Thread: What spark plugs do I need? Thanks in advance...

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What spark plugs do I need...plz help. Small Block Chevy '99 suburban block, stock 350cid configuration ZZ4 Corvette heads 2.02/1.60 valves

Cam specs: Cam Style Hydraulic roller Basic Operating RPM Range Idle-6,000 Intake Duration at 050 inch Lift 218 Exhaust Duration at 050 inch Lift 228 Duration at 050 inch Lift 218 int./228 exh. Intake Valve Lift with Factory Rocker Arm Ratio 0.525 in. Exhaust Valve Lift with Factory Rocker Arm Ratio 0.525 in. Valve Lift with Factory Rocker Arm Ratio 0.525 int./0.525 exh. Lobe Separation (degrees) 112

Holley 650 "double pumper" StreetHP Carburetor Single plane intake... Heads are approx. 190cc intake runners port matched to intake. running shorty headers w/ 2.5'' collector Pertronix Ignition "Ignitor III" w/ 5,800 rev limiter 8.5mm wires manual t-5 tranny Car will be daily driven...thanks Not sure if you need all this info, but thanks if you can help me!!!

all components are "factory" except bigger valves on the heads

I personally don't see much reason to change from the factory recommended plug for that application. I would change to as good of a plug as you can find. I've always been a fan of NGK plugs and recently pulled the Autolites out of my sbf in my 27 and went to NGK's. Car runs MUCH better and cleaner. But that is just my personal choice.

Don

NGK's are OK but there is nothing wrong with AC Delco spark plugs.
I'd put the factory ones in to start with and check them in a couple of days of driving to see how they are burning, to see if you need a colder or hotter plug.

by factory, you mean the factory plugs that were recommended for the FI application? Is it correct to use the same plugs for a carburetor application?

you'll need plugs of the size to fit those heads---I don't remember if they are 3/4 reach or not or if they use a gasket or tapered seat--one you determine the type of plug end the cylinder head needs, pick a heat range somewhere in the middle and then adjust hotter or colder according to a plug reading

okay (sorry I'm a young newbie dumdum)

so the most important first step is the relationship between cylinder dimensions and plug reach...i get it.
And then I'm home free from there by fine tuning the firing heat of the plug....thanks a bunch, I can't put into words what your knowledge means to me...thanks thanks thanks!
-ZC

now just waiting til we hear the auto zone story---what year,make,model---