420 c rough idle

[H-D]

Tetraethyllead had the beneficial side-effect of lubricatin' the valve & seat contact 'patch'. An additive to 'help' the valves & seats IS beneficial! The possible exception to this are some air-cooled engines (Corvair for sure) which had harder than average valve seats. Did y'all know that the EGR valves which were initially employed by the automakers to lower combustion chamber temps (which lowered NOx) also had the beneficial side-effect of allowing more total spark-advance & a more agressive spark timin' curve? Ya never know what 'good' will come outa the Yankee government!

[Paul Buhler]

Ok, so what and how much is added to the gas to make up for the missing tetraethyl lead? Thanks.

[jdemaris]

Tetraethyllead had the beneficial side-effect of lubricatin' the valve & seat contact 'patch'. An additive to 'help' the valves & seats IS beneficial! The possible exception to this are some air-cooled engines (Corvair for sure) which had harder than average valve seats. Did y'all know that the EGR valves which were initially employed by the automakers to lower combustion chamber temps (which lowered NOx) also had the beneficial side-effect of allowing more total spark-advance & a more agressive spark timin' curve? Ya never know what 'good' will come outa the Yankee government!

There were a few engines, but not many, that used hardened valve seats - in cars, trucks, tractors, etc - long before the US changeover to unleaded fuel. Deere didn't have any that I recall. The first hardended seat inserts I ever saw in a Deere were when they added turbos to diesels. Before that, the diesels had soft cast-in-head seats also. I also add that the diesels also had a recession problem - and Deere diesel engines are very touchy when it comes to valve-in-head recess specs. Do one valve job by grinding and refacing - and the valve heads get too deep - and you get an engine that starts poorly in cold weather. Once the intakes get deeper than .025" and the exhausts deeper than .040", problems show up.

As you mentioned - several air cooled engines e.g. the Corvair, some Volkswagens, etc. had hard seats, stellite or sodium valves, etc.

Valve recession has been more of problem overseas since many countries switched to unleaded much more recently than here in the US, and many people overseas keep their old equipment longer.

When the USA and Canada switched over to unleaded fuel, a new additive was put into the unleaded gas to offset the wear problem. I can't remember what the chemical was - but it was later banned and was causing new pollution problems.

The reality is - any kind of noticable excess wear only occurs on engines that are run hot, hard, fast and/or long. For a farm tractor - or collector tractor - most people will never notice the difference. If a tractor was being used full time, every day, on a farm - the valves and seats wear around 30% faster without the lead.

With John Deere stuff - the all wore anyway - regardless of fuel. I've done countless valve-jobs for customers over the years - many of them "budget" valve jobs. A farmer would pull up to the shop with a two-cylinder head in his trunk off his Deere, we'd regrind the seats and reface the valves in less then an hour, and he'd take it back home and have it running again by lunch-time. If, 10 years later, the valves needed some work again - it was no big deal.

Funny thing now is - many of these tractors are being fixed for intemittent use - and often, no real work at all. Yet, most automotive machine shops want to do the whole deal - or nothing. New valve guides, new hard inserts, new valves, surface refacing, etc. In many cases, it's. Nothing wrong with spending the money and doing things perfect if you want to. But, I've done many fast, parts-less valve jobs and they've been fine and lasted many years.

[jdemaris]

Hi: My 420 c sort of lopes when idling . . .

When I try to adjust the idle screw, the tractor runs smoothest with the jet completely closed leading me to guess that the idle jet is worn, or that I have an air leak between the carb and the cylinders somewhere. . . .

Any ideas on how I might isolate the problem would be appreciated. Thanks. Paul

I've worked on many tractors that idled and ran fine, even though the idle-mixture screw didn't do very much when turned in.

If it was my machine - especially with a Deere two-banger - I'd unhook one plug wire at time and try running it with one cylinder. A 420 will purr on one cylinder when all is right - just won't have much power. Unhook one, run it - and if it runs smoooth - hook that one back up and then unhook the other. If you find it runs smooth on one of the cylinders, but not on the other - it's doubtful the carburetor is to blame.

I bought a 420 a few months ago - and the guy that was selling it was bragging it up about how smooth it ran - and also commented how he loved the "Johnny-popper" sound. Funny thing was - it wasn't the right classic sound - and noticed right-away it was only running on one cylinder and sounded more like an old lawnmower. That was easily verified when I ran the machine. It is a crawler-loader and takes some power to move. With only one cylinder, it felt like it has a Briggs & Stratton lawn mower engine powering it.
I was trying to load it onto a trailer and didn't even have a spark plug wrench. So, I pulled plug wires and ascertained #1 cylinder was dead. I then held the #1 plug wire near the spark plug terminal - forcing it jump a large spark-gap. This, all-of-a-sudden, made #1 kick in and start running. Creating this large gap forces the coil to make higher voltage.
Did this for awhile and was finally able to put the plug wire back on the plug and have almost two cylinders. It idled rough, but smoothed out under load. Later, when I got the 420 home, I put a new spark plug in it and now it's fine.

