292 Questions

[May70]

Originally Posted by Steeveedee

Are you absolutely certain that the heat riser valve is open, hot? You can verify that by poking the counterweight with something, since it will be hot. I believe you replaced the exhaust manifold, so the heat riser valve is new? Didn't want to read through it all again, sorry.

Yes the whole exhaust manifold is new. The only thing not new on it is the carb auto choke spring assembly.

Just to be certain im thinking of the same thing, the heat riser is on the bottom side of the exhaust manifold and it has a plate inside that either opens to allow heat up to the bottom of the intake manifold or 'closes' directing heat away. Is this what you refer to as a valve?

If so the counterweight is not stuck, I can move it with the engine hot or cold I just have to oppose the little heat spring. However I have not seen it get hot enough to release the heat spring letting the weight fall down (closing the plate). I have only seen the weight up so it should be open.

[Steeveedee]

Did you check fuel pump flow? I didn't look back through for that, either. My dad had a car once that had a piece of balloon in the fuel pump suction line that would close it off when the flow was high enough. Took awhile to figure that one out.

[RichardJ]

"68gmsee" posted these two pictures years ago. I labeled them and I hope I didn't screw up. I've had tube headers on my truck for twenty years.

[Steeveedee]

Last straw to grasp. High vacuum like that could be from flat(ish) cam lobes because the valves aren't open for a long time. Maybe that's part of the lifter noise. This would be related to the cam going flat over the last few months, which you indicated that the performance got worse over time. What kind of measuring equipment do you have? Maybe take the valve cover off and measure the stroke of the push rods by cranking the engine by hand to see what the lift is for a few of them. Other than that, we've pretty much covered all the possibilities.

I have seen where cams with flat(ish) lobes really cut into a vehicle's performance.

Anyone out there know what the lift is for a stock cam in a 292? He'll need something to compare his lift against.

[VWNate1]

Fascinating read here .

Subscribed to find out the end cause .

[Steeveedee]

Originally Posted by VWNate1

Fascinating read here .

Subscribed to find out the end cause .

It's a stumper, for sure.

[VWNate1]

I've been an i6 engine lover since the early 1960's and I wish this one wasn't so far away .

I've been able to make clapped out InLine engines with 60# compression run very well .

This one clearly has some internal issues but, judging by the spark plugs it's running way too rich, apart from the oil wetted # 2 one .

There's a bit of art to tuning the InLine engine, I think perhaps he still has some sort of vacuum leak .

[May70]

Originally Posted by VWNate1

I've been an i6 engine lover since the early 1960's and I wish this one wasn't so far away .

I've been able to make clapped out InLine engines with 60# compression run very well .

This one clearly has some internal issues but, judging by the spark plugs it's running way too rich, apart from the oil wetted # 2 one .

There's a bit of art to tuning the InLine engine, I think perhaps he still has some sort of vacuum leak .

The inline 6's seem to be a pretty popular thing, yet a lot less references/videos on them (especially the 292). So many people throw a v8 in these trucks. Im not looking for performance, but I know you can get these 6's pretty crazy with deep pockets.

I do want aftermarket AC and power steering eventually. Ive seen a few pictures of some rigs with both, definitely not as clean as a v8 or as common. Haven't found a bracket kit for sale that looked legit, saw one on ebay that looked interesting. Ive also seen some videos of a guy who put a 5 speed on his 292 and it looked like a smooth ride. The 4 speed with a granny gear I have is cool but not too smooth for what I do and Ill never need a granny gear like this has. Those are really the only "things I am not sure about" with keeping the 292. Its obviously possible but im not too good with this stuff.

Thanks for joining in.

[May70]

Ok so going back to my post #174.... I did a few things but one issue I noted was after checking the mechanical advance by turning the shaft/rotor (engine off) the shaft did seem to spring back into place. However the timing was advanced more that what it was set to at idle when I started it back up afterwards. That should NOT happen correct? Me manipulating the mechanical advance to check it should not have changed the initial timing I set prior?

I can try doing that again to see if it changes the timing again. If so perhaps the distributor mechanicals are messed up or the springs are warn out (something like that)?

[geezer#99]

I had a points dizzy once that produced changing timing like that.
Found the points plate that the points and condenser are attached to could flex upwards which would change the dwell and timing.
Easy test is to lift upwards on the condenser. The points plate shouldn’t move upwards.
Mind you, this was back 40 years ago so my memory is a bit fuzzy!

