Putting together a SR kit.

Using lobes from comp, a split between their hi tech and hi tech .420" series.

I wrote comp and asked about a spring recommendation. They suggested spring #943-16 with 240 lbs @ 1.900, Open pressure is 598 lbs @ 1.250. The rate of the spring is 551 lbs per inch.

I currently have a set of dual springs with dampers. I just tested them on a digital scale and got between 227 and 240 closed at 1.850, and 572 and 594 open at 1.18, that’s a spring rate of about 515-520 lbs/inch on average.

My question is, will I be ok? I have always read springs generally will have a 10% variance in a box, and then after break in will lose even more pressure. Since the springs I have already have been used, shouldn’t have any more break in loss, where the comp springs will.

Thanks
jared

EDIT: I forgot to check the coil bind height on my set to see if I can install them a little shorter. Ill do that today and have an answer this evening.

 

Yeah let us know about the coil bind. I have SR billet in my car and its great. I put down 421hp with mild heads. Let us know

 

1.098 bind, no go on shorter install height unless I run 1.5 rockers.

I just wrote to CC and they thought those springs would be ok, any of you still wish to chime in, that would be great

 

i think one reason they push those springs (pacalloy) so much is because they will last longer. you should be fine if you arent looking for 25000-30000 miles.

 

Ya can shim under the bottom to bring them more equal on seat pressure if ya won't run into coil bind.Just don't shim the ones with the most pressure and try to get them within 5# are as close as ya can and ya should be good to go as long as ya got .050 between coils at max lift.

 

Jared, I would go with the pacalloys....I have used them and they are the best for a street motor in my opinion.

I actually have a set of very low milege used ones with ti retainers forsale for quite cheap. Email me if you are interested. jhsformula@aol.com

Thanks, Jason

 

We run our GTA race motors at 200-210 on the seat and 550 open - with absolutly no valve float issues. Those numbers will be fine, but like you said, the .080" to coil bind is the very bare minimum that I would ever use...always try for .120"

How much shim are you using to get that installed height?

You do have a rev-kit right?

 

Jason-
Im going to stick with what I have for now because thats easy and they should work, thanks.

I think I have an .060 in there currently. I just chose 1.85 since thats what it is setup for now, been a few months since i put that together though.

No rev kit on it, whats the point if you can just add more spring pressure? (honest question?)

 

Don't need a rev kit unless ya are turning in excess of 7000 or have a really really severe ramp rate like an in rad cam of a few years back.
If I had more than .050 clearance in my springs I would be ordering a cam to take up the excess and anything over .050 is a waste of installed height. It also cost a bunch extra to put it there and a 1/8" clearance ain't needed.

If ya are running 2.0 installed and a coil bind at 1.100 with a cam that is .786 net lift that is .064 before bind so for me to get another set of valves or springs that will duplicate my seat pressure --well. I have set up customers sprint engines at .050-.055 with no ill effects and run them all season 3-5 nights a week.
That big installed height does not make shaft rockers fit well, unless ya have a box full of shims or special cut mounting bars.Does weird geometry patterns until ya take the time to shim them right.

 

Those lobes are pretty radical for a street car. Is that what you are building? How did you come to pick those particular lobes?

Rich

 

It started as a street car just like they all do, but it really doesnt get driven any more than a day or two a week anymore.

Those lobes were chosen because my buddy had a cam like this ground awhile ago and made good power. The car was plenty streetable (IMO), so i copy catted.

 

Bret on the old mans account again...I wouldn't put that much on the seat Jared... Like MachinestOne said 200-210lbs is all you really need on a street motor SR cam.