How much boost before you float the valves?

[Dozerboy]

I'm getting ready to do HGs and looking what other up grades I want to do now. My understanding is your ok if you stay under 4,200 rpms, but how much boost before you float them?

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[Burn Down]

Mine makes 70psi with stock springs. 65 Danville and a bullseye s480, 30 overs at 3250 pulse, 4250 rpm. It won’t go above that so I’m sure that’s the limit with mine

 

[Chevy1925]

It’s more valve float from rpm but added boost/drive pressure does not help the valve train. I thought I read somewhere the lbs/square inch on the valves from boost/drive pressure really doesn’t add up to much more bless you have really weak valve springs

4k seems to be max but guys have ran them higher. You usually bend a push rod before valves kiss pistons unless you really rev it.

 

[Dozerboy]

Well I will probably stick with the stock springs until I build the engine.

Since James mentioned push rods should I upgrade them? I though you didn't really risk bending them unless you had a stiffer spring too. If there is some weight savings or other benefits I don't mind doing them since there isn't any machine work needed.

I have a stg2 3794, but might end twining it I the stock engine. I just won't push it very much while twined. I have a 12mm and plan on 100overs while doing HGs.

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[Chevy1925]

if you are staying stock springs, stay stock push rods if they are straight. Just have the valve springs shimmed to the max they can go before coil bind. machine shop should be checking valve seat spring pressure and evening them out as it is, just have them verify what they can bump them up to.

 

[DAVe3283]

If you are leaving stock valve springs, I see no reason at all to upgrade pushrods. I'm running the SoCal beehive springs with stock LB7 pushrods, and I haven't had any issues so far.

Pushrods are relatively easy to change, so if you do somehow bend the stock ones, you can swap them out in a day. That was my thought when I stayed with stock pushrods and aftermarket valve springs.

 

[Dozerboy]

James
Thanks I’ll talk to the shop about it they seem pretty capable.

Dave
Good point about it being an easy swap later.

I just check my stock 190k injectors balance rates 1 is a 5 and 2 are high -2s. I’ll just keep telling myself I might as well just do 100s....lol

I took my 3yo little girl out for a ride. She like to go Zoom. She had a blast and me too. I haven’t done burnouts like that in many years.


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[ikeG]

Maybe grab a set of aftermarket valve bridges. They weigh quite a bit less than stock. Losing valve train weight will increase spring pressure, without actually increasing spring pressure. (Cant think of a better way to describe currently). Because stock pushrods hold up well and aftermarket ones are always heavier, I would rather do bridges in a situation like yours.

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[MarkBroviak]

60psi at 4500rpms is where my original lbz motor in White Lightning would float. 5200rpms with 40psi never had an issue. It's a combo of the two and the shape that the springs are in also that will determine when they start floating and you will know it quickly as it makes a really distinct sound!

 

[Dozerboy]

I'll look into the valve bridges thanks


Thanks for chiming in Mark

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