Thank you everyone so far. Part 1, vacuum testing at home setup and results.

Setup:
1/4 inch plexi, thermostat o-ring to seal port lubed in dow111, guide bushing for oring to seat properly (white thing), hand pump, Dow111 thick silicone.
Hand pump goes to 25inches max. All stems lubed up, added more oil on valve stem/guide end junction at spring side during testing, no change in results, therefore guides not leaking for the purpose of this test.

Test Try to prove in setup:
No spring, DOW111 under Valve lip and seat: 20.5 inHg. (Second Image)
No spring, cleaned valve seat interface: 15 inHg if lucky.

REAL Test:
Spring On, clean valve seat interface: ~17-18 inHg (EDITED). That's what the local guy I took it to said as well, for the same cylinder. The vacuum is hard to keep constant at that leakage rate so I take the near max vacuum reading as it jumps up.

Does this sit well with you guys? Please let me know, next I'll try the liquid test.

EDITED: I have added a T connection with a one way valve to a shopvac to assist in vacuum in parallel to the hand held vac pump. Reading 19 inHg and possibly 20.

Phil

http://forums.pelicanparts.com/uploa...1594434038.jpg[img]

I use a very similar arrangement with a brake bleeder, only I use a closed cell foam pad with a center attachment for the brake bleeder hose. Hold against the hole then pump bleeder. Does the job just fine.

this:
https://goodson.com/products/dvc-plates?variant=29264024390

Ivporschepilot,
That looks a lot simpler and would work for the intake as well.

An update:
I've improved the setup by inserting a T splitter and a one way valve attached to my shop vac in parallel with the hand held pump, this gave 5 inHg on it's own. Then I used them together, the result was less choppy (hand pump) and looks like ~19 and possibly ~20 inHg, the hand pump is not the best and has it's limits.

Phil

Hello, I've just done the liquid test results as requested before moving on to the next test.

Summary so far:
All exhaust valve/seat contact areas show bubbling and leak light.
Exhaust valve/seat holds ~19 inHg, but the quality of the handheld pump is questionable, so +/- 1 inHg, say.

Liquid test Results: Springs on, contact area clean, spark plug in.
Exhaust Port: Pooling of liquid, ~15min. Image Included.
Intake Port: No liquid ~1/2 hour so far.

What to make of this so far? I'm off to do the Prussian blue test as requested.

Phil

http://forums.pelicanparts.com/uploa...1594486449.jpg

Hi, next test done, prussion blue.
Did as recommended, added blue to seat, dropped in valve and rotated several times around. First 5 images show that result.

Then, cleaned off seat, placed valve back in the head and rotated a few times. Last two images of seat. The light test that help start this thread in that spot there is little/no blue, it requires very minute amounts of prussion blue for that test, but it shows up as no contact. Not shown in image but can provide, it's a test with faint marks and I use a jewler's mag glass.

Does the contact area look ok? To my eyes it looks good, at least where the overall contact position is, but I really don't know for sure, should I repeat without rotating the valve as much, say 1/4 turn?

Phil

http://forums.pelicanparts.com/uploa...1594492722.jpg
http://forums.pelicanparts.com/uploa...1594492722.jpg
http://forums.pelicanparts.com/uploa...1594492722.jpg
http://forums.pelicanparts.com/uploa...1594492722.jpg
http://forums.pelicanparts.com/uploa...1594492722.jpg
http://forums.pelicanparts.com/uploa...1594492722.jpg
http://forums.pelicanparts.com/uploa...1594492722.jpg

Final operation for the day.
Light lapping with the permatex. I don't think there is any chance this will lap out.

A .001inch feeler gauge can be slid into 1/4 of the circumference for the worst exhaust valve/seat (which is the one I've been working on) without even needing to lift the valve. If I press the valve down a little, then it won't enter freely. Always the same area as the light shining through of course and no springs on.

Summary:
Light bleeds through all exhaust six valve/seats with springs on, intakes do not. (Image in first post)
Liquid in chamber bubbles when port fed with shopvac pressure for all six exhaust valve/seats, intakes do not bubble. (Image in first post)
Exhaust valve that was tested showed around 19 inHg vacuum. (Setup image shown)
Exhaust valve that was tested doesn't hold rubbing alcohol as shown in image, takes about 15 min to puddle. Springs on. (Image shown)
Prussian blue shows the exhaust valve/seat contact, but when applied sparingly not in area of gap. (Images shown)
Exhaust valve that was tested accepts a 0.001 inch feeler gauge (cut to a point) between seat and valve for about 1/4 of the circumference without the springs on, but only if you don't push the valve down by hand.
Light lapping has no beneficial or other effect so far.

