The Stovebolt Site Forums The Shop Area Engine Shop starting rebuilt 235

So I am ready to fire my 235...I actually did start it, but stopped because I wanted to double check that what I am doing is correct. I'm pretty sure it is, but it can't hurt to double check right? I have a rebuilt 235 with Tom Langdon's dual carter weber carb setup on a fenton intake with his HEI. Everything seems to be going good. It fired right up after priming to motor, but I had a pretty good exhaust leak so I killed it. I tightened up my ehaust connections and re-fired it. I still had a bit of an exhaust leak but this time the rpm's were higher and seemed to keep increasing, so I once again killed the motor after a few seconds. I am guessing the rpm's were higher because of the chokes, but I stopped just incase I was too lean or something else possibly. My initial fuel mix screw settings were 1.5 turns out and the idle screw wasn't even near the linkage to do anything at that point. I'm fairly certain that the break in procedure for the new motor with solid lifters is to fire it and run it for about 20 minutes at 2000rpm. My question though, is that since there is no way of having all 3 things (timing, fuel mix, and getting it up to 2000rpm) happen perfectly all at the same time, how can I not screw up my new motor by possibly running it too lean or having my timing too far off while getting the rpms up to break in the cam? I am guessing that I want to get the rpms up first. So if I fire it again and it is running well enough should I just get the rpms up for the 20 minutes and then start dialing everything else in?

Correct timing, valve adjustment, cooling, and fuel mixture is simple, and should present no problem during a cam break-in run. The idle mixture adjustments will have no effect whatsoever at 2,000 RPM. Ignore them and get on with your break-in run. Starting and stopping repeatedly is going to ruin your camshaft by scuffing it before it establishes a running fit with the new lifters.
Jerry

Spend a little time going over the intake / exhaust manifold mounting bolts. It sounds like you have vacuum leak at the intake. With both manifolds bolted together, its hard to believe you had a exhaust leak with out also having a intake leak. You might try taking some weight off the manifolds and loosen the bolts holding the intake to the exhaust manifold. Then tighten the manifolds to the head. If you did not get the manifolds to head surface machined flat with both bolted together, it can be tough to get them to seal right with out some fussing around. Also be sure the alignment rings are correctly located if you are using them.

Don't fire it back up till you are sure about the leaks, and as you are aware already, don't keep running it for short burst like this. Once it starts, let it go. Adjust the timing while running and watch the temp gauge for excessive heat or quick heating. RPM is key to cam life, its the crank throwing oil on to the cam lobes, and low rpm will not get it done!

If you can get it to run at 2,000 RPMs for twenty minutes without over heating, don't worry about anything else.
You are breaking in the cam. You only have one shot at that. Everything else can be dialed in twenty minutes later.
The fact that it will run at 2,000 RPMs is close enough for now, and you won't hurt anything during twenty minutes at 2,000 RPMs.
Carl

Excellent advice Carl, Joe and Jerry. Thank you all very much! I have to go to Carlisle to help a friend out, but as soon as I get home I will get back into it and let you know how everything goes. I'll go over everything again before I fire it. Thank you!

Got the engine broken in, timed, and carbs tuned. So far so good, and so much better with the fresh motor!!

Congratulations, greasymatt

I'll be doing a break-in tomorrow. A friend from Mass. is coming to see me through the break-in.

My start-up is complicated by also having a newly restored Hydra-Matic transmission that has to be "run-in" at the same time as the 235 engine break-in.

1954 235 original block that came with the H-M/truck - professionally rebuilt
261 cam
848 head
bigger valves
.040 over bore

My fingers are crossed. I have not broken in a rebuilt stovebolt engine since 1972 (I did not know enough back then to be worried). That 261 is still running nicely in my Suburban.

Keep us posted Tim. Sounds like fun!

Not a good day with the engine start-up.

Problem 1:
The re-builder removed the "plug" in the middle-top of the coil-side of the "848" head (the hole some people run an external oil line from the other side of the block, in order to get more oil to the rocker arm assembly). I did not notice it missing until we spun the oil pump and oil came out the small hole. The odd thing is that the hole is smaller diameter than on any of my 1954 235 heads AND it is not threaded. It looks like some sort of plug must have been in there.

Has anyone ever seen this in an "848" head (1958 head)? I guess I will look for a brass plug to seal that hole.

Problem 2:
My torque-tube bell will not slide back on the torque-tube. I dimly recall we had to pull the rear-end backwards to separate the torque-tube (about 10 years ago). I do not know why it is so tight - maybe heat distortion. I am slowing cleaning/sanding and removing a little metal with strips of emery abrasive-tape. The tight spot appears to be at about 1" from the front of the torqe-tube.

Oh well, it's always something (or two).

I have seen a lot of 235 heads, but none that are not 1/8" pipe thread.

My suggestion Tim would be to tap it for a 1/8". I have never seen one that isnt tapped either. Be sure to clean in there with a cleaning brush to make sure it just looks like its not threaded. No help on the torque tube sorry.

Best I can do is a 1956 Chevrolet Truck 235 Cylinder Head GM 3836848 Photo Album of the plug.
Looks like a 3/8 threaded plug.
3836848 is the head that is on my 1954 235.


I guess it's better to be tight than lose.
It could be ether the torque tube OD or the U-joint ball housing ID.
If you have another U-joint ball housing laying around, slide it on and see what happens.

I think I do not want to risk getting metal in an oil journal, if I tap that hole. I think I am going to first try a brass plug.

