Couple of Mods Done Recently

[jsawduste]

Was talking to Chris the other day..........BTW I got your text but it was a white screen...........about a couple of mods I've done recently.

Baseline is an OBD1 controlled 4.9 with one of Jeff's 62/63 TB`s. Hesco 274/480 cam. 24 lbers @ 42/43 lbs FP. Manual trans YJ.

Bennie told me about this a few years back but until this past season I had not done much with it. Improved idle (closed and open loop) by drilling a small air bleed in the throttle plate. Seems the IAC cannot pass enough air/react fast enough for a fairly long duration cam and a deeper breathing stroker. Started small and worked up allowing for the ECM to "learn" the new setting. Running a .1094 (7/64ths) hole and might try going a touch larger to something around .1130. Coast down and low speed response is much smoother and the idle more consistent.

Another change was to go back to a factory fan and shroud. After three Spal temp sender (highest rating 185/215) failures I gave up making an electric fan work. Engine temp with the electric would cycle between 185 and 215. With the factory parts it now runs at 180-190. 195 stat with a 3/16ths bleed hole. Seems the ECM likes the narrower temp range to calibrate off of.

With ambients in the upper 70`s I`d like to see it running a bit hotter. Suspect when it cools off I may have to impede airflow through the radiator. We have some 90 degree days coming next week so lets see what happens. Betting I will see 190 to maybe 200 at best. Hesco 3 row brass radiator.

An interesting find was walking through the Jeep graveyard and noticing OBD1 YJs (ccw waterpump) with the fan blades pitched in opposite angles. The owner of the yard and myself looked at 4 or 5 different 4.0`s and saw the different fans. Only conclusion we could come up with is that YJ`s with factory AC had the more aggressive pitch which is what I snagged.

YMMV but those two mods have really improved drivability. An indivual on another forum was writing about his stroker idle problem and I mentioned the .1094 hole. He drilled the TP and was very pleased with the results.