67 Cutlass Freak

This tool shows installed spring height, not stem height-
15cc75eb-d602-4083-9f31-1f310a330c90.jpg

For the stem height you need this tool -

CIMG4553.jpg

80 Rocket

The only way for your valve to contact the piston would be if it got stuck open........and the only way for that to happen would be to tight of stem to guide clearance. If you mean when the cam is at full lift, how could it not touch the piston? Because if your cam is at full lift when the piston is at TDC, somebody really screwed up degreeing your cam.....hell, if it was that far off, I'm not sure it would run.

It is no big deal to ask about pushrod length, but I already answered and the answer is that it needs to be measured first. Cutlass Freak mentioned that you need an adjustable pushrod to establish proper geometry and that is correct.

When you say they did the research, I don't think you understand that it is not that easy. How could anyone take into account your head gasket thickness, deck height, or how much you mill off the heads before you even do it? All of those things affect geometry and subsequently, the proper pushrod length. Yes, they sell kits that "might" work......if I was selling a cam that "might" work, would you buy it?

80 Rocket

And what did the chassis service manual say?

olds 307 and 403

Thanks Don, I knew the spec was close to that. You are not the first for this to have happen, give him that spec .0028", make sure he follows it. Tight guides are great till valves seize and mass destruction happens. I assume once the center cross overs are filled the .0025" spec works for all exhaust valves?

MDchanic

... And at this juncture, please allow me to interject, before Earthdad goes on too much of a wild spec chase on a work day, that the Chassis Service Manual does not actually give a specification for valve stem height. They state that the clearance between the Oldsmobile tool pictured above and the end of the valve stem is to be 0.005" for big blocks and 0.035" for small blocks.

When everything is measured, this translates to a valve stem height of 1.215" above the valve cover sealing surface for big blocks and 1.180" for small blocks.

This cannot be measured accurately without a tool, and you have your choice of buying one used, if you can find one, or buying one from Mondello (a distasteful proposition), or making one.

If you make one, it might look like this:






Also note that some heads had valve rotators and some didn't, and the ones that did had their spring pockets cut deeper to accommodate them.
Spring installed heights should be about 1.860" without rotators, or 2.015" with rotators.

If memory serves (and it may not...), #5 and #6 heads had no rotators, #7 had rotators on intakes only, and #7A and #8 had rotators on all.

I hope this helps.

- Eric

pogo69

some people do not care for mondello perfomace products i have not had a problem they have good stuff and if you get Lynn on the phone he certainly knows oldsmobiles better than most....he was raciing a 68 H/O andothers back in the day when many here were still sucking on mom's teat

Earthad58

Okay okay, thanks guys, so new valves going in today, turns out the if I understand correctly that valve seat was about done, so installing a new seat, new valves, re honing all the guides etc, also as far as valve springs go, I called the manufacture and have them the part # and she told me springs pressure at 1.7 is 120lbs and something like 320 open. I looked them up online and it's says nominal load for checking is 115@1.625 and 220@ 1.150, also what I was saying was the valve stuck open at the top of the cam lobe, like it stuck, in the guide, then as the piston came around and smacked it. When I first started the car for break in, I raised the idle to 2500 with the idle screw and started advancing the timing as it started running smoother I was able to back off the idle, we'll I didn't realize I went too advanced and headers started glowing and water temp got hot, and that's when the I heard the clacking. I'm thinking I just got it hot advancing the timing and just seized valve in there.

cutlassefi

You would have had to get it pretty hot.
And last time I checked, aren't the center valves on a SBC (exhaust) the same as an Olds? Hmmmm.... So wouldn't those need more clearance too?
Here's my point. I'd rather have a smart "Chevy" machinist than a dumb "Olds" one. My guy could count on one hand how many Olds he had done in the 20 years before me. But he's smart as hell and can think on his feet. Now he's as proficient as the best "Olds" machinist.

And your spring pressures are still wrong. 320 open is too much and 220 isn't enough. Do you have a part number?
Just sayin'

P.S. rockers alone are $165.00.

Earthad58

Yeah sorry I honestly usually leave springs and valve work up to my machinest, I am no engine builder, I can open a summit catalog and pick out parts to make a engine work well for different applications but I usually leave it up to my machinest to figure out how to make all those work right together lol so don't quote me, the springs are made by pioneer and the part # is 810204 it says nom dia 1.384 I'd od .810 nom load for checking 115# 1.625 and 22o# 1.150, the 120 is what the girl on the phone told me at 1.7 and she didn't sound like she knew what she was saying like she was reading it off her computer or something, that's all I know

80 Rocket

Have your machinist check the spring installed height, and then have him put the spring on the spring tester to actually check the spring load at actual installed height and open. This is something that should have been done if not already. Again, not busting your chops here........you are learning, and that is good.

Earthad58

Installed height was 1.680"

olds 307 and 403

Mark, what stud size and ratio do those rockers come in?

cutlassefi

That particular one comes in a 3/8, 1.6 ratio. Thanks.

Earthad58

We'll got it all back together, checked all the lifter preloads as I was installing all the rockers and everything was in spec and fired it up and runs great! No noises, thanks everyone

MDchanic

Fantastic! Glad you got it done!

- Eric