[lizardking7750]

I am building a 355 Vortec motor. I have a new set of plugs for the older style 350, which the block is. They are Bosch plugs, can I use them in Vortec heads?

[V8&4spd]

They won't work. You need the spark plugs for the vortec heads.

[Pre-Tuner]

AC Delco R44LTS (or equivalent) I believe is the plug you want.

[F-BIRD'88]

In the Chevy OEM L-31 vortec heads (062-906 castings)
You want to use a Champion RS12YC for normal street duty and a Champion RS9YC for hard racing or moderate nitrous. Gap at .035"

[Custom10]

yes the R44LTS fit the L31 vortecs and are what i run,,,

Fbird are there advantages to using the champions vs the delco's, or is it a just a matter of preference, curious

also how do the R44LTS and RS12YC heat ranges compare?

[lizardking7750]

Ok, thanks for the info, I had a set of Bosch for the older style and my buddy needed some for older and had vortec ones, what an awesome coincidence. Anyways I now have the Bosch Platinum Plus, are these pretty good performing plugs?

[FastOrange]

Older plugs dont work in vortec heads, they thread in, but not far enough.

I would stay away from the champion's, i bought them , Regapped for my HEI (.045) and truck wouldn't run right.

Bought a set of NGK TR55's (Favorite among Fullsize Truck Forum guys) regapped, and my problems went away.

Also, just dont buy a set and leave the factory gap it is .060 (Unless you want this gap)

[F-BIRD'88]

Originally Posted by FastOrange

Older plugs dont work in vortec heads, they thread in, but not far enough.

I would stay away from the champion's, i bought them , Regapped for my HEI (.045) and truck wouldn't run right.

Bought a set of NGK TR55's (Favorite among Fullsize Truck Forum guys) regapped, and my problems went away.

Also, just dont buy a set and leave the factory gap it is .060 (Unless you want this gap)

if you ever get a new spark plug that mysteriously does not work right check very closely for a cracked or separated-loose-mis bonded porcelain.
Then check with a OHM meter. Very easy to break the resistor inside.
If that new spark plug got dropped somehow it is now trashed.

If /when you are re-gapping a spark plug that has a factory .060" gap, to a smaller .035" gap you may have to trim-shorten the ground strap length. The end of the ground strap should not go past the center electrode. Even or slightly shorter is best.

These are the two most common cause of new spark plug troubles reguardless of brand name.
Dropping the spark plug box almost guaranties most all the plugs in the box or shipping case will be trash.

New spark plugs have a warranty. If you get a new set that are damaged or .... return them to where you bought them for free replacement.

In 35 years I have never had a problem with Champion brand spark plugs.

AC Delco work fine too.

[F-BIRD'88]

Like this................

[FastOrange]

Thanks for the Info F-Bird!, didn't realize that.