70 LT1 Distributor Detailing Question.

[Ralph B.]

I'm getting ready to detail the TI distributor and need some help for color/finish correctness.

Housing Casting: Semi Gloss Black?

Clamp Flange (just below the casting): Natural?

Vacuum Advance: Natural ?

Distributor Hold down Clamp: No Idea ???? (has aluminum manifold)

Thank you !
Ralph

[Terry M.]

Re: 70 LT1 Distributor Detailing Question.

The visible base of the distributor is black. We can debate semi-gloss or gloss -- and probably will here.

Vacuum advance is silver colored plating. Zinc I think, but some will call cadmium. Without chemical analysis it is your call.

Distributor hold down on aluminum manifold is a black plated -- probably balck oxide. It looks too shiney to be phosphate, I think.

There is a colored mark on the distributor to allow the assemblers to select the correct distributor for the engine application. See the TIM&JG for the color and location for your application.

[Ralph B.]

Re: 70 LT1 Distributor Detailing Question.

Thank you Terry ! ------- I also noticed that it still has it's original orange daub, it's a little faded but still apparent --- I will will carefully work around it to preserve it . --- Terry when you say "the visible base" can I assume that this is inclusive of the clamp flange which lays directly onto the intake
Ralph

[Terry M.]

Re: 70 LT1 Distributor Detailing Question.

--- Terry when you say "the visible base" can I assume that this is inclusive of the clamp flange which lays directly onto the intake
Ralph

That was my point. That ledge IS visible.

The only reason they would have masked that area was to preserve electrical contact. The body of the distributor has to be grounded to the engine on the points type distributor. I doubt they would have painted TI distributor housing differently than points type. I would suggest there are other paths for that ground, including the hold-down clamp itself.

Do you have any of Colvin's "Chevrolet by the Numbers" series. Some of those have prints for the distributor. If you can read the fine print, there may be something about paint on them.

If you are refinishing the exterior of the housing, just reproduce the orange mark. Take a good close-up before you recreate it, so you have a reference beyond your memory. If it is faded and worn it will look poorly next to the rest of the housing. One can't have refinished and old original next to each other. One or both will stick out. The car will look better if it "flows" with respect to finishes.

[Ralph B.]

Re: 70 LT1 Distributor Detailing Question.

Terry,
Much obliged!
Ralph

[Wayne M.]

Re: 70 LT1 Distributor Detailing Question.

------- I also noticed that it still has it's original orange daub, it's a little faded but still apparent --- I will will carefully work around it to preserve it . --- Terry when you say "the visible base" can I assume that this is inclusive of the clamp flange which lays directly onto the intake
Ralph

Ralph -- here's two of my most original T.I. distr's. Top is of an "almost" NOS 1111296 ('68 435 hp -- notice paint dab and black marker "Q" on vac can); bottom is an absolutely NOS (never been in an engine) 1111263 ball bearing race distr. I would call the paint gloss, but appears semi only on the rough cast surfaces. The bottom was probably assembled in 1976 or 1986 (long production run), and it appears a little less glossy than the '68 production unit. Absolutely no paint under the block contact flange (where the gasket goes).

Can I ask you what the assembly code is on your '70 LT1 distr ? I had a '70 350 hp distr with 0_B_23 with no hole opposite the tach drive gear (like the top distr. in pic). A 1971 T.I. distr 1112038 I have, dated 0_J_3 (Sept 1970), HAS the hole. Just trying to narrow down the introduction date of the thrust button.

[Terry M.]

Re: 70 LT1 Distributor Detailing Question.

Wayne according to the research we did for the 1970-1972 TIM&JG, back in the late 1980s, the hole for the tach thrust button came into being about the same time as the RFI shield for the points type distributor. These changes to the distributor happened at about the same time as the chanages in the distributor shield. If I remember right around 11,00 to 12,000 of the 1970 model year. Around the beginning or first couple of weeks of June 1970.

[Jim T.]

Re: 70 LT1 Distributor Detailing Question.

Terry my original owner 70, built July 8th S414651, does not have the hole for the tach thrust button. It also has the shielding over the points.

[Terry M.]

Re: 70 LT1 Distributor Detailing Question.

Thanks Jim. I guess we will have to see what others have to say in order to see if yours in an anomaly or TFP. I had better sneak a peek at the TIM&JG to be sure my memory is up to snuff also. I was pretty sure I had this one, but maybe I had an attack of NCRS disease.

[Wayne M.]

Re: 70 LT1 Distributor Detailing Question.

..... I had better sneak a peek at the TIM&JG to be sure my memory is up to snuff also....

Terry --- while you're checking the book, does it specify (or do you know) when two other highly visibleT.I. distributor changes occured in the C3 era: specifically,

(A) the stationary magnet form change to add "lips" to either side of the three screws that mount the stationary pole piece to the advance plate.

And (B) the change from the siamesed white lead wires from the magnet coil (with a single faint green stripe on one) to two separate white and green wires, held together at upper and lower ends with a band of friction tape.

Here's my guesses: Lips appeared around mid-calendar 1970. Siamesed wires with thin green stripe carried through at least to end of T.I. distibutors in C3's [1972 ZR1 and ZR2's ?], and probably didn't go separate until the '80s; ie definitely service.

Examples of lips / no lips and the two types of wires can be seen in my above picture.

[Terry M.]

Re: 70 LT1 Distributor Detailing Question.

Well Wayne, I guess we copped out. The TIM&JG simply says distributors ".... after mid-1970 have a small hole opposite the tachometer drive cable."

I know there is no mention of the lips or the siamese wire. I take it the lips, or lack of them, are visible through the distributor cap door. If not it will be difficult to judge them.

FWIW: I believe there was no TI originally installed on any Corvette in model year 1972. At least none that we have found yet. I am pretty sure the 1972 ZR1's had points, but I will verify that soon. There were no ZR2s in 1972.

[Timothy B.]

Re: 70 LT1 Distributor Detailing Question.

Wayne, What lips are you describing, I don't understand??

[Terry M.]

Re: 70 LT1 Distributor Detailing Question.

Tim -- look at the pictures Wayne posted on 2/15. The magnetic pick-up coil (dark brown piece) on the upper distributor has no "lips" around the mounting screws. The lower distributor does. See how much of the mounting screw is visible in the upper distributor?