1850 backfires and shoots flames out of exhaust.

[Plumb3360]

Looking at a 1850 and it started fine. Let the engine warm up a lil bit and then have it some throttle and it started backfiring and shot flames out exhaust. Plugs, plug wires and distributer all appear to be new. Carb also looks like it has been worked on as it"s clean, on the outside anyways. Seller says tractor hasn"t been used in 8 months. Also noticed what I think is a vacume line that has been left open, possibly tied into old distributer and runs to manifold. Any help or should I just walk away?? Tractor is reasonably priced in my opinion. Thanks.
 

[Gr2]

Maybe a valve stuck or sticking open.
 

[Dick W.]

Any chance the distributor cap is wet on the inside?
Check the timing, find where the vac line is to go, is the manifold connector fitting open? Is the carb adjusted too lean? A few minutes of work could make a big difference.
 

[DBer60@1]

Sounds like it is time for a set of AUTOLITE spark plugs,OLIVERS do not run good on CHAMPION plugs. I am repeating the exact words that a dealer told me when I had this same trouble with a 1650,thought it was going to blow the manifold off. AUTOLITES solved the problem == took the CHAMPION plugs back to parts store,they said I was not the first person to complain.
 

[greg krush]

vacuum hose probably went to the ditrubutor that had a vacuum advance, these were notorious for failing, probably replaced with a different distributor. i would also look for moisture in in the cap and or build up on rotor or inside cap.
 

[Tramway Guy]

Don't overlook coil and/or condensor!
 

[Bob M]

A bunch of things to check:

Ignition static timing. Must be set to spec or the engine will run poorly. (See manual - I think it's TDC but I'm not positive) .

Vacuum advance. The distributor diaphragm chamber must be connected to the manifold vacuum port with a small (1/8"?) hard line. And the vacuum mechanism must work freely and not leak.

Centrifugal advance. It must not be stuck.

Breaker point gap. Set to 0.020. If the gap's too small or the points are worn it will cause misfiring.

Carb mixture. Fire out of the exhaust can mean a lean mixture. Try turning the power screw out a turn or two and see if this helps.

Carb accelerator pump. The stock Marvel USX carburetor is notorious for accel pump diaphragm problems. A failed diaphragm will give a temporary lean condition on acceleration. And for reasons I don't understand a new diaphragm is not ordinarily included with rebuild kits.

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The 1850 gasser is a generally solid, trouble-free tractor. It's only real downside is it's thirst for gasoline!
 

[BradWi]

I'll second that on those junk champion plugs!!
 

[D, Schwantes]

I have had 3 that's right 3 Olivers run less than 15 mins on Autolite plugs. Use AC only.
 

[Larry Hyde]

If it hesitates a bunch before it backfires, another possibility is not getting enough fuel to the carb. Make sure the fuel flows freely.
 

[Kent Kroft]

My son says before you fix it - GET PICTURES!!!
 

[Plumb3360]

Thanks everyone for the answers. I don't know if I'll purchase or not. I'm looking for a tractor to do 40 acres of hay with. Hay season is rapidly aprroaching here, I hope. So I really don't have time to get this tractor and possibly have it ready in time. I'm going to look at a AC D19 this weekend. I know there is a sizable HP difference between D19 and 1850 but from what I'm hearing there's a big difference in thirst of fuel also. I'd immagine the 1850 would have no troubles pulling hay equip. However, not so sure on the D19. Any more hints on D19's?