408 hyd roller, too much spring pressure?
They are grossly overrated & they don't like rpm? Another brain surgeon at work.
Speed Talk website, post started on Aug 3.
BH/Conical springs used:
- 0.900" valve lift using dual conicals
- BB Chev Twin Turbo 2.35: int valve, 0.750"lift, 7200 rpm, 135 lb on the seat.
- roller cammed engine, spinning to 8000 rpm
- BB Chev, 2.30"valve 135 ln on the seat, 750 lift, 27 psi of boost, 1800 whp, 7400 rpm.
I do not know how to link the post. If you know how, the date of the post on ST was Aug 3, this year.
There WAS a bad batch of Comp Cams BH springs about 15-17 yrs ago, which Comp acknowledged.
Are you calling dual conical springs beehives? I don’t.
I was using either PSI or PAC springs on that engine. In fact, it was a 2300 Ford and the cam grinder I used refused to grind cams for those junkers.
So I ended up buy a cam from another cam company. As I was getting off the phone with the dude, he asks me what I’m using for springs. I said I haven’t a clue yet. I’ll see where I end up for installed height and ****.
He says I’ll send you out the springs we designed the lobes for. So I’m thinking ok, saves me some work.
They show up beehives. I check them out and they seem a bit light on spring rate but this was a Ti valve deal so off we go.
On the dyno it broke a spring. I took the whole set off and sent them back. He sent out a “fresh” set. Back on the dyno and it lived, but the graph was weird. It had little dips and **** and we wrote it off as a “computer glitch”. I should have known better.
It made qualifying and almost half the main, and then it broke a spring, beat the **** out of a valve and broke the hell out of the rest of it.
We got to eat that one. So I called this cam grinder (who I will NEVER use again) and said who makes these **** springs. Today, I can’t remember if it was PAC or PSI. It was one of the two.
So I called them and told them what happened. He says “WTF are you running THAT spring for”??? So I tell him the cam dude says this spring is the **** for these lobes.
And the spring guy says “don’t use a beehive for THAT type of application”. And he sent out a set of double springs and his retainers.
I don’t know how many laps that engine went but it won a regional championship and two track championships IIRC.
I’ll go see if I can find the thread on ST and see if I can post it here. I may not be able to do it either.
