420 crawler engine surging
- lurch85
- 430 crawler
- Posts: 95
- Joined: Fri Feb 01, 2013 6:11 pm
- Location: Upper Peninsula of Michigan
I've caused myself a lot of headaches with inline filters that were too restrictive... found some that seem to do ok in the marine area of Walmart... its more of a screen than it is a filter. The one i'm thinking of is clear with a white plastic screen inside..
John Deere 420C, John Deere 350 straight with Gafner loader, John Deere 4020
Re: 420 crawler engine surging
Can any of you provide an audio snip of what a good, smooth running 420 sounds like?
I've been fighting multiple issues and am now concerned I burned the exhaust valve on #1. Unit ran fine for an hour yesterday, moving brush and pulling trees. Shutdown to cut more trees and after setting for about 30minutes, I could not get it restarted. Noticed it was back puffing through intake while trying to start and suspected a valve leak. Found #1 exhaust with only 0.003"tappet clearance. I adjusted all valves back to spec and can now restart hot, but engine still sounds like it is skipping every 3rd or 4th cycle. Timing is dead on according to timing light. What am I missing?
I have unplugged the inline fuel filter and filter bowl valve, cleaned all passages of carb (could not get main jet out) replaced condenser/points /plugs. Checked /replaced ignition coil, plug and coil leads, cleaned the flyweights in distributor. Ignition key switch test alright (hot or cold). Unit 420 gas, 6V NEGATIVE ground (alternator installed) and ignition coil wiring changed accordingly.
SUGGESTIONS APPRECIATED. Where can I order carb parts?
I've been fighting multiple issues and am now concerned I burned the exhaust valve on #1. Unit ran fine for an hour yesterday, moving brush and pulling trees. Shutdown to cut more trees and after setting for about 30minutes, I could not get it restarted. Noticed it was back puffing through intake while trying to start and suspected a valve leak. Found #1 exhaust with only 0.003"tappet clearance. I adjusted all valves back to spec and can now restart hot, but engine still sounds like it is skipping every 3rd or 4th cycle. Timing is dead on according to timing light. What am I missing?
I have unplugged the inline fuel filter and filter bowl valve, cleaned all passages of carb (could not get main jet out) replaced condenser/points /plugs. Checked /replaced ignition coil, plug and coil leads, cleaned the flyweights in distributor. Ignition key switch test alright (hot or cold). Unit 420 gas, 6V NEGATIVE ground (alternator installed) and ignition coil wiring changed accordingly.
SUGGESTIONS APPRECIATED. Where can I order carb parts?
Re: 420 crawler engine surging
Do a compression test, that will tell you if a valve is leaking.
Lavoy
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com
Owner and moderator www.jdcrawlers.com
Re: 420 crawler engine surging
Compression test cold was about 55psi for both cylinders. Not sure how accurate the gauge is, but at least they were the same when cold. Did not check hot. Since I adjusted valves already, cannot tell.
Ran for another 20minutes in driveway, shutdown and let set for 30minutes. A quick pull on choke and fired right up. Hope I don't have to tow it home again.
Wish me luck. Taking out to do more trees today. Where can I order carb rebuild kit to have on hand?
Ran for another 20minutes in driveway, shutdown and let set for 30minutes. A quick pull on choke and fired right up. Hope I don't have to tow it home again.
Wish me luck. Taking out to do more trees today. Where can I order carb rebuild kit to have on hand?
Re: 420 crawler engine surging
If I remember correctly the cold compression test should be around 100 - 130????
1956 JD420, gearmatic 8a winch, custom 6 way blade and FOPS.
Re: 420 crawler engine surging
Yeah, you are way light on compression. Squirt some oil in each hole just to verify it is valves, but that is way too low.
Lavoy
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com
Owner and moderator www.jdcrawlers.com
Re: 420 crawler engine surging
Be sure you have the throttle plate and choke plate in the carb. wide open for no air flow restriction. Possibly even remove the air cleaner. For Compression tests. The added oil in cylinders helps the rings to seal, if compression stays the same after adding oil it indicates the leak is at the valves.
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
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