Hey I've got this cam in a motor, Jegs #555-200123 - 296°/306° - .540"/.540" lift, 114 l/s and that's all Jegs website and the cam card has on it. No recommendations for valve springs or open close pressures/ heights.
Not a crazy motor. Just a run of the mill 454. Doing a little top end upgrades and since I need to put valve seals in anyway I though I might as well put the right springs in it while I was at it but I don't know how to figure which one to look for. Any help.

ps, I'll listen and more then likely do what you all say this time.

Call Ron Potter at Potter Performance..

The gm 3970627 spring and 3964264 retainer should get you back to specs if you have the gen 4 and 5 mag with compareable cam

I have 2 sets of brand new Erson springs that I bought and didn't use, they put you at 140lbs on the seat, and 380 open at .650 lift - I went with a Comp cam spring without a damper is the only reason I didn't use them. I also have some Comp spacers I could throw in with the deal too.

thats a little to much seat pressure,,
for flat tappet,you should stick around 125lbs on the seat.these cams have a hard enough time living w/ todays oil.

I looked up a couple cams that were close (still cant find this cam, I'm sure Jegs didn't make it and just relabeled someone else's). Found their specs any where form 125 to 160 closed and 456 to 560 open. That's why I'm asking. The best I can do with those numbers is a wild pitch at it.

Slim pickins on marine grind shelf cams unless you want to dance with the reversion animal.
I would be a little nervous about sticking a mystery cam in there unless i had the quick change cam option in by boat . Which i dont .
The ls6 - mag springs should keep you in buisness to 5500 rpm anyway
if it was do or die for me 3/8 stems ect ect would prob go for mag springs and lots of zinc phisphate old school oil , messy inspection for rotating lifters at idle after the break in jam all that

Even back in the day , when those guys could sell flat tappet boat cams to the people i believe the offering in the catalog went from mild (prob about what the non emmissions 310 ran ) performance , then lumpy idle pull to 6500 better be stingy with the exhaust water rad. 3 cams . From crane comp and the boys ..men of science went team custom with isky .
I would call jegs before i stuck that sucker in there and try to match it with its target purpose some bad lsa mojo could have you starting your season off unfavorably

Hey Air, the motor has been built for about 2 years now and runs fine for as little as it has been run (about 5 hours). It is just one of the 2 motors in the race boat (that were used for showing the boat) that are being replaced this year with real race motors. Plan on using one in another boat that requires a lot less power and figured I would do some upgrades while I was at it. Well, the heads I thought that were 113cc are really 123cc and will not work without domed pistons and I'm not ready to go that deep on 5 hour old motor. So I just hold onto the info until .... well lets just hope there's not a until.

If you have flats and 120cc mag style heads just toss a mag cam ls6 or mag springs be dirty dirt cheap and prob live well .youll be back in action weather u have logs headers high rise quadrajet ect
besides sounds like your at some low compression