John Deere G power

[bajamonkey77]

Hey guys, I've been reading up on building engines on here lately. I'm going to be putting my 47' G back together shortly, and I'm just looking for some advice.
I want to build a competitive puller, but not to over the top. I'm not going to stroke it. I'll probibly go with high compression aluminum pistons, cold manifold, and the head is the part I'm not sure about. I have a cyclone. I don't know if I want to deck it, or get a flathead. from what I've found, a flathead with high comp pistons will be about 12:1.
I don't want to go too high with the compression, and kill the lugging power. I was thinking about just decking my cyclone about .150 I'm going to port and polish, valve job, and eyebrows...
I'm going to pull it, but I still want to put it in parades and stuff like that. so a good mild/ moderate puller. Just looking for some words of wisdom here guys. Thanks

 

[Anonymous-0]

Hi there, I'm not sure where you are at with buying parts but I have a complete setup for a 8.5 inch stroke late G. Pistons .250 over, rods and camshaft, no crank. 616 902 0633

 

[Anonymous-0]

Personally I would go with .125 high compression pistons and the flat head your compression ratio will be between 11 to 12 to 1, and that is pretty high but it is also safe. It probably won't get hot and you will be fairly competetive, the only down fall is you will need to run racing gas I wouldn't recomend using pump gas. As far as lugging power goes you may lose a little bit of the lug but you should gain more than what you would lose in horsepower on the top end. Just my opinion.

 

[JDGnut]

Just cutting .150 off the head isn't going to get you where you want to be.. I would use the styled head, and lengthen the rods, and push the pistons to the top of the block. That is going to be cheapest, and easiest.. and you can go back to stock. If that doesn't get your compression where you want you can cut the head down.. but that should get you close.

I've built them both ways.. Since you already have most of the parts to built it like this.. a little easier to go this direction.
JDGnut

 

[bajamonkey77]

Well, what I was trying to get at was I don"t want to be at 12:1 compression. It would be nice to beable to still run pump gas, or even 50/50 with 110. I think I want to be around 9:1. The only thing I have for the build so far is the manifold from Murphy"s. I"m on the market for a block, if anyone knows of any for sale.

 

[jd b puller]

It's really hard to build a multipurpose tractor unless you sacrifice on both ends. To make HP you need displacement and compression amongst other things.

Compression will take better fuel, displacement will use more of it. So you back those down so you can parade it and you lose HP and you won't be happy as a pulling tractor. Now you've just got an expensive parade tractor that's still has a drinking problem. Put them where they belong, and you can't afford to run it in a parade... I start mine up, it runs for 10 minutes at idle before I hook (scales, waiting in line), run it down the track, and 1-1.5 gallons of fuel disappears. Imagine that on a G in a parade.

G's are nice, but for the money you are going to spend building your "compromisor" you could likely sell the G and buy both an A and a B. One for parades (paint and basics) and one for pulling (bored/stroked, etc).

 

[bajamonkey77]

I'm not going to take this tractor to a dozen parades a year, I'll go to one maby two. I mentioned that becuase I don't want to have 800 cubes trying to run in a parade or something alone those lines. I'm shooting for 65-70HP, I realize its going to chug fuel in a parade. But I just want it tolerable to run for a while, and not just start to stage, then pull. I guess I'm getting at I don't want to have just a pulling tractor, if I can't use it every once and awhile, its just a expensive toy.
I've been reading on others setups on here to get some more ideas.. So far I think I'm going to go with high comp pistons, deck the head .150?, roller rockers, cold manifold, and port and polish/ triple valve grind. By what I've found that should give me 60-65HP? Does this sound way off? Also any suggestions welcome, and tips on building these engines. Thanks!

 

[Drew]

The 60-65HP is probably in the ballpark for what you mentioned.

I'll agree w/ JDGnut that cutting .150 off the head isnt going to be the gain you think it is. There is so much compressed volume in a 2 cylinder that the little bit of compressed volume you lose when you cut the head is little more than a drop in the bucket.

If you are really wanting more toward the 70HP number, put a Murphys head on it. If you do this, you will probably want to cut some off the pistons to keep from having too much compression.

 

[gpuller]

If you are going with M&W style pistons I don't think you'd gain anything by cutting and lengthen the rods. With high compression pistons in a late G block the pistons are approx .25 down in the hole. Any more compression and you'll be running expensive gas.
With .090 over pistons, cold manifold, styled head cut down to the eyebrows, good valve job and cleaned up ports 60hp is possible, no need to run $7/gl gas, or whatever the cost is these days.

 

[Anonymous-0]

I've got a G that has 62 HP Dyno. No stroke. .125 over aluminum pistions, head decked .150, port matched, no eyebrow cleanup 55,000 volt coil with electronic pickup 90degree distributor. So that will get you close. About 125psi cylinder pressure. Will run on regular gas all day long. Pulles good but as they say more is better and sometimes I wish I had more.

 

[Little G puller]

I've got a G that has 62 HP Dyno. No stroke. .125 over aluminum pistions, head decked .150, port matched, no eyebrow cleanup 55,000 volt coil with electronic pickup 90degree distributor. So that will get you close. About 125psi cylinder pressure. Will run on regular gas all day long. Pulles good but as they say more is better and sometimes I wish I had more.