Can a 420 LP head be installed onto a gas 420 ?

DoubleO7 · Jul 23, 2018

I have a 1957 420S and am wondering/curious to know if a head off a LP fueled 420 would be a bolt on mod.
And thus increase power via the difference in compression ratios of a 420 gas at 7.1 to 1 and the 420 LP at 8.5 to 1 ?

buickanddeere · Jul 24, 2018

(quoted from post at 23:12:13 07/23/18) I have a 1957 420S and am wondering/curious to know if a head off a LP fueled 420 would be a bolt on mod.
And thus increase power via the difference in compression ratios of a 420 gas at 7.1 to 1 and the 420 LP at 8.5 to 1 ?

I would be fixed up the rate LP 420 instead of parting it to repair a a dime a dozen gasser 420.

buickanddeere · Jul 24, 2018

(quoted from post at 23:12:13 07/23/18) I have a 1957 420S and am wondering/curious to know if a head off a LP fueled 420 would be a bolt on mod.
And thus increase power via the difference in compression ratios of a 420 gas at 7.1 to 1 and the 420 LP at 8.5 to 1 ?

I would be fixed up the rare LP 420 instead of parting it to repair a a dime a dozen gasser 420.

MSD · Jul 24, 2018

There are other ways to up the compression on the 420. We have one running near diesel rated compression. Email is open if you want more information on how.

Glen D Anderson · Jul 24, 2018

Would your 420 compression mods. apply to the 40 as well?

What was the goal for your mods. - pulling or improvement for regular use?

(quoted from post at 07:34:51 07/24/18) There are other ways to up the compression on the 420. We have one running near diesel rated compression. Email is open if you want more information on how.

David G · Jul 24, 2018

Compression is always good, I would run 91 octane in it with that compression, and 12V starter.

ss55 · Jul 24, 2018

You might also look into the pistons used with each fuel. On new generation tractors the pistons were different between gasoline and LPG. Were any aftermarket "high altitude" pistons available for 420's?

buickanddeere · Jul 24, 2018

If looking for a power up on a 420. Find a 440 gasser industrial , they were souped up from the factory .

DoubleO7 · Jul 24, 2018

(quoted from post at 15:02:41 07/24/18) You might also look into the pistons used with each fuel. On new generation tractors the pistons were different between gasoline and LPG. Were any aftermarket "high altitude" pistons available for 420's?

Okay then, so the difference in compression ratios is due to different pistons? Or is the LP head chamber also less than the gasoline head?

The original question is merely out of curiosity at this point.
As in: is more HP as simple as bolting on an LP head.

MSD · Jul 24, 2018

It can be done to a 40 was well. We did it to make a puller out of it. We run 120 octane fuel in it also.

Glen D Anderson · Jul 25, 2018

I can imagine somewhere between 12 to 15 : 1 along with other mods. would provide a noticeable kick in the pants. LOL

When I eventually get around to the O/H on our 40 I'd like to sneak a bit more hp & torque out of it but not to the extent that I need to run race / av fuel or even premium for that matter.

I was thinking of shaving the cylinder head & having the cam re-ground. Maybe check the transition between the manifold & ports and clean that up if needed.

Just a little more oomph for running the Bush hog & tiller......

BTW, how do I find your email?

TIA

(quoted from post at 18:43:16 07/24/18) It can be done to a 40 was well. We did it to make a puller out of it. We run 120 octane fuel in it also.

Ray · Jul 25, 2018

On the 420 LP I had the pistons were domed and the head was rounded to
match.Putting a LP head on a gas tractor would probably lower compression.

M-MAN · Jul 25, 2018

Considering any decent running Dubuque has
enough ump from the factory to flip it's
self even loaded what is the point?

Mike M · Jul 26, 2018

Usually they just used different pistons on most LP models to boost compression. The different part numbers for the cyl. heads is the LP heads have valve seat inserts in them.

buickanddeere · Jul 26, 2018

A 420 is going to be hard pressed to equal the power of a modified Farmall Super H built without sleeves, high compression, a cam and a stroker crank.

DoubleO7 · Jul 27, 2018

(quoted from post at 23:13:16 07/26/18)
A 420 is going to be hard pressed to equal the power of a modified Farmall Super H built without sleeves, high compression, a cam and a stroker crank.

Okie Dokie.
Now to figure out why you felt the need to make that statement in this thread.

But good to know I guess.

buickanddeere · Jul 28, 2018

(quoted from post at 22:11:50 07/27/18)

(quoted from post at 23:13:16 07/26/18)
A 420 is going to be hard pressed to equal the power of a modified Farmall Super H built without sleeves, high compression, a cam and a stroker crank.

Click to expand...

Okie Dokie.
Now to figure out why you felt the need to make that statement in this thread.

But good to know I guess.

Telling you #1 that the 420 is not capable of the same speed down the track as a Farmall H.
Telling you #2 that you are missing HP by souping a 420 engine instead of souping a 440 engine.
The 440 engine had better manifolds, larger carb etc to make more power than a 420/430 engine.

Can a 420 LP head be installed onto a gas 420 ?

DoubleO7

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Glen D Anderson

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