69 350 bent pushrod cam swap
#41
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
15cc75eb-d602-4083-9f31-1f310a330c90.jpg
For the stem height you need this tool -
CIMG4553.jpg
#42
Why would you think it's not possible for the valve to hit the piston if stuck open at the top of the lobe? And yes I am learning Oldsmobiles, I knew nothing about them prior to buying this car so bear with me I'm trying to learn and use the knowledge I have of other engines to help me out here. As far as the pushrods go, mondello sells only one length pushrod for their small block olds, same with comp... So why is it such a big deal me asking about pushrod length? They did the research already I'm just basically copying one of their kits...I can respect constructive criticism just back it up, explain why
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?
#44
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?
#45
... 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
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
#46
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
#47
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.
Last edited by Earthad58; March 19th, 2015 at 02:04 PM.
#48
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.
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.
Last edited by cutlassefi; March 19th, 2015 at 03:21 PM.
#49
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
Last edited by Earthad58; March 19th, 2015 at 04:07 PM.
#50
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 1.15# 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
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