Most problems are NOT solved this easy - but it happens once in awhile.

Back to your 420, it will behoove you to find out if this problem is equally distributed across both cylinders, or just dedicated to one.

If your valves are way out of adjustment, it changes the valve timing.

[Paul Buhler]

Thanks for sharing you experience. If time allows, I try your suggestions.
My Dad used to show off his Model As running on two cylinders and taught me how to tune them and use the retard/advance lever on the steering column effectively. Unfortunately these lessons occurred over 40 years ago, so I've forgotten much of what he taught - your suggestions brought back some memories. Paul

BTW, Did you work near Pine Island, NY? Your mention of black dirt farming elsewhere leads me to ask. I grew up near there, and saw many lightweight crawlers with wide stances used on a regular basis for planting, tilling, and harvesting.

[Paul Buhler]

Oops, I've got to proof read my messages more carefully when drinking wine. I meant to say, If time allows tomorrow, I'll check out the running on one vs two cylinders. Paul

[jdemaris]

BTW, Did you work near Pine Island, NY? Your mention of black dirt farming elsewhere leads me to ask. I grew up near there, and saw many lightweight crawlers with wide stances used on a regular basis for planting, tilling, and harvesting.

Yes, I worked for two dealers in that area and also in Chester - another black dirt farming area. Lettuce, onions, and lots of migrant pickers.
The polish onion farmers used small crawlers with wide tracks and three point hitches for plowing - usually Deere 350s, but also a few Cletracs. For the onion seed beds, they had a lot of Planet Junior walk-behind equipment.

I worked for Nelsons Deere Equipment, Imperial Tractor Deere, Dombrowkis Farm Equipment (Florida, NY) and Bellows & May Farm Equipment in Middletown, NY. Then moved furtrher north and went to work for Laneway Deere Ind. Farm, and Ag - in Oneonta, NY - Otsego County.

[H-D]

jdemaris's post makes me homesick for the days when snatchin' one plug wire at a time from the distributor cap was the accepted method of searchin'for for weak & inop cylinders. Now, with Direct Ignition Systems (no distributor) ya need the mega-buck scanner to kill the appropriate injector to do the job, or some creative wiring to 'kill' a coil or coil pack. Oh yeah, no more pullin' plug wires at the cap without supplyin' a GOOD ground path for the spark 'less ya wanna buy a replacement ignition module. Reckon maybe that's why these ol' crawlers are so popular. As long as Lavoy can keep scroungin' parts up, any '55 Chevy or Ford mechanic can "git'r done!". Regardin' Paul's question as to the amount of Mystery Oil to use, the can reccomends 2 ozs to 5 gal of fuel & up to 20% of the regular oil volume to be replaced with the stuff. As an aside the stuff isn't as good as it usedta be it was diluted with what smells like Dexron ATF around 20 years ago. Question: Does anyone know where the original 'sweet' smellin' version was obtained? I'd swear I was around that smell as a kid, but don't remember where. Been around cotton gins, cabinet shops, & beaucoup other places, but I can't 'member the source. Reckon maybe whale oil?

[H-D]

jdemaris's post makes me homesick for the days when snatchin' one plug wire at a time from the distributor cap was the accepted method of searchin'for for weak & inop cylinders. Now, with Direct Ignition Systems (no distributor) ya need the mega-buck scanner to kill the appropriate injector to do the job, or some creative wiring to 'kill' a coil or coil pack. Oh yeah, no more pullin' plug wires at the cap without supplyin' a GOOD ground path for the spark 'less ya wanna buy a replacement ignition module. Reckon maybe that's why these ol' crawlers are so popular. As long as Lavoy can keep scroungin' parts up, any '55 Chevy or Ford mechanic can "git'r done!". Regardin' Paul's question as to the amount of Mystery Oil to use, the can reccomends 2 ozs to 5 gal of fuel & up to 20% of the regular oil volume to be replaced with the stuff. As an aside the stuff isn't as good as it usedta be it was diluted with what smells like Dexron ATF around 20 years ago. Question: Does anyone know where the original 'sweet' smellin' version was obtained? I'd swear I was around that smell as a kid, but don't remember where. Been around cotton gins, cabinet shops, & beaucoup other places, but I can't 'member the source. Reckon maybe whale oil?

[Lavoy]

I would not be too concerned about lack of lead in the gas. Yes, valve seat recession may occur, but you are talking about engines designed to run many thousand hours. I doubt any of us are putting that many hours on them any more. You can put hard seats in the heads too, I do this on all of the heads I have rebuilt. It eliminates the no lead worry, and brings the valves back up to the correct height if someone has ground the valves a few too many times.
Lavoy