doradox

Xenon 3124.

If it's a dual plane manifold per "side" of the carb it will feed the front and rear cylinders on one bank and the middle two on the other. This gives roughly equal length runners.

My one data point dis-proved your hypothesis. That's all it takes. Also my Denali doesn't have variable valve timing or cylinder deactivation. It's a relatively simple analysis to do if you remember your thermo. Draw a box around the engine and account for inputs and outputs. I wouldn't exactly say I recommend it either. That's a lot unburned of fuel/air mix washing the cylinders down in a carbed car.

You did read the key off part didn't you? At low throttle openings you aren't pumping much air. At large throttle openings you pump a lot of air. Which is harder? On a recent trip to Colorado we climbed and descended Pikes Peak. The automatic grade braking system in the wife's Denali was most certainly opening the throttle while holding a low gear. You could hear the intake noise dramatically increase when normal compression braking wasn't doing the job. I wanted to see what was happening so I stopped and hooked my scanner up (I always carry a lot of tools when I'm on the road) and continued down. TPS reading verified what I was hearing. You have a car. Give it a try. Steve

With the engine off as long as it was still in gear there would have been vacuum for the power brakes. The engine need not be "running" to make vacuum just turning. Also, maximum engine braking occurs in gear with the key off at full throttle. Many modern vehicles will hold speed on a downhill by cutting fuel and opening the throttle to increase engine braking. Steve

One of the crankshaft main bearings also controls thrust (fore/aft movement of the crankshaft) and could be worn. Steve

One of the crankshaft main bearings also controls thrust (fore/aft movement of the crankshaft) and could be worn. Steve

One thing to consider. If you were running rich/flooding you may have a lot of fuel in the crankcase. You should check your oil and change it if there is any question about that. Won't solve your problem but fuel thinned oil won't do your engine any good. Good luck.

You have a fuel oversupply problem. IF you actually have fuel dripping from your carbs at the end of the test that is a physical indicator that the carb bowls are overflowing. There is only one place that too much fuel comes from and it's not the ignition system or anything mechanical in the engine. MEASURE the fuel pressure.

Have you actually measured the fuel pressure instead of relying on the "setting" on the regulator? Steve

Put it back on the car and push it out with hydraulic pressure. Steve

A screw and washer assembly. Glossary of Terminology Related to Nuts and Bolts

Nice. Stainless steel has an even lower heat transfer coefficient. Copper however has a really big one. About double that of aluminum. Steve

Remember that your booster will see and hold the max vacuum your engine has produced since the last brake pedal application. So when you release the throttle to begin braking, unless you pop the trans into neutral, there should be plenty of vacuum available. If the check valve or booster are leaking then all bets are off. Steve

Another consideration on the "hot" adjustment is that your valves, and really the entire head, will be a whole lot hotter running along at a constant 80 mph than simply letting the coolant warm up to operating temp. As Leon said, a sure way to burn your valves. The recommended clearances take that into account. Steve