1970 Ignition & Spark Plug Shielding

[John M.]

I am in the process of doing a full nut and bolt NCRS restoration to a 1970 LT1. In the judging manual it states that around serial number 14,000 the ignition sheilding changed and I have figured out that my car had the later style one piece ignition shield because my two orange brackets only have one nut welded to the inside. My question is should I have all four spark plug shields or only the two rear shields??? The judging manual is not clear on this. There are four inner shields of which I have all four originals, but I do not have any of the chrome outer spark plug shields. My car is 13,238. Thanks John.

[Gary B.]

Re: 1970 Ignition & Spark Plug Sheilding

I would expect to see all four spark plug shields. I think the shielding changes came about with the CTK engines, but need to search more on that.
Gary Bosselman

[John M.]

Re: 1970 Ignition & Spark Plug Sheilding

Thanks Gary, My car has the CTK engine!

[Deane M.]

Re: 1970 Ignition & Spark Plug Sheilding

Cars after s/n 11000 (approximately) would have the two rear shields only.
Hope that helps.

[John M.]

Re: 1970 Ignition & Spark Plug Shielding

Thanks Deane, Thank you for the info. Does that mean that my car would still have the two forward inner spark plug heat shields, just no forward outer chrome shields?

[Mike F.]

Re: 1970 Ignition & Spark Plug Shielding

Thanks Deane, Thank you for the info. Does that mean that my car would still have the two forward inner spark plug heat shields, just no forward outer chrome shields?

That is correct.

[John M.]

Re: 1970 Ignition & Spark Plug Shielding

Thanks Mike!!

[Richard K.]

Re: 1970 Ignition & Spark Plug Shielding

Interesting stuff. Why did the General feel there wasn't a need for the two forward chrome shields?

[Terry M.]

Re: 1970 Ignition & Spark Plug Shielding

Interesting stuff. Why did the General feel there wasn't a need for the two forward chrome shields?

Because they began using a RFI (Radio Frequency Interference) shield inside the distributor. This RFI shield prevented most of the electronic "noise" from the points opening and closing from interfering with the radio.

[Deane M.]

Re: 1970 Ignition & Spark Plug Shielding

That is what I would expect to see.

[John M.]

Re: 1970 Ignition & Spark Plug Shielding

Thanks Terry, Very interesting information. I am surprised they felt the need for any sound noise shields on LT1's with TI ignition (No Points??)

[Terry M.]

Re: 1970 Ignition & Spark Plug Shielding

Thanks Terry, Very interesting information. I am surprised they felt the need for any sound noise shields on LT1's with TI ignition (No Points??)

I am not convinced any of that stuff was needed, points or not. I have friends who use solid core spark plug wires and no shielding and the radio works as well as expected until a spark plug or wire goes bad. Back in the day most of that chrome was removed at the first spark plug change. That is why so few cars have their original shielding.
I am surprised Chevrolet didn't eliminate it all as a cost saving measure. They seemed to nickel and dime every other part and system.