Spark Plug type 70 LT-1

[Wolf S.]

Re: Spark Plug type 70 LT-1

hi
i ordered the ac delco r45 spark plugs.
in the mean time i've started fitting the r43 ones i have.
cleaning the plug ports was a pita. i did two today and took me a good half an hour. tomorrow i'll do the rest.

do you use a copper based anti-seize on the plug threads?



here's a photo of the cleaned port!

[Duke W.]

Re: Spark Plug type 70 LT-1

I've never used anti-seize on iron heads. And I no longer use it on Al. heads. It makes to big a mess.

Install the plugs with a torque wrench to the specified torque and pull them for inspection every 10K miles or 5 years and they won't seize.

Duke

[Wolf S.]

Re: Spark Plug type 70 LT-1

hi everyone,
since the last post i been running ac delco r45 spark plugs in my '70 lt-1.

yesterday i broke one of the plugs. the porcelaine part just broke off while trying to take out a plug.
i put in an order but i have to wait about 10 days to have a set delivered from the states.

i have a set of r45s plugs (extended tip). can i use these on the lt-1 engine?

what cross reference does the ac delco r45 or the r44 have with ngk or
bosch plugs? ngk or bosch are much easier to source in europe.

has anyone tried out ngk or bosch plugs on a corvette engine?

thanks again for the help
wolf

[Duke W.]

Re: Spark Plug type 70 LT-1

NGK and Denso both make high quality, moderate price replacements for the AC 45 (non-resistor) and R45 (resistor type). Resistor type plugs were used as original equipment beginning IIRC in 1969, so your engine would have originally had resistor type, but there would be no harm in using non-resistor plugs, and they may actually make the engine run a little better though it would be tough to tell.

AC 45 equivalent - NGK B4, Denso W14-U

NGK only offers an equivalent to the R45S (extended tip) - XR4

Similarly, Denso only offers an equivalent to the R46S - W-14PR-U.

The above information is from older paper catalogs. All brands have online catalogs with cross reference data, so you should check their Web sites for the latest information.

Any "name brand" spark plug of correct geometry and heat range as discussed in this thread will provide satisfactory performance.

Duke

[Lawrence M.]

Re: Spark Plug type 70 LT-1

Yes you can use the AC Delco R45S. I run them in my 1969 L46 that uses essentially the same piston as the 1970 LT1.

[Keith W.]

Re: Spark Plug type 70 LT-1

hi everyone,

what type of spark plug, tapered or flat with washer, was used on the 1970 LT-1 engine?

tapered plugs came in 5/8" hex while the ones with washers came in 13/16" hex.

my 350cu" has an assembly date of april 9th and the left cylinderhead is dated march 31st.

the engine came with champion rv17yc tapered plugs. probably not the correct plug but engine runs ok (plugs are brownish).

owner's manual states ac delco r43 as original equipement and the r44 for city driving which are plugs with washers.

thanks

Replying to an old thread I know. Curious what others are using for spark plug gap on a 1970 LT-1. I just bought new AC Delco R-45S plugs.