[VWNate1]

Still laughing about the 'Obama gas' comment ~ just in case some didn't know you're a scared racist fool, you made sure .

[VWNate1]

Originally Posted by May70

The inline 6's seem to be a pretty popular thing, yet a lot less references/videos on them (especially the 292). So many people throw a v8 in these trucks. Im not looking for performance, but I know you can get these 6's pretty crazy with deep pockets.

I do want aftermarket AC and power steering eventually. Ive seen a few pictures of some rigs with both, definitely not as clean as a v8 or as common. Haven't found a bracket kit for sale that looked legit, saw one on ebay that looked interesting. Ive also seen some videos of a guy who put a 5 speed on his 292 and it looked like a smooth ride. The 4 speed with a granny gear I have is cool but not too smooth for what I do and Ill never need a granny gear like this has. Those are really the only "things I am not sure about" with keeping the 292. Its obviously possible but im not too good with this stuff.

Thanks for joining in.

You're welcome .

I'm a geezer who had GM factory training and was Dealer Mechanic when these were current production .

The order in which you do things is critical to avoid chasing your tail .

That it ran well once and began smoking tells me the engine per se is prolly just fine .

Not having deep pockets is a problem, join the club .

Not knowing what you're doing is less of a problem because many here are well learned and have experience working on and with these old rigs .

Each one degree of dwell change alters the ignition timing by 3 degrees, more than one degree is a _lot_ although most doesn't realize it as they simply stomp the throttle and make noise and smoke over revving the engine .

My last 292 would foul the spark plugs in 250 miles plus it was a 1976 GMC and so needed to pass smog testing, I peaked and tweaked it, had to go to a $45 junkyard HEI from a 1977 Nova and open the spark plugs up to .070" before it stopped fouling plugs, then it " flew through the test " (quote from my smog guy) even though it still burned oil and you'd smell the burned oil out the exhaust.....

[May70]

Originally Posted by geezer#99

I had a points dizzy once that produced changing timing like that.
Found the points plate that the points and condenser are attached to could flex upwards which would change the dwell and timing.
Easy test is to lift upwards on the condenser. The points plate shouldn’t move upwards.
Mind you, this was back 40 years ago so my memory is a bit fuzzy!

So I just went out and tried it. I could lift the plate straight up like a quarter inch. I made a crummy little video of a series of blabbling with what Ive done/whats going on so excuse the garbage quality I dont know how to do the youtube thing. Youll probably have to pause the video to read the text because for some reason it flips really fast. The first part of it shows me looking at dizzy.

https://youtu.be/Zf4fD4nMNiA

Lifting that plate changed my dwell because before it was 31 and afterwards it was 29. Tell me if this was what you meant.

I said in the video that my timing didnt change but now im confused because it should have changed more than what it did. It may have increased the timing 1 or 2 degrees. If every degree of dwell is three degrees of advance it should have been way higher. Keeping in mind the engine wasn't quiet warmed up all the way. Thoughts?

[geezer#99]

IIRC you shouldn’t be able to move the point plate much at all. But like I said it’s been many years since I had that problem.
Maybe someone else knows for sure.
Have you tried ignoring your tach and timing numbers and just advance your distributor to see how the motor runs.
Just loosen the dizzy enough that it will move with a bit of effort.
If the rpm increases be sure to control it with the idle screw.

Have you had the point plate out to inspect the weights and springs?

[May70]

Originally Posted by geezer#99

IIRC you shouldn’t be able to move the point plate much at all. But like I said it’s been many years since I had that problem.
Maybe someone else knows for sure.
Have you tried ignoring your tach and timing numbers and just advance your distributor to see how the motor runs.
Just loosen the dizzy enough that it will move with a bit of effort.
If the rpm increases be sure to control it with the idle screw.

Have you had the point plate out to inspect the weights and springs?

Ive adjusted it a few times just by hearing but I dont think ive put it much farther than 10-12. Yesterday when i messed with the distributor and it jacked the advance up to like 16* after it was almost sounding as if it were missing and the idle was super high. I can try it again though.

No I have not had the plate out.

[geezer#99]

Just plug the vac advance off when you test.

[VWNate1]

O.K., the deal is :

You set the points using the dwell meter then rev. the engine, the dwell *must*not* change more than a degree or two .

