Yep... 112 lsa.

 

Well with a .686 lift (1.6's or 1.7's) that puts the lobe lift higher than any street SR lobe, so it's kind of hard to tell what lobes you are running but they are pretty aggressive so the need for more spring. I've got a pretty good guess at what lobes they are, and a slight change would bring down your lift and give you better spring life and a less pressure on the lifters for a more durable combination.

I know those Crower lifters are nice and I hope for your sanity that they don't have any problems down the road.

Bret

 

0.43" at the lobe by my math, 0.688" at the valve with 1.6:1 rockers.

 

I know which ones they are now

 

You can get mild street rollers that are kind to springs and lifters and don't need as much pressure. You just have to know what you want.

 

I totally agree. I ran a mild SR roller for a few thousands miles with no problems. I'm thinking about going back to it but then again why when you can just run an aggressive HD?

 

So what is the generally accepted range of seat/open pressure for a "street" solid roller valve spring?

 

Again it matters on the Lobe ramps IMO. Thats more important than worrying about high spring pressures

 

I've had a couple of SR street cams and numerous HR street cams in my Cutlass over the years. Most everything has been Comp Cams stuff. My last SR was the most aggressive one yet. I used a TK series intake lobe rated at 255 intake dur and .688 lift w/ 1.6 rockers. The exhaust lobe was a Hi-Tech Exhaust 264/.672. This was ground on a 112 LS. I put many street miles on this one (5000+)including one trip from Memphis down to Montgomery, AL (5 1/2 hrs) and one trip to Baton Rouge (8 hrs) w/ the A/C blowing cold. With the 3.42 gears and the 4L60E transmission, the engine only turned around 2000 rpm on the highway. You would think that this would be a worst case scenario for an aggressive SR, but I never did have a problem with it. Oddly enough the cam that this one replaced was an aggressive HR that did break a lifter. I never did have a problem with the SR.
Kevin

 

Im running a Lunati SR in a weekend bruiser/occasional driver
355 chevy
Cam is a Lunati .597".600",259°266° ground on a 106
springs are K-motion 571-K-950
Lifters were Crane horizontal bar Solids

Lifters and springs had 2 summers(summers in Mn are not long)
I just took the lifters out and they were in great shape no slop or play in anyway(sold on ebay). I just had the heads redone with new springs. I swapped to a Comp vertical bar(only because I found them at a swap for 150 off summit price new in the box).

I have had GREAT luck(knock on wood) with running an SR on the street.

Ray

 

So the Pacaloys may not be too much spring for the street, but a milder lobe would help the lifters last longer, right? What about using a lifter bore grooving tool like Comp Cams PN 5003, to improve oiling to the lifter and cam lobe? My lifter bores are already bushed.

BTW Bret, if my installed height is 1.900" instead of 2.000", that would mean that seat pressure would be higher than it would be at 2.000". All I can tell you is what is on my build sheet, although I do know for a fact that they are 943 Pacaloys, because I bought them directly from Comp Cams myself, PN 943-16.

 

Jim,

I've been following this thread and I'm now confused. Comp's online catalog, pages 334 & 345 shows specs for P/N 943. It's recommended maximum lift is .650 and recommended installed height is 1.900 @ 240 lb. They have a 551 lb/inch rate.

By my math, if yours are installed at 2.000 they would have 185 lbs on the seat, and at .688 lift about 565 lbs. At coil bind 943s would only be 648 lbs. IOW, you can't get where you say you are with .688 lift and 943s. Perhaps you don't have all the spring loads you think you do. Maybe that's the good news.

Another senerio: 943s are recommended not to exceed 1.250 when open giving 598 lbs. If that's where they are over the nose, add .688 to this and you are at 1.938 in. where installed load would be about 220 lbs. I can believe this.

IMO, running a 943 about 6% over it's rated lift of .650 probably isn't a good idea, even with Pacaloy and when installed at lower than recommended load. However it sounds better than 260/675 you quoted. No flames intended at all. It's just that the numbers don't add (or multiply) up.

My (probably confusing) $.02

 

Could be... of course, my build sheet also says my compression ratio is 12.2:1, but by my calculations (using the figures on the same sheet) it's only 11.4:1. Someone may not have been very "awake" when they filled it out.

Here's what it says...

Valve spring type - Comp
# - 943-16
DIA. - 1.550"
Install height - 2"
Pressure: Closed - 260
Open - 675

I hear you, and like I said, they're not "my" numbers, so I take no offense...

 

Probably the only way to know for sure is to measure the installed height and use an on-head valve spring pressure tester like the one made by Buxton Engineering...

http://www.buxtonengineering.com/vst_600.htm

Of course, I could just measure the installed height, we can take a guess at what the pressure is, and I can just go with a bit less lift when I have a new cam cut, and save the $595 for the tool.

 

They may not be too much but time is what will tell on them.

The lifter bore groove is mostly a flat tappet setup since you are trying to get excess oil on the cam lobe. It might help the lifters stay oiled though.


Yeah the seat pressure if they were installed at 1.900 would be around 240lbs there. 260's at around 1.850.

As far as the coil bind issue comes out, the springs are about right at a installed height of 1.900 with a clearance at max lift of .062 so they should be fine in that reguard.

A street setup will run all day at 2000rpm on the highway, it's the low RPM idle where the problems are going to be. Excessive idle time is when the lifters are not oiled enough. That and crappy lifters will cause most of the problems. Getting the lifters rebuilt when you change springs would not be a bad idea either.

Bret