• To ALL forum users - As of late I have been getting quite a few private messages with questions about build ups here on the forum, or tech questions about your personal project. While I appreciate the interest, sending me a private message about these topics distracts from, and undermines the purpose of having a forum here. During the day I wear many hats as a small business owner-operator and I work tirelessly to provide the absolute best service possible to you, our valued customer. When I created this forum I rounded up some of the best minds I knew so that any tech question you might have could be asked and answered by either myself or one of my highly experienced moderators, this way the next time this same question is asked the answer can be easily found and utilized by the next IH enthusiast having the same question. This allows me the freedom to run the day to day operations of the business and minimize the impact to shipments and shop activities that these distractions can cause. It is of the up most importance for me to complete the daily tasks in order to best take care of you our customer, all the while providing you a forum to get the level advice and input you have come to expect and deserve from the premier IH shop in the country.

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    Jeff Ismail

timing and carb adjustment logic


I swapped out my 4 cyl 196 for 345 V8 in a 77 Scout. pretty stock (2bbl, P/S, P/B, 4 speed, D20 T/C, 4.09 gears, headers with 2 into one exhaust) Followed rebuilders instructions, pre-oiled, started, ran for 30 min @ 2000 rpm. I now have about 500 miles and have tinkered with the timing/carb. I have the timing (via timing light) right @ 10 degrees with the vacuum advance disconnected and plugged. To adjust the carb settings (via vacuum gauge) I turn out the idle screw until I get to about 650-700 on the tachometer. I then turn in/out the idle mixture screws, and by reading the vacuum gauge, try to get the vacuum to read somewhere between 17-21. I am right at 19!. Scout runs just fine. So, my question is: is the 19 reading good to go? I noticed that when I went up to 12-13 degrees in timing, vacuum went up to 20-21. Do I leave the timing at 10 degrees, or should I go to 12-13? I am guessing the engine runs more efficient with a higher vacuum reading, but would like some input from the forum.



Future Owner of IH Parts America
I would probably back the timing a couple degrees, 18 inches of vacuum is perfect. If you increase the timing to 12-13, it will probably run hot and ping on hot days.


so, I have pulled the plugs this weekend (600 miles now). please see attached. I appears to me that the carb is running a bit rich? given the carbon build-up. would appreciate feedback. does anyone notice any other issues that I am not seeing? it is a new engine and just breaking, so one question I have is: would the plug condition clear itself out after more miles, and that this carbon is due to engine break-in? thanks for the input.



Active member
Looks like the mixture is ok to me, based on the clean plugs. Perhaps the rings on some cylinders haven't seated yet.


I agree with FDChappie. Plugs look good. Maybe you need to stand on the go pedal hard for a few miles and spin 'er up real good. Rings will love you for that!


Hey all: thanks for the quick replies. I plan to do a 200 mile trip this weekend (IH Scout work party) and the location is at 4000 ft elevation (i'm at 180 elevation), so I'll see how she runs uphill (temp wise). I am thinking that I should be getting somewhere around 12-14 mpg on the open road as this is a 2bbl Holley. Time will tell.