28Eliminator

Did you happen to change the valve springs? I have heard the stock springs are not good for the upgrade to that cam.

Budman II

iTrader: (1)

Well crap, that one sold on me - should have jumped on it!

I know where there is another one that is currently installed in a boat, but my concern is that it has been ridden much harder. The upside is that I can hear it run before buying it.

trent77969

Dont forget Inconel valves, I unfortunately thought severe duty would work, but they didn't, trashed a block and merlin heads in 30hrs poof

Budman II

iTrader: (1)

Actually, I think it is a misconception that ALL the Merc big blocks had inconel valves. For a while, the common thought was that the Mag motors (along with, obviously, the blue motors) had them, but I actually talked to an engineer at Mercury Racing a few years ago, and he told me that the black motors had whatever GM put in them. Merc tore down and blue printed the blue motors, and upgraded the valves and valvetrain, but they just ran the black motors as GM shipped them. Now I guess it is possible that GM put their own inconel valves in the black motors since they knew they were going in boats, but in my view that is unlikely.

If I was going to run this thing hard or had a ton of money invested in it, you can bet I would install the inconel valves. My "good" motor that I am building now has them.

MILD THUNDER

iTrader: (3)

Gm used inconel valves in some truck engines. Pretty sure the 8.1 truck engine and maybe even L29 engines. Trucks pulling trailers up steep grades towing 15k lbs can see some pretty good exhaust temps too

FIXX

iTrader: (2)

all the late model 7.4 have inconel valves,,had to because of running the truck so lein and the retard in the cam to get them to pass emissions...

tpabayflyer

Sorry to not mention that but I did buy a set of brand new vortec heads with new springs installed. The spings were taller and did not use the original style valve spring rotators....... Valves were 2.19/1.88 size and I did some significant bowl blending but I don't think it helped much withheld larger valves. Springs were not very expensive, just get the stock magnum/HO stuff and use it...... Easy 500 ft/lbs of torque all day long! TBF

bethgadb

The springs should be replaced with new springs & rotator eliminators.

Budman II

iTrader: (1)

So what are the rotators for, and why are they used on the L29 but not in other applications?

28Eliminator

Where did you get the new heads and how much did they cost, I may be looking at a valve job on my old Suburban, but replacing with upgrades sounds better than messing with that.