Factory engine testing?

[Jack H.]

Re: Factory engine testing?

Don't ask me how I know about this...I vowed NEVER again to set foot in the Flint Engine plant!

But, in the mid-70's the hot engine test stand system was automated using mini computers to control/run/accept-reject the individual hot engine test stands. An intermediate 'scheduling' mini computer battery was used to interface with the plant's production main frame, and control over-head 'picker' equipment to grab completed engines off the assy line coveyer and move them to/from the individual test stands.

The computer portion of the project (lion's share) consisted of suppling the hardware, writing & debuggng the factory automation control code and doing turn-key installation as a sub-contractor to the prime contractor who supplied the mating material handling system.

Different engines (configuration based) had different run times on the hot engine test stands against GM defined performance tables for run time, run profile and accept/reject criteria. When completed, the system was JOY to behold!

But, let's NOT revisit the PAINFUL ordeal of defining the overall system's performance specification and who was going to eat what cost(s) associated with the lack of definition prior to open bidding and contract award!

[Joe L.]

Re: Factory engine testing?

I worked the summer of '69 at Tonawanda. Duke and Terry have it right.

Ed, if you're asking if the engines were tested for power, the answer is no. We did test some engines for durability. They were run for 200 hours at mostly full throttle. Very few had problems. One dynamometer ran small blocks and one ran big-blocks.

Even the ZL1s were not tested for performance!

Bill-----


I think the engine test run time depends on what engine is being tested. Engines which require final balance require a longer run time than those that don't. In the 60's, 70's and early 80's, I don't think there were any engines that required final balance, so the run time may very well have been very short.

After the mid 80's when small blocks went to one piece seal cranks, I believe they all required final balancing as part of the run test. My recollection of the run time when I was at the Flint engine plant in 1992, (when most small blocks were one piece seal cranks) was that it was longer than 30-60 seconds. I don't know that it was 5 minutes, but it seemed like it was ABOUT that long. But, that was 16-1/2 years ago.

[John H.]

Re: Factory engine testing?

Photo below of a typical hot-test stand - you can see the natural gas adapter, and note the slave ignition harness that plugged into the top of the distributor, had its own coil, and included fixtured press-on plug wires with heat shields.

In the 60's-early 70's (before the computerized system Jack mentioned), the actual engine run time was less than a minute - just long enough to verify oil pressure, set the initial timing and chisel-mark the distributor and intake, check for leaks, and listen for any odd noises. Actual time-in-station was more like 2-3 minutes, in order to connect natural gas, coolant, and oil adapters, exhaust adapters, fill the oil, run the engine, drain the oil, drain remaining coolant from the lower drain plugs, and disconnect the slave harness and all the adapters. No balancing was done in the hot-test stands until the mid-80's.

The next time the engine was started was at the end of the Final Line at St. Louis.

[Bill M.]

Re: Factory engine testing?

John and Joe:

I clearly remember the Tonawanda engines being balaced at hot test in 1969. There was a balance weight added to the front damper and/or the flywheel. The weight was a little cylinder added to a hole in the damper and/or flywheel.

Bill

[Joe L.]

Re: Factory engine testing?

John and Joe:

I clearly remember the Tonawanda engines being balaced at hot test in 1969. There was a balance weight added to the front damper and/or the flywheel. The weight was a little cylinder added to a hole in the damper and/or flywheel.

Bill

Bill-----

I am not aware of that. However, if you were there and saw this, then I guess it must have occurred.

The mid-80s and later small block balancing was definitely done just as you described.

[Duke W.]

Re: Factory engine testing?

drain the oil, drain remaining coolant from the lower drain plugs, and disconnect the slave harness and all the adapters.

Why didn't they leave oil in the engine? ...something to do with risk of spillage during shipping, handling, and installation into the chassis?

Duke

[John H.]

Re: Factory engine testing?

Why didn't they leave oil in the engine? ...something to do with risk of spillage during shipping, handling, and installation into the chassis?

Duke

Duke -

There was no oil filter on the engine at hot-test, and they may have had concerns about machining particulate contamination; they had a very exotic high-volume oil circulation/filtration/post-processing system that served all the hot-test stands which supplied oil to fill the engines and collected the drain oil at each station.

All Chevrolet engines/transmissions/rear axles were shipped "dry", and filled at the car assembly plants.

[Bill M.]

Re: Factory engine testing?

One more thing (I just thought of) re. dyno testing of production engines: The engines run at full throttle on the dyno at Tonawanda went through an extensive break-in procedure (of many hours) before running at high rpm or full throttle. The procedure varied by engine. This would have been prohibitive for an engine shipped to an assembly plant. Even with this long break-in, we still occasionally burned exhaust rocker arm balls. When that happened, we moved the intake rocker and ball to the exhaust position, and installed new parts on the intake.

[Steven B.]

Re: Factory engine testing?

I can't recall the edition but a Corvette News of the day (1969) showed Tonawanda use of shaving cream to keep particles out of passages while machining. I believe the engine was a ZL-1. I can't recall if the story covered start-up and running. I need to go look at the article.

Steve

[Duke W.]

Re: Factory engine testing?

That article with the shaving cream deal was circa 1965 in a CN issue that discussed the new 396. The shaving cream was injected into the head water passage openings to prevent core sand from dropping into the engine as the heads were installed. That or another article also discussed the hot test.

Core sand contamination must have been a significant problem for them to go to that length to prevent it. Fresh block and head castings go into these huge "shaker" machines that vibrate the casting to loosen all the core sand, but depending on the design of the component, not all is expelled.

Duke

[Lawrence M.]

Re: Factory engine testing?

That Corvette News article was in the 1966 Vol 9 No 5 issue. The article was titled Building the 427. The cover photo is of the #9 Blue Penske coupe at Sebring. Duke is correct in the explanation of the use of the shaving cream.

Larry

[Steven B.]

Re: Factory engine testing?

Thanks Duke and Larry! I need to look at that article and alot of others. CN was really great and I miss it.

[Bill M.]

Re: Factory engine testing?

I can't recall the edition but a Corvette News of the day (1969) showed Tonawanda use of shaving cream to keep particles out of passages while machining. I believe the engine was a ZL-1. I can't recall if the story covered start-up and running. I need to go look at the article.

Steve

That technique was used on all Mark IV as I recall...it's been 40 years! The guys who installed the Mark IV heads were very big and very strong!

[John D.]

Re: Factory engine testing?

Back in the late 80's while on business at the GM tech center I wandered into the engine test lab. There were a bunch of engine labs going 24 hrs a day. I went onto one where the lab tech was running a thermal shock test. They would run below freezing coolant through the block until the outside of the engine was covered with ice. Then they would start the engine and go to full throttle until the exhuast manifolds would glow red then start over agian. It was all automated, the lab tech was there to halt the test if there was a failure which he said was very rare...very interesting indeed.

jd

[Dale S.]

Re: Factory engine testing?

Thank you to all who posted, I really enjoyed it. The guy on the test stand without ear protection. It must have been like us working on the flight line in the Air Force with them running cabled down F-100's in afterburner on the trim pad. Dale