timing and carb adjustment logic

R

Richard

Member
so:
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.

Thanks.
Richard
 
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.
 

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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.
 
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