Technical He's got some SBC woes

When you wrote:

Well sometimes it just Boggs and falls down and stalls-wont start back up until it cools off. and I'm pretty sure that's a fuel delivery problem someplace between the tank and the carb.

Had the same thing, turned out to be the Holley Carb. Holley had a secret recall !
Ran fine, until a piece of shit got in to needle and seat

 

I'm saying if its driven much, it'll tear the bearings up, and THEN you'll see a noticeable drop in oil pressure...hence the comment about seeing it on the drain plug. hence the sad face...

 

now that I look at what I posted, I didn't word it well. Should have put the "if he has driven it much" first, then it would have been clearer...

 

I knew what you ment.

 

Drain your oil in a white paper paint strainer and you will see if you have any junk in the oil

Learned this trick from the guys at Traco while running on their dyno, its good to know how your oil looks when having a problem like this

Don

 

at least someone did. I admit, I phrased it badly...

 

that works well. I just rub it between my fingers. My daily has to come apart, pretty sure the top timing gear has started chewing up the cam thrust face in the block. I started hearing a squeak from the timing cover, and theres some cast iron debris on the drain plug, haven't pulled it apart yet, but you add those two things together with moderate/big springs, and its a pretty safe bet. If Im going to have the engine out, that gives me an excuse to do a little headwork and plug a tighter lsa cam in while I have it apart...

 

65 up cams have a grove in the rear journal the flat spot is a 265 thing.

 

Clocking of the cam bearing is one thing, the fore and aft or bearing depth can limit the oil flow. The only way to check it kinda sucks for a fishing expedition.

 

seen it happen. Bearing wasn't seated all the way back. shut off oil to the rockers almost completely.

 

I have seen a push rod hit the head and cause a lifter tick this was on a set of eldebrock heads on a sbc the owner had the engine out and apart three times before it was found. the oil flow would make me pull the lifters if the first guy cranked it a lot before the cam was broken in it could have wiped the lobe

 

subscribe!!

 

In a SBC the cam bearing cannot shut oil flow off to the lifter galley, it can move and uncover the galley though which would lose pressure to both lifter galleys. Notice the oil holes are in the center of the groove.
It may also be as someone else stated before the oil galley plug missing or leaking very badly behind the timing chain.

 

And As you just said, if the bearing isnt all the way back in the journal you have no oil pressure to the cam galleries.
The pressure at the gauge is good. If a cam gallery plug is missing, you have a 3/8 hole at the end of the oiling system PISSING oil. The gauge would read zero. If a cam gallery plug was leaking enough that there was no oil up top, it would still show a VERY low number on the gauge. The only place I can see that would lose virtually all oiling to the top end, and still show good pressure at the main gallery at the back of the block is the rear cam bearing. Look at an oil system schematic for the sbc, and figure it out.

Oh, and I ignored it the first time, chevy got rid of the flat spot on the cam a full 8 YEARS earlier than the 1965 date you are throwing around.

 

Going to pull it and get the engine on the stand tomorrow.

 

While on the engine stand, pull the pan, and do a "leak-down" test. If the rear cam bearing was not installed far enough in, oil will gush profusely through the two holes in the rear cam journal. Also, if oil is gushing from the timing cover area, you may have an oil gallery plug missing. Yes, it is a pain setting up the equipment for a leak-down test, but it will reveal much in your diagnostic procedure.

 

If you think it's a fuel issue, check to make sure the fuel tank is vented properly.

 

Went through something similar a while back and as far as passenger oiling, the right bank passage goes straight through the distributor. You can use a pre oiler (shaft only) to spin the pump and easily see if you have good flow to the base of the distributor without pulling engine. After that make sure you don't have an early iron distributor with the partial groove at the base with it clocked incorrectly. Also could be due to distributor height (adjustable collar dist, defective intake) pinching off passage.

In my case the rattling was all kinds of machine shop screwups, 3 different dampner heights and loose guides. Lack of oil to rockers was most likely a geometry problem since the screw in studs were all tapped and faced out of square so bad the rockers rubbed the valve cover on one head.

 

Holy shit, now heres a man whose thinking! Never even thought of it maybe having an early style distributor in there! I just got home from 2 days out of town, so I am kinda foggy right now, but I'm thinking an early style cam could also cause the same issue?? I'll have to sleep on that one, my brains are a little sleep deprived right now, but it feels right.Whatever it is, Im still about 85% its gonna be related to the rear cam bearing area, including the distributor. Anything else would show low on the verticle gallery at the back, and low at the mains, it would be knocking. Could be debris in the back of the cam galleries,wasted back cam bearing, or distributor related, but its gonna be something around where the two galleries take off from the cam journal, if it were further downstream in the cam galleries it would only effect one bank, upstream or a leak at the end of the galleries, and the whole system would be low on pressure. If its lifter/pushrod related, its gotta be all 16, not completely impossible,but stretching the boundaries of probability.

