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Chapter 14: Takeoff….again. Dialing in to make it practical.

5/26/01 Well, I got it running again for the summer with the new mods.  Can’t get it to idle yet, but the engine revs well, and the distributor seems to work like it should. The car gets up and moves starting in second gear like it did in first before, so I can assume that there is significant improvement in torque.  The speedo is disconnected and the 12 volt overdrive solenoid hasn’t been hooked up yet, but it seems to reach a rapid velocity in a short time.  I have tracked down what I think is the cause of the lack of idle: the seal between the intake and the block is poor.  I sprayed some carb cleaner at it in two places and found that the idle would change.  Problem is that I may need take the whole thing apart to get good sealing.  I’ll try retorqueing the bolts tomorrow to see if I can cut down on the air leaks.  Only other problem is a leak of gas out of the primary throttle shaft on the linkage side.  Hard to do much about that now, but if everything else works well, maybe I’ll pop for an Edelbrock carb, which is a remake of the carb that is on there (and the one used on the R-2 motors). The Edelbrock website is very helpful in sorting out AFB carbs. I seem to be seeing some gas pressure at the gauge (attached at the regulator) as I accelerate.  The boost kicks in, and I set the boost control for “stock” Mopar, which is a ramp up to 6 or 7 pounds.   The boost control when set higher will bring boost higher before it opens the gate.   Right now, just after the turbo, I see boost going to about 6 pounds with spikes up to about 10 when I back off throttle.  The radiator cap has been strangely quiet lately.  Now that I routed the boost control into the dashboard, I can hear the goings on as air rushes thru the ball-spring valve.  It squeals rather loudly!   Haven’t had a chance to fool with the variable runners or plenum yet.  Getting it to idle down is going to be an achievement!5/28/01 Well, I got it to sort of idle down though I still think there is an induction leak, probably between the block and my intake manifold. Getting that thing on and off is a bugger. Have retorqued it now and it is better, but haven’t checked with carb cleaner again around the joints. Did ride around early this morning and it felt like a small v-8. Got back and noticed the waste-gate diaphragm shaft had come off the flapper valve, so what I was feeling was mostly just the AFB and not turbo. I changed from 6v to 12v and haven’t changed the electric temp gauge yet, and it LOOKED like the engine was overheating on the gauge. Do have an infra-red temp tester gun and intend to monitor all parts of the engine, just no time yet. I need to optimize the timing on the vacuum advance boost retard distributor I made. This week will be getting a small digital voltmeter to attach to the O2 sensor on the outlet of the turbo to give an idea of air/fuel ratio. The plug chops begin in earnest.May ultimately need to abandon the 61′ Pontiac AFB which I have modified in favor of a new Edelbrock without a “history” of unknown insults . Guess a Holley would be better in terms of sealing and maybe solid floats, but I’m getting to know the AFB now between this one and the one I’m rebuilding for an R-2. Anyhow, I have already proved my hypothesis that I could get the little 169″ to run with the “bigger” guys. Stay tuned. Later this summer, I’ll be adding in the variable intake manifold adjustments and the air amplifier I built in just above the bonnet will get some compressed air off the line.

5/31/01  Think I determined the cause for my lack of idle circuit in the carb…..  It is old and the throttle shafts are just leaking too much air.  The cross-drilling I did to inject air to create “air-bearings” to keep gas/air from coming out under boost are all connected in my base plate to a tube which came up to the turbo.  Under idle, this was the path that air took into the space below the throttle plates thru the oblong throttle shaft holes, so the engine had no trouble breathing despite throttle plates held decidedly closed.  Another route may be thru a passage around the outside of the secondary venturi where the balance weights swing.  The bottom of this passage may be communicating with a groove in the bottom of the carb which runs over to the throttle shaft passages.  The carb is still in place, but I plan to remove it tonight and plug the bottom appropriately and then bush the throttle shaft passages with bronze bearings I obtained.  If this gets botched, we go to the marine version Edelbrock performer 600 cfm carb set up with rods, springs and jets as suggested on their website. Check back 6/3/01 for an update…..6/6/01  Throttle shafts are probably the culprit, along with the throttle plates which have holes drilled in them.  I have now sealed the holes by threading in brass screws and peening them down.  The throttle shaft for the primary side now has 4 grooves which hold o-rings.  They shouldn’t leak now…..  I looked at an R-2 AFB (from a supercharged Avanti) which I’m rebuilding, and got the throttle plates in as square as possible for the best seal.  I added a plate on the side of the carb to hold the cable for manual choke and also removed all the extraneous linkage for fast idle.  I adjusted the rod which controls when the secondaries come in.  This will probably need more mods after I get that far into open throttle conditions. Hopefully, I’ll button things up tonight and get idle…..
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