valve covers, engine rebuild, other stuff

[vancelot69]

Is it possible to find OE style valve covers, or am I only going to be able to find chrome ones that don't seal right?

I'm asking because I have a huge oil leak, Last week I checked the oil, and it wasn't registering on the dipstick, so I added two quarts to get it in the cross hatch, then drove about 80 miles, and it's already off the dipstick again. And, while I don't think the valve covers are the worst leak, I'm pretty sure they are leaking pretty badly, so I want to get rid of them and get some OE style if I can. Thing is, I don't know exactly where the worst of the oil leak is either. I'm pretty sure the timing cover and seal are leaking as well, but I don't know if they are the worst leak either. It could also be leaking from the head gaskets too. I also thought rear main seal, but the flywheel and bell housing are relatively dry.

So, I was thinking that maybe I should just rebuild the engine, like get one of the "re-ring kits" with gaskets from Summit Racing or something, they seem pretty cheap there. Or rebuild a 454 my dad has sitting around. If I were to rebuild my engine, how would I know if it's been bored out, like, how do I know what size main bearings to get? The previous owner didn't mention anything like that.

What all is involved in an engine rebuild? I always thought it was essentially what is in those re-ring kits - rings, main bearings, and gaskets, and maybe reseating the valves.

Thanks in advance for any input.

[geezer#99]

I see you have a pcv valve on the drivers side valve cover but do you have a breather on the passenger side? If not then your leaks are caused by excessive crankcase pressure.

[vancelot69]

uhh. I don't think I do?

This help any?

edit2: don't worry about the air cleaner being cut up. The previous owner cut the breather because the brake booster vacuum hose is too tight... I plan to replace that soonish.
edit3: deleted edit1, and: if I put a breather on, instead of the PCV, will I need to plug wherever it's going to now? Do you really think that could be causing this horrendous oil leak? That would be amazing if it is.

[vancelot69]

oh, wait, I just realized you said on the passenger side, so no, I don't. Do you think I should replace the oil filler cap with a breather? That's how it was on the 70 Jimmy I used to have:

[jaros44sr]

basically, what Geezer is saying is, you're building pressure in your engine, and blowing oil past your seals. when you get your new valve covers, make sure they have two holes on one side and one hole on the other. I think I have a set laying around, you pay shipping.

If it were me, I'd buy a short block, and use my heads( if they were in good condition), but you may not have to if what Geezer said works

[vancelot69]

oh, wow, I didn't realize that was even a possibility... Learn something new every day!

Here are a couple more pics of my previous Jimmy. I can see that it does have the same PCV valve on the driver's side as my current Jimmy, but then I can see on the passenger's side that it has 2 holes, one looks like it has a mesh cover (breather?), and the other looks like the filler cap has been replaced with a 2nd breather.

So, should I get a breather cap to replace the filler cap? I mean, that would be better than no breather, right? Or would it be best-case to get a set of OE covers?

jaros44sr - how much is shipping to 76148? That sounds like a deal that's too good to pass up. Before I commit though, they will fit a 72 350?

Pic1 (orange): 70 Jimmy I used to have. I can see the two holes on the passenger's side.
Pic2 (blue): 72 Jimmy I currently have. Looks like only the oil filler cap on the passenger's side.

[hemi43]

Without trying to sound too harsh, it sounds like you don't have much experience with engines, so rebuilding one may not be what you want to do. If I were in your shoes, I'd go and get a crate engine from GM and put that in. It will bolt right up, have decent heads, have a warranty and really won't cost much more than to rebuild the engine that's in your truck now. Even without that breather you wont be pressurizing the block as long as your PCV is working properly. Just my 2 cents !

[vancelot69]

Well, I don't know anything about vacuum other than if the hoses aren't connected properly it won't run right. However, I have rebuilt a few engines in the past and just made sure the vacuum lines were connected like they were before I took the engine out, although the last time I did that was over 20 years ago.

Is it because I don't know if valve covers will fit from year to year? Or because I don't know about the crankcase pressure? Yeah, I had no idea that would cause oil to blow out the seals.

Seems to me like $83 for a re-ring kit, or even $400 for one of the more expensive ones, is a heck of a lot cheaper than $6000 for a crate engine...

[hemi43]

Originally Posted by vancelot69

Well, I don't know anything about vacuum other than if the hoses aren't connected properly it won't run right. However, I have rebuilt a few engines in the past and just made sure the vacuum lines were connected like they were before I took the engine out, although the last time I did that was over 20 years ago.

