farmall H ?

[Anonymous-0]

I have been wanting to put the bigger carb and manifold on my H for some more power. I have been told that the new replacement manifolds are junk and I need to get a old one off of a super H,300,or 350. How true is this. Thank you.

 

[james rumph]

You need to speek with Chad , theres more to it then just adding a manifold and carb. Every change effects some other part, carb jetting,timing ,governor setting etc etc.

 

[jhb]

I was happy with my replacement. It had a sand hole in it that was plugged but it allowed me to add a M carburetor and since I had the cubes of a 350 it worked great. About 40 hp at 1815 rpm.

 

[Anonymous-0]

If your running the original manifold, a new manifold will adapt to both carbs, H-350. Big difference just in the casting alone on the replacement VS factory stock H. In a way, the replacement manifold being larger, it would almost be a trade off. Stock H, with low cyl pressure,, lets say 130 psi or less, The M carb would have to be using a smaller venturi in it anyways, and a new manifold and adding the M carb, may be too much for it. It would sound good, but no lug worth a darn in the lower rpm range. The air moving thru the manifold is moving too slow, and vacuum would drop more quickly and it falls off quick. Id say a new manifold, and use the H carb if its a stock H, or even bigger ci, but the cyl pressure will tell you if you can stand the upgrade to the larger parts. If its 150 or more, then its a good canidate for both, manifold and carb. If its under 130, I think you would see it perk up with just a manifold swap and tune the carburator in. Have a look a the valve lash adjustments, check the rocker arm tips for wear, even pull the lifters out one by one and see if they are worn. Making sure the governor weight pins are in good shape, and have the magic governor spring and if needed shave the weights down. Recondition or replace any worn parts found. Distributors are usually shot if not taken care of. Good time to make sure the advance is working, and maybe swap the little springs out with some lighter tension set.

Your main objective is to know your working rpm range to tune for best results on the track. If you run a tach and watch it, if it never drops below 1800, then its a pretty strong engine, or they are not using it all up and hooking up. If its running 1400, or down to 1000 rpm, making adjustements to help a particular working rpm range will see good results on the track. On pto dyno, I dyno from 540 and lug down to 400 pto rpm and work from there. If a good gain, and a good 3-5 hp is possible could be worth a couple of feet or inches. ChadS

 

[Anonymous-0]

Thank you for the info. My H was rebuilt 4 years ago and it has the 350 kit in it. I have never checked the cyl psi I guess I will have to do that. Right now it dynos at 39 hp and I am looking to be around 45-50 hp. hat else might i do. Thanks

 

[CGpuller]

Stick with a 24 venturi out of a 300, the M venturi is to big. Make sure you have a late model cam(300, 350).

 

[Andy Motteberg]

New manifolds are not junk, I have one on my H and they are good. I've had it for a few years and I'm very happy with it.