How to jet an aftermarket cam, #91 Webcam |
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How to jet an aftermarket cam, #91 Webcam |
Kansas 914 |
May 21 2009, 05:23 PM
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#1
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
The symptoms (with 2 different sets of carbs Webers and EMPI same jettings) were the same. It will sit and idle at 1000 RPM with no problem (after a warm up) but is boggy on the low end under load - really have to keep the revs up to pull away from a stop light. Slight throttle increase after rolling creates a studder. Stomp it (WOT) and it runs great - pulls strong. It is like the throttle is an on/off switch, all or nothing - not much in between!!
I think I am close with the jetting but still not quite right. I wonder what the timing should be on a 1.8 with carbs and the webcam? The car also has electronic ignition (Crane Fireball). I read in depth the thread on jetting Zach's 2056 with 44 Webers. I also read a good bit on Harney's Carb Clinic (great read - printed it for reference). Using the formulas in the Harney Guide I am close based on the 28mm venturis. Idle jets should be 1.6 X 28mm = 44.8 (mine are 50) Main jets should be 4.1 X 28mm = 114.8 (mine are 115) I have 1.8L with a #91 Webcam (hydraulic cam & lifters) and Dual 40MM Webers. Here is my current Weber jetting: Vents = 28mm Emulsions = F11 Idles = 50 Mains = 115 Air Correction = 200 Here are the cam specs: LIFT = .430 DURATION = 265 DURATION @ .050 Degrees = 234 DESCRIPTION = Hydraulic grind for high performance street engines. Not recommended for engines with fuel-injection. TIMING CARD: As always your thoughts are appreciated. |
jmill |
May 21 2009, 09:14 PM
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#2
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Green Hornet Group: Members Posts: 2,449 Joined: 9-May 08 From: Racine, Wisconsin Member No.: 9,038 Region Association: Upper MidWest |
Your mains seem small and your AC seems large. The F11 will also lean up the low end. I like the F7. I would run at least a 130 to 150 main and around a 175 AC jet. The F11 ET, small mains and large AC jets all will lean you up down low. When you stomp on it you toss a bunch of fuel in there from the accellerator pumps and all is good. You need to get some more fuel in there.
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