Pontiac plugs

[buick7332]

It's been a while since I posted here and I could use some help. I'm not sure what spark plugs I should be using in my Grand Prix. I have a 73 Pontiac 400 block with 4X heads but I have a 75 intake manifold with an EGR and 75 exhaust manifolds. For spark plugs should I be using the R45TS or the R45TSX with the.055 gap? Also, is the TSX plug the same as the TS8? I have a set of both in my garage but I'm not sure if I should use them. Any advice would be appreciated. Thanks, Dave

 

[melloelky]

i think you're on the rite track with the heat range,the majority of these cars are fine with a stock heat range like that delco 45..i think the 0.55 gap's on the excessive side,start with .035 see how the car behaves.it's a good all around size.

 

[buick7332]

i think you're on the rite track with the heat range,the majority of these cars are fine with a stock heat range like that delco 45..i think the 0.55 gap's on the excessive side,start with .035 see how the car behaves.it's a good all around size.

I have always used the R45TS but what has me concerned is a thread I read on another site said if your fuel contains ethanol those plugs are to hot. I recently had the passenger side exhaust manifold split right through the center port. I don't know what caused it and I don't seem to have any issues with the motor running hot but I did read that low compression motors with an EGR should use the R45TSX plugs gapped at .055 and I'm just not sure what to do. Car runs great but the cracked manifold has me scared.

 

[melloelky]

I have always used the R45TS but what has me concerned is a thread I read on another site said if your fuel contains ethanol those plugs are to hot. I recently had the passenger side exhaust manifold split right through the center port. I don't know what caused it and I don't seem to have any issues with the motor running hot but I did read that low compression motors with an EGR should use the R45TSX plugs gapped at .055 and I'm just not sure what to do. Car runs great but the cracked manifold has me scared.

I'm no pontiac guy but that's a stock plug and a .35-.45's a stock(ish) gap starting point.i think the cracking's a coincidence but...