Datsun Roadster Forum-311s.org

A elect. Drill with a 8mm stud and tough gasline with clamp. To grab the stem makes it easier than the suction cup tool
I would narrow the seats more if you havent

Put the valve springs on and a S plug then with a narrow tip blow nozzel see what extent you get bubbles thru washer fluid with the comb chamber turned up ..any over 8th in I would work with it more

redroadster wrote: ↑Fri Feb 21, 2020 6:13 pm A elect. Drill with a 8mm stud and tough gasline with clamp. To grab the stem makes it easier than the suction cup tool
I would narrow the seats more if you havent

Put the valve springs on and a S plug then with a narrow tip blow nozzel see what extent you get bubbles thru washer fluid with the comb chamber turned up ..any over 8th in I would work with it more

Red, I see that this could be a valid test of valve seal, I have also heard of pouring solvent in the combustion chamber and watching for penetration, but what is an S plug, and don't you need a timing component to the measurement of accumulation of air? and how do you measure the air? Doesn't it bubble up through the washer fluid and is gone? Please explain.

S ...spark plug. just to seal the hole .ypu need the head upside down , wedge something to make it level , with the valves assembled, I used winter washer fluid , but another fluid will work , then with a compressed air pointed blower nozzel inside the valve ports give a blip of the air .
I did many a 4G63/ 6G72T head valve job and others , I started checking this way after finding a valve that leaked still after all done. You can tell the leakage before assy. Some valves you can't blow but foam thru others 1/2in bubbles just a tiny release of blown air .I used to call back the machine shop wanting a better fit if it had near 3/16th in bubbles. and they would fix / improve ( this after I opened valve and blew and wiped to get any grit out. sometimes lapping )
Don Garlits won many races with tighter sealing valves and he changed heads nearly every race ...for clean valves / ports

Here is a you tube vid on a 4g63 head

redroadster wrote: ↑Sat Feb 22, 2020 10:31 am S ...spark plug. just to seal the hole .ypu need the head upside down , wedge something to make it level , with the valves assembled, I used winter washer fluid , but another fluid will work , then with a compressed air pointed blower nozzel inside the valve ports give a blip of the air .
I did many a 4G63/ 6G72T head valve job and others , I started checking this way after finding a valve that leaked still after all done. You can tell the leakage before assy. Some valves you can't blow but foam thru others 1/2in bubbles just a tiny release of blown air .I used to call back the machine shop wanting a better fit if it had near 3/16th in bubbles. and they would fix / improve ( this after I opened valve and blew and wiped to get any grit out. sometimes lapping )
Don Garlits won many races with tighter sealing valves and he changed heads nearly every race ...for clean valves / ports

So 3/16 in. and 1/2 in. are not depths but are size of bubbles?

Thanks for all the info, great video, unfortunately I don't have all the precision tools to go to that level, but confident I did a good job building the head and valve assembly. I will run the fluid test and look for bubbles before I install it, it's actually a great idea. I do believe I have hardened seats, the PO said it was rebuilt, and the coloring looks like steel seats.

C.Costine wrote: ↑Sat Feb 22, 2020 11:26 am

redroadster wrote: ↑Sat Feb 22, 2020 10:31 am S ...spark plug. just to seal the hole .ypu need the head upside down , wedge something to make it level , with the valves assembled, I used winter washer fluid , but another fluid will work , then with a compressed air pointed blower nozzel inside the valve ports give a blip of the air .
I did many a 4G63/ 6G72T head valve job and others , I started checking this way after finding a valve that leaked still after all done. You can tell the leakage before assy. Some valves you can't blow but foam thru others 1/2in bubbles just a tiny release of blown air .I used to call back the machine shop wanting a better fit if it had near 3/16th in bubbles. and they would fix / improve ( this after I opened valve and blew and wiped to get any grit out. sometimes lapping )
Don Garlits won many races with tighter sealing valves and he changed heads nearly every race ...for clean valves / ports

So 3/16 in. and 1/2 in. are not depths but are size of bubbles?

Yes ...be 1in size, if you could get the pressure to 120 going thru the valve
..think what size the bubble or air leak will be at combustion
back into the intake port... not good and is a unbalanced engine.
Looking at the pics he has the intake seats are not ground right as they are not narrowed IMO. exhaust look pretty good .
..on the cutter in the vid he has it has a valve seat narrower. cutter built into it. It cuts 3 angles he talks of
A wide contact area on the valve seating is not good

.

Not a bad time to paint the engine bay while some of the larger PITA items are out of the way...

I actually did over the weekend, not happy with it. I'll most likely do it again.

bossbob wrote: ↑Mon Feb 24, 2020 10:57 pm I actually did over the weekend, not happy with it. I'll most likely do it again.

I've really learned that it is more about the cleaning and prepping than the actual painting.
Some quick tips that have helped me:
- Clean all junk off
- Degrease & wipe down with alcohol (or something similar to remove oils, residue, solutions, etc)
- Sand to desired level starting no less than 250grit. (I say "desired" bc most will say to sand down to the base coat/primer but not to the metal bc then you will have to use primer again - but I actually preferred to sand to the metal to remove surface rust and get a very smooth surface - sure more work but looks a lot better)
- After sanding completed you will need to wipe it down again with alcohol wipes
- When painting go very light for the 1st coat and then slightly heavier on each.
- Use a heat gun after you spray each coat (this extremely helps speed up the drying time - just make sure to not overheat the paint and cause it to bubble. keep the heat gun moving and not too close to paint)
- Clear coat (I found that gloss finish looks amazing but really hard to maintain. For engine bay I recommend going with either a matte or semi-matte finish)
- And finally I feel this is extremely important: Do not touch the paint for 4 days. Just put a tarp/plastic wrap over the engine bay and leave it.

Hopefully this helps

I bought my roadster in 1999. At that time the paint had a number of problem areas, but in between those it looked good. 15 years later a lot of the "good" areas had a lot of 1/16 inch bubbles. Sanding it down revealed rust spots on the metal under three coats of paint. As Mack said, sand to bare metal.

Well it's back together now, but not getting fuel. I replaced the fuel pump diaphragm last year. I remember it would take forever to get fuel back up to the filter if it had gone dry. Oil pan smells like fuel, lucky me. I'm really thinking about going with an electric pump. But then I think about an inertia switch, hard wire to the ignition, toggle switch? I don't know. Or just replace it again?

Any thoughts are appreciated.

This is what it looks like after my home garage valve job, It's not perfect, but looks a lot better. Compression is reading 125 psi across all 4 cylinders, I'm sure that will come up as the rings get a little oil on them.

bossbob wrote: ↑Wed Apr 01, 2020 8:21 pm Well it's back together now, but not getting fuel. I replaced the fuel pump diaphragm last year. I remember it would take forever to get fuel back up to the filter if it had gone dry. Oil pan smells like fuel, lucky me. I'm really thinking about going with an electric pump. But then I think about an inertia switch, hard wire to the ignition, toggle switch? I don't know. Or just replace it again?

Any thoughts are appreciated.

This is what it looks like after my home garage valve job, It's not perfect, but looks a lot better. Compression is reading 125 psi across all 4 cylinders, I'm sure that will come up as the rings get a little oil on them.

Engine 4.jpg

I have been using this electric pump for 3 years now. No failures. No inertia switch. Works great. You can see it mounted in front of the rear wheel on the frame in the pic. Your car is looking great underhood.

https://www.ebay.com/itm/New-Universal- ... 1282010018

Bob, for my first start I pressurized the gas tank a little. Just a couple quick shots with the air blower while holding a rag over the opening.