502 heads
 

Looking for some ideas on what to replace the stock 502 MPI heads with in a 27' Baja? The current heads have issues with pitted valve guides and would like to upgrade. I would like to keep from having to upgrade the ECM and to stay with iron heads. Any ideas would be great.....

Going with a better flowing head will require ECM tuning. If you go that route a cam upgrade would be wise to take advantage of the increased air flow, combined with a exhaust upgrade would make a even better combination. In that case Dart makes a nice iron head, World products Merlin heads are a good head at a nice price but they don't flow all that great and also allot of people are saying good things about RHS heads. If you really don't want to get that involved reconditioning your stock heads or new GM castings is probably the way to go

The stock heads were not maintenance well by the previous owner after a run. 90% of the boating in my area is in salt water and when you don't flush the motor after the runs, bad things happen... One exhaust valve guide has already rotted through letting excessive water into the cylinder costing me a block. I lucked out and was able to replace the guide without busting the casting. Figure the other guides are not far behind. Rather replace the heads and know I have eliminated the issue. Hopeing Dart or Merlin have a "replacement" style head that will work? I know valve train will have to be upgraded also.... Not looking for performance, just peace of mind...

If you change to any heads that are not stock GM rect ports, you will need to have the ECM retuned.

+1 ...... But don't think that by sticking with GM you are somehow sacrificing quality. GM has the best casting ability, machining equipment and tooling money can buy. Dart, World Products or any other aftermarket head just offers more options than GM does. If your completely against remapping the ECM stock GM is the only option.

You will also lose the non adjustable valvetrain if you go with an aftermarket head. That's a good thing, however, it will cost you a little more. You can get rid of the stock stamped steel rockers and use an aluminum roller rocker arm. You could also do this with the stock head if you wish. I have a few sets of 088 heads if you are interested. I have them with both the 2.19 intake and the 2.25 intake valves. The 454/502 Mag uses a 2.19 intake valve and the 500 efi, 500 hp, 575 SCI, etc, used the 2.250.
Eddie

I have a set of 088 heads also that need gone through if interested. Randy

502 heads
 

Thanks for the help guys. I found a local guy who said he could rebuild the heads with new guides and seats. I was told there was a risk of busting the casting while removing old valve guides, which is why I was looking at aftermarket. This company said they can rework the heads and guarantee the work. I do plan to replace the non-adjustable roller rockers before the top end is put back on and possibly upgrade the ECM program? Again thanks for the help...

If the heads been neglected and run in salt, I'd strongly recommend new or good used freshwater castings