Squirter/pump cam tuning?

[justinp61]

Guys I have a lean spike (LM-2) and a tiny hesitation at the hit, I can hear it in the car but it almost unperceivable outside the car. The squirters were 37F/35R, I have since swapped places with them. The cams are pink and in the #1 hole.

The car is a street/strip 69 Dart with a 434" pump 93 Indy headed small block, 11.2-1, 263/271 @.050", .711/.719" lift at the retainers Comp solid roller, 727 with a 8" converter that flashes 5400, Dana 60 with 4.10 gears, 3350 with me in it.

The carb is a 1.59" venturi, stepped down leg boosters, BLP BX4 main body on a 1.75" base plate, 30cc pumps on both ends.

What cam would you guys recommend and which hole for the screw? Do the squirters sound about right?

Thanks, Justin

[Banjo]

What does your t-slot exposure look like?

[justinp61]

Square.

[dcmd21]

My car is street/street; no similarity in power, gear ratio, etc. But had the same instant lean during "the hit" whether fun mashing it or gentle takeoff. As soon as the blades opened, it wanted immediate fuel gratification. Green #1 did the trick for me. I think pink #1 provides 30cc and green #1 24cc. Not much less squirt volume but arrives much sooner with green. This is assuming the cams in the kit were formed right, I have some green cams that are flat like pink ones. I had a new Holley carb with pink cams that really tripped me up once. The secondary cam had a sharp angle on it, and the secondary lever stuck on it and held the blades open. I thought the base was warped and the shaft was sticking, nope, a crappy pink cam. Typical new millennium stuff...

[GTO Geoff]

Here we go...again.

What is the ign timing at idle?

Would probably want to be 30+ deg with that cam.

[justinp61]

24*, no need for 30. The engine tune is well sorted and the only issue with the carb is the lean spike at the hit. It’s been 6.25 @ 110.02 in the 1/8 on pump gas. I’ll try a green cam and see if it helps.

Thanks

[GTO Geoff]

Justin,

A little info for you, from somebody who has written 30+ books on the subject: 'The optimum idle advance is typically 35-40* for short cammed street engine & [ though not commonly realized ] as much as 50* for a street/strip engine'.

Also, some production cars [ Pontiacs ] with cams as small as 197@050 were driven off showroom floors with 26* [ more than your 24* ].

[Right hand drive]

List all the carbs bleed dimensions,
IAB:
IFR:
MAB:
EMULSION top down
#1:
#2:
#3:
#4:
#5:
Pri MJ:
sec MJ:

With a 1.59” venturi the mains might need a calibration to help them start up easier to be less dependent on squirter. This may well alter top end calibration from where you are now yet could be mostly regained with tuning. There are always compromises with the street/strip tune.

[dcmd21]

[justinp61]

I don't recall the emulsion set up exactly, it seems there were five emulsion holes and I plugged either two or three and the remaining are .026" IIRC.

Jets: 78/87
IFR: .029", moved to bottom
Bleeds:.026"/.073"
PVCR: .064", primary only
Nozzles: were .037"P/.035"S, now .035"P/.037"S
Pump cams were, pink #1 hole, now, primary blue #2 hole, secondary green, #2 hole
N&S: .110"
TSR: .063"
Boosters: .166" stepped down leg, .435" ID, .612" OD

BTW, it has a MSD distributor and Digital 6 ignition box, 24° initial and 34° total, all in around 2000.