C-3 1970 Air Cleaner

[Chuck S.]

Alternator Brace Bolt Headstamp

Hey, Jim...Just for grins...what headstamp does your alternator adjusting bolt have? From what vendors sell, and what I found on the car, I assume the correct fastener stack-up is plain washer, star lock washer, and 5/16" bolt, all zinc plated. AIM calls for plain washer, spring lock washer, and 5/16" bolt (AIM finishes believed to be black from the washer PN).

[Joe L.]

Re: Alternator Brace Bolt Headstamp

Chuck-----

The AIM does specify a 5/16 bolt, split lockwasher, and flat washer for BOTH the 1969 and 1970 model years. In fact, exactly the same parts are specified for both years. The specified bolt is a 5/16" bolt which is zinc-plated and of GM material grade 280-M (i.e. SAE grade 5, 3 line). The lockwasher specified is a plain finish (i.e. not plated or otherwise finished). I have no specs on the flat washer.

However, I can tell you, for certain, that the parts originally used on my 1969 were a 5/16" grade 5 bolt which was zinc plated. The flat washer was a special thick washer (about 3/32" thick) and zinc plated. There was no split lockwasher used, at all. Instead, there was an external tooth star washer of plain finish.

[Chuck S.]

Re: Alternator Brace Bolt Headstamp

Hi, Joe...Thanks for confirming my belief and adding additional important detail. I have made a note in my AIM for future reference.

[Dennis D.]

Re: C-3 1970 Air Cleaner

OH OH. Steel shroud and overflow on an L-46? I've been told no, but I wonder....

BTW Chuck I have the clamp by the horn relay.

[Terry M.]

Re: Alternator Brace Bolt Headstamp

I believe the split lock washer on the alternator adjustement came into use during the 1969 model year. I am used to seeing the split lock washer (where used) in a dark finish.

[Chuck S.]

Re: Alternator Brace Bolt Headstamp

Uh-oh. Terry, by "where used", do you mean you see lock washers of both types (star lock washer and split lock washer), and "where used" the split washer is black?...Or, are you saying you typically see only the split lock washer, and it's black? The AIM part number for the lock washer is PN 103320, which is a 5/16" split lock washer, probably black oxide.

[Terry M.]

Re: Alternator Brace Bolt Headstamp

Sorry for the confusion. Maybe it is too late at night for me.

The "where used" reference was to emphasize the alternate external tooth washer. On those Corvettes with the split lock washer I am used to seeing that split lock washer being dark colored. I believe it is black oxide, or perhaps the heat treatment used turns it dark colored.

If I were judging 1968 and early 1969 I would expect to see the external tooth washer.

It might be interesting to determine the washer style break-point, if there are enough board members with reasonably original 1969s on the board.

[Joe L.]

Re: Alternator Brace Bolt Headstamp

Terry-----

My original owner 1969 was built mid-September, 1969. In fact, 37 years ago TODAY it was somewhere in transit between St. Louis, MO and Fremont, CA. Anyway, my car definitely was originally equipped with an external tooth star washer for the alternator brace-to-alternator fastening.

[Joe L.]

Re: C-3 1970 Air Cleaner

Dennis-----

I think that it's possible that some 1970 L-46 were originally equipped with aluminum radiator, circular steel shroud, and external supply tank. This combination was used alternately during 1969 for L-46 applications, although most of the 69's found with it will be early cars. Nevertheless, I believe that some 70's with L-46 were similarly equipped.

[Joe L.]

Addendum

By the way, I believe that the major reason for the use of the copper/brass radiator on most 1969 and 1970 L-46 as well as the vast majority of 1970-72 LT-1 had to do with the much improved efficiency of the plastic fan shroud and sealing system which the copper/brass radiator enabled. As far as cooling capacity, the 3155316 aluminum and 3018803 copper/brass were roughly equivalent. However, although it generated less drag and wind resistance at cruising speeds, the circular steel fan shroud was very inefficient at cooling, particularly at idle conditions.

[Dennis D.]

Re: Addendum

Joe,

Guess my sarcasm didn't come across. My 70 L-46 has a steel shroud/ expansion tank since I have had it.(1973). Inquired about it many many moons ago here.

[Mark P.]

Re: C-3 1970 Air Cleaner

I have a 70 350/350, June 4th car with no air cleaner and no ignition shielding. Would I be correct in getting an open cleaner and the one piece distributor shield, or could I go either way?

There also seems to be several options on valve covers, too. Could anyone shed any light? Mine has some nasty leaky aftermarket chrome ones on it that really need to go.

Thanks for the help,
Mark

[Chuck S.]

Re: C-3 1970 Air Cleaner

Yep, by the book, the open element air cleaner and the box type distributor shielding should work for you. Your VIN would be JUST BEFORE they started using the either the dual snorkel or one piece distributor shield, so you really have no choice.

In 70, the L46 used the same valve cover as the LT1...it's a good news/bad news situation. The good news is you have the perfect right to wear really classy valve covers on your engine because it came that way, but the bad news is they're going to be expensive to buy, and then you'll probably have to pay big bucks to get them restored.

[Mark P.]

Re: C-3 1970 Air Cleaner

Thanks for the help, Chuck. Didn't want to go down the wrong path....that's exactly what I wanted to hear.

Are the reproduction valve covers any good if I have a hard time finding originals (or money for originals)?

Thanks again.
Mark

[Chuck S.]

Re: C-3 1970 Air Cleaner

I didn't know they were being reproduced, but it's not too surprising. I considered them once to dress up my base engine...NOS were still out there a few years back, but relatively expensive. Used originals could also be had, but they usually needed restoration to be presentable. Sorry I can't be more help.