My Tuning Adventures

[brasil]

...what accelerating pump cam do you use ?  the green cam...is also a good one...  perhaps a little better than the orange one..

Greetings Juergen

[CUDA JAS]

...what accelerating pump cam do you use ?  the green cam...is also a good one...  perhaps a little better than the orange one..

Greetings Juergen

Currently running the orange cam and a 28 shooter.  I have the cam kit and various sizes of shooters.

Jason

[brasil]

....28 shooter ?   go for a  31 shooter   and stick with the orange cam for now..

Greetings Juergen

[CUDA JAS]

....28 shooter ?   go for a  31 shooter   and stick with the orange cam for now..

Greetings Juergen

Well what do you know, I was just out in the garage and made that change...had a 31 in my carb tuning box.  I am also using the hollow screw.

I switched back to the 4.5 pv. as well.

Road test results to come, as long as the heat dies down a bit.  With the heat index today, it was 97 and tomorrow they are saying 104.  Weekend is not supposed to be that hot.

Jason

[Cudakiller70]

Jason, enjoying your thread. Didn't catch what AFR your using? Are their different types?  See the benefit and want to try this. Thanks

[CUDA JAS]

Jason, enjoying your thread. Didn't catch what AFR your using? Are their different types?  See the benefit and want to try this. Thanks

Thanks man...I hope it helps some one out somewhere down the line.  Gives me a good sounding board for changes and feed back form those that know way more than me.

I am running a FAST AFR.

http://www.fuelairspark.com/fas/gasoline-air-fuel-meter-single-sensorhtml/

Currently I have it setup as a single sensor unit, but plan to upgrade it to a dual unit sometime in the future....

I bought it used of a member of a different site. Seems to work pretty good.

Pros - large display, upgradable, has some recording features.

Cons - a little bulky and not permanently mountable.

There are other makes of gauges available.  usually its a smaller round gauge.  I have seen numeric readouts, and multi color LEDs, analogue.  I think it bills down to preference and cost.

I highly suggest picking one up.  When I fist got it I was battling a stinky rich idle condition....the AFR should 16.6 at idle...yep it was lean!  Sort of changes how you tune the carb!

Jason

[Cudakiller70]

Appreciate the info Jason. I was never a good tuner, but this looks to be a very good tool. Thanks for posting, this is helpful and best of luck. 

[CUDA JAS]

Finally got out for a drive tonight.

Overall the results of the pump nozzle and 4.5 PV changes worked well.

The increase in pump nozzle covered most of the lean spots during cruise. 

Still not perfect, still a little stutter at light throttle.  At WOT from idle the AFR meter shows rich 11.xx but leans out quickly.  Its better, with the smaller nozzle, it showed 10.xx and did not lean out as quick.

I think what that is telling me is that the pump cam is right...providing the right total amount of fuel, but I need it earlier.

I think I will go up on the pump nozzle one more step.  I figure that will provide more fuel earlier, and should lean out the WOT a little as the fuel gets in faster.

During cruise, 1500 RPM around town, to AFR meter reads 14.xx.  Does not seem to be a problem, but does flash to 15.xx at times.  I think I need a bigger run at highway speed to see what it looks like.  Could always go one step bigger on the jets.

Jason

[CUDA JAS]

Hmm looking at the pump cam chart I found online, I may try the green cam first.

That seems to provide a little less fuel overall, and more fuel earlier in the pump shot as compared to the orange cam...that and it is an easy switch.

Jason

[brasil]

Hello Jason...

where did you find the pump chart ? Do you have a LINK ?

Greetings juergen

[CUDA JAS]

Hello Jason...

where did you find the pump chart ? Do you have a LINK ?

Greetings juergen

http://documents.holley.com/pumpcamgraph.pdf   

[brasil]

 

Thank You !!   JUst printed the chart.. so I have the chart by the hand...while tinkering with the carb

Greetings Juergen

[CUDA JAS]

Thank You !!   JUst printed the chart.. so I have the chart by the hand...while tinkering with the carb

Greetings Juergen

No problem man , always happy to help out.

Well the car seems to like the green cam...much less of a hesitation.

After 125 miles or so on the weekend and lots of that on the highway, the car does not like the combination of the 68 jets and 4.5 power
valve.  The AFR meter shows about 14.3 at 2500 rpm / 65 mph and will often flash up to 16.XX.  Anything over 2500 rpm and you can feel the car stumble as the AFR meter flashes lean.

I think that  6.5 power valve was open at cruise causing the richer mixture and now the 4.5 is closed and relying only on the main jets, which is a little lean.

So, back to the 70 main jets and see how that feels.

Jason

[YellowThumper]

Thanks for all your updates. Been an interesting read. Almost makes me want to tinker on mine...

[CUDA JAS]

Thanks for all your updates. Been an interesting read. Almost makes me want to tinker on mine...

Thanks Man.  I just hope it helps someone along the way. 

I finally have the tiem to play with it a little bit and I enjoy the process of trying to squeeze the best out of the combination.

I had the car out for a spin this afternoon, a quick spin on the highway and the car runs much better with the  larger 70 jets.

The lean flash is gone on the AFR meter and the car does not chug at all over 2500 rpm.  The AFR shows high 12s to mid 13s. 

Around town the car runs good and the green cam seems to work well. 

I did not get a change to test WOT from idle and see how it works, so I may make a few changes yet, but I am getting closer.

Jason