Need some help ! Northpuller,VicS,southpull,LarryM,dblair,km

[V8S10]

hey fellas! im in need of some advice on what to do! got my fisrt pull in a week and a half! got alot of guys counting on me bringing my M that im building! well sunday i got the motor in the tractor(Its a M block bored with 450 c281 sleeves in it with domed pistons from tisco i beleive, 400 crankshaft, stock goveneor, petronix electronic ignition, a brand spankin new lp head and manifold, the top of a IHC M carb with a ih bowl off of a 301 combine engine ibelieve with the big metering stem, a #35 venturie. someone on here told me i needed to run higher octane gas. well i got antsey this sunday and decided to get the motor in since it has been sitting on the stand done and ready to go and i got it in just put 87 pump gas in the tank to run it to get warm and retorqued everything and checked valve clearence and well it proably hasnt had a good 45 mn of run time yet but i did a compresion test and it has around 130 psi. it had a slight puff of black smoke when i opened the throttle up on it like it needed more fuel and was kinda pingy ? im in need of knowing what i should run for fuel since it doesnt have quite as much compresion as i thought, what spark plugs i should run? and what i should do for my carb problems? need some serious help guys cuz that pull is creepin up fast!

 

[Tim Yates]

First off, when you did your cranking pressure check, did you have the throttle all the way open? That can a big difference on numbers.

 

[north puller]

If its pinging you need better fuel. Cranking pressure seems low but could come up fast after as little as one hour run time to seat the rings. Do a compression check at wot.

Have you checked can timing as this can seriously effect cranking pressure and performance.

If it were mine i would use a smaller venturi.

Keep us posted.

 

[V8S10]

yeah i had the throttle open when i did the compresion test. someone told me i should tack weld the advance in the distributer after i get it in time so it doesnt pop and back when you open the throttle.... north puller what fuel do you think i should run? i have a #27 venturie and a bit biger one that doesnt have a number on it but seems like it would be a 29 or 30 ? it didnt make the pigging noie when it was cold it just spudered like the carb was out of adjustment but then when it got warmer it would make the pinging noise and pop and spuder when i opened it up fast and would let a slight black cloud of smoke out and it would do the same when you would let the clutch out!

 

[VicS]

Don't go so fast, slow down it will all come together. A friend of mine told me 40 yrs ago. There is just probably one thing wrong. Don't go changing everything. First I would at least get some 100LL airplane fuel (at the local airport) it will last in your tank and carb, and not gunk up. Or 105-108 racing fuel. I would borrow a stock carb, from something you know runs right, second. Then I would recheck the timing and advance, third. Good luck, let us know how it turns out. Vic

 

[north puller]

Vic has some good advice. If you can get one, try using a stock carb for the purpose of testing. Get some 110 fuel. May be more than you need, but then you know that fuel isn't your problem. Once its running, slowly open up the throttle until youget to about 1600 rpm, and then check timing with a timing light. Set it at 25 for a modest start.

Sometimes those carbs can load up on fuel at an idle and give you a short puff of black smoke when you hit the throttle, even if the carb is lean. Start by getting a half descent tune for load and put 4-5 hours of moderate to hard work on the motor. Things will be easier to tune after a bit of break in.

 

[V8S10]

alright thanks guys! ill give th a try... ive got a race shop a few miles from here that sells race fuel where my father use to get it for his drag truck and ill maybe get a few gallons tommorow... ill try that and i have a dyno to break it in... should i do a light load on it for now to break it in or should i work the hell out of it on the dyno like grinding feed?

 

[north puller]

Run it on the dyno at full throttle/high idle. Start at about 25hp load and over 45 to an hour slowly work up to full load. Vary the load up and down by 5-10hp every 3-5 min.

weather fast or slow, idling and no load running is bad for break in.

After you get up to full load, run for another 3-10 hours on the dyno. Vary the load back and forth to run between 650 and 540 pto rpm. I don't like To lug a new motor, so i don't pull it down below 540 before 6-10 hours of break in. You don't have to do 10 hours all in one shot. You can break it up. Something like three hours a day over three days works good.

A good idea after the first half hour is to change the oil and re torque the head.

 

[Dblair]

I gave you everything you need on the spark-plug question you posted and if you don't use 110 you'll melt the top of the pistons . it's that simple .

 

[V8S10]

yeah thanks dblair! i seen you replied to my spark plug question now! ive got some 110 fuel now and some of the spark plugs you suggested using! thank you for the help as you guys are much more knowlegeable then i am and have experienced ALOT more then me im sure! thanks for the help again it was muchly needed!