Its very difficult to get good information on jetting by asking what other people run unless you are running a virtually identical combination. .... Most who jet for performance look at ET and mph from the track and pull spark plugs and read it for color as an indication of rich or lean conditions.....just giving you my experience. Lee G.
finally the voice of reason within a "what jets do I use" post LOL
I jet pretty dam good these days but it certainly wasn't always like that... Worse, I took some advice on jetting a few times and things got worse instead of better. It wasn't the other guys fault, I was too uneducated to know the difference. I'll just say that there is no magic jet combination that works. There are some generalities that will get you close, but ask your doctor whay you should do after telling hime "I have this pain in my side". Any doc worth his salt needs to test, look at the results, then try something. I went several years with pulling a spark plug after every pass, noting the air temp change and plug color. It's pretty easy to see the cause and effect after a few times of doing that, especially day versus night racing, Sac, sac winter versus Sac in summer which could easily be a 40 degree spread, Palmdale/Vegas then mile high "no air" Denver.
a few truths about tuning and jetting:
* Jetting will not fix another problem, in fact other problems might seem like a jet problem.
chasing the idle tune when you have two tight valves is almost a complete waste of time
* the plugs don't lie, unless you are trying to get the mains right and you drive at low speeds after making a top end blast
make a blast, shut it off and coast to the side of the road. pull a plug and read it.
* air temperture AND altutude need to be taken into consideration.
* Jetting starts with zero vacuum leaks, synchronized carbs and linkage, adjusted float levels, adjusted valves, set timing
adjusting your idle mixture while the engine has two tight valves is almost a waste of time
* To evaluate weather or not the jetting is right, you need to read the spark plugs (there is a real good NGK site that will help)
there is nothing like an experienced guy showing you a real sparkplug and what to look for, though
* A street car tune and a racecar tune are different... it maybe the same engine but a street car needs more fuel to stay cool.
A fat racecar is not consistant, and usually blubbers throught he mid-rpm range, then 'comes on' at higher rpm.
