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I am slowly putting the C3's engine back together. After finding the cylinder heads were in very sorry condition, and seeing no issues with the cylinder walls, I bagged the replacement short block and proceeded to re-assemble my engine in the car.
As I was installing the q-jet, I found the throttle sticking. Checked with Lars and he suggested I ship it to him for a refresh and possibly throttle shaft repair.
Lars' initial inspection (after reminding me that I used the wrong shipping box... the one he cautions AGAINST and has since damaged the throttle linkage $$$) is that the accelerator pump has failed.
The car has sat a lot since the 2013 cylinder head rebuild and retro-roller cam conversion. That and the foul 10% ethanol fuel and the carb needs a rebuild.
Lars rebuilt my carb in 2003 so am glad he is the one tending to it this time. I am looking forward to installing it.
I have the new parts in-hand and will be running the carb through cleanup, setup, and test this weekend - should have you back on the road very quickly.
The binding in the throttle linkage was caused by the accel pump "catching" in the accel pump bore, and then "snapping" free once enough force was applied. It wasn't actually the throttle linkage that was binding - it was the pump. Installing a new pump in the bore has solved the problem, but I want to give the entire carb a good cleanup and re-setup for you since I have it here.
I have the new parts in-hand and will be running the carb through cleanup, setup, and test this weekend - should have you back on the road very quickly.
The binding in the throttle linkage was caused by the accel pump "catching" in the accel pump bore, and then "snapping" free once enough force was applied. It wasn't actually the throttle linkage that was binding - it was the pump. Installing a new pump in the bore has solved the problem, but I want to give the entire carb a good cleanup and re-setup for you since I have it here.
I got Ted's carb cleaned up and back in service. It was a little gummed up, and the accel pump was not looking good - it was causing some sticking and binding, but the new pump now has the carb running great. Tweaked a couple of other little issues to make sure the carb will run well on Ted's mild roller-motor.
Here is his carb running on the test engine after cleanup and repair:
Carb was tested with the electric choke hooked up, and here it's running with the choke wide open after setting up the fast idle during cold-run:
Perfect air/fuel numbers on the wideband sensor:
Hopefully, the carb will now deliver a few more years of fun performance!
Always nice to have a test motor to check that
Feel your pain Ted...my AED 850 has about 50 mi on it but after sitting over 2 yrs it has to be completely gone through that gas gums things up bad. Fear my rings have stuck too, smokes like a chimney.
I've found that there is absolutely no way anyone can rebuild a carb and know it's right without actually running it and testing it. I've been building these carbs for over 40 years now, so I have a pretty good idea what I'm doing. Yet, I have roughly 1/4 of the carbs fail the test procedure, or there is something that I don't like about the way the carb behaves. I re-do those carbs and keep testing until they run right. I've had carbs take 3 or 4 runs on the test engine before I find and correct all the odd issues that can be problems in these old carbs. The test engine is the only way to assure a reasonable level of quality - those who build and sell carbs without testing them are questionable at best...
You are so right! I’ve been there and done that, as they say. My years at the Valvoline Engine Lab has proved that. If you ever in KY let know and I’ll arrange a tour of our facility. Though I’m retired but still have connections.
Vic
I appreciate the work you do, THANKS! Can you post a picture of the test engine from a little further back. Is it on an regular engine stand or a custom built stand?
It's a custom-built stand that I built for testing engines and for operating the "house" test engine during carburetor testing. Any engine can be mounted to it in less than 30 minutes and test-run, but I keep a 357 SB on it to test the carbs. Here is the 327 L79 that I built (see photos and writeup here: https://www.corvetteforum.com/forums...oto-story.html) on the test stand. This engine was run with the actual exhaust system from the car. The "house" test engine is run with headers and race mufflers with an O2 sensor in the collector:
Here is the "house" 357 test engine being pulled in preparation for installation of the 327 shown above. I test-run and break in every engine I build:
08-04-2018, 08:56 AM
Sent my Q-Jet to Lars
