[Greg 66]

I was looking at the 68404-16 - Crower Valve Springs. Is the seat pressure of 113lbs going to be sufficient or is there a better choice.

[ta man]

Good choice.

[steve25]

thats fine for break in, but after 1000 to 1500 miles I would add atleast a .030" shim as that 113 lbs will drop off to around 106 and you really want to see 120 to 125, so at that point a .060" shim would do the trick.
I would try both size shims now and note how much pressure they add so 1000 miles from now you know what shim to stick in.

[track73]

Why would you need that much spring pressure for a hydraulic cam that won't see 6000 RPM? I'm just curious.

[PONTIAC LARRY]

Seems like 110# @ 1.59" would be plenty...after break-in

[Kenth]

steve25 is on the money.
Pontiac used 125lb@1.586" installed height on the #744 for a reason, valvefloat.
I tried the "std" valvesprings of my lowmiles 1971 #96 heads with the #744 and the engine refused to rev above 4500rpm´s, i switched over to the valvesprings (used) from a set of #48 heads with the correct strength and the engine now rev´s until the TH400 shifts at 5400rpm´s.
Also, a quick look at the lobes of a #744 will give you an idea why the somewhat high valvespring pressure is required?
I think most people trying the #744 and dislikes it used too weak valvesprings for it.
1973-74 455SD uses the same grind as the #744 with 110lb@1.800" installed height springs.

[bobzdar]

I used stock springs and did not have an issue with this cam. I missed a shift and the engine saw somewhere around 7000rpm and did not float the valves. I probably was lucky (well, maybe not, it would have been nice if the valves had floated at 6200rpm and the springs weren't worn out or had been replaced at some point. I'm now running crower springs, not sure on the pn. This is a good cam in a manual trans car, lots of fun with good top end and still pulls 12-14" vacuum at idle.

Track73, In a 400 it will pull to 6000rpm easily. I ran it with a T1 and it felt like there was more left after 6000rpm but I didn't dare go higher with stock rods/bolts. I think an unmodified stock intake will have best shift point at 5700rpm or so.

[PONTIAC LARRY]

[QUOTE=Kenth;3556477]steve25 is on the money.
Pontiac used 125lb@1.586" installed height on the #744 for a reason, valvefloat.
I tried the "std" valvesprings of my lowmiles 1971 #96 heads with the #744 and the engine refused to rev above 4500rpm´s, i switched over to the valvesprings (used) from a set of #48 heads with the correct strength and the engine now rev´s until the TH400 shifts at 5400rpm´s.
QUOTE]

Kenth,
Using 35+ year old stock springs on a build is never a good idea.. I doubt they had over 75# on the seat. I used to use the Erson springs all the time and also had good results, I have swapped aftermarket used springs from one set of heads to another but only if I new the history/age of it.. worked good.. 125# on the seat is on the high end most hi-perf cams and with a low-lift cam with gentle ramping I don't see the need. I have yet to try a 744 would like too..

[68bird400HO]

I am using the HO VS-11 springs. They are stock dimensions and give around 120# seat pressure @ 1.59. They list that they are good up to 0.517 lift but Ken at HO says they will handle much more than that without a problems. Great spring and they are very reasonable pricewise.

http://www.hoenterprises.com/WSFF/ho...?vCompID=27383

[track73]

Springs I have tested usually loose about 10% after run a while.