Projects Mild custom '51 Pontiac Chieftain

Yeah, the KC put on a nice little show with a pork roast and stuff. Just little, local- nothing like the one in Gonzales but it was a really pleasant day out.

Phil

 

I had tried forcibly putting some solvent on the valves from the top and from the bottom but they're just to the point where they need to come out, be cleaned and polished and that should sort it out.

Gearbox is actually doing better as it's driven.

Phil

 

Not much this week, but the replacement 6v converter arrived so it got wired in.



Powered it up and instead of clouds of stinky smoke, I was rewarded with a gauge moving to full (normal behavior).



Touched the gauge wire to ground and it dropped to E so it's all good. Going to put it all back in tomorrow hopefully.

Phil

 

Dash all back in, working properly.


Started on a little wiring, now have 2 parking lights and turn signals.
Headlight wiring needs running, need to loom that up and then rewire the headlight connector.

Phil

 

Great job you are doing. Thumbs up.

 

Let there be light.

Phil

 

Valve spring compressor is on its way doc, said it will be to you Thursday

 

Thank you sir. I have a list of things to do on the car. Right now it's been 5 minutes here and there.


All loomed up nice and tidy. Yup, that's 10ga wire for the headlights. I'm a firm believer in as few ohms between the battery and the bulb as possible.
It makes the old Fed-spec bulbs actually passable- even better when the generator is putting out.

High beam works on both at the same time too, which is better than one on high and one on dim as it was when I got the car. Also, before the rewire and switch cleaning the light output was positively orange. Now it's bright yellow-white as it should be.


Phil

 

Been busy. Have sorted this space out now to be enclosed. Makes a nice little workshop now.

Progress soon on the car, I promise.

Phil

 

Had to modify the tool slightly but it holds nicely now.


Damn valve took 40 minutes to coerce out of the guide.


Checked and the valve is straight.


Cleaned the guide


All grubby but yuk. Valve now falls down happily under its own weight. Going to lap the seat in now.

Phil

 

Looking good brother, take a long bolt that'll reach through the guide loosely and cut a slice in the end of it so you can put a small piece of 320 or so sandpaper in it and turn it by hand.

 

Didn't even need that! Just a bit of carb cleaner on a twisted up piece of cloth.


Lapping in valves. Not the easiest position ever...

Phil

 

Lmao!! Tie a rope to your leg for a tag line, or suspend yourself from an engine hoist

 

Whoever built this engine didn't bother to lap the valves in.


This one was sealing around perhaps 1/8 of it's circumference- one cylinder would "wheeze", I'm guessing this was it.

Plus, shiny valve? That's worth a few horsepower, surely.

Phil

 

Have just finished reading thru from the 1st post, a most enjoyable read, as others have said you are a persistent buggar...........lol..........trust the latest escapade fixes the valves..........regards from Oz...........andyd

 

I'm betting Phil is a surgeon at his day job, therefore i give him the new nickname... "Doc"

 

Haha, no. But my job does involve methodical troubleshooting and patience, so I guess that's rather where that skill set comes into play with the car.

I figured that I should be able to chip away at this until it's good again. I'm trying to. This is just a regular maintenance item though. The manual states that if you have to pull the head then a valve job should be considered.
Well, I ignored that and look what happened. So, valve job now and that should see it right for a little while at least.

Phil

 

I just picked up this ol 54 starchief cleaned the carb put some fluids in her and was driving her down the road in less than 24 hours and that straight 8 ran smooth.. no I need to either replace or upgrade the brake master cylinder car came with new pads and hardware and lines..I have a few wires not hooked up on one side of the fuse box on the fire wall and needs some body work but shes going to be good

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Pretty neat...all these Pontiacs that are showing up lately.

 

The weather changed for the cooler- yesterday I ran out of time after work, today is probably going to be the same but I bought another suction-cup valve tool.

Nowhere locally sells the little suction cups that fit to a twist drill- a few of the valves don't seal well at all and require a fairly heavy lap. They're not bent, they just aren't very even.
I felt like I was dying of old age doing it by hand so I'm going to cheat to get the baseline grind done with my drill on the worst ones and finish up by hand. So, I think I'm going to modify this tool to fit my drill. Yes, I know it's not the proper way of doing it but I've done enough that I know not to go all gung-ho...

--Phil

 

Dad taught us how to use this a long time ago, saves the old feeling! Are they even made today?

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I have no idea but that's what I'm going for, just using my electric drill. It is fully speed adjustable on the trigger so I can go as slow as I need to, back and forth.

The action of lapping valves did rather vanish as manufacturer specs changed- I do see nowadays that manuals state not to lap-grind valves, but instead the seats need to be correctly 3-angle cut and the heads of the poppets machined to match.

Did GM even use a 3-angle cut valve seat back in the 50's? If so, it is long gone on my engine because the seats have been lapped in the past, I can see the score marks.
I'm just going to have to hope for the best- a single angle lap grind will be better than the thing not sealing at all.

--Phil

 

Phil, the blocks were originally cast accurately enough that one 30 or 45 degree machining operation was all it took for the seat to be done. Some manufacturers were more accurate than others, with GM being among the better of them.

 

IIIRC you do not want the valve face too wide, may burn the valve.

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The seat is still narrow, it also appears to be quite a lot harder than the valve seat looking at the way the grinding paste is working. The valves aren't original, they have been replaced with new ones when the engine was taken apart (fairly recently in terms of miles) by the previous keeper.

It seems as though they just threw them in and assumed the fresh machined faces of the valves would match the seats perfectly...

--Phil

 

Seems that even if they had done it you would still be here cleaning the guides, now you'll have it running better than they thought possible!

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That's the plan! I desire unprecedented smoothness and quality of running. I know it can do it, after all, if it didn't Pontiac would have ditched the L8 years before and moved on to something new, instead it was worth milking a few extra years out of the design...

Someone elsewhere was telling me I should be uprating the valve springs while I'm taking it all apart. I don't see why, if the valves start to float at 3750RPM then I'll just tolerate that as inbuilt engine speed limiting.

--Phil

 

So, I bought a new valve sucker cup stick tool.


Stripped it down and adapted it to my drill.


Spun it round a bit and didn't really see an improvement in the way it was sealing.


Saw the lip it was creating in the valve. Nah, that ain't right.


Nope.. Sure as hell ain't right. The stem is straight but the head of the valve is bent. You can see it visibly in that animation, even without the dial gauge. Granted, the stem has about 0.08 runout because the chuck doesn't hold it 100% central, but eesh.

New valve time. I'm going to pull the rest out and check them and order replacements as necessary.

Phil

 

Awwww man that sucks... but you know it'll be good when you're done

 

If I was there to help, I'd take those 16 valves down to the machine shop along with the springs. I'd reface the valves & test the spring pressure on the old Rimac tester, throw a straight edge on top of the springs to see if they're close to being equal in height, and buy enough V.S.I. shims to bring them up to the required pressure. Pressure can be tested at home using bathroom scales - will someone please help pull up the procedure for us ?