How to jet an aftermarket cam, #91 Webcam Options

[Kansas 914]

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.

[Jake Raby]

Unless you specifically order the EMPI carbs prepped by Art Thraen (I also sell them fully prepped) they require some mods.

I know what your issue is, undoubtedly as we have to address this one every set of carbs that we prep.. We are working with EMPI to rectify the issue.

We can do this prep work for you, for an hours labor... Or if you can take the top of the carbs off I can walk you through it..

The 28 vents love a 200/115 set up here in my world.. It optimizes on 85% of the combos, BUT is dependent upon fuel pressure and float settings.

The EMPI DVD that Art and I did will be available soon from EMPI, we are just the two guys showing you what we know and how to do it..