Installed valve spring height - 1.70" at 80-90 lbs, or 1.727" at 100-110 lbs ???

[Rob_85Ttype]

After a search on the topic, I'm not convinced that I know the answer.

I want the proper installed spring height to yield good performance with an aftermarket cam (MM 208/208), but I don't want to end up with a flat cam. The springs are those sold by Poston's or Kirban's.

So, is it 1.70" at 80-90 lbs, or 1.727" at 100-110 lbs ???

 

[KendallF]

I would try for closer to 80-90 lbs on the seat with a mild cam. The only way you can lower the rate is with machine work to the spring pockets, new valves/seats, or raised locks..you can shim the springs for more rate but you sure shouldn't need it.

 

[49-blues]

what springs could i use to get the 80-90 lbs seat pressure @1.70?do the stockers make it to 80 or 90 lbs? thanks-doing the same install with a 208/208

 

[Rob_85Ttype]

Thanks for the replies. Anybody else have comments?

 

[REDS HOT AIR]

on mine i set it up with raised locks around 85# then after a month or so i removed the raised locks and went back to stock locks that set me up around 105# and havent had any problem

as many comp cams as i see on here going flat better stay with the lower setting...but keep in mind that valve float will wipe a cam out too thats why i stepped up my pressure since i see 6000 rpm on a regular basis

 

[gofstbuick]

The GM springs in my sig are 110# @ 1.7. But I'm running a Poston cam (and per their recommendation), and was told these springs would work fine for their cam. My rebuilt engine currently has 25000 miles on it, with no problems. As others have posted, I would rely on the recommendation of the cam manufacturer.