454 cam upgrade questions/opinions..
 

I am rebuilding my 400HP 454's this winter, I have a set of Merlin heads to go on, with a small runner single plane intake,9.0:1 compression, and 454 CI.

I want to try to get the most I can from them, my 400/420 cam is decent but would a cam change be worth it? what cam have guys been running with a combo like this? I am not looking to go roller at this time, not in the budget this year, any suggections would be great, thanks..

Exhaust??
 

Tell us more, what exhaust are you running?? Aftermarket?? Wet or Dry??

Well, that is a tricky one...
Right now I have an old school 3" stainless marine setup, I plan to go with GIL or IMCO but I need to do the hull work and engines first, then see if the money is there for the exhaust, I figure I can run these one season if I have to, I know I will not see a good gain until the exhaust is done but I want to do cams while the engines are out.

Here is what I have now, some guys say it may not be that bad but it cannot be great! these were done in 89, back then this must have been a upgrade!

http://i36.photobucket.com/albums/e4...g/105_7518.jpg

Like I said, I know the exhaust is going to kill it if I use these for another year, but I cannot do the cams in the boat, and I have the engines out now...

WOW, props to the heilarc guy. I imagine these pipes are not the best for water reversion, so being there wet, i would not get crazy. Even on some of the new, good stuff, if its a wet system, with any sort of mixing in the tailpipes you have to be careful. With a wet system and a hyd. flat-tappet, I would go with something around [email protected], .525-.540 lift and a 112 LC. Although we have been able to use some larger hyd. roller grinds with wet systems with great success. As large as 244 and .600+ lifts with no problem. Mainly due to the function of a roller design. I know you said you cannot go that route now, but if you can swing it, you'll be far ahead of the game. It sucks there are not any reasonable hyd. lifters for an older style block. This is were the cost is really incured. You figure $200 at best for a reg. hyd cam&lifter kit. The roller cam alone is $250, then the retro lifters if your using a gen-4 block, these are $375 alone. You would then need shorter pushrods to complete the swap. And a cam button of course. Triple the cost, but money well spent, as far as performance, reliability, and clean oil goes.

If you're not going to go to a roller cam, then the cam you have is pretty decent. Changing to roller cam will cost you at least $1000 per engine.

The stock cam is a .530/.551, 228/236 on a 114 lobe sep.

Kind of at I am thinking, the roller just cannot happen this year, maybe in a 2-3 yrs, I will prob refresh again, then do roller cams, The 420 cam is a decent cam, I just wondered if going bigger would not really be worth it.

How important is it to make sure all the flat tappet lifters stay in order? I had them sitting in order then knocked them over, is it really that big of a deal?
I did a small block years ago and did not keep them in order, it did not hurt nothing then, but with the boat it is more involved if there is a problem..

I would just replace them for the $150. Its not worth the headache of wiping out the cam.

Thats true.

If you go with a bigger flat tappet cam, you will push your peak torque and hp into higher rpm ranges and loose lower end torque. The stock cam is good to 5400rpms. You won't gain more than about 15-20hp with bigger flat tappet cam and the only gain will be at WOT. 30-40hp is possible with a roller cam.

I gained about 150 rpm switching from the same cam in my 525SC to a Crane 731 roller.

The boat planes great as of now, what do you think the low end loss might be? I may be able to lose some, but I don't want to make a mistake either..

You can experiment with more cam if you want...it's your choice, but if you're not willing to go with at least a hydraulic roller cam, then the stock Merc 420hp flat tappet hydraulic cam is already a lot of cam for a 454. This is especially true in light of the dual plane intake manifold and the exhaust system you're running, but who knows....you just might get lucky with a larger flat tappet cam. Of course I'm always chanting about a well breathing exhaust system....and so, the first thing I would do is upgrade to a better breathing aftermarket exhaust like Stainless Marine or something comparable. Just my .02....hope it works out for you.

I agree that the exhaust should be the first thing normally, but in my case, I had a bearing spin due to an oil line break, so I had to redo one engine, and since I am doing one, I may as well do both, scored a deal on merlin heads and some other good parts, I am doing hull work too so the exhaust is not in the budget as of now, maybe if things go well I can do the exaust still, I figured at least if I cannot afford the exaust right now I can use mine to boat for the season, at least it will run, the cam thing is mainy just so I don't have to pull the engines again next year when I DO have the exhaust done. I am trying to pay cash for this as I go so the budget has to be affordable.

I would leave the stock cam at least until you upgrade the exhaust.

I agree upgrade exhaust first. If I could do it over I would do that first.
Good Luck!!!

OK, I got a nice exhaust now... stock 496 stuff, everyone has said it will support my engines power easily, I just realized that since I spun a bearing the particles must have went through the lifters too... I forgot about that, so now I will for sure be buying a new cam and lifter set.

Here is the deal, the stock 420 cam that I have now is expensive, 290.00 for cam and lifters.
I have found a few from summit that are 226 intake duration in stead of the 228 that the 420 cam is, should I worry about 2 degrees duration smaller?

Now I am open for cam grind suggestions, roller is still not an option this year, exhaust is not a problem now either, any help would be great!

I have a Crower custom grind in great shape. lift is 561/561 with a 1.7 rocker 594 with a 1.8.
Lobe seperation is 112 and duration at .050 is 229/229 with the hydraulic roller lifters.

I also have a 1998 454 Mag set of heads just rebuilt Ported as far as i would take them. 2.25/1.94 Valves and new springs just freshened. let me know if there is interest.
Bob

I bought a used prop from Bob. The prop was in great shape and he was pleasant to deal with.

Are they retrofit lifters? I have old blocks, I need lifters with the tie bar... you have 2 sets?

I should have paid more attention just 1, sorry.
Bob

A single pattern cam will work, but a dual pattern cam would probably be the better choice for a marine application---just my own .02.

[QUOTE=Full Force;2486820]
Here is the deal, the stock 420 cam that I have now is expensive, 290.00 for cam and lifters.
QUOTE]

I've got a stock 420 cam and lifters with 125 hours on them in perfect condition. You can have em for $50. if you're intersted

[QUOTE=HaxbySpeed;2487621]were the lifters kept in order? I will see maybe, depends on if I change grinds. Thanks

Yes they're in a comp lifter box and everything is marked..

Ok, let me see what I will be doing.

This worked ideal in a blown injected aplication.

I am most likely going to just buy a new 420 cam, just to be safe and keep things the way they are now.