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]

Originally Posted by 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.

..................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.

[05snopro440]

Originally Posted by soltz

Thats a well used dist.

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.