Technical > Spud Miller's Cave

lost my tune up

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Curly1:
That is a really nice car. Okay on the tune up I would say go back to original tune and go from there. So you do not know where that is then my thinking is to fatten it up and see what it does. Will not hurt it as much to be fat.  If you have a 170 in there then I would put a 150 in there and see what it does. 
Barrel valve, how I set mine is adjust it to where it spits and stumbles at idle when I give it gas then fatten it up a little from there. Then I do a leakdown test on the barrel valve to get a baseline to return to.
Watch everything you can water temp, EGT, O2 if you have it and see what it is doing. There should be clues as to what it needs.

But if your car has been sitting a while I would say do a complete clean out of your fuel system before you do much. The alcohol can sometimes turn to a gel and that makes it act stupid. If you have trash in the lines then one cylinder may look lean while the others are fat and it will slow your car down. I had a problem with my car recently on the dyno and luckily my dyno guy had 8 O2 sensors. We were able to determine the cylinders were not all tracking the same. The dyno session was a success so I called it a day but it tells me there is a little more there. Some were getting richer while a few cylinders were getting leaner my thinking is it had some gel in the lines.  I cleaned all of the nozzles real good and have flushed a full gallon of alcohol through the lines to get everything out. Will test to verify this weekend to see if it did the trick.

Now I have had the alcohol turn to get several times with my carbs and I always use top lube. I really do not know what causes it or how to prevent it. Of course our injection systems with very small nozzles may be more sensitive to it even though they work at much higher pressure.  Do not know for sure but something to consider.

As I think about it more I would look closer at trash in the system than the tune up itself.

There are several places like Spud here that may give you a baseline tune up as a starting point if you can give them all of your information. I think there are many variables though and would be hard to get it perfect with out dyno or testing.

32bantam:
What are you using for and ignition? Do you now what the pump flows? Not advertised but from having it flowed? What pump is it?
If you know the fuel system is functioning and you have a tune-up you know goes 7.50 and you have made two big main fuel changes and it does not improve 90% it is a bad ignition. I chased a 3 tenths slow problem for two races...I tried everything...including checking the cam timing. Finally I threw on the spare Super Mag III from spud ...put the original tune up in and went right back to where it belonged.
Hope this helps.....

coffeehound:
Thanks for all the help.Because  I could not answer some of the questions due to lack of info/knowledge,I have sent the mag and fuel system to Spud for testing and service to insure the mag is100% and give me a good base tune and info to help me get back on track.This is my first bln/inj motor and I realize its an ongoing education ,but I wouldn't be able to get down the track without the help and support of like- minded racers with much more experience than I have who don't mind helping the new guy.THANK YOU , Coffehound

32bantam:
Excellent choice.....your system will come back ready to go....and information for your to make changes.

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