I've been using my 420 with good sized loads a lot lately. It starts easily and runs strong and smoothly under load. The governor works as it should.
My question is why might it run a bit rough at idle? It huffs, farts and chugs at low rpm. As soon as it starts to move, it smooths right out and gets the job done well.
I cleaned the fuel bowl today, the air cleaner has new oil, and the load jet seems to be in a good position. The idle jet is screwed all the way in - it's been that way since I rebuilt the carburetor last year. The points have been cleaned and set recently. I haven't checked the timing in a while. I haven't had a chance to run the dozer since the maintenance, but I thought I'd ask for any thoughts? Thanks. Paul
Fine tuning a 420
- Paul Buhler
- 350 crawler
- Posts: 991
- Joined: Wed May 21, 2008 6:25 pm
- Location: Killington, VT
Fine tuning a 420
Paul Buhler
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch
- DukeofDeere
- 1010 crawler
- Posts: 443
- Joined: Wed Oct 26, 2011 7:12 am
- Location: Hudsonville Michigan
That is by no means an even fire engine, just look at the distributor cap, it fires both cylinders and then waits a long time to fire them again. Sorta like a Harley!! If you idle it down too far it is NOT going to be smooth. Not saying that is your problem but it could be part of it. Just a thought.
Bryce
Bryce
No trees were hurt in the creation of this message.
But, many electrons were terribly bothered.
440IC/602, 2-440ICD/831 MM UBU-LP, 445N-LP, 445E-LP, BIG MO 400-M, 4 Star-LP M5-D, M5-LP, M602-LP, M670-LP, G900-LP, G900-D, G1000 Vista-LP Case 580CK
But, many electrons were terribly bothered.
440IC/602, 2-440ICD/831 MM UBU-LP, 445N-LP, 445E-LP, BIG MO 400-M, 4 Star-LP M5-D, M5-LP, M602-LP, M670-LP, G900-LP, G900-D, G1000 Vista-LP Case 580CK
- gregjo1948
- 350 crawler
- Posts: 1000
- Joined: Mon Aug 30, 2010 5:58 am
- Location: Newark Valley,NY,USA
Fine tuning a 420
Have you checked the compression? gregjo1948
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford
- Paul Buhler
- 350 crawler
- Posts: 991
- Joined: Wed May 21, 2008 6:25 pm
- Location: Killington, VT
Thanks. Time to try all your suggestions. Bryce, thanks for your thoughts too; I hadn't considered the one-two, skip a beat setup. I believe that the compression's good, and close between the cylinders from past checks, but like I said, the crawlers been working hard (but not abused) and some things are bound to need re-adjusting or tweaking at the very least. I'll get back with more info soon.
Paul Buhler
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch
- gregjo1948
- 350 crawler
- Posts: 1000
- Joined: Mon Aug 30, 2010 5:58 am
- Location: Newark Valley,NY,USA
Fine tuning a 420
Have you determined if it's miss fireing on one or both cylinders? Could it just be plugs? Better get it fixed soon for your snow plowing. gregjo1948
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford
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