Tuesday, May 30, 2006

Further Fiddles with engine

Got to the point I was happy to do 7K WOt runs. Wasted an evening doing 1st and 2nd gear jet tests switching the motor off as soon as 7K was reached in 2nd then plug checking and ended up back where I started! doh.

Tried various main jet combos and the best seemed to be 120main-7tube-150 corrector, but not perfect...I have ordered some more jets and will continue when they arrive.

Tested main jets 112-115-118-120-130 on 5 and 7 emulsion tubes, tested 130-150-170 correctors against some of the main combos. I think I need 122 or 125 maybe 127 mains, so thats what I ordered plus some 140 and 160 correctors... Setup the carbs with longer progression for a test using the 5 tube to delay the main a bit...actually worked ok, punch was good in the mid range.

I ended up on 48idle and a 7850.3 holder in the end, the engine seemed to be changing, I am still stuggling with it, also between a quick afternoon and evening test the atmospherics changed and threw me, it was very damp in the afternoon and richer a result.

To be 100% honest I am not happy with the cam's power at 6250+ but I leave my final verdict till I can be sure I am not lacking on the jets..Getting there.

As such I prepared the roller rockers for fitment today, they bashed the rocker box, so I had grind half the screwdriver slot from the adjuster screws, perfect now.

Very odd findings running at idle in the garage n the 1.75 rockers,...The old rockers wouldn't give an idle till the engine was at 40C from cold and needed to be kept alive on the pedal (no chokes) on what was a good jet setting hot.

Now with the rockers the engine starts and will run and idle sweetly cold from the first turn of the key @ 700rpm without any help, thats a new thing to me....I rev'ed it up a bit after it warmed up and sounds sweet as sweet can be!! It picks up much better than the normal rockers, give it throttle it revs up much easier with less throttle...Sounds lovely! Dunno how they run on the road as I didnt want to get into an obsessive jet chasing session today I had to have a massive tidy up in the garage and do some real work! Anyway marked change, big change in something...really nice sounds!

Promising....Dunno why that would be but it certainly has effected something big time.

I will have a fiddle tomorrow night if its dry...

Basically my only dissapointment with the cam is it does feel that potent in the top, my engine has potential for big numbers at the high end...If the rockers give me the predicted results i.e power increase all the way to 7500 instead of power increase to 6250 then flat power - It'll be exactly what I want, however if they don't change the character as the software dyno says - I will be forced to change cams.

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