Valve spring installed height question

[mattsinger]

OK...I'm a bit of a rookie when it comes to valve train specs, and I ran into an unexpected snag. My son and I are rebuilding a 71 383 and got a kit from Comp cams...their extreme energy 274 cam which had their 911 springs. I dropped the heads of at a well known Mopar machine shop here in Michigan. I received a call today that they cannot use the springs because they have too much seat pressure when the valve is closed. come to find out, they want to and did install them at 1.85" instead of 1.9. They said for this size cam, they always use a crane spring that installs at 1.85. So now I'm stuck buying a different set of springs. My real question is will a change of .050 change or mess anything up? Is there a "normal" install height for a big block?...or is everything manipulated around the springs you are using?
Matt

 

[BBBCUDA]

If they are the 911-16 springs, I doubt you will get anywhere near coil bind with the XE274. I wouldn't imagine being .050" shorter installed height will add much more than maybe 20# of extra seat pressure. Could you ask them for the on the seat number at both 1.85 and 1.9"? I would gladly check them if you were local. I would run them myself, but a call to Comps tech line should clear that up for sure. The cost is likely as much or more than a new set of springs, but you could get a different retainer that increases the installed height.

 

[mattsinger]

They said, and Comp cams agreed that being 050 off on install added 40.5 lbs at closed. The machine shop said they were not comfortable with it as it would be too high for a mild hydraulic cam. I'm trying to save a few bucks and to the assembly myself...and don't want something to go wrong...and have the machine shop say "we told you not to use those springs".

 

[BBBCUDA]

Well, if their numbers are correct, that would put you at about 160# on the seat, which is indeed stiff. I would say they are right if that is indeed the case. New springs or a different retainer are your only real choices. I'm trying to remember where I put the set of 911's I have. If I remember I will go test them.

 

[68sedan]

I would shop around and find a set of retainers like BBBCUDA said,I ran into this on a set of small block heads and spring combo I have.Called Hughes and bought a set of theirs which added height,only had to shim a few after that.

 

[mattsinger]

Thanks for the input. For now, I bought their springs...mainly to speed the peocess up and get my parts back. Its been 5 weeks...and the quote was 2. I may look around for different keepers....or maybe just sell the 911 springs.