setting up 4412 for chp

[justramit]

I was wondering what needs to be done different on a 4412 to switch from vp 110 to CHP. Was thinking about running it in Street stock motor 11:1 compression. Is it only a jet change? Motor is 360 ci sbc 4412, hi rise 2bbl HARD TO FIND cast iron intake with 2.02 1.60 EQ 64cc heads with 220 intake runners, running ar133 plugs, camshaft adv dur 268/268 @.50 dur 244/244 .500 lift on 110 ( vacuum rule). This is new motor, I know heads are probably big, but I had them so gonna try them. probably 7200 rpm max

[dynoman14]

You can get by with a jet change but it is not ideal as CHP likes to burn off pretty quick so I normally run rich 2500 to 5000rpm and then start leaning out the curve up to 7500rpms.

It also has a significant affect on combustion timing so the timing will usually have to drop some to make the best power with the fuel. I have dropped out as much as 4* without losing torque ( if you add fuel back in properly ).

I don't know if you have access to a dyno or chassis dyno but I normally do a jet sweep at the current timing and max out the HP. Then I drop 2* and try and hit the max number with a little more jet, if you can you are going to hit a sweet spot of 2-4* retard and +5 to +10 jets.

In jetting I have seen +4 to +10 jets depending on how much air the carb flows you might also have to work the HS bleeds to dial the top end in just right.

I also go up about .010 on the squirter and go up .010 on the Power valve orifice.

I like to see a burn ring on the plugs of about 1/8 to 1/16" about 1/4 inch up from the seal ring and grey on the porcelean from the ring to the tip.

If you want your plugs read you can number them and send them to me after your first practice or race and I will read them for you.

[justramit]

Thanks for your help, didn't realize there was that much difference. Most guys around here are just running VP 110 either straight or mixing with pump gas. Some running AVGAS . Didn't know if CHP really made that big of a difference.

[mudcrasy]

what is chp is it a new fuel?