I have put a cam in my 350 that is equivalent to the ta212 and the 3.0 pistons bring me up to about 10 to 1. Should I still use the normal plugs or need something different?
It really is trial and error with spark plugs. No one size fits all. Rule of thumb is to use the coldest plug that doesn't foul. I would try one step colder. IMO, it is hard to beat the NGK UR-5 as an all around great plug. It has a pretty wide heat range. If you have an HEI, gap them at .045. https://www.rockauto.com/en/parts/ngk,2771,spark+plug,7212
With the hei, I would stick to the recommended ac delco plugs. Did you get block decked? I would suggest it to get the 3.0 pistons up closer to deck. And that will give a close to 10 to 1. But do recheck your cam compression ratings. And the dynamic compression of cam. Don’t want it to be too high. Stay under 8.0 You can retard cam timing when degreeing cam if you need it too drop dynamic compression down a bit
Those NGK plugs are the best ones to use the UR5 works well . 045 gap is a good place to start. no need to tax the system any more than needed by going higher gap
Engine has same casting numbers as my 76 350. It was a long block that had been rebuilt to stock except for 30 over slugs. Owner didn't pick it up so they sold it to me cheap. I am having them put in lunati's mild voodoo cam. (Advertised Duration (Int/Exh): 250/256; Duration @ .050 (Int/Exh): 207/213; Gross Valve Lift (Int/Exh): .451/.470; LSA/ICL: 112/108; Valve Lash (Int/Exh): Hyd/Hyd; RPM Range: 1000-5200). Also got a set of 3.0 flats from eum that should arrive any day to replace the sealed power low comp 657P -30s. Will use stock logs, manifold, and rebuilt qjet from my 76 free spirit. I want the stock look with just a little more than it had. Was told this should get me between 9.6/10 to 1. I will measure it once installed to find out.