The breaker plate is allowed to move up and down a tiny bit and it's possible to not have it properly set in place .

Once you have the 31 ~ 33 degrees dwell, attach the vacuum gauge to the open manifold port on the leading outside edge of the carby, start the engine and allow it to idle 600 ~ 800RPM, slowly move the dizzy _NOT_ touching the vacuum can, watching the vacuum gauge ~ the needle will rise and eventually will begin to flicker like it did in one of your videos ~ what you want is the highest steady vacuum reading .

Once you have that, tighten the dizzy's pinch clamp (don't go crazy here, use a stubby box end wrench and DON'T FOOL WITH IT AGAIN .

Now, put a tight fitting cap over that vacuum port and connect the vacuum gauge to the dizzy's advance pie using a 'T' fitting, goose the throttle, the *instant* you open the throttle you *must* get a vacuum signal to the dizzy or you'l et stumbles & flat spots .

I assume you've replaced the leaky vacuum advance can ? .

If not, STOP until that's fixed then go back and laboriously do every step in the proper order :

Set dwell .

Set timing, either to 10* BTDC or using the vacuum gauge, the vacuum gauges more accurate because it compensates for your engine's wear, altitude, low quality gasoline and so on .

Once all this is done you can adjust the idle speed then the mixture then the final idle speed .

If the carby is still dripping fuel, there's a serious problem ,most o the time it's the float is too high because you touched the floats as you assembled the top of the carby to the bowl .

Use the printed cardboard float gauge supplied in the kit .

These Rochester MonoJet carbies are the last, final and very best iteration of the 'B' series that began in the 1940's .

That compensating valve do - hicky under the sheet metal plate ? don't worry about it, stick shft engines don't normally have it .

If you think the ignition coil is bad, try to afford the correct DELCO HEI one, there are two versions, one has a separate coil, AC / DELCO sells rebuilts or a junkyard one will do .

If you're strapped, buy an EPOXY FILLED coil from NAPA or other high end place, when I sold 'standard blue streak' ignition parts the coils were often bad right out of the box or failed in a week or two .

Accel coils are outstanding if $pendy and FUGLY because they're eye searing yellow .

[straight6chevyguy]

First off, good video! I was able to follow pretty easily and the picture quality was not bad at all (Some peoples videos you can hardly see what your looking at)

I think It's still a vacuum leak but I don't know for sure. I would consider getting a different carb.
Not to many more things that could be the problem since you have almost replaced all the common problems.

The only things left are maybe replace the carb and then start looking internally starting with the valves.

I do here the noise you are talking about. My 292 has something pretty similar but not as loud.

[VWNate1]

Here it is appropriate to remind you that the thinwall, long stroke 292 C.I.D. engine is a Chevrolet engine and that "C.H.E.V.R.O.L.E.T. itself is an acronym meaning :

Can

Hear

Every

Valve

Rap

On

Long

Extended

Trips

.

[Mike_The_Grad]

Lol, I like that one Nate. First time I've heard it.

May, how about a few pics of your engine bay? Maybe there is something that is not mentioned as you may feel is unrelated to the problem but may be visible to some of these guys with more experience than you or I.

[straight6chevyguy]

Actually the noise I'm talking about is not valves (at least I don't think so) (there is definitely valve train noise but there is also something else there.
It's more of a knock.

Been trying figure out what it is on my 292
Not sure if its the same noise or what, just was mentioning it.
Ok, I wont hijack the thread! LOL

[straight6chevyguy]

Just watched the video again still not sure about the one noise but for sure you do have noisy valves. In most cases engines will still run with raping valves, but if you have a really bad hydraulic lifter or an rocker arm really loose I could see it causing some bad problems.

Just another possibility!

One other question I have is have you tried to run or drive the truck without the vac. advance hooked up?
It may be something to try.

[Steeveedee]

His vacuum advance was broken when he was driving it before. When he discovered that it was bad he replaced it, but that didn't help, either. This is one knotty problem!

[May70]

I took some pictures. I also made a video of the inside of my distributor with the plate off. The weights and springs are there. Other than that im not sure if they look good/bad. When I was taking the plate off I noticed the shaft actually had some vertical play, minimal but it moved (in video). Is that normal?

If you watch my video are those weights considered sticking? The weight toward the cab maybe?

https://youtu.be/46xmfcEZ0SQ

[May70]

Here are stills of the distributor