That's all the info and tests recommended I believe.

Do I lap more? Send it to be re-worked? Put it in as is? What sort of issue would it run into putting them in as is?

Phil

Why are you wasting your time on this? Get the exhaust valve seats cut correctly and then put it together.

Sorry ahh911 but those valves are way off. Something went wrong during the seat cutting.

If I were you, I'd send them to Neil /PD as he has bent over backwards to help here.

I just finished a DIY valve job on my 912 heads for fun and achieved very good results. I know because I devised a bench leak down tester and got 0-1% leak down on the combustion chambers.

Don't even bother with lapping compound, it will make this leak even worse when it gets up to operating temperature.

PM me if you want more DIY techniques, but I'd suggest you send them to a pro.

This really pains me that shops get away this stuff.
Tom

I may very well seek Neil's kind offer of help.

By the way, the last thing I did tonight was test vacuum with the springs on, I get vacuum of 19 inHg as stated earlier. By just adding thick silicone paste around the valve seat to help block any air leakage a vacuum of 26 inHg is achieved. As I added the thick silicone to the area where the light shone through increased the result to 23, but it needed the silicone paste all around the valve perimeter to achieve the 26 inHg. 26 inHg is the maximum the hand pump can achieve on it's own, therefore, in my mind the vacuum test setup is solid and the 19 inHg result is valid. For whatever that means.

Phil

I'm with Eagledriver , why are you wasting time ? Send them back or to Neil .

Sage advises.......
 

Phil,

Nobody could stop you from what you are doing. You could do whatever you want and be satisfied. It is your engine but you are going against common wisdom. Those exhaust valves are leaking and need work. What are you thinking? Anyone in his right mind would realize the condition of these valves are unacceptable. Find someone who could fix those valves correctly.

Tony

Ha, yeah for sure a proper re-exam and re-work would help considerably, especially the experience I am lacking. I have to be careful of the churn though, I need to be sure that transporting six heads across north america and borders is justified in time, risk and cost. Shipping is the risk and time factor (things sit here at UPS for weeks lately in the local depot, another time two months ago I had stuff sit at the border for many weeks and a member can attest to that (rockers), I've also had terrific shipping, but at a cost, another member can attest to that (Cams) , all great work by the way guys.) Also, these heads themselves were dropped I presume on re-delivery to our house, broken fin+damaged fins, though the repacking was not up to my standard. So there is risk in this that I'd like to balance out with potential reward. This is a 81 small port sc, and I can always dissasemble very quickly later in time at little expense to fix things up, I just don't want things grossly wrong or valves head breaking off or valve stem guides wearing down to the point where all hell breaks loose.

I don't mind spending a few days exploring, if you don't mind as everyday I learn something new.
For instance, this morning when the springs were compressed to remove the valve spring retainer clips, the vacuum goes up again to 22 inHg, so it's moving in the right direction when there is pressure applied in the combustion chamber.

One more test I think I'll try, that is leakdown of the head. Plexi, 1/4 inch glued to 1/4 inch thick and mounted to the cylinder head with a gasket cut to the right diameter, or an o-ring of the right size. Clamp them down (just as I did for the port as shown in the earlier images) then go to a shop and have them do a leak down test through the spark plug hole as usual. I think at 100psi, it may be anyone's guess, but since the intakes are very tight, I'm thinking around a percent or two may leak through the exhausts, maybe I'm wrong, that's for sure, but we've come this far. But really, I didn't want to have to do all this, remember I sent these to a Porsche centric machine shop that does work for air cooled race teams here in Canada, so I did commit to what I thought was the correct shop, so now before sending them through our highly delayed and drop prone delivery systems, I'd prefer to see this to a best at home decision based on a battery of tests, the final test being a leak down test of the head. This may take a day to setup, hopefully the plexi doesn't explode! Trust me, I wanted to send them out...

Phil

Update:
Didn't bother with leak down test.

