Howdy
I bought a set of tapered seat spark plugs (iridium TR55s) for my (as far as I know) stock '95 f-body LT1. When I went to install them I realised the spark plug holes dont have tapered seats and instead have a flat surface for a washer style plug. Did I buy the wrong plugs? For some reason (I thought I had read it here) I thought I needed the taper-seat plugs for stock LT1 heads? Do I have non-stock heads?

 

You sure your looking at them correctly?? LT1 heads (as well as just about every other factory head AFAIK) use tapered seat plugs, NOT flat seat. Where did you ger the car? Any maker marks on the heads (World, Brodix, TF, etc.. ).

Just wondering, cause bottom line is that stocker LT1's are tapered. I suppose there's an outside chance that someone machined them to use flats, but I can't imagine what the point would be!

Dave C.

 

Hmmmmmmm. The plot thickens. I bought the engine complete on its own for a custom install, apparently out of a '94 Camaro, apparently with 69k miles on it. The first weird thing that happened was I pulled the water pump off to get the opti out to do a vented opti conversion and the bloody thing allready had a vented opti in it!? Looked at the block numbers and they say 2S2232918 which means its a '95? http://web.camaross.com/forums/showt...9&page=1&pp=15
Anyway, pretty much down to the wiring now for my install, go to put plugs in it and it has flat seat plug holes in the heads? So I guess this means they're aftermarket heads... Im gonna strive to get down to the shop to see if I can spy a manufacturers stamp on the heads, should this be obvious?

 

Actually the LT1 heads do have a machined flat for gasket type plugs, but they came with taper seat plugs.

There is a good chance the AC FR3LS plug (as used in the Aluminum TPI heads) will work but I currently do not have a plug to confirm the test fit.