I have two sets of GM 049 heads (good cores) that I am rebuilding, emphasis is maximum reliability not maximum HP. They have the stock 2.08 and 1.72 valves, and are totally untouched from the factory as far as I can tell. They will be getting a valve job, new stainless valves, and guides either bushed or replaced.

My question is, do I need to install hardened seats? If so what is the largest I can go before there a significant chance of hitting water?

I would like to install bigger valves, and I read a lot about 1.88 exhaust and 2.19 intake for these heads, but I’m fine with stock size valves to guarantee I don’t hit water (if I need hardened seats). All the info I can find on these heads is for automotive applications, seems like hardened seats are not needed but this is for a marine engine…

These are going in my Fino (Arneson drives) which is under 7k lbs, will usually be under 5k RPM since its more of a cruiser, with occasional top speed blasts. The currents props should keep it at 5400 max if my HP guess is right at 425/side or less.

Since it will be asked… engines are Mark IV 454's .030 over, GM cast crank, 4130 i-beam scat rods, SRP 4032 material pistons for a 8.9:1 compression ratio, Crane 132561 cam (Merc 420/525sc) with 1.7 ratio rockers, valve springs are merc 525sc, Edelbrock performer 2.0 dual plane intake, Holley 850 mechanical secondary carbs.

Ignition is TBD but it will be an electronically controlled distributor type like Merc. thunderbolt, or a setup from DUI.

Exhaust is aluminum HGE stock replacement manifolds, currently with stock risers but they will be changed for some Gil style risers I am fabricating.

- Alex

Alex, Check with George at G&G Performance in Tomball (Maybe Hockley address) 281-351-6202. He did mine with the 2.19 and 1.88 Fierra valves. He also did a lot of porting work on them and they produce great torque. I was also shooting for 5400 RPM. Great people and very good head work people. They even flow them for you. Good luck with the build. Gary

I know Teague only uses a particular valve seat these days, not just for big power but reliability with today's fuels on even the basic 500hp rebuilds. That may be worth a check into seeing what he's doing and why.

Sometimes its just not cost effective, to sink money in these old heads. by the time you install new seats, guides/liners, valve jobs, milling, etc, youre money and performance ahead to just go with new castings like the EQ heads, dart iron eagle, etc.

I’m not keeping these heads for $ reasons, and I’m not looking for max HP, this boat isn’t that kinda deal.

As I said in my earlier post I had G G Performance do mine. He is THE go-to guy for headwork in the Houston area. I am extremely happy with his work.