C3 Flint Engines & Spark Plugs

[Tom R.]

Engines are painted at Flint (or T...) and the plugs came out nice and shiney at the St Louis...so how did they do it? How did the engine plant paint the engine without paint entering the spark plug holes...slave plugs? Did they replace some type of slave plugs with specified plugs?

[Michael H.]

Re: C3 Flint Engines & Spark Plugs

Tom,

For at least the 60's cars with Flint engines, the spark plugs were installed in the engines at the time the engines were painted. There was a cup or mask, about the size and shape of a spark plug socket, on each plug that was removed after the paint operation. It covered about the exact same amount of the plug that a plug socket covered and left about 1/8" or 3/16" exposed at the base of the plug which means each plug had a ring of orange paint on it that would be quite visible. I think this was also the system used at Tonawanda but I'm not 100% sure and also I believe the later 67 "Detroit" built engines may not be this way.

Michael

[Tom D.]

Detroit Engines & Spark Plugs

Michael: Where in Detroit area? For what period of time?

Thanks
Tom D.




Michigan Chapter Site

[Michael H.]

Re: Detroit Engines & Spark Plugs

Tom,

I don't know exactly where the Detroit engine assembly facility was in Detroit but starting in 1967, Detroit built engines started to appear in Corvettes. They are identified with the plant code "V" instead of the normal "F" for Flint.

The reason I question weather or not these Detroit engines were shipped anywhere with their spark plugs installed is the fact that they may have left that facility without exhaust manifolds, which would have left the plugs vulnerable to breakage in shipping. That plant typically built up engines for pass car and specifically, Chevelle which would have had a totally different exhaust manifold than Corvette. Somewhere along the line, the correct Corvette manifolds were added and that would explain the absence of any traces of paint on the manifolds of these particular engines. I've looked at some very low mileage 67's with Detroit built engines and saw no traces of moly orange on the manifolds but you can always see some on an original car with a Flint motor.

Much of this is speculation and heresay so take it for what it's worth. I'm only assuming this was possible on the spark plugs but they may indeed have been painted just like all of the Flint built motor spark plugs.

Michael

[Tom D.]

Good Information - THANKS! *NM*

[Terry M.]

Re: Detroit Engines & Spark Plugs

I can't speak for 1967 engines, but beginning with 1968 MY small blocks were painted before the spark plugs and exhaust manifolds were installed. A strip of tape covered the exhaust ports (unless it blew off), and a cardboard cup fit in the spark plug holes. The plugs and exhaust manifolds were installed before shipping to St. Louis in the early C3 era.
The V stamped engines were assembled at Flint. I think it was a different assembly line, but in the same building. John will tell us once he sees these posts.

[Tom D.]

Yep - Alan Colvin's books say V = Flint *NM*

[Michael H.]

Re: Detroit Engines & Spark Plugs

Terry,

That is probably exactly right. I bought a new Z-28 Camaro in early 68 and I'm pretty sure I remember there being no paint at all on the exhause manifolds. (we removed them almost immediately) I really don't recall if the plugs had the ring of paint but I think if they would have, I would have remembered. I still have the original set of plugs that came out of my new 64 Corvette and they definitely had the orange paint on most. Also, the original plugs that came out of the 1500 mile green 65 FI conv had orange paint on them, along with several other cars from that same era at Classic Motors. Looks like the process changed in the late 60's

I suppose that could be correct on the "V" blocks being cast in one location and machined in another. I guess that would pretty much shoot holes in my theory about "V" motors having unpainted manifolds.

Michael

[Mark G.]

Re: Detroit Engines & Spark Plugs

Michael -

My understanding of the "V" code for Chevrolet SB's is because of the name change from Flint Engine plant to Flint V8 plant. The number of engine types and volume may have been increasing in the late 60's. The orange paint variation is caused by line, rate, and how many painters the relief man let go on break that hour of production.

Mark #35760

[Michael H.]

Re: Detroit Engines & Spark Plugs

Mark,

I've seen engines cast as early as 1963 with the 3782870 casting number that were not the same as a normal Flint cast block with the same number. There were a number of changes in the actual casting and some of the machine operations. The casting number itself was about 2/3 as large as a normal 870 Flint block, the date cade was in a slightly different locatopn and the small 1/8" hole in the front of the block just above the timing chain cover was never drilled/tapped so I have to assume these blocks didn't come from the Flint plant. I don't know any of this for sure, just going by what I've heard over the years and the many differences in the actual block.

I'm told that in the early 60's, most of these Detroit cast blocke wound up in truck applications but, again, I really don't know. I'll see if I can dig up more info on this and if so, I'll post it.

As far as the paint, it would be quite difficult to paint an engine with the manifolds in place without painting most of the manifold, even if you were trying to avoide it. The pressure feed guns that were used for this had quite a wide spray pattern and if you hit any part of the cylinder head, you would have painted the manifold also.

Michael

[John H.]

Re: Detroit Engines & Spark Plugs

Up through 1966, the "F" prefix was used both at Flint V-8 Engine on Van Slyke Road and at the "Flint Motor Plant", which was in downtown Flint, "on the river"; Flint Motor only made L-6 and L-4 engines. At the 1967 model year launch, the Flint V-8 Engine plant prefix changed from "F" to "V" to eliminate the confusion for the warranty clerks in the Chevrolet Reliability Group whose job was to assign responsibility to the correct engine plant for the warranty CM&R forms from the dealers who replaced failed engines. Flint V-8 didn't like being debited for failed L-6's, and Flint Motor didn't like being debited for failed V-8's. Yes, it was as simple as that

[Michael H.]

Re: Detroit Engines & Spark Plugs

John,

In the late 70's, I removed a bogus restamped block from a 63 FI car and the block was what was described as a Detroit block. The casting number was the correct 3782870 but the characters were only about 2/3 as big as the normal characters. The normal 1/8" pipe plugged hole in the front of the block was just not ever drilled and there were a number of other oddities that I can't remember now. Even the basic casting had varations in it's shape in some areas and the machining in some areas was different also. We were just a few doors down from the GM tech building in Hinsdale and Harvey Kenesek, one of the instructors, said that was a "Detroit" motor instead of the more common Flint assy. That was the first I'd ever heard of it but he seemed to know all about it. He also told me about the "V" code being the code for Detroit built. I do vaguely remember reading about this somewhere years ago but I really don't remember much about it. I did take several pictures of the bogus motor and casting numbers and I'm still trying to find them. I'll send if/when I find them. Thanks,

Michael