I will take Deve's advice and clean the hole to be sure it is not threaded. We slid a small screwdriver on the edge of the opening/hole - it seems to be smooth. I'll try to take a photo that gives a decent depiction of the hole.

There is no question about the hole being a smaller diameter - as if it had not been tapped/threaded.

I made an error on plug size.
It is NOT 3/16
It is more like 3/8 or 6/16
It is close to 5/16

Yeah, Tim, thats true. You want to be careful when tapping or I can see you not wanting to do that. I would suggest a magnet, a very slow tapping procedure, and then run the oil pump with a drill for awhile to make sure what you didnt get ends up in the pan, then change the oil. But I agree that even then, its no guarantee.

Jorb.. you are experiencing what I also am confused about... 1/8" NPT has NOTHING to do with 1/8th of an inch. I wish someone could explain to me what these geniuses were thinking when they came up with NPT system. A 1/8th NPT is about 5/16". I just dont get it. Yet somehow, they had the political clout to get that approved as a standard. Too much Hooka Pipe and not enough measuring the pipe! I mean, what am I missing? 1/8th of an inch really? Not anywhere close! I wasnt invited to the NPT meeting. Now you know why. LOL!

The 1/8" has a lot to do with size of the pipe, the 1/8" refers to the inside diameter, and schedule 40 pipe is pretty close the nominal size.

Oh I know how its measured, but still.. a bunch of dudes in a frat house could have done a better job while high on who knows what. Heres an idea! Lets measure ID and change the threads just enough to be annoying and then call it a standard. LOL! I'll shaddap now!

The hole in the 1958 "848" head is not threaded and it is a much smaller diameter that either of the plugs I have for other 235 heads.

By the way, I have two different threaded-plug diameters from different heads. I'll post the dates and sizes and photos tomorrow or Monday.

Pipe threads are for pipes. Pipes flow material at a specific flow rate. That is the critical factor of any given pipe. To call it any other "size" would take away from that fact.
"Its a plumbing thing. You wouldn't understand."
If they called a 1/8 pipe thread 5/16", then dummies like me would reach for the 5/16" straight thread tap instead of the correct tapered tap.
Carl

the sizing of pipe, and the associated NPT threads are really basic, and very well organized. As this has been an industry mainstay for probably 200 years now. It may be easier for me, as I work with this sort of stuff nearly every day. The part that gets me is the metric, along with those companies that for whatever reason, decide to use BSPP (british standard parallel pipe) on the same piece of machinery with SAE products. You have the "AMERICAN" metric, the "EUROPEAN" metric. Then of course you get the different schedules of pipe, the OD needs to remain the same to facilitate threading, and basic fitting with/to the various fittings. Schedule 160 has a lot smaller ID than schedule 40.

I am not trying to win an argument. LOL! I know how it works, but to me, 5/16" tapered, makes just a tad more sense than 1/8" NPT. Nonetheless, thanks for listening to the inevitable whining.

"Problem 1:
The re-builder removed the "plug" in the middle-top of the coil-side of the "848" head (the hole some people run an external oil line from the other side of the block, in order to get more oil to the rocker arm assembly). I did not notice it missing until we spun the oil pump and oil came out the small hole. The odd thing is that the hole is smaller diameter than on any of my 1954 235 heads AND it is not threaded. It looks like some sort of plug must have been in there."

All of you were correct regarding a threaded plug in the middle of the coil side of the head. The "non-threaded smaller diameter hole on my 1958 "848" head was the remainder of the "hollow" brass plug. Someone must have tried to remove that plug and broke the head off of the plug, leaving a smooth bore, smaller diameter "hole".

I got the hollow piece of the brass plug out with an easy-out. A new threaded brass plug in now in that hole.

"Problem 2
My torque-tube bell will not slide back on the torque-tube."

I am still working on the end of the torque tube with emery abrasive strips. The bell will now go back about two inches. The "high" part of the torque tube is about 1" back - above the bushing/bearing. Maybe the bushing/bearing failed and the heat distorted the tube around the bad bushing/bearing? (just a WAG).

I have honed the inside of the ball/bell cover - it is not distorted. I have two spare ball/bell covers and I might have a machine shop hone out the interior of one (in small increments).

Nice Tim. I didnt know the plug was brass. They may have done that for similarities in dissimilar metals so leaking at temperature isnt an issue. I always thought they were just regular steel 1/8" NPT fittings. Not sure how you even found a brass one. Glad your easy-out process went well. They don't always. Looks like you are on the road to having an awesome engine.

Out of my 4 heads, there were:
- 2 hollow brass plugs (solid hex head),
- 1 solid steel plug (square head), and
- 1 steel/alloy solid plug (indented hex head).

Yes, the easy-out process is a crap shoot. The brass could not "rust weld" to the head, so I guess that made the removal easier.

I am still slowly working on the torque-tube and ball/bell. I think I am about half way there - I want to remove no more material than necessary to allow the bell to slide back, yet still provide a tight fit of the bell to the tube.

Most all I have seen are steel with a square head.

Back in the early 80's.
While driving home in my 1954 Chevrolet panel truck,
In the corner of my eye, I saw the oil pressure gauge needle suddenly drop to ZERO.
I had about a 1,000 feet to go before I was at my driveway.
At about 500 feet I shut the engine off and coasted the rest of the way.
It turns out that This Fitting snapped Off. (oil pressure gauge feed line fitting)
Leaving just the threads in the block.
I did what tclederman did and used a easy-out to back out the threads.
It was easy to get out, no pun intended.
The only thing that was bad about the whole problem was the 500 foot
streaking path of oil on the street.

Hope that that snapped off plug didn't screw-up your paint job!