My plenum gasket was leaking , got it fixed but I need to remove the carbon from my cylinders. I keep readingon this forumabout using Sea Foam sucked in through a vacuum line to clean out the carbon and I am sure that works as we used to pour some water down the carb of a running engine to do the same thing. We called it a water tune-up and you should have seen some of the black smoke this method produced. Now that I am much older and hopefully wiser I have a concern about the rapid, mass removal of deposits using either sea Foam or water (or what ever else ). When the carbon is removed in this way I have to believe it has the potential to come off in relatively large pieces which then must exit past the exhaust valves and /or get forced past the piston crown into the piston ring area. Neither of these scenarios sounds like a good place for a hard abrasive material to be in an engine. Does the valve sort of "chew" these deposits up as it opens and closes on themas they flow by? That would be hard on the valve seats and maybe the seals. And who wants a sand like material between the piston and the cylinder wall ? I think a slow removal of deposits using some type of additive in the gas may be a safer way to go but have not heard of anyone who had real good results with that method. AmI paranoid and over-thinking this whole deal? Please post your opinions/experience on this and we might get a real lively discussion going here.

 

well i suppose a good additive and a long trip of highway driving would do the same thing gradualy but then again i've never heard anyone complain about sea foam hurting anything. But then again water in an engine cant be good. You get too much in an engine and you can hydrolock it believe me been there done that. The way i see it try an additive firstif it doesnt work then your only out a few bucks

*a little off topic but what kind of fuel mileage do you get with that 3.92 Rear end because i've got the 3.55 and have been debating on swaping my rear end out*

 

I am not even considering using water to clean out the deposits- it's just something we used to do back in the 70's and it does work but your right about it not being good for an engine. However I think the hydrolock danger is there whether you use Sea Foam or water. Pour a liquid in your intake too fast and your in trouble no matter what the liquid is.

My gas mileage of course depends on the type of driving I do. Stop and go in town gets me around 14.5 mpg and I am currentlygetting 18 mpg driving all freeway 30 miles one way to work . Overall I average mid 16'sbutI would expect that to be higher if I had 2wd. Spinning that front end all the time takes it's toll.Best mileage seems to top out at around 65 mph, after that the faster I go the more my mpg drops. I have got over 19mpg on a 3 hour drive but I was holding a pretty steady 55 mph and I think I had a good tail wind cause the return trip only got me high 17's. The 3.92 is great for towing but with the 5spd manual 1st gear is way to low for normal driving. I typically start in 2nd gear unless I am stopped on a hill or towing and sometimes I use it in traffic jams when I can just slowly crawl along - keeps me from using the clutch every5 seconds.The3.92 gives me a lot of grunt for accelerating even in 5th (O.D.) and on twisting dirt roads I can just leave it in 3rd gear and be good for anything between10 mph up to about 50mph. Hope this helpsyou make a decision one way or t'other.

 

well your getting the exact fuel mileage as me so i might go with it if it will give me a little more grunt. my 1st gear is useless anyways lol even with the 3.55 but anyways back on topic try some of that Lucas Fuel injector cleaner 10 bucks at oreileys treats 100 gallons of fuel run it over the course of 3 or 4 tanks seems to clean stuff up pretty good and is very good for the valves in your engine. It creates a seat for them and helps prevent wear

 

rice worked back in the day on flatheads...