Is GM Vortec 454 essentially the same thing as the 300-HP L29 7.4L?
#1
Is GM Vortec 454 essentially the same thing as the 300-HP L29 7.4L?
Thinking about just dropping in a truck long block to ride out the season - that way I can take my time and maybe find someone to dyno my 489. Came across a low-mileage L29 long block out of a late 90's GMC dually for $500. I know I will need to swap the 11-lb oil filter bypass for a 30-lb valve, but aside from this, is this essentially the same thing Merc was dropping in for the 7.4L MPI? This would also give me something to drop in the boat if I ever sell it.
Thinking about changing out the wimpy cam for a Merc magnum roller if I can find one. Also wondering if a ZZ502 cam would run in this engine - yeah, I know, it has the smaller port Vortec oval heads and cast crank / pistons, but thought that might wake it up a little and at least sound a little nasty. I will probably go ahead and run my Holley and Lightning headers on it just to simplify things.
Anyone have a magnum or ZZ502 cam laying around that they want to unload cheap?
Thinking about changing out the wimpy cam for a Merc magnum roller if I can find one. Also wondering if a ZZ502 cam would run in this engine - yeah, I know, it has the smaller port Vortec oval heads and cast crank / pistons, but thought that might wake it up a little and at least sound a little nasty. I will probably go ahead and run my Holley and Lightning headers on it just to simplify things.
Anyone have a magnum or ZZ502 cam laying around that they want to unload cheap?
#2
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They are pretty much the same motor, but heads and intake. You can't get carried away with a cam without doing head work and changing springs. I have not done this conversion but have read about it many times on the truck forums. The springs should be replaced with new springs & rotator eliminators. The merc 12551622 cam, which is stock on the 454/502mag is what most of the truck guys go to if they don't want to go crazy and do a bunch of head work. You should be able to get a pullout cam pretty reasonable in the swap section. I don't know anything about the zz502, but would be concerned about reversion.
#3
28, I think the ZZ502 cam is ground on a 110* LSA, so yes, it may be reversion-prone with stock exhaust. I think lift on that one comes in around .510. Not sure what the springs in the Vortec heads are good for. Might be safer to stick with the Mag cam, as it is about the same lift, just more duration. It should be pretty much a bolt-in. I don't want to get carried away with this engine if I elect to go this route - it is only meant to get the boat moving under its own power so I can drag the kids around the lake on the tube.
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That'd work. Really not bad engines. A definite step up from the old peanut port 330 flat tappet engines. The cam in them is factory installed retarded like 7 degrees or something like that. I suppose if you were gonna do the carb, then maybe slap the 454 mag cam in it if you can find one cheap. They're 9:1, I actually think with the mag cam, intake and carb it be a pretty decent running engine!