 

Distributor intersects the passage that feeds all the cam bearings and the mains from the top, right? Not distributor related, gauge would read low, mains would be starved. Early cam with the flat spot on the back journal??

 

Another one. Just did a quick search on Speedtalk re:early cams and oiling didnt find that info, but I did find something else. A guy had a crack in the plug above the rear main, it only showed low at idle, not when the rpm was over about 1500...hmmmm, little more food for thought there. I gotta get some sleep, I am all in.

 

I got shot down early in this thread guys

 

Up late so I hope I get this right. Oil should go to mains first then to center passage above cam, around rear cam bearing and forward toward lifters through right and left passages. Distributor only intersects passenger lifter bank.

Early 265 distributors had a partial groove on one side and flat on opposite end. Lower distributor bushing was pressure oiled in groove and dumped out, draining through flat side into crank case. Not likely, but if someone did install one of these in a later block with it clocked wrong there would be oiling problems to the lifters on the right.



http://www.chevytalk.org/fusionbb/showtopic.php?tid/242923/

 

Got some more info on it.
80's truck engine.
Aftermarket newer hei dizzy
New 355 rebuild in 2010, sat till 2014.
Major problems getting it fired.
Less than 200 miles since the instal last year.

Don't know what "major problems" were exactly but the guy who dropped it in couldn't get started. The Next guy got it started, but couldn't get it running right. No ideas on any type of cam break in that was or wasn't done.

 

Did you pulled it yet?

Or at least the pan, the timing cover and intake?

For the purpose of further diagnose!

 

LOL I guess I don't really understand major problems getting one started, I know it happens but I still don't understand it. I think that you have the same problem that some restaurants have with the soup too damned many cooks.

I know that an SBC has an oil groove on the cam journals in the block, but I was taught that you need to line the oil holes up ( I use an allen wrench) maybe that is to insure that the cam bushing is all the way in or maybe it is just a quirk that was passed down to me but I do it and never have oiling problems.

I think you are the right track tearing it down, it takes time and the cost of gaskets but it damned sure beats guessing.

 

I agree with Beano on this one. You could stand around looking at it and guessing for days, or just bite the bullet, pull it apart and find the answer in a few hours.

I think the main problem is this motor is the victim of a handful of guys knowing just enough to almost scrap by, but not willing to pass on a job. The first guy did a sub-par job building it, and the problems compounded as the chain of 'mechanics' grew.
31Vicky will have this thing sorted and the old guy driving it around before you know it.

 

good info, thanks LSA, I was thinking central gallery above the cam. But wouldn't be the problem here, as both galleries are low. another thing I didn't think of last night (I really was pretty groggy) as far as I know, all the early '55/'57 distributors were standpipe oiler, so readily apparent at a glance if you had one. That's one you never see on those silly "how do I make my 350 look like a 283" threads, but I try to stay away from that kinda thread nowadays...

 

It was sometime in the mid-to-late 60s that the rear cam bearing was changed up from a full width bearing to a narrow width bearing (same width as the front four bearings). If, perchance, that narrow rear cam bearing was installed flush, the oil groove in the block would remain open and a massive oil hemorrhage would be the result. No oil pressure at idle, 25 to 30psi at rpm! Been there! Chasing down another "mechanic's" screwup is always challenging at best, not to mention multiple screwups.
As for post #53, the only main that is direct oiled is the rear main.

 

Just as an aside, I am not a big fan of factory, mass-production lubrication systems. Too many turbulence generators where oil galleries intersect. Chrysler hi-performance engineers advised their engine builders to modify their oil routings in the LA blocks to prevent oil starvation to #4 main and its #6 and #7 rod bearings. Ford did something interesting on their 427 side oilers: the oil pump had a pressure relief valve but there was also a pressure relief valve at the end of the main gallery of a lower value, guaranteeing sufficient lubrication to all the crank bearings. As for SBC oiling, that 135 degree dog leg gallery at the rear of the block is just so engineering wrong, along with that convoluted route to the mains via the annular grooves around the cam bearings. Why else would Dart build and market priority main oiling SBC blocks?