70 questions re-visited

[robert leazenby]

I just spent several hours going over archives for some questions. I answered some but now have others.

1. Spark plug shields. My car is a late (last month) LT-1. Currently there are no spark plug heat shields. (Sometimes called inner shields) In the archives I read that these were concelled in late 70 but am unsure if this was in reference to the outer ignition shield or the inner heat/sperk plug shield. Could someone clear that up. Should I have all 4 inner heat shields on a late 70. Also missing and not sure if I am supposed to have are the 2 hole plug wire grommets, two to the oil pan and two to the block, as well as the 4 hole inline grommet at the bottom of the ignition shielding at the rear of the block. Should I have all of the above.

2. Thermostat housing. Mine is orange on an aluminum manifold, should be natural aluminum, no? The two bolts attaching the housing are different. The right one is a stud/bolt, with unused threads above the bolt head, while the left (driver's) is simply a bolt.

I have several other questions, but this is a start.

[Joe L.]

Re: 70 questions re-visited

Robert-----

Your car should have all 4 of the inner heat shields. These were used on all Corvette small blocks. These are the zinc-plated shields which attach to the block with one screw each.

The outer shields are the stainless steel or chrome plated radio interference ignition shields. These are found only on cars which are radio-equipped from the factory. They are attached to brackets which fit under the exhaust manifold mounting bolts and there are 2 brackets per shield.

Early 1970 Corvette had 4 shields, 1 for each pair of spark plugs. This same configuration was used for 68-69. Later 1970 Corvettes may have had only the two rear shields, 1 on each side.

You should have all of the spark plug wire brackets that you described.

Your thermostat housing was originally natural aluminum for LT-1. It was NOT painted orange. The thermostat housing was attached by the fastners that you described. The top portion of the double-ended 3/8-16 stud was unused.

[robert leazenby]

Re: 70 questions re-visited

Thanks Joe, the inners are on order. Would you have any more specifics on how they attach, type of bolt needed etc. as I only ordered the shields. I have all four ignition shields, so may have changed a little later than 13904.

Obviously I need to also order the plug wire grommets, do you have any specifics on where they attach and with what. I have an original service manual and parts manual, but they are confusing to say the least.

I do appreciate the help, believe me. I'm trying to get the thing correct.

[Terry M.]

Re: 70 questions re-visited

When I get back from Florida I can look at the head of the bolts for the heat shields, if no one else comes forward in the mean time.

We generally believe that 1970 Corvettes after 12000 or so had only the rear ignition shielding. The change was not sudden - that is they did not just one day stop putting on the front shields. We also generally see the 1971 style distributor shield after 12000. The 1971 style shield and the two rear shields generally, but not always, go together. If you have the 1969 style box shaped distributor shield then I would expect four shields.

The good news is that you are in a gray area and you can "run what you brung" so to speak. On the other hand I can't imagine anyone adding additional ignition shields. Usually they are deleted. If the car is reasonably together, believe the evidence it presents and restore it that way.

[robert leazenby]

difference between "69" and "71"?

what is the difference between the 69 and 71 style of distributor box? Also the front (as well as the rear) ignition shield brackets are stamped with something from Canada. Is that correct?

[Joe L.]

Re: difference between "69" and "71"?

Robert---

The 68-70 distributor cover was a 3 piece arrangement consisting of front, rear nad top cover which were attached by the same sort of wing nuts that attach the spark plug shields to the brackets. 2 zinc plated, phillips sheet metal screws were also used on one side to attach the front to rear.

The 71+ style distributor cover was a 1 piece, stamped cover.

"Made in Canada" labels are often found on current SERVICE replacement spark plug shield brackets. I don't think that I've ever seen this actually stamped into the brackets, though. But, they may be now so-stamped. Originals were not stamped this way, whether or not they were made in Canada.