BBC troubles still

[Leadfoot]

A few months ago I swapped out the lifters in my motor (used but supposedly in good condition) as they were making noise. The motor sat for some time (protected) so we figured the possibility of a collapsed lifter was causing my problems. When I swapped in new lifters, my buddy told me to swap in a set of roller rockers at the same time. The problem was that the rollers required a longer stud as the rocker arm nuts were only being held on by a couple threads. The motor sat while I ordered the parts (first time ordered studs too long ). I removed the studs, installed new ones, set the rocker arm preload and then again with the engine running and up to temp....., I still get what sounds like a lifter knock and not much oil up top. The cam is getting tons of oil as I can see it through the windows in the head and the gauge is usually 60 psi or more (high volume, high pressure pump). My buddy started looking at the old rocker arm studs and noticed that 14 of them looked great, but two were worn where the rocker arm rides (looked like lack of lubrication), the problem is that since I did not expect to have problems with them, I did not mark which valves they went to. Have any of you had problems with worn rocker arm studs (especially on a BBC) and if so, what was the cause?

I'm getting ready to pull the motor again and send it to a machine shop if I can't figure out why I can't get rid of the "noise". Any suggestions?

 

[78Suburban]

Just checking, you did keep those used lifters you installed in the same order didn't you? I think they have a very specific wear pattern.

 

[thatK30guy]

What cylinder were the lobes on the cam aligned with?

I've heard the back two cylinders, 7 and 8, have had problems with oiling on the BBC's, hence the reason so many of these motors blow up due to lack of lubrication. Heard it was a flaw in the GM design of these motors. But they can be fixed to gain more oil back there to lube the lobes and cylinders better.

 

[Leadfoot]

Just checking, you did keep those used lifters you installed in the same order didn't you? I think they have a very specific wear pattern.

Nope, brand new lifters were used. I still have the old ones for "decoration".

 

[Leadfoot]

What cylinder were the lobes on the cam aligned with?

I've heard the back two cylinders, 7 and 8, have had problems with oiling on the BBC's, hence the reason so many of these motors blow up due to lack of lubrication. Heard it was a flaw in the GM design of these motors. But they can be fixed to gain more oil back there to lube the lobes and cylinders better.

I've heard these motors have oiling issues, but not to the point of not being able to keep new/used lifters filled with oil. I was just wondering if the worn rocker arms are the "norm" or somewhat "common" or should I be looking deeper.

Wes, do you know what the "fixes" are?

 

[thatK30guy]

I've heard these motors have oiling issues, but not to the point of not being able to keep new/used lifters filled with oil. I was just wondering if the worn rocker arms are the "norm" or somewhat "common" or should I be looking deeper.

Wes, do you know what the "fixes" are?

I read in one of the mags and I think Shawn did it, too, that Bob Cherveny (sp) invented a tube thing much like the steel brakelines which have the threaded end and small holes drilled in them to aid each lifter with more oil sprayed on them. The fitting requires one of the plugs in the lifter galley to be removed and then drilled out and tapped to fit the brakeline fitting. This little plug hole is said to be very vital to oil passage as it allows more oil to flow thru therefore getting more lube to the rear part of the engine in the 7 and 8 cylinders.

Send Shawn a PM or look up Bobs name on any search engine. I will do the same and see what I can find.

 

[Leadfoot]

I read in one of the mags and I think Shawn did it, too, that Bob Cherveny (sp) invented a tube thing much like the steel brakelines which have the threaded end and small holes drilled in them to aid each lifter with more oil sprayed on them. The fitting requires one of the plugs in the lifter galley to be removed and then drilled out and tapped to fit the brakeline fitting. This little plug hole is said to be very vital to oil passage as it allows more oil to flow thru therefore getting more lube to the rear part of the engine in the 7 and 8 cylinders.

Send Shawn a PM or look up Bobs name on any search engine. I will do the same and see what I can find.

