Ignition advance/retard

Not speaking of loosening the distributor and advancing or retarding the timing. Im speaking of something like a vacuum advance. Our Oliver 1650 gas has vacuum advance in the distributor. Did other tractor manufacturers use ignition advance like this or some other type ? Were there any tractors made without any ignition advance/retard like this ? Just curious. I know my 300 Farmall does not have vacuum advance, perhaps mechanical. After owning it for years, and doing a full in frame engine rebuild on it myself Im embarrassed to admit I have little knowledge on this subject.

(quoted from post at 12:38:51 10/10/23) Not speaking of loosening the distributor and advancing or retarding the timing. Im speaking of something like a vacuum advance. Our Oliver 1650 gas has vacuum advance in the distributor. Did other tractor manufacturers use ignition advance like this or some other type ? Were there any tractors made without any ignition advance/retard like this ? Just curious. I know my 300 Farmall does not have vacuum advance, perhaps mechanical. After owning it for years, and doing a full in frame engine rebuild on it myself Im embarrassed to admit I have little knowledge on this subject.

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any and likely most older tractors did not use vacuum advance, but used centrifugal advance (fly-weights/springs).

I could be wrong, but I thought some Ford tractors vacuum advance as well

Some may have at the end of the 70s the reason for it is to allow the timing to be advanced when under high vacuum conditions. (near no load and at many speeds) At idle the vacuum can be high but the centrifugal advance is retarded to near the initial static timing. (IIRC all distributor systems from the early 50s on up have centrifugal advance under the breaker plate) Then when the engine is increased in speed (but under little load) the centrifugal advance and the centrifugal both advance the spark. this allows better fuel consumption and still avoids spark knock at high vacuum low load conditions. When the governor opens the vacuum advance pulls the timing back to load condition to, again, avoid knock. The centrifugal advance is only RPM controlled, so the advance does change with engine speed under loaded, or partially loaded conditions. Early tractors were designed without consideration to pollution, or smooth running. Magnetos used in that era had no advance or other timing mechanism other than the impulse coupling delay to get them running without breaking the cranking persons arm. After starting they ran poorly at idle because the timing was set at full throttle full load timing. Jim

Your vac advance is usually done while your under wide open throttle as carb vac over comes manifold vac and the suckem line is one the carb thru the up side of the butterfly . Olivers are the only one i can think of that used this, now granted i do not work on that many off colors. I H I H uses the centrif. advance and at full rated engine speed ya got it all and speed is pulled down so does the advance start backing up . To check them it's nice top have a dist strob/ machine where ya can see what is going on at engine speeds . Like everything they ware and things change over time due to the ware ya end up with more advanced timing then ya want or the retard springs break and really mess things up . Some stick and now do nothing . Not many of us old goats around that can still set up a dist to work like it should or change it to make things go better . all depends on what the engine is used for and how many RPM's it is going to turn. . World of difference between a race engine and a working pulling engine Took me a good while to get that thru my thick head as the advance wioll start to fight you if tomuch when the engine is coming down due to load . On Ford cars from back in the late sixty's early seventy's had a double vac system , once the engine started at Curb timing and the vac came up one side of the dist would pull back ing. timing as much as 10 degrees ATDC then when ya went wide open throttle between base set and Vac ya came up to 34-38 degrees BTDC . one side drew on Manifold vac for retard and the other side went on carb vac. for the power side . .Lots of problems with that once . Chrysler use to try and set base at TDC on Std. shift cars like the Road Runners , Super Bee's GTX and Chargers ,that lead to a ton of back fires while tryen to start and lots of french fried air filters and air filter housings . Us guys that worked on them did not go by EPA rules and bumper the ing. base timing to 10 Degrees BTDC and now your Mopar started like a Ford on a sub 0 day , No more the Chrysler long wind up on the starter hopping it was going to start. . On the ones i work on with the ones not stuck or broken springs i find them to be over advancing due to ware.

(quoted from post at 12:48:30 10/10/23) I could be wrong, but I thought some Ford tractors vacuum advance as well

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expect tractorvet knows for sure, but I think the thousand series Fords used high manifold vacuum to advance timing (idle & light load), which would pull back advance when you pulled it to wide open throttle, killing the high manifold vacuum. Also had centrifugal mechanical advance.

