viking9990 Posted April 11, 2009 Report Posted April 11, 2009 what should i gap my spark plugs at right now i'm at 140 psi compression on each side with cool head and 19cc dome spark plug at 28 br8es 100LL GAS BUT I WANT TO INCREASE my compression by going to 16cc domes and mabe use 110 race fuel or c16 should i gap my plugs still at 28 or 18 ? Also is there some kind of chart tells you what type of fuel to use depending on what compression you have ? Quote
1996dragshee Posted April 11, 2009 Report Posted April 11, 2009 what should i gap my spark plugs at right now i'm at 140 psi compression on each side with cool head and 19cc dome spark plug at 28 br8es 100LL GAS BUT I WANT TO INCREASE my compression by going to 16cc domes and mabe use 110 race fuel or c16 should i gap my plugs still at 28 or 18 ? Also is there some kind of chart tells you what type of fuel to use depending on what compression you have ? I would definatley tighten that gap to 18-23 man.i would also think that with your 19cc domes you should be around 165 ish and hold it.but your elevation would play a part in that too.Anything over 155 160 you should run higher octane fuel. Where do you live/elevation? Quote
2001Stroker Posted April 11, 2009 Report Posted April 11, 2009 16cc domes with 110 octane? You're gonna be detonating like a champ. I'm also wondering about your elevation. Quote
viking9990 Posted April 11, 2009 Author Report Posted April 11, 2009 i'm at sea level when i got this cub setup i also was thinking that the compression was kinda low so you think mabe a problem with base gasket this was brand new 68mm pistons stock stroke if i get the compression over 165 then what c16? Quote
1996dragshee Posted April 11, 2009 Report Posted April 11, 2009 I'm not sure on c16 fuel,i've never ran it.I've only run 110 and alky.But being sea level your 140 sounds a bit shy of what you should be..I would for sure double check on any leaks.Do a compression check and see if it holds and then go from there.You have to think that the size of your base gasket will also have a small factor in your compression.. Quote
rubberneck Posted April 11, 2009 Report Posted April 11, 2009 Before you go swapping parts and changing fuels, what kind of compression gauge did you use? If its a cheapy, you might want to get a quality unit and double check your numbers. Quote
1996dragshee Posted April 11, 2009 Report Posted April 11, 2009 Before you go swapping parts and changing fuels, what kind of compression gauge did you use? If its a cheapy, you might want to get a quality unit and double check your numbers. I have an auto zone gauge (bout 25 bucks) and a buddy has a snap on gauge.the psi difference was only negative a couple pounds.thought I would share just as an example on the gauges.whats your squish at? Quote
2001Stroker Posted April 11, 2009 Report Posted April 11, 2009 Also, if the guage that you're using has shorter threads than your spark plugs, it will read low. Quote
viking9990 Posted April 11, 2009 Author Report Posted April 11, 2009 i took apart the cylinders today and found that my crank has a lot of play like so much so that when you move the rod side to side you can see the rod bearings. maybe time for a new crank right and the base gasket seemed fine ? Quote
viking9990 Posted April 11, 2009 Author Report Posted April 11, 2009 i took apart the cylinders today and found that my crank has a lot of play like so much so that when you move the rod side to side you can see the rod bearings. maybe time for a new crank right and the base gasket seemed fine ? oh and buy the way guys thanks for all the help :biggrin: Quote
1996dragshee Posted April 12, 2009 Report Posted April 12, 2009 ouch! yea man you definately need a welded crank running that kinda set up.It's good cheap insurance... Quote
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