1946 gmc

[MercuryMac]

Congratulations on your wedding.

I'm glad you showed your finished hotrod to us. I wish more people would do that sometimes. It's not that I don't remember your truck, it's just that I like my memory refreshed occasionally. Good show.

 

[05snopro440]

Finished?!? What's that?

Thanks Mac, I'm trying to post more photos. I agree, once something is done we don't see that many photos here.

 

[earthman]

Congratulations on your wedding.

I'm glad you showed your finished hotrod to us. I wish more people would do that sometimes. It's not that I don't remember your truck, it's just that I like my memory refreshed occasionally. Good show.

..................X2

 

[lowbudget50]

Truck still looks good man!!!! Keep up the cruisin!! Congrats on the wedding!

 

[05snopro440]

I've been fighting an issue that I thought was related to limitations of my knowledge of carburetors. When I go to full throttle the truck stumbles for several seconds before it picks up and goes.

A friend and I tried to change a bunch on the carburetor but it didn't help. We narrowed it down to thinking it might be timing.

Curious, I took off the cap and rotor to see if the weights were moving freely. As you can see in the photos, my weights and the pins that hold them are heavily worn. This allows them to move all over before the springs even move, which can't be helping matters. Unable to find a new shaft, I ordered a reman distributor from Rock Auto it will be here next week. Hopefully this and resetting the timing will cure my issue.

 

[soltz]

Thats a well used dist. [cl

 

[05snopro440]

Thats a well used dist. [cl

It clearly doesn't owe me anything at this point!

I really hope the new distributor is the simple solution.

 

[05snopro440]

I'm at work but my distributor and ignition parts showed up at home this afternoon! I really hope this solves my issue and I'm not chasing something else as well.

 

[kenny c]

It needs to be changed before you go any further. It is slap worn out.

 

[05snopro440]

The distributor was far from a simple change and didn't solve the problem but it runs better. I've tried different carburetors, power valves, jets, squirters, did a full tune up, still doing it.

Last weekend, I set out to change the intake gaskets. Still trying to troubleshoot my full throttle stumble, I did a compression test first. All were good except #4, nothing. So I oiled the cylinder and tried again. First try I got about 25, eventually got 50. Increased compression with oil usually means rings. It wasn't running like it had bad rings though.

So I pressurized the cylinder and air was flowing out of the exhaust.

When I pulled the head off, I found that the exhaust valve on #4 was carboned up and stuck open.

This Saturday my dad brought over his valve spring compressor
and we pulled the exhaust valve out. Didn't burn the valve or the head, but you can see the valve wasn't properly sealing and eventually got carbon in it and then really wasn't sealing. The engine I got these heads off of had about 50km on them and were rebuilt but by a high school shop class.

So I'll get the valves redone and I hope this ends my saga of searching for this full throttle stumble/surge. Luckily the cam, pistons, and cylinders look really good.

 

[soltz]

Problem solved [S
?[P?

 

[05snopro440]

Gosh I hope so. This has been irritating to find. I've had my vacuum gauge taped to my windshield since September since I was doing laps around the subdivision trying to see if I solved the issue with each change.

 

[soltz]

Hope so

 

[lowbudget50]

Damn, I hate problems like that. So frustrating!! You get it!

 

[05snopro440]

Thanks guys! If this doesn't work, I'm running out of ideas.

 

[05snopro440]

Well I have two sets of heads, I spoke to the machine shop and I think I'm going to send them both and get them both redone. This is the second time I've had the heads off of this thing, in the unlikely event it happens again I want to be able to put something back on quickly. And if I have a spare set in the shelf it will probably live forever.

I hoped to drop them off yesterday but spent a bunch of time fighting with the drivers side head so it will have to wait till next Saturday. The machine shop comes highly recommended so I'm not anticipating further issues. The second set of heads I have are 68CC chambers while the originals are 76CC for this engine, I might as well try to use them to gain some compression and horsepower in the process.

 

[soltz]

Good luck, will be watching [P

 

[05snopro440]

The machine shop called today. The small chamber heads are cracked . So the plan is to do up the large chamber heads and if I want more power in the future I can come up with a new plan. Oh well

Hopefully get the heads back in a couple weeks!

 

[lowbudget50]

Well at least you have a set!!!

 

[Old Iron]

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