D19 gas engine mod suggestions

Well pulling season is over and I'm trying to be ahead of the gun for next year. Tractor is right now a bone stock d19 that I pull in paced 5 mph farm stock classes from 7000-8500. Most of the places I pull have the turbo and non turbo classes separated.
Would like to do some things to give her a bit more snot as it seems like I got her balanced right and she usually runs out of snort and I have to drop in low range before I spin out.   I have 18.4 x 38 firestone radials on now that are quite worn so I might splurge and get a new or newer used set with more bite before next year so I should have even more need for more power.
Right now engine runs like a top, head was just redone replacing all the exhaust valves, all new guides and valve job. Petronix ignition and that's about it.   I do have a zenith carb from the same size engine off of a gleaner combine I could try.   Looking for some suggestions as to what I could do to make the engine stronger without going absolutely crazy and completely rebuilding it.   Tractor is very competitive as is right now, would just love to get her on the top of the podium next year. Here's a video from two years ago as I didn't video much this year. I think this pull got me third.
http://m.youtube.com/watch?feature=g-high-u&v=U7xBN6Kuuuw

Edited by ChuckLuedtkeSEWI - 27 Oct 2013 at 10:13pm

Chuck...Try that Zenith carb. off the Gleaner combine. It's got way more bark than that M/S carb. without a doubt. I've got a Gleaner combine engine in a D19 here with the Zenith carb. on it and it runs a lot harder...thanks, Don ol' buddy! Of course, it uses even more gas, but hey...depends on what you want to do, right? LOL!  Rick

I do want to try that Rick, just never got that far.    It does pull good, just to want to make it to the top once in awhile.

Even if u stay naturally asperated suggestion is to have the cylinder head bench flowed . Bigger valves and port work will allow air increasement . This way bringing in some fuel u can gain a little power . I always look At an engine and see how to fix the asthma the release the constipation . U can always add fuel! What's the cam duration like ? Lift ? As agreed tho kinda tuff engine to build power. Supposed to be a feller around. Rapid city SD has d19 with big automotive pistons and tri power carbs off a Pontiac on custom intake manifold . I never seen it tho.

When I had the head gone through I had the head milled a bit and I think he cut the valve seats different as well but I can't remember exactly what he did.   I did not have ant porting work done on the head at all as I was in a hurry to get it back as I had already missed one pull.

Most of the pulls are farm stock nonturbo class. I try to stay in those as I know the few pulls where they lump turbo and nonturbo together I get run over by the turbo tractors.   

I've seen some of these engines apart, but am not real familular with them. A friend of mine is building a Cockshutt engine and there's only slight differences that i'm aware of.

I'm guessing we'll be doing a bunch of head work this winter and expermenting on the flowbench with it. I don't know about the D19 gas manifold, but the gas manifold from the Cockshutt is terable. I think with some modification the diesel manifold will be much better. As far as port and valve work, I'm not sure yet, I really need to look at the heads closer and see if seating the valves at a different height and cutting some angles would be any improvement or if a guy should throw things away and start with other parts.

I'm guessing as choked as the engine is and as small of a cylinder as you have to feed, some slight head work, manifold modification and a carb swap will be about all you want to try. Diesel pistons should be abundant, I'll grab a camcan from one sometime sometime and map out the profile, I'm guessing there's some room for improvement.

I'd not go wild with the compression ratio, it an engine that is going to have to lay down and lug a long time.

Have you opened up the manifolds and head at all? If the carb off the combine has larger butterfly on it and more stream line inside im sure that would help. The 262 manifold isn't very big and is a huge restriction. Guessing you are running stock rpms? Im working on my own D19 gas and hope to have it going this coming season running in 3k rpm classes in WI and MN some are dyno some are pace. Your tractor runs nice but those pace classes always leave you wanting more power.