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Discussion Starter · #1 ·
Hi ~
I recently purchased new Autolite APP 608 double-platinum plugs for my '93 350CI Chevy C1500 (Gen 1) engine. When I got them home, I noticed that they were about 1/4" deeper (from tapered seat to end of electrode) than the ones I pulled out (AC DELCO R43T). Also upgraded to MSD 48K volt coil & big wires (was getting some RFI on radio) so I could set 0.45 gap.

My question is... do I have that much clearance (extra 1/4") between TDC & plug for this to be safe? I'm kindof afraid to start the engine since I don't want the pistons to be hitting the plug, of course.

Has anyone run these plugs... and is there enough clearance??
Why would they sell these plugs for a '93 350 if there wasn't enough clearance?

Any help/opinion would be greatly appreciated.

Thanks
 

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Discussion Starter · #3 ·
Hmmm...
Summitracing says these are (among) the right plugs... doublechecked fitment, etc.

Weird... how could they be so wrong (bought from them for years)??
 

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The plug for a later model GenI Vortec engine is an APP 605. It has the .705 reach whereas the App 25 is a .465 reach plug.
Do you have Vortec heads(8 intake manifold bolts, not 12)?
 
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