Need advise on IH-c301 engine December 06, 2014 12:59PM
I have a stock 301 with a little head work and a bigger cam. It puts out 95hp @ stock 460 rpm on 87 octane. I now have bored it .125, raised the compression ratio to 10.4 to 1 & am getting 103 hp on 102 octane. I was expecting 110+ hp on 93 octane. Am I expecting to much or am I missing something. On 93 octane it misses out & falls @ about 85hp & the plugs are getting fried. I think I am not getting enough cfm threw a stock carb to feed the engine but I have not heard of anyone else have a problem. Please give me your advise on all of this. Thanks Jim



Edited 1 time(s). Last edit at 12/06/2014 01:01PM by Jim Couden.
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Re: Need advise on IH-c301 engine December 07, 2014 12:01PM
Just to put in in perspective I had a stock 560 with a mild cam and some head porting many years ago and it made 85 hp . I had the largest venturi available and adjusted fuel and timing while on the dyno. I would do some carb work and find out what the timing is set at make sure you are not leaning out and that the timing is not advaned too much. I had some problems running too hot of plug as well , the champion D21 was not working for me. I would also make sure your ignition is up to snuff , can you run a MSD ?
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Re: Need advise on IH-c301 engine December 07, 2014 12:55PM
Thanks for the info. I set timing by the book, then when on the dyno. I also went to d16 plugs and It helped a little . I was thinking the colder plugs and high octane fuel was just hiding the fact that it is way to lean. I can open the main jet til it is way to rich but I think it needs more air to go along with it. Does the bigger ventura do this or is there something else that brings in the air. I think we are on the same page I just don't know what I need to do. In my mind a stock carb just can't feed a engine that has that much hp gain. The main jet has been bored out but the rest of the carb is stock 301.
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Re: Need advise on IH-c301 engine December 07, 2014 01:17PM
If I remember right the 301 came with a big Venturi 37? and you should if you have not already have the biggest venturi available for that carb. I have built several combinations of this engine and never had a problem, Without hearing it run I feel that you have an ignition problem of some sort. I hope this helps
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Re: Need advise on IH-c301 engine December 07, 2014 01:31PM
try less timing,you are most likely too advanced with over 10-1.
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Re: Need advise on IH-c301 engine December 07, 2014 02:01PM
I don't recall what the timing is set at but when I had it on my dyno I adjusted it up & down to get the most hp under load & the carb but nothing seems to help. I don't think it's the ignition, it runs good & smooth from idle to full load & then pull it down with dyno til I could kill it. Since going to the high octane it never misses a beat but I think its just covering the fact it's running to lean. I know of a few of these set ups & they are running 90 or 93 octane with no problems. Why is it always me? (lol)
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Re: Need advise on IH-c301 engine December 07, 2014 03:04PM
How many Rpm are you running?
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Re: Need advise on IH-c301 engine December 07, 2014 10:11PM
Stock + 10% so about 2150.
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Re: Need advise on IH-c301 engine December 07, 2014 10:43PM
I don't think those numbers are terrible. You will have to run the better gas at much over 9 to 1 to prevent detonation. Did you degree in the cam with a degree wheel?
That has a huge effect on engine performance. Sounds like you are doing everything right on the dyno.
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Re: Need advise on IH-c301 engine December 08, 2014 01:25AM
Yes we degree the cam. The other engines I know of are running 9-9.5 to 1. I believe detonation was what was happening but 102 octane I thought was a big jump. Since I have a dyno I try one thing at a time. I'm not very smart so I'm slow & cautious.(lol). I tried different mixes of fuel from 93 octane to 110. 102 performed the best. I lost hp at 100 & at 104.Anything more or less ran like @#&?. I suppose I'm expecting to much with to little. thanks for your input.
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Re: Need advise on IH-c301 engine December 08, 2014 04:32AM
Back in the day when the muscle cars were running 10 to 1 you could buy gas over 100octane. You are on a dyno so all the b.s. stops. If you want to feel better you can dyno at 700 PTO rpm. Lol. You have gone a few steps farther than a lot of your competition, it will show on the track.
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Re: Need advise on IH-c301 engine December 08, 2014 05:36AM
You are right I guess. I am dealing with the facts. At 700 pto I could tell people I have over 125 hp like most.(lol) . I don't know if you are a doctor but thanks for the support. I will learn to live with it & be happy.
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Re: Need advise on IH-c301 engine December 08, 2014 05:58AM
what are you running for plugs and ignition system and what fuel are you running(brand)
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Re: Need advise on IH-c301 engine December 08, 2014 06:10AM
Stock ignition, champion D16 plugs, VP 110 fuel mixed with Marathon 93 octane gas.