It's the BC (I assume for Bob Cherveny) cam oiler. This motor has one installed. It helps lube the cam lobes where the lifters contact, but does not feed the actual lifters. I've had a few guys look at this motor, but I'm hoping to have the guy that builds most of the BBC's for Superstock and Modified classes take a look at it. I know it's a street motor, but hopefully he can shed some light.

 

[Greg72]

I continue to have similar sounding problems with my 396BBC.... very little oil in the top end.

The initial discovery was burnt and blued ball washers (the ones under the rocker arms themselves) and almost NO oil coming out the tops of the pushrods.....(like drizzling, NOT squirting).

I had the motor torn COMPLETELY down, looking for any signs of oil galley plugs or oil restrictors installed that might explain why so little oil was making it to the top end. Everything checked out fine.

The block and heads were completely disassembled, hot tanked and re-assembled with new bearings, cam, rockers, high volume pump (not high pressure) and wouldn't you know it....the engine STILL won't oil worth a damn on the top end!!!

I'll run this motor until it burns up the rockers (again) and then maybe swap in a different 396 or BBC. I think I just must have a bad block casting or something obscure going on with this particular engine.

It's frustrating, I can sympathize with that....

 

[smalltruckbigcid]

Hate to sound dumb but did anyone check the pushrod holes? The rockers lube through the pushrods so if they are plugged you have oiling problems at the rocker. The other thing to check is the lifter bore size. If the bore is worn and allows to much side clearance then that lifter will have low oil pressure going through it to the pushrod and that gives you a lack of pressure and flow to the rocker.
A way to test this is set the motor to the firing position on the problem cylinder, lifters all the way down. Pull the distributer and install an oil pump priming tool you can spin with a drill. Fire up the drill turning clockwiseand watch for the oil. If no oil or very little see if you have any going out the top of the lifter bore or past the pushrod ( and not going up the pushrod).
You have no oil flow on top for one of three reasons, 1 the lifter is plugged internally, 2 the pushrod or rocker arm feed holes are plugged, 3 the lifter bores are wore out and need to be rebushed $$$. The last one is more common on a mopar but anything wears out over time. Hope this helps.
George

 

[diesel4me]

one more possibility...

I have seen GM motors come with lifters that are .010 oversized where they ride in the block factory..evidently they "saved" a few blocks by reaming the lifter bores out,and using those special "oversized" lifters!..(only available at GM dealers,AFAIK)..

They only install them in the bores that need them,not all of them..engines with this modification have ".010" stamped into the rail where the oil pan bolts on..sometimes!.(according to GM,all the motors with lifters like this are supposed to be marked--but I've seen more than one that wasn't)..

You see things like this in automotive machine shops..one customer put 3 sets of lifters and new cams in a 454 once,before we discovered two lifter bores were .010 oversize!.. ...AHA!..so THATS why it always ticked,had little oil to the rockers,and ate cam lobes!!.. ...

 

[Greg72]

d4m,

That's an interesting one.....not the kind of thing most people would even consider checking, and would certainly explain why even my carefully rebuilt motor didn't oil any better than before!!!!

 

[Leadfoot]

d4m,

That's an interesting one.....not the kind of thing most people would even consider checking, and would certainly explain why even my carefully rebuilt motor didn't oil any better than before!!!!

Makes me wonder too. This motor acts just like yours, oil drizzling from the pushrods (which were thoroughly cleaned when the new lifters were installed).

I'm running roller rockers (which will hopefully help stop the galling), but it still doesn't explain why the lifters are still "ticking". I would like to run this, but I don't want to ruin the motor entirely.

As for what a previous poster said about lifter bore size, it seems to make sense, but wouldn't some rocker arms get more lube than others??? It seems like NO rocker arms are getting what I feel is an adequate amount. I was told this motor was running "fine" when I bought it, so I might have the local engine guru adjust the valves and run it.............

 

[TJS]

If this is a 396 block the rear cam journal on the camshaft needs to have the machined groove in the cam to let oil by for a feed. Ask me how I know. It is mentioned in most of the big block chevy books as well at mortec.com tech section somewhere. Hope this helps.

