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I was correct about the compression between a Z120 head and

J

Jason S.

Well-known Member
So I entered in the numbers using a compression ratio calculator. When a Z129 head is installed on a Z120 engine with flat top pistons the compression is raised to about to 8:1. Way too high for a working tractor. You may get by with it on a parade tractor but on a working tractor you would have holes in the pistons in a short period of time from spark knock. Especially if the Z129 camshaft is used because it has an earlier closing intake valve than the Z120 did,therefore the Z129 camshaft builds more cylinder pressure. Dished pistons must be used when installing a Z129 head on a Z120 engine. If a Z120 head is installed on a Z129 engine the compression is lowered to about 5:1. Kind of low but that is better than being too high.
 
All-Righty sparky. . .
Camshaft.
REF No.(30) 1750074M1 (Order 836543M91 Kit) TO-30.
REF No.(30) 1750293M1 (Order 836543M91 Kit) TO-20.

It seems the replacement cam for the 20 and 30 are
the same going back to my 5/73 parts book.

TE/TO 20 used the same cam.
MF 35 also used the same cam 836543M91.

The TE-A20 80 MM used a lo lift cam stamped 56216
and the 85MM used a high lift stamped L.O.

Now as for the TO20/30 tghe cams might have been
different from the factory but the replacement cam
was the same for both engines.

So your going to recommend, What? A '20 block with
the '30 crank and head keeping the '20 cam?
Inquiring minds need to know. . .
 

The Z129 and early Z134 engines used a different camshaft. Later Z134's changed back to the earlier cam used in the Z120's. All of the replacement cams are the Z120 cam. The biggest difference is the pistons. Whether the Z129 head is installed on a Z120 or Z129 dished pistons must be used to keep the compression at a decent level. According to my calculations anyway. You may be able to use the Z129 head on a Z120 with flat top pistons if the Z120 cam is used, if you set the valve lash tighter than recommended, backing the timing off a little,and making sure to use a TO-20 distributor which had 24 degrees of advance built in,whereas the TO-30 distributor had 26 degrees of advance built in. Even with all those precautions it would be a gamble especially if the tractor is put under a load often.
 
I don't have access to my manuals, but is did Ferguson have a recommended octane rating for these tractors' fuel?
I know the gasoline available in the '50s was a lower octane and as cars came out with higher compression engines the oil companies responded by increasing the octane in their gasolines. Remember "fill 'er up with Ethyl?", that's a reference to tetra-ethyl lead that was put into gas to raise octane. Cute little commercial here- https://www.youtube.com/watch?v=mkTxI0o9Hfw

Back to the question at hand, could you use a higher octane fuel in order to stop the spark knock and take advantage of the greater power you'd get from raised compression? Just a thought.
BillL
 
(quoted from post at 04:50:27 01/25/15) I don't have access to my manuals, but is did Ferguson have a recommended octane rating for these tractors' fuel?
I know the gasoline available in the '50s was a lower octane and as cars came out with higher compression engines the oil companies responded by increasing the octane in their gasolines. Remember "fill 'er up with Ethyl?", that's a reference to tetra-ethyl lead that was put into gas to raise octane. Cute little commercial here- https://www.youtube.com/watch?v=mkTxI0o9Hfw

Back to the question at hand, could you use a higher octane fuel in order to stop the spark knock and take advantage of the greater power you'd get from raised compression? Just a thought.
BillL
Click to expand...

Well it isn't quite that simple. The static compression ratio isn't as big of a problem as the dynamic compression ratio is. The dynamic compression is affected by cam timing and other variables. Dynamic compression is the true running compression of an engine. I need to calculate that number.
 
Not Z120-Z129 but interesting

http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=mf&th=154576

IH and Oliver had CR of 7.6 to 8.5 on some big gas 6 cyl way back when gas was better.

Timing advance I think would need to be backed up to 20 degrees more or less.

Might or might not work.
 
(quoted from post at 15:07:35 01/26/15) Not Z120-Z129 but interesting

http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=mf&th=154576

IH and Oliver had CR of 7.6 to 8.5 on some big gas 6 cyl way back when gas was better.

Timing advance I think would need to be backed up to 20 degrees more or less.

Might or might not work.
Click to expand...

Well that goes back to cam timing and what the dynamic compression is. A later closing intake valve will build lower cylinder pressure therefor lowering the dynamic compression. That is why I said it may help to run the Z120 cam because it has a later closing intake valve. Are there motors that are 8:1 that can be used like tractor engines are under a load all the time with no ill effects? Yes...but those engines were designed to be used like that. But in this case we are putting an engine together with components that were not designed for the compression to be that high. So its a gamble, at least until I run the dynamic compression numbers then I can say for sure whether or not it would be safe.
 
Ran the dynamics for you using this calculator- http://www.wallaceracing.com/dynamic-cr.php

I figured rod length at 5.25" as an educated guess with a tape measure with pistons/rods in my motor. If you have the correct length, let me know.
400 ft corrected altitude.

Z120 stock dynamic CR=5.71:1
Z129 stock dynamic CR=6.31:1
Z120 w/8:1 static CR and stock cam=7.49:1
Z120 w/8:1 static CR and Z129 cam=7.79:1

IMO I don't see a problem with this, especially if you use a higher octane, like a mid-grade, fuel. It'd be cool to do a before and after dyno test to see how much HP and torque gain you get.
BillL
 
My dad work at a Ferguson dealer from 1948 till 1959 had a TE20 z120 had a TO 30 head had no problem it sure would out work a TO 20.Would like to find the tractor was sold when I was is the army
 
I wouldn"t be so sure that 8:1 compression would cause a great problem with the piston crowns IF you retard the timing to preclude knock and enrich the mixture to get more charge cooling. Today"s gas has a higher octane rating then the old 80 RM octane stuff that was used when these engines were designed.

I"d be a bit more concerned about cooling because of the increased high cycle temperatures from the increased compression ratio. Even that may not be an issue if you aren"t running at max power most of the time.
 
(quoted from post at 23:42:51 01/28/15) I wouldn"t be so sure that 8:1 compression would cause a great problem with the piston crowns IF you retard the timing to preclude knock and enrich the mixture to get more charge cooling. Today"s gas has a higher octane rating then the old 80 RM octane stuff that was used when these engines were designed.

I"d be a bit more concerned about cooling because of the increased high cycle temperatures from the increased compression ratio. Even that may not be an issue if you aren"t running at max power most of the time.
Click to expand...

My only issue with that is if you retard the timing you are killing off the power gains that you would be getting from the swap.
 
Going from CR 6.6 to CR 8 will give you a substantial power increase and a few degrees of spark retard will unlikely loose all that gain.
 
My only issue with that is if you retard the timing you are killing off the power gains that you would be getting from the swap.
Click to expand...

Jason, got anybody nearby with a dyno? You could do some pulls with different timing and advance settings and get the best power. 8)
Maybe do a back-to-back cylinder head comparison. I'll buy the head and manifold gaskets for you if you decide to do it.
BillL
 
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