[Charles Martin]

What would be correct spark plug to use in a 492 angle plug head? Know is a small 5/8 and tapered seat
Thank you
Charles

 

[flat tire]

What would be correct spark plug to use in a 492 angle plug head? Know is a small 5/8 and tapered seat
Thank you
Charles

what is your engine specs?

 

[Charles Martin]

350, +.030, 11.00 :1 pistons. Not sure what the cam is, but suspect is a 370HP hydraulic cam. Suppose to be a about a 1970 370HP shortblock. Heads are the 492 casting 2.02 valves with angle plugs. Been stuffed into a pickup 4 bolt main block.

 

[flat tire]

i prefer NGK V-POWER myself. my engine came off the dyno with R5671-8, but was to cold for my driving style. I went to a #7 and that is where I been. you could start with a #8 and make a couple WOT runs, shut it down and pull the plugs and see what they look like.
what will work in one engine may not preform well in another
it is kinda crap shoot
this is just my opinion . I make no claims to be a professional

 

[DOUG G]

I'm thinking good old AC Delco 45's. But I would buy just 1 to be sure it cleared first...burnt plug boots due to header clearance bites.

 

[Charles Martin]

Needs to be a 10mm tapered seat for the angle plug heads. used to call them peanut plugs

 

[Everett#2390]

Autolite 25

 

[Chevyhp]

Always used AC Delco R43, 44 or 45. More R45 then any other.

 

[bilodeaulynn]

Always used AC Delco R43, 44 or 45. More R45 then any other.

None of those are tapered seat plugs. All are flat gasket with 13/16 hex.

OP needs the tapered seat plugs with the 5/8 hex.