T.J.

 

[Greg72]

If this is a 396 block the rear cam journal on the camshaft needs to have the machined groove in the cam to let oil by for a feed. Ask me how I know. It is mentioned in most of the big block chevy books as well at mortec.com tech section somewhere. Hope this helps.

T.J.

How do you know?

 

[TJS]

How do you know?

Had a 396 in a Jet Boat (friends). He bought the 396 from someone and it wiped out the mains and also had a lack of oil problem to the "top" after less than an hour of running. Pulled the cam and found the rear journal was not groved. As I said look on the mortec site and you will see what I mean.
T.J.

 

[TJS]

Better yet here is the text from Mortec


Big blocks, cast in 1965 and '66, used a "grooved" rear cam bearing with a matching "groove" in the rear journal of the camshaft itself. This groove provided an oil passage to the lifter oil galleries. 1967 model and later Mark IV blocks have an annular groove oiling passage cast into the block itself. The blocks cast from the '67 model year on use a smooth, non-grooved cam bearing and the rear cam journal for these '67 and later blocks is smooth and does not use a grooved rear cam journal. The reason this is important is that if the wrong cam bearing gets used in the '65-'66 blocks, no oil gets to the lifter galleries or up to the rocker arms. The '65-'66 grooved cam bearing has three oil holes to feed the cam journal and the two lifter gallery passages. The '67 and later cam bearing is smooth and only has one oiling hole in it. A few of the cam makers will provide a big block cam with the groove cut in the rear camshaft journal, but you can have your machinist cut a groove that is 3/16" wide and 7/64" deep in the center of the rear cam journal if you have a big block cast in the '65 or '66 model year.

 

[diesel4me]

more info...

I'd forgotten about the groove in the cam on early blocks (65-66)!..and I had read about that in the "how to rebuild your BBC" book too...they had this to say in addition to what TJS just posted..

"There is no way to use a later (non grooved) cam in a 65-66 block without machining a groove in the rear journal-so that is simple enough..If you did fit the later non-grooved cam to an early block,there would be no lifter oiling"..



-67 and later motors have a annulus groove behind the rear cam bearing that feeds the lifters..on theese later engines,the rear cam journal,and bearing are exactly like the other four.."

"Early grooved cams can be used in later blocks..No modifications are nessasary to the cam,but the rear cam bearing must be the later,non-grooved type..before the rear cam bearing is installed,the hole must be soldered shut,and re-drilled to .060 to 1/6" is close enough,and then installed in the block..the original oil hole is too large,and will allow an internal oil leak that will disrupt engine oiling.."..

Hmmmm...

I've also read where the distributor housing is incorperated in the oiling of the right bank of lifters on all chevy v8's..and having it installed in any position other than stock can restrict flow to the lifters on that side!..

I think even one or two lifters flopping around in .010 oversized bores would be enough of a hemmorage to drop oil pressure to ALL the lifters,and maybe the bearings too... ...

 

[smalltruckbigcid]

Actually the lifter bore doesn't have to be all that big,
maybe .004 or bigger. But the groove at the back of the block makes a lot of sense to look at. Hope this helps
George

 

[Greg72]

Does this cam groove issue apply to the later 396 blocks as well???? Mine is a casting from a late 60s/early 70s.... I have the casting number around here somewhere!!!

 

[diesel4me]

??..

My book states only 1965-66 motors had the groove in the cam--67 and later should have the groove in the block..396's first came about in 1965,so its possible yours might be an early casting one that needs the groove in the cam..however,if you did use a later(post '67)non-grooved cam in it,they claim NO oil will flow to the lifters..

I have a casting # listing in the book,post yours up and I'll see if it shows up in the listings..

The book also goes into a lot of detail about the cam bearing installation,and how to be sure the oil holes are lined up with the passages in the block,and not "shrouded",which can reduce oil flow to the lifters..one "loose" cam bearing with excessive clearance can have the same effect by letting too much oil pressure bleed off there...