Replacing exhaust rotators with intake non-rotator retainers. 360 smogger heads. What brand and part number lock do I need, please. Thanks for the help!
I wasn't. Was going to use the factory spring with a factory grind cam. Should I? I am open to suggestions, though. Up to and including just run 'em cause at less than .450 lift I'm good.Were you planning on replacing the exhaust valve spring with something else?
Not in 2 or 4 groove format.
Thank-you sir! That's what I needed to hear. New valves it is!Using the stock 2 groove keeper (As found with rotator set up) with an intake retainer, the installed spring height will change by 100 thou. looser, shims of the equivalent amount would have to be added under the stock short exhaust spring to make up the difference. No off set keepers are not available. Using an intake spring with this set up on the exhaust also has a installed height issue. It becomes 100 thou. too tight, spring pad surface of the head would have to be modified (not advisable). The correct math is only found with the use of the 4 groove valve and keeper to use with a stock length intake spring on the exhaust.
So coil bind is an issue? In rookie terms what is recommended? I don't mind buying aftermarket springs if that's a better option. I guess "getting rid of the rotators" is not as easy as some make it sound?Using a stock intake spring with an intake retainer on a 4 grove exhaust valve will actually change the seated pressure from 70 lbs to 120 lbs, allowing for a "used condition" seated height of 1.500 stock to a 1.600 installed height (the attempted combo from above) and the open pressure changes from 172 lbs to 212 lbs at a low lift of .400 inch . coil bind IS not much more of a pull on the spring tester.
Over my head, but I'm listening and learning.Mmmmm... doesn't your closed pressure change vs installed height say a spring rate of 500 lbs/in? 50 lbs difference divided by 0.1" = 500 lb/in. Not a stock spring rate.....
Or are you saying the installed intake spring height changes from 1.6 to 1.4" with those parts on the exhaust side?
OR in reality since I looked and don't have enough of either, I get to buy new toys! Thanks so much for the education!Valve keeper location with a 2 groove exhaust valve and using a rotator nets about a 1.500 spring installed height in used condition. This is using the non dampened spring for the comparison, seated pressure is 70 lbs. Then take the rotator off and install the intake retainer, still using the 4 groove keeper set up, you now have an installed height available at 1.600. But the original short stock exhaust spring now needs to be shimmed to rectify the loss of seated spring pressure OR select a spring that would net a sensible seated pressure, (not use the non dampened stock intake spring with the intake retainer and 4 groove valve/keeper combo that nets 120 lbs on the seat).
He can use stock intake springs and retainers with a new 4 groove exhaust valve to accomplish the correct math. Either way it's an 8 pack of springs or an 8 pack of valves.
Roger...makes sense on the height now. But I believe the 120 lbs on the seat is in error for a 1.6-1.65" installed height for a stock 360 single spring of that vintage; should be in the 80-90 lb range ....????But the original short stock exhaust spring now needs to be shimmed to rectify the loss of seated spring pressure OR select a spring that would net a sensible seated pressure, (not use the non dampened stock intake spring with the intake retainer and 2 groove valve/keeper combo that nets 120 lbs on the seat).
Yes I bought the SP VS510 springs. Had 12 stock, so for the budget build my son and I are doing they'll be fine. Just a factory 340 grind for cam in a cruiser car. $1.99 @ Summit. For that matter the rotators probably would have lived, lol. Mostly doing this for his edumacation. Just something to run around while I plan a 408. Thanks for the help! That chart is awesome!Thanks. Wouldn't have expected that based on the FSM data I have.
The OP can look at Melling VS-150 or Sealed Power VS-510 for a stock replacement spring. 80-90 lbs seat pressure at 1.650" installed height. Coil bind at around .450" lift if installed height is 1.65".
That is the problem with a stockish SBM springs... coil bind comes pretty easily, too easily for any cam of consequence. So a stiffer spring is needed with fewer coils or thiner wire to get a higher lift w/o getting too close to binding. And that leads back to higher seat pressures. I personally would not worry over 120 lbs seat pressure if the spring rate is not too high.
Melling VS1011 is a $2 spring for which coil bind occurs at about .485 lift with a 105-120 seat pressure and a 232 lb/in spring rate. That might work for the OP if the stock springs do not.
https://www.melling.com/wp-content/uploads/2017/03/valve-springs-identification-chart.pdf
Good info. I'll check when it's back together!Good for you and working with your son! That is great!
OK, just look at coil spacing on a couple springs, (intake and exhaust) when you get the cam in. You won't see the problem when you put on the rockers and clamp them down; the lifters will likely be collapsed and not show this issue.
So you'll have to figure out a way to compress the valve and spring on the head by the amount of the valve lift for your cam; then check the coil spacing with a feeler gauge; you ought to be able to slip a .008"-.010" minimum feeler between the coils.
A SP VS510 is about the same as a Melling VS150 and those can be right at coil bind for .450" lift so you need to check for sure, because that is not adequate margin. .060" is the conventional wisdom for margin to coil bind, and you can often 'get away with 'a bit less until it gets over-revved. I.e., for a .450" lift, the valve should be able to move about .510" to coil bind. If the valve spring binds, then the likely results will be bent pushrods, with possible broken rockers.
Also, keep an eye on the retainer clearance to the valve stem seal and the the valve guide boss. This is easiest to check by assembling a valve, retainer and locks but no spring.
Noticed Edelbrock makes a rotator valve spring while I've been searching this out. P/N 5977. Figures.............Stock cam - just leave them in place. If the cam is being upgraded to something mild, you can just replace the springs with Comp 901-16s and run the exhaust springs at the lower height. If it's getting a better camshaft beyond "mild" then replace the valves and all the retainers and locks.