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Re: Need advise on IH-c301 engine December 08, 2014 11:57AM
How do you know tht you are running lean, what does the plug look like? what are you running for a plug gap . Im not telling you what to do, the problem with champion plugs is that they like to fuel foul. Is your ompression figured or is it cranking psi.
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Re: Need advise on IH-c301 engine December 08, 2014 06:27AM
As I'm sure others will chime in I think you would benefit from hei ignition, upgraded coil and about any other spark plug with good wires.
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Re: Need advise on IH-c301 engine December 08, 2014 07:31AM
I know, I know. But I am one of those few that has never had a champion plug fail me. As for the electronic ignition & coil I do agree but it starts & runs smooth as it could & I don't understand how that would help it from running lean. Ignition is my next addition. Thanks for your reply Jim
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Re: Need advise on IH-c301 engine December 08, 2014 07:56AM
If you are running rich and you know you are the next option is more air. Are you maxed out N/A, as in no other carb can flow what you need, cam is maxed out, head work and valve size is as good as it gets? Is boost an option? Keystone turbo makes a nice setup. I know very little about building gas tractors but have done my fair share of car hot roding.
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Re: Need advise on IH-c301 engine December 08, 2014 09:08AM
Lovespullin: I think I am running lean.But the high octane is cooling the problem. Like I said earlier I felt I could run 93 pump gas but as I load it down it misses & falls at about 80- 85 hp. I can screw the main jet open til the black smoke rolls but I did not know if that would also produce more air. Like you say I think I need more cfm to feed the bigger motor. But don't know if that is possible to do to a stock carb.
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Re: Need advise on IH-c301 engine December 08, 2014 07:57AM
Not a Champion fan either... What issues did you have with the higher mixed fuel.. My experience.. (not on an IH) was that it took needed more fuel.. (I know every fuel is going to be a little different.. ( Changed from C12 to C16.. and had to redrill.)
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Re: Need advise on IH-c301 engine December 08, 2014 08:55AM
JDGnut: When I went from 102 to 106 I lost 2hp at max load. When I went to pure 110 I still had 2 less hp but the engine just seemed to run rough.
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Re: Need advise on IH-c301 engine December 08, 2014 10:26AM
I put a big zenith carb on my 460,it's at 400cubes and it was a big help, it runs much better and uses far less fuel. Did you drill out the main jet a couple letter sizes bigger than stock?
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Re: Need advise on IH-c301 engine December 08, 2014 11:02AM
What is your cranking compression and do you have to run a stock carb
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Re: Need advise on IH-c301 engine December 08, 2014 10:04PM
Compression is 170-175. And have to run stock IH carb.
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Re: Need advise on IH-c301 engine December 08, 2014 10:32PM
Yea stock carb is gonna hurt ya it sounds like. No mods you can do to it to help out.?
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Re: Need advise on IH-c301 engine December 08, 2014 10:01PM
Yes, can't recall how big but it takes the adjusting screw to choke it down.
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Re: Need advise on IH-c301 engine December 09, 2014 01:48AM
do you have a combine or 806 carb now?
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Re: Need advise on IH-c301 engine December 08, 2014 08:50PM
I found that a factory 301 carb was too small for my bored and stroked 301. I went with a very large zenith and the tractor ran much smoother and made more power.
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Re: Need advise on IH-c301 engine December 08, 2014 10:10PM
That's my feelings too. When a person uses a carb for a 75 hp engine and puts it on a100+ hp engine it surely can't be enough. But I guess it is what it is & what I get is what I got.
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Re: Need advise on IH-c301 engine December 10, 2014 02:44PM
You need an 806 carb, bore the ports, run 110 octane, and turn about 4000 that what i run in my 460 with a stock bore 291 and it runs around 120 hp on a good day.
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Re: Need advise on IH-c301 engine December 30, 2014 07:08AM
My family has a c-301 in our 656 bored to around 335 and we have an 806 carb not modified. The sleeve inside the carb can be swapped out since the 806, 706, and 606 carb are all the same size but different size sleeves. Our tractor for years turned 5000rpm but couldn't really idle so we put in the sleeve for a 706 and it helped tremendously. But the c-301 is not a cheap date so to speak as for us it won't really run at 93 octane. With 104 octane boost it is alright but no matter what you need racing fuel with a minimum of 103 octane but the higher octane the better. Even now with it being stock 656 rpm + 20% it still likes the high octane.
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