1974 K10 Dirty Sancho

[mrk5]

I got around 13 at 800 rpms. Runs a lot better with the adapter plate on and new plugs. When I blip the throttle from idle it pops out of the carb. It was a little too late to keep messing with it so I’ll play with it more later.

Where's initial timing set?

easy there, no clanking on this one (yet at least).

It happened to me and there was no noise. It was our 71 cuda, and I was driving on the interstate when smoke started pouring out the back. Pulled over and oil was dripping profusely from the rear of the block and hitting the exhaust. I replaced the rear main and it still leaked. That's when I was informed it was probably the main bearing wiped out and submitting the rear seal to full oil pressure. I also had really low oil pressure.

Just thought I'd throw that story out there in case you weren't worried enough about your engine.....

 

[Babaganoosh]

I was watching a episode of roadkill last night and they mentioned their intake manifold didn't match the carb so they used a adapter as well.


If roadkill did it you will be fine.

 

[HankScorpio]

If roadkill did it you will be fine.

Only if you take the hood off.

 

[skunked]

Where's initial timing set?

it looked like it was around 14 but the distributor vacuum was still hooked up and I was more focused on the carb idle setting and I was messing with the idle mixture screws once it warmed up.

It happened to me and there was no noise. It was our 71 cuda, and I was driving on the interstate when smoke started pouring out the back. Pulled over and oil was dripping profusely from the rear of the block and hitting the exhaust. I replaced the rear main and it still leaked. That's when I was informed it was probably the main bearing wiped out and submitting the rear seal to full oil pressure. I also had really low oil pressure.
Just thought I'd throw that story out there in case you weren't worried enough about your engine.....

I've heard of that and it's always a possibility but I'll bet the seal is smoked based on the fact this truck has sat for so many years and appears to be bone stock. Oddly enough it didn't leak very much last night, I had maybe a 3-4" stain on the piece of cardboard under the truck when I looked this morning.

I was watching a episode of roadkill last night and they mentioned their intake manifold didn't match the carb so they used a adapter as well.
If roadkill did it you will be fine.

good, I'm not alone on this one

Only if you take the hood off.

don't threaten me with a good time

 

[imiceman44]

it looked like it was around 14 but the distributor vacuum was still hooked up and I was more focused on the carb idle setting and I was messing with the idle mixture screws once it warmed up.



I've heard of that and it's always a possibility but I'll bet the seal is smoked based on the fact this truck has sat for so many years and appears to be bone stock. Oddly enough it didn't leak very much last night, I had maybe a 3-4" stain on the piece of cardboard under the truck when I looked this morning.



good, I'm not alone on this one




don't threaten me with a good time

Only a 3-4" stain?
Check your oil level, you might be low.

 

[skunked]

Only a 3-4" stain?
Check your oil level, you might be low.

yep and oil level is good. However I should probably change the oil again since I'm sure it's contaminated with gas.

 

[82355]

It does not matter that your Quadrajet was an 850 cfm.

GM used Quadrajets on 4.3 V6’s.

Like any carb, it would just need to be tuned for the application.

Martin

 

[Bent77]

I’m with Martin, use the Q



how are your crank vents? Getting blow by?

 

[skunked]

The oil ended up having a lot of fuel in it so I changed the oil and put a new filter on it. Of course the damn oil filter was stuck on the block so I ended up cutting it off and using the air chisel to break the base of the filter loose. That was fun....

It’s still running rich although it starts and idles fine. When I drive it under load it sputters and coughs when I give it any kind of pedal. Plugs are black again.

@Bent77 it has some blow by. I only have a PCV valve on one cover but I pulled it off and felt some air puffing out.

 

[Bent77]

The oil ended up having a lot of fuel in it so I changed the oil and put a new filter on it. Of course the damn oil filter was stuck on the block so I ended up cutting it off and using the air chisel to break the base of the filter loose. That was fun....

It’s still running rich although it starts and idles fine. When I drive it under load it sputters and coughs when I give it any kind of pedal. Plugs are black again.

I’m with Martin, use the Q



how are your crank vents? Getting blow by?

 

[skunked]

I edited my post above answering your question. The Q-jet is on the bench although I don’t know shit about tuning those either.

 

[Bent77]

So here's my dilemma:

At 13" hg, you either have a vacuum leak or a major timing malfunction. (could be bad rings, but I doubt it)

1) Is the timing mark verified as correct?
2) Where is the vacuum leak if not timing? My old engine with 160k on the clock would pull 15" on an after market cam. You are 2-5" short on vacuum

 

[skunked]

I don’t recall if I confirmed the TDC mark on the dampener but it’s easy enough to check. I can also take a can of carb spray in effort to track down any vacuum leaks.

 

[Bent77]

Probably the best use of time before you cuss at the carb some more

If you go Q, I should be able to help you out

 

[6872xtc]

I have ignored the timing marks more than once in my life and just cranked the timing up to see what happens. Maybe the timing is late and it is rich?
I always judged the base timing by how it started when hot, and if it would ping at any time, as long as it wasn't a lean condition causing it.
And hopefully it doesn't have a balancer and timing tab mismatch. I have found that before, and it wasn't because of a slipped outer ring.

 

[skunked]

It starts really easy when it’s cold, hot it took a little more cranking and a little pedal. The base timing is set to 11 based on the timing tab.

 

[6872xtc]

It starts really easy when it’s cold, hot it took a little more cranking and a little pedal. The base timing is set to 11 based on the timing tab.

That doesn't sound too bad, maybe the slow starting when hot is partially due to being too rich.
Do you have the vacuum advance hooked to timed vacuum or manifold vacuum? As in, what do you have for initial timing with the advance hooked up? Or does it bring the timing in fast enough with the advance to keep it from stumbling?
I would still advance it and see what happens. Just to experiment.

 

[mrk5]

The vacuum advance should be hooked to manifold vacuum.

In my experience the part throttle stumble is a lean stumble, but all your indications are that it's running rich. Was this a new carb? I wondering if something in the carb could be leaking fuel into the engine.

 

[skunked]

That doesn't sound too bad, maybe the slow starting when hot is partially due to being too rich.
Do you have the vacuum advance hooked to timed vacuum or manifold vacuum? As in, what do you have for initial timing with the advance hooked up? Or does it bring the timing in fast enough with the advance to keep it from stumbling?
I would still advance it and see what happens. Just to experiment.

I have it hooked to the timed vacuum source on the carb and that's another subject I've found that's heavily argued. Left port in the highlighted pic below. Confirming TDC and giving it more timing seems like a good move......

 

[skunked]

The vacuum advance should be hooked to manifold vacuum.

In my experience the part throttle stumble is a lean stumble, but all your indications are that it's running rich. Was this a new carb? I wondering if something in the carb could be leaking fuel into the engine.

Manifold vacuum you say? I hear it both ways.....

Carb was bought used.

I think it's running rich enough that it's been dumping fuel past the rings. The last year or more I just fire it up to move it, then repeat over and over. My second theory is a bad fuel pump, if the diaphragm is tore it will leak into the engine. The pump was installed new by me a year or two ago when I did the manifold and carb swap. I need to get it running right and then I'll see if the oil/gas situation still exists. The rear main stopped leaking btw, the gas in the oil apparently made it leak.