The Indian chief had ignition advice on one hand grip. Gas on the other.

Did the old AC have a lever for spark and another for gas?

My 1950 Farmall has a magneto, no vacuum adv.

No vacuum adv on Jubilee.

The vacuum advance makes for smoother light load use when throttle plate is almost closed. Most tractors SELDOM work this way. The centrifugal advance NEEDS to work right, the vacuum advance is not needed at all for tractor use.

The TractorVet attempted to explain this but his self-fangled wording kind of took away from the true explanation. What he was explaining is ..ported vacuum.. Most road vehicles from the 40s up through the 70s used this. This configuration places the signal port or opening for the vacuum advance supply just above the throttle plate at idle. So for one the vacuum advance (VA) at idle is inactive so there is no fluttery idle from to much advance. Secondly, as you just open the throttle a bit the edge of the throttle plate moves over the port activating the VA, advance of the spark at this point helps reduce throttle ..tip in.. bog working in conjunction with the accelerator pump. Third, while cruising the VA continues to be activated varying with load to help eliminate detonation and increase fuel economy. Lastly on deceleration the throttle is closed deactivating the VA reducing exhaust back fires.

I do understand the basic concept ! Thanks !

If the centrifugal doesnt work right what happens to the tractor operation ?

So if the centrifugal advance didnt work what would be the symptoms on a tractor engines performance ?

Engine will not pull right, exhaust manifold will get red hot, water temp will go up too.

As to JMOR's comment. My '72 Ford 2000 has a vacuum advance. FIL acquired it from a horse farm, non-running, and never used it much. It was hard starting and got to where it needed ether at under 50 degrees. When I got into it I found the points were really gone but that the advance mechanism had a stack of washers essentially eliminating the advance. I got it as good as I could without a distributor analyzer. Funny, I also got into the carb and found it had a vacuum operated accelerator pump.

(quoted from post at 17:53:08 10/10/23) So if the centrifugal advance didnt work what would be the symptoms on a tractor engines performance ?

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ou have to know which of three types of vacuum advance you are referring to, as they are very different. For example, some yield high advance at idle & slower speeds and knock it back abruptly as engine throttle is quickly opened. Some use ported vacuum to increase advance as engine speed increases. Another used no centrifugal advance and a dual diaphragm, two port system to adjust advance. This last one wasn't in production for a long duration. I suspect to was not a good idea. Corvettes with the higher performance 327, 340 & 360 hp engines did not use any vacuum advance.

This post was edited by JMOR on 10/10/2023 at 03:47 pm.

Most of the old tractors I worked on (AC) had either a magneto which had timing at near TDC while cranking(impulse working) and then ran at a fixed 25 to 30 degrees BTDC, or a distributor with centrifugal advance which was supposed to have timing near TDC for cranking and idling, then advanced to around 25 degrees BTDC at wide open. Unfortunately, in my experience, distributors are terribly neglected. The screw/plug should be taken out of the housing and the cavity filled with light oil. The felt under the rotor should likewise be lubricated. So often water in this NY wet climate has raised havoc with the advance mechanism. I've seen the little springs rotted right away to nothing. I like to spray some kind of light lube down in the mechanism. I've been criticized by purists who apparently live in a perfect world for this. I'd rather see the inside of a distributor oily any day over being rusty.

Some times hard starting , some times poor performance , BUT unless you have run the tractor for years you my never notice , over heating , Pinging but on a tractor this can be hard to hear . And on the tractor it is hard to tell what is going on . Only on the machine / Strobe will it really show up where ya can control the RPM's and see the advance on the dial and having the spec sheet to go by. On my machine i can get down to 1/2 degree and vary the RPM's from below ideal to WAY over the top as i can reach 5000 Dist RPMs that is 10 grand engine RPM's , ya can see point bounce real clear .

Welp i can't say on later ford gas tractors as believe it or not i have never worked on one older fords i have had some experience with and knew enough to have a packet of then rotor clippy things on the truck , i think there are two left in the glove box.