Valve springs
- Thread starter cspangler
- Start date
You'll for sure have to replace the valve springs. I have a similar lift cam in my 340hp 409 (Isky 286) and it needed different springs. I would also reccomend converting to screw-in studs. Are the 1147 studs pinned? I can never remember. I would reccomend getting on the phone with Isky and see what they say. I would measure the spring seat area on the head first so you can use that as a guide. Also know 1.78 installed height. On my 817 heads its pretty large so I would bet you shouldn't have to worry about machining. If this isn't a race engine you should be able to get away without having too stiff of a spring. But the most important issue is coil bind. Best of luck!
Ross
Ross
Thanks for the info. Yes my heads are pinned but we had to get that done ourselves. Did you mean 1.68 installed height? In the show cars catalog the have a 1.439 OD spring at 1.68 height and is supposed to handle a cam lift of .530. We have a set of 333 truck heads. Would these springs work?
Yes, you're right on the 1.68! Thats my goof up!!
Sounds like if those springs fit your head they should be ok. I would just to a quick check on the spring seat area. Those pressures seem about right for an engine thats just a street engine. Not sure you'll be able to rev much more than 5500 rpm. Should give you plenty of wiggle room when the valve is open. I don't see any problems with coil bind. I would have them match up the retainers and locks for you, also.
Looks like you are looking at the 296 hyd isky. States .515 lift but thats calculated with a 1.7:1 rocker ratio. Your stock rockers are 1.75:1, roughly. So the lift will actually be slightly more. I noticed this on my 286 cam card.
MAKE SURE that when you get your springs that the retainers fit on the spring without any forcing. They should fit just like the stock retainers fit on the stock springs. I had a problem like this once before.
If these springs are going on the 333 heads you'll need to get the exhaust valve rotator eliminator shims. Show Cars can help you with that, too.
Best of luck!!!
Ross
P.S. I sent you a private message.
Sounds like if those springs fit your head they should be ok. I would just to a quick check on the spring seat area. Those pressures seem about right for an engine thats just a street engine. Not sure you'll be able to rev much more than 5500 rpm. Should give you plenty of wiggle room when the valve is open. I don't see any problems with coil bind. I would have them match up the retainers and locks for you, also. Looks like you are looking at the 296 hyd isky. States .515 lift but thats calculated with a 1.7:1 rocker ratio. Your stock rockers are 1.75:1, roughly. So the lift will actually be slightly more. I noticed this on my 286 cam card.
MAKE SURE that when you get your springs that the retainers fit on the spring without any forcing. They should fit just like the stock retainers fit on the stock springs. I had a problem like this once before.
If these springs are going on the 333 heads you'll need to get the exhaust valve rotator eliminator shims. Show Cars can help you with that, too.
Best of luck!!!
Ross
P.S. I sent you a private message.