The stock jetting was 70 I replaced with 72, so now I need to go to 74?

The hesitaion happens at any time the throttle is at idle or any constant RPM and then stomped to WOT. Best way to describe is you want to pass a truck on the expressway and your car has an automatic trans. You go to pass the truck and the trans drops two gears to get you to pass. That same pedal motion is when you get the hesitation.

If you drive the car normally you never get the hesitation

Hope this helps

 

Lars, how are you... Please do not take this the wrong way because you are the man , but correct me if I am wrong. Looking in the manual the secondary spring does have a direct impact on the opening of the secondaries. The spring he has on there now opens it immediately, which is likely too fast and would be simular to a 1to1 opening rate on a mechanical secondary, again too fast. The purple opens it at 1900 RPM's, plain spring 2200, and the brown 2700. How can you say it is irrelevant?? Please correct me if you think I am wrong.

Changing the jets was my next step I just wanted to take it slow and to mark the progress. Actually, I was going to say a 76, becasue we have pretty much the same engine and I just came back from the dyno and was running lean and went up 6 sizes and the AFR came back perfect.

 

The Holley 80508 carb is jetted with #72 primary jets. The 80508S is a 50-States emissions-legal version of the 80508, and runs very lean in its factory setting in order to obtain the C.A.R.B. certification. So in jetting, we ignore the "S" spec, and use the straight 80508 as the jetting baseline. From the 72 base setting, I would immediately bump up jetting at least 2 sizes to 74. But as you note, the 76's may be even better.

On a any 4-barrel carb, primary jetting has a huge effect on secondary tip-in stumble. I did not state that the secondary spring has no effect on opening rate - I said that the soft spring has no effect on stumbles at the rpm he is having a problem with. The springs are rated for opening point rpm and full-open rpm. We tune carbs for full-open point to assure that the secondaries will open fully before redline rpm. If you note, the 2nd softest spring available (short yellow) achieves WOT on the secondaries are a whopping 5,680 rpm. That's almost useless on most street engines - you want the secondaries to get wide open below 5,000. The white spring, not rated for WOT, achieves this. And it's not a 1:1 ratio with the primary - try a white spring out, and you'll see that it barely starts to crack the secondary at about 2000-or-so, and then brings it in very gradually - I've done this on a dyno while watching secondary actuation. This is not enough to cause a stumble IF the primary side is jetted rich enough to work correctly. But if the primary side is a tad lean, you will certainly get a lean stumble going into the secondaries, regardless of which spring is used.

 

OK, so I am leaving the white spring in. Again the carb came with 70 jets, I increased to 72. Which size is next?

 

I checked Jegs for nossles. Is this the one I need 510-121-35. I saw others, I just want to be sure I order the right ones.

Thanks

 

Correct

 

I am glad I asked, I now better understand what you were saying and agree with you fully.


Spedaleden-
74 or 76's are the next step as you are running lean....good luck and leave in the white spring.

Also, I would bump up the accellerator pump discharge nozzle to a #35 and see if she like it. I bumbed mine from a 28 to the 31 and it was a little snappier off the line. I will try the #35 next and see if it gets better.

good luck!

 

I am ordering the parts and put them in by the weekend. I will advise

Thanks for all the help