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I cracked a valve so friend gave me a set of used heads since money’s a little tight right now. They’re stock heads, but they’ve clearly had some work done — screw-in studs, guide plates, upgraded springs, and a few other mods.
I don’t know much about their history.
When checking valvetrain geometry, I noticed the valve tips are shorter than the ones from my original heads. The rocker tip doesn’t sit correctly on the valve tip and looks like it’s contacting the spring retainer instead.
Did I overlook something, or are these heads supposed to be used with roller rockers. The valve tips are little shorter than the originals I removed.
Thank you for helping
That looks like one of those stock rail type rockers that have the walls that surround tip for location of the pushrods. They which not be run with guide plates, which are also locating the pushrods. The two can interfere with each other.
As the valve and rocker tips wear, the rails will get closer to the retainers. Check the retainers to see if they have a shiny ring on top; a tell-tale sign of contact.
You should get some new rockers that do not have the rails.
Along with the already mentioned non rail tip rocker arms you'll also need to use hardened pushrods with the guide plates. They don't need to be fancy, they just need to be hardened. You can test them using a file. If a file cuts them then they are not hard enough. The length requirement of the pushrods also changes when the overall length and tip height of the valve changes.
I mentioned this problem in another thread regarding rail-type rockers. We ran into this with my buddy's '70 Torino GT 429.
The stock cast rail-type rockers are fine for the stock valvetrain. They guide by the ears of the rocker ride against the sides of the valve stem. No guideplates needed. The stock retainers for those style rocker heads are almost flat - there is no 'lowered' section near the valve stem (taller at the spring) It is when you start introducing aftermarket parts into the mix, that the problem starts. Those particular retainers 'room' for the aftermarket valvesprings. It also looks like those rocker studs are too long/pushrods too long. the valvetrain geometry is all wrong! Time to drop back five yards and punt. Start over.
Since those heads have been suped up a bit they might have been fitted with Chevy valves. They are almost exactly the same length as the valves for the older style heads.
A year or so ago I reground a cam for some guys who are running a 429 in a two wheel drive truck pulling class. They have D0VE heads with the stock rail type rockers. Not knowing the real limits of those rockers I used some shorter lobes to help keep the valve lift from getting too high. I ended up with about .520 and .490 and they turned it 7200rpm without problems.
Thank you all so much. I thought I would need roller rockers. The engine is a 302 with a big turbo stuffed in a 64 f100 on Crown Vic suspension. I was trying to stay away from the high performance rabbit hole but I have now found it with a upgraded roller cam, linked lifters, so it need different pushrods anyways and now the roller rockers LOL seems to happen every time. Thank you all for your time
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