator.. I'm planning on going through the ignition system.

"Was it running at speed before you did this? If not something else to consider is valve timing. "

It did fine at speed before, I dove into the carb to see if I could get a good idle and to reduce the jet size since the plugs were so sooty.

"Check ignition timing. What kind of carb? Doesn't sound like a stocker??? "

It came with the carb when I got it. It's a 91-99 with a few 8BR parts on it (but nothing that really matters) so, it's basiclaly a 91-99. It had unmarked jets that measured .069 and with all the soot I figured they were way too big. I put .045's in it when I rebuilt it but have had these problems since.

I'll check ignition stuff next chance I get (I'm getting married this weekend and although since fully supports my hobbies, I dont think the future Mrs Socal would appreciate me fooling with it right now).

Does it seem odd to anyone that it would seem fine in the shop, I mean excellent throttle response and all, but on the road have nothing?

I need to find someone who actually knows about these engines to take a look at the crank endplay...
By the way, I think the idle issues I was having was due to vacuum leaks in the wiper motor supply and a mangled needle in the carb base.. pinching off the hose and replacing the needles made it reliably idle as slow as my hit-miss engine.. niiiice.
 
Hmm.. if this is the same machine that in your other post is well over 100 psi and has a high compression head (and likely larger cam) it may be getting starved out on the secondaries when the motor is open under load for a longer time than blipping the throttle at a standstill.

I have a mod 94 downdraft on an ansen single intake and am running, if memory serves right, jets in the low 50's at 2500 ft elevation on a b cam motor with high comp head.

Try soaking the plugs in Ammonia to fully clean all the carbon off them, check gap, reinstall and try some jets in the 50's range.. I think your motor is likely pulling more air than a standard a and you may need a bit more juice.. at least that's what I think when it fades under load..

Other options may also be coil or condensor getting weak, giving poor spark and leaving unburnt or poorly burnt fuel in the cylinders and sooty plugs..

Hope this helps,

- Dave
 
san diego.. try jets in the .056 range I would think? Lots or air at sea level usually means a larger volume of fuel than the .045's would allow?
 
ken_ct (ken in conneticut) is a true pro on the downdraft carbs, and will hopefully chime in, as I am *very* new to the downdrafts
 
jrapose said:
Check your float level, sounds like it is too low.

Joel
Chester
Click to expand...

checked.. 1 11/32 I just went through it so that was easy...


Dave - thanks a bunch, your comments actually help quite a bit.
It is the same engine, all 4 are right at #100 using my little tapered rubber-nosed tester. I know it's pulling a lot of air, when I removed the air filter it was noticeably better. I tried increading the jet size but stopped at .059 thinking about the sooty plugs. I'll try putting the old ones in to see if that has any change.
The old plugs were 3 different part numbers but one thing I noticed was while the old ones all had the same massic electrode hovering over the end of the plug (like modern plugs) the 3X plugs had a finer wire that approached the center from the side. maybe that's a clue...
Other than the plugs, I didnt change anything electrical but it wont hurt to check it, everything else on the engine has been a mess...
 
Hmm.. Sounds like a good approach.. also with those improvements to the engine, i would also run a hotter plug.. look for one with about 3-4 mm or electrode showing on the center post.. they burn a bit hotter.. I think the W16's are warmer than the 3coms.. I run Blue Crowns and have been happy with them in the higher compression engines, but don;t have much experience with the Champions.. :D

Here's a list of values that were provided by Larry Brumfield (and others perhaps, copied from this board) quite a while ago.. Hope it helps..

>>>>>>>>>>>>>>
>>>Parts Number List:
Motorcraft DC-1 Condenser
Motorcraft DP104 Point Set
Points CS30 Echlin
(original style)
Points CS751 Echlin
(new Ford style)
Condenser FA5 Echlin
Rotor FA3 Echlin
Condenser-Mallory Dist MA3 Echlin
Starter Brushes F502 Echlin
Spark Plug 561 Champion (Wl6Y)
Spark Plug 3X Champion
(avail on special order)
Coil (6 volt) IC9 Echlin
Coil (12 volt) IC14 Echlin
Plugs:
HOTTER DOWN TO COLDER - Spark Plugs
--------------------------------------------------------------------------------
For those who may be interested, the following 7/8"-18 spark plugs will fit the Model A and were available as of a few years back. They are also not all the ones that I know of.
Champion (hotter down to colder):
W95D
W89D
W16Y
C95F
W20
W14
W10
W85N
W80N
Also the original 3X and W18 which Champion lists as norm. Also according to Champion, the W16Y is hotter than the W18 at low speed but cooler at high speeds over 5500 RPM....(over 5500 RPM? ... maybe Speedy ED J, Pete, George Miller, Dennis Pierce would be interested... maybe even Brent)
Motorcraft (hotter down to colder):
TT15 (the same as Champion W89D)
TT10 (the same as Champion W14)
TT8 (the same as Champion W14)
TT4 (the same as Champion W10)
Autolite:
3076 (the same as Champion W14 and Motorcraft TT10)
Mopar (hotter down to colder):
P-9-7S
P-9-6S
P-9-5S
Prestolite (hotter down to colder)
78-10
78-8
Stitt (hotter down to colder)
137 BSP
197
147 B
13/10
 
The wobbly CS pulley may be due to a poor repro 2-piece one or even a 1-piece one.Some times they are made a fraction to short & will not tighten up when the CS nut bottoms on CS.If the pulley is correct & the slinger is missing in front of CS gear,it will not tighten up either.You may need a thin washer behind nut that will clear the CS & allow nut to tighten pulley.If it has been loose for sometime,it will need a new pulley.I prefer the one piece type. As for the carb,why not install an A manifold & a B carb?I use B carbs & higher comp heads on both my A,s & they have lots of power.
 
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