Instead, lapped with 320 Grit Wheeler lapping compound for a couple of minutes (light oil of very minute quantity dapped onto grit on face), light seepage is all but gone (without springs) so I tried the vacuum test, now it pulls to 26 inHG (without springs, the max the handpump can achieve), the handheld vacuum dial is nice and smooth, it no longer jumps around and the needle returns to zero nice and slowly, around 35 seconds (with cleaned valve/seat). A very big change from before where the needle might make it to 19inHg and jump around as you pump and drop very rapidly after you stopped pumping. No spring for any of these latest tests, also, I rotated the valve around and tried a new non-lapped valve as well, same results, 26inHG and good vacuum. I don' t know if it's the rougher surface (EDIT: surface chatter from minimal machine cut was lapped out, you could see the light and dark banding with a very light lapping in areas of light penetration, after some lapping the vertical banding on the seat would diminish, light would not pass through and vacuum jumped and would hold) but obviously it holds vacuum really well and the contact area between valve and seat hasn't noticeably changed and it still sits nicely for road car performance (I hope because that's what I'd asked for, I wanted it similar in performance to when it left the factory) as the pictures above indicate. Also, the valve stem tip to valve spring seat distance are all at nominal (measuring with new uncut valves), so one more seat cut available (that's what I was hoping for as well, but a little more could have been taken off). This was all for the worst head, I'll try the others.

Thank you for your help, it looks like these are fine and I'm going to use them and see how they perform.

Phil

Sounds like you are finding a way. Just make sure that they don’t leak. Intake valves are more forgiving because they are cooled by the intake air and fuel.

-Andy

Lapping valves to seat them isn't advisable. When the valve face and vave seat are lapped at ambient temps, an abrasive slurry between the two helps form a conforming sealing pattern on each part. If the lapped pattern remains constant, the seal will be good.

However, as the engine comes up to operating temperature, engine parts expand. In the case of the aforementioned valve face and valve seat, the sealing ring area migrates as the valve expands from heat.

When both valve face and valve seat angles are identical or if cut with an interference angle, the valve can expand all it wants. The contact area merely shifts due to heat expansion.

Sherwood

Sherwood,
I'm not sure I follow. The seat/valve were cut to within .001 inches both with 45degrees. An additional .001 inch was removed from the face and valve simultaneously. The seal became fluid/vacuum tight when I inserted brand new untouched valves (non-lapped), given the 45 degree angles haven't been disturbed, the valve simply rides up or down the 45 degree seat slope as it heat and cools. So in summary: basic cut was close, a little more was pruned off, brand new valves are inserted in the lapped heads and it seals, so no special seal formed between a particular valve and seat, therefore a generic seal. I expect this to work well. Perhaps you are thinking that .01 inch or greater has been lapped in, I don't know what to expect then, but in this case 320 Grit is used for several minutes, it's really not removing much and shows the precision needed for a really good job, which is in my opinion not what I received, unfortunately.

Phil

Understood. Before there were valve grinding machine tools, valve seating was accomplished by lapping the valve face>valve seat surface. Perfectly adequate for the level of engine performance in thos vintage times. Even when valve facing machines were in use, there were old school mechanics that did it by lapping. Even today, many techs still rely on some level of lapping to ensure a tight seal. Things is, if overdone, the lapping process can create a lapping rut that causes the valve face and seat to be uneven (I.e. no longer a flat, machined surface).

Will the customer know the difference? Probably not, maybe a loss of compression 50k miles down the road. More demanding engine performance goals might result in some premature power loss or power not realized due to some level of combustion chamber leakage.

Can someone quantify the power difference between a leak down difference of 2% vs 4%?

Sherwood

Yup. We tried the gapless rings on a few race engines. Leakdown was zero. So was the difference on the dyno. As in ZERO difference in hp or torque. As long as the valves and rings somewhat seal, there's very little if any difference in power output.

Way back when, when I started racing, before Serdi and Rottler machines, the final test before checking on the flow bench was to put on the VERY lightweight flow bench valve springs and fill the ports up with solvent at the solvent tank. Flush any leftover grinding dust out and see how well they hold. If the solvent held tight on the chamber side, it was off to the flow bench before final cleaning and assembly.

I do my own heads ... I just hold the valve in with finger pressure from the chamber side, hold the head with the appropriate port pointed up, and fill the port with water. If nothing shows at the valve edge after 15 - 20 seconds, I call it good. The valves are stainless - they won't rust...

Valves on cylinders that had 2-3% leakdown (measured while the engine was still assembled) have shown slight weeping with this quick check, so I feel it is sufficient.