I used to speak with Tim a lot back then---like around 1983-1984 and ordered some of their Merc 440hp/454cid hydraulic flat tappet cams. We used those cams in our modified Merc 330hp/454's, but you really needed aftermarket exhaust system to make them work well. The Merc 440hp cam (231*/239* at .050" lift on 110* lobes) from Ultradyne was a bit too large for a marine engine without an aftermarket exhaust system.

I knew of several guys who would try to run them in the Merc 365hp back then and they would end up with several problems....reversion/breaking exhaust valve heads off and this was because they would always keep the STOCK MERC cast iron and very CRUDE breathing exhaust system and didn't want to spend the money for a better breathing aftermarket exhaust system. If fact, they were more expesive back then than they are today! Back then we didn't always know what it was and today it is pretty much common knowledge. Those cams actually ran much better with a single plane intake manifold and an exhaust system such as a Stainless Marine, GIL or Hardin P-1000's or something comparable. Merc used the same cam in their Merc 460hp/482cid engine! As far as I know Crane did most of Merc's cams for their other engine packages.

A good cheap replacement cam for the 454mag is a crane #134241. It comes in a kit with lifters under #134242.

226/236, .534/.553 on a 112 lob sep.

Hey guys, thanks for all the input. I ended up going with crane pn# 132561. I wanted to get back on the water without spending a bunch of cash or tearing the heads off. The stock spring pressures were OK for this cam, and it had a bit more lift and duration. Didn't notice much difference in performance, but I wasn't really looking for any... I did have to tweak the AFR at idle a bit, but that's it. I'll probably do some exhaust work this winter - I'm running stock exhaust w/ the silent thunder platform.

That is the stock 420/525SC cam. With that being the only change, its not surprising that you didn't any gains. You need exhaust and maybe some carb tweaking. A 1" spacer under the carb might help a little as well.

What kind of hp do you think it would bring with the mods?

That would make about 425-440hp. Those mods are the same as a 420 with a roller cam.

I have a pair of the420's sitting in my garage and I am thinking of a build for these engines.

500 hp seems possible. What about 600+ hp form this start point?

The only way to get 600hp out of a 454 is with a solid roller cam at 6000rpms + with dry exhaust. Even 500hp is pushing it on a 454.

How goes it Mark???? You gonna be down for OSS????

Come on man you can't tell me stuff like that! Your supposed to say go for itcan't wait to see it when it's done!

I am there for the races! The usual suspects will all be tied up together. We need to find us a good spot this year. Hopefully the wind will be died down a little more this year. Last year was tough.

You gonna make it?

I onced owned a pair of 454cid engines (bored to 468cid) in my boat that had Merlin oval port heads with 2.30" intk valves 1.88" exhst valves, bowl/pocket ported, 9.5 comp ratio, bore notched cylinders, Dart single intake manifolds, Holley 1050 Dominator carbs, and Crower mechanical/solid roller cams that supposedly dyno'd at 618hp or so with dyno headers and no pullies (water pumps, alternators, etc). I think this was accomplished at about 5700-6000rpms.

I can no longer find the dyno sheets, but I still have the cam cards/specs.

Crower Part number E-1964
Grind number: special

Duration @.050" lift: 248* intk, 254* exst. on 110* lobe seps.

Lift: .639" intk, .634" exst.