Very high vavlespring pressure - advice please!

[HairbearTE]

What dangers could i encounter running high valvespring pressures on my RV8 race engine? Its a solid cam, the valvetrain is lightweight, the rockers are full race adjustable rollers and im using crower lifters with the tiny oiling hole in the face that allegedly allow more spring pressure to be used. I calculate that at peak lift im going to have 280-290lbs spring pressure with the springs i want to use. Its only action on the street will be to and from the strip, its 95% race engine. I expect i might get a higher rate of cam and lifter wear, but what more serious problems could i expect?

[katanaman]

you will probably need heavy duty pushrods but you will know that already. You only need to use the spring rate that the cam manufacturer states. Going any higher doesn't have any benefit just high cam and lifter wear and possibly rocker to shaft wear. They will have worked out the pressure needed to stop valve float for the ramps of the cam. If that is what they recommend then they will have figured it into the cam design and it should be fine.

[Paul B]

What dangers could i encounter running high valvespring pressures on my RV8 race engine? Its a solid cam, the valvetrain is lightweight, the rockers are full race adjustable rollers and im using crower lifters with the tiny oiling hole in the face that allegedly allow more spring pressure to be used. I calculate that at peak lift im going to have 280-290lbs spring pressure with the springs i want to use. Its only action on the street will be to and from the strip, its 95% race engine. I expect i might get a higher rate of cam and lifter wear, but what more serious problems could i expect?

Dangers? I'd guess at high cam wear, high lifter wear, bent pushrods, high rocker gear wear, cam flex, cam flex, cam chain wear, high horsepower consumption opening and closing those heavy springs hundreds of times a second. In short, just what Katanaman said.

[ian.stewart]

Valve springs serve 2 purposes, to control & shut the valves and keep the followers on the cam, Valve train and valve weight is your enemy with higher loads needed to control the inertia of the of the valve when it changes direction from opening to closing, Have a look at modern engines, the valve stems are 5 or 6 mm and titanium is becoming more common in valve construction,
The spring pressures should be run at the minimum poundage you can get away with that control the valves effecently, Heavy pressures cost you HP, make excess heat, create deflection and wear problems

[GreenV8S]

I'd add valve seat recession to that list. I haven't seen it myself, but I've had reports from people who have had the valve seats literally hammered back into the head, with the soft casting yielding. I can only hope that this is the result of valve bounce or something, but it does suggest that damage to the business end of the valve is a possibility.

[Boosted LS1]

I reckon you'll be fine. Those pressures aren't all that high especially spread over the diameter of the seat. Have you got good collets? I read something about nascar racers where they used really high pressures and said it never caused any problems. It just kept the valvetrain under control. So they rated higher pressures.

Boosted.

[HairbearTE]

Thanks for the advice guys, the springs i want to use are ls1 style and because the ls1 uses a roller lifter the spring pressures are higher. My valves are slighly longer than stock and my cam has a lot of lift so the slightly higher installed height of the ls1 spring is ideal. Im not skimping on pushrods and like i said rest of the valvetrain should be well up to it, its just that it's more pressure than i've seen on a rover before. I'm going to play around with different height locks to get set up spot on. I've got chevy grooves in my valves so there's loads of good quality locks to choose from.

[ian.stewart]

Have a read here, especially as you are ysing chevy style valves,
http://www.corvettefever.com/techarticl ... ring_info/

Ive known about them for years, and despite what the yanks say about the new design, My mate had a circuit engine for an Imp built by George Bevan, that had similar beehive type springs,
Do a Google on the "Beehive Spring" Lots and Lots of info makes intresting reading

Another disadvantage of high spring rates is the yeild point of the rocker post threads, may be worth getting them Helicoiled before you start
Ian

[IainB]

Only speaking from the advice I was given with my setup (700lb open pressure!!) that if I had used it on the road it, well, wouldnt have lasted very long. I had titanium caps to keep the weight down, together with lash caps and good quality valves.
Otherwise I agree with what everyone else has said
If its more of a race engine, could well be worth dropping the lash off when its laid up to rest the springs a bit?

[HairbearTE]

Ian S: I've also been following the beehive springs success story for a while now! Anytime the OEM's put something new in an engine you can bet its worth a second look, roller cams are a good example. Recently since Comp Cams started producing aftermarket versions there have been numerous articles in the US mags covering the advantages (who said the US mags editorials were advertiser driven? surely not!). The advantage of the smaller retainer and indeed the lower weight of the spring itself (a fact often overlooked) are well know to those who have followed the beehive springs developement with interest but did you know that they also reduce valve "bounce" drastically because they dont resonate in the same way as a regular spring due to the varying size of the coils? All good stuff. The fact that their size means they could be easily adapted to a rover engine is just too tempting to ignore. Your point about rocker post threads is duly noted. Its exactly the kind of thing i was worried about - more the structural side of things - and it hadn't occured to me. Something else i am considering is spring cups or shimms to protect the ally, but i dont have a great deal of room left for more height on that side of the rocker. Would it be worth it do you think or completely unecessary?

[Boosted LS1]

Hairy Bear if you need some springs to play with I've got lots but they are used and stock poundage.

Boosted.

[HairbearTE]

Ok Mike, thanks for the offer that could be useful, i'll have to pop in and see you next time i'm up that way. I just worry that i cost you half a days work through benchracing every time i see you!

[Boosted LS1]

Ok Mike, thanks for the offer that could be useful, i'll have to pop in and see you next time i'm up that way. I just worry that i cost you half a days work through benchracing every time i see you!

You're welcome. I can spare the time for some people.

I had a chap here for 5 hours the other day. Talk about having a sore throat and I know he's not a genuine punter. I could kick myself when I give up a day for people like that.

[ian.stewart]

Even with cast iron heads, my mate has problems with spring seat wear in the head on his pre X flow,even with shims under the springs the head is wearing, the rev limit on this engine is 8800, so this may have some influence on the problem, I would suspect that you will have to put somthing under your springs to prevent this, and you may also have to modify the the heads to regain the spring installed height to an acceptable level, as the shorter you make the spring installed height the higher the spring rate throughout the range, and binding problems may also become a problem.

[ian.stewart]

what rev range do you intend to take the engine to?? and where does the cam start to decay??