Is it because I don't know if valve covers will fit from year to year? Or because I don't know about the crankcase pressure? Yeah, I had no idea that would cause oil to blow out the seals.

Seems to me like $83 for a re-ring kit, or even $400 for one of the more expensive ones, is a heck of a lot cheaper than $6000 for a crate engine...

Your engine right now HAS vacuum (assuming PCV isn't clogged), so you shouldn't be building pressure in the crankcase at idle or cruising speeds. To verify that the PCV system is working , try these two things.
First, removed the PCV valve while the engine is running, and verify that there is indeed vacuum. If there is, then put it back in .
Second, remove the oil filler cap on the passenger side valve cover, again while engine is running. With your hand or a piece if paper, cover the hole. You should be feeling vacuum. If you don't, then that means you have too much blow-by and the engine needs rebuilding.
The PCV system should always be able to remove more volume than what gets passed the piston rings (Except under WOT )

The main purpose of a breather is two things. One, it allows fresh air into the crankcase so that explosive gasses don't build up in there at idle or cruising, and two, to allow any pressure buildup out of the engine and back into the air cleaner under WOT when the PCV system loses it's vacuum.
Hope this makes sense.

As far as a crate engine, they are around $2400. There's no way you can do quality rebuild for that much less on yours.
Throwing a set of Chinese piston rings in your engine is only a band-aid, and IMHO is not worth the effort.

[mattfranklin]

It takes a lot of finesse and patience to do an engine. Without the experience of having done it before the risks get higher. I think the suggestions are to give you a high probability of success.

If you really want to do it, the small-block Chevy is pretty forgiving. There is a good book by David Vizard (https://www.amazon.com/How-Rebuild-Y.../dp/1557880298). I'm using that book on mine. But I've already done several valve jobs and a complete Ford FE 390 V-8.

Summit has a set of cheap micrometers that are not quite machinist grade, but still can tell you if the engine has been machined oversize on the cylinder bores or undersize on the crank journals.

I'm rebuilding mine because the previous rebuilder used standard rod bearings on a 0.010 undersize crank. It made quite a noise. ;-)

And as a fallback position (if something is seriously wrong with the engine, or goes bad during the rebuild) a crate engine would be a safety net.

Good luck!

Originally Posted by vancelot69

Well, I don't know anything about vacuum other than if the hoses aren't connected properly it won't run right. However, I have rebuilt a few engines in the past and just made sure the vacuum lines were connected like they were before I took the engine out, although the last time I did that was over 20 years ago.

Is it because I don't know if valve covers will fit from year to year? Or because I don't know about the crankcase pressure? Yeah, I had no idea that would cause oil to blow out the seals.

Seems to me like $83 for a re-ring kit, or even $400 for one of the more expensive ones, is a heck of a lot cheaper than $6000 for a crate engine...

[Maximus]

Cheap mexican block new GM Crate 350's are only $1,600
https://www.summitracing.com/parts/n...7353/overview/

nicer 350's can be had in the 2k-3k range,
https://www.summitracing.com/parts/m...4ct1/overview/

$6k is alot of engine, and more than double what you would need to spend...

[vancelot69]

Originally Posted by Maximus

Cheap mexican block new GM Crate 350's are only $1,600
https://www.summitracing.com/parts/n...7353/overview/

nicer 350's can be had in the 2k-3k range,
https://www.summitracing.com/parts/m...4ct1/overview/

$6k is alot of engine, and more than double what you would need to spend...

Cool. I didn't know that. I mean, I haven't really searched for crate engines, I just assumed they were way to expensive for me.

[Maximus]

Originally Posted by vancelot69

Cool. I didn't know that. I mean, I haven't really searched for crate engines, I just assumed they were way to expensive for me.

for a big block, a dodge or ford your not going to find a $1600 long block, but thanks to the SBC 350 being produced for nearly 50 years, they are affordable.

Spend some more time tinkering with yours, but just remember there's always a plan B

[vancelot69]

hemi43: Yeah, that makes sense. Thanks for the education.

So, it wasn't WOT, but it felt to me like I was hammer down and it was revving pretty high (without having a tach to know for sure) when I drove it last, with an SM465 doing 60-ish, 33s, not sure of the diff gearing, I assume stock, and the SPID plate says 3.73. Another thing last time I drove it, it was about a 35 mile trip, 80% on highways. About halfway through, while on the highway, it started losing power and slowed down to about 52 and was running rough. After a moment, it straightened out and was ok the rest of the drive... And, I've been hearing an almost constant lifter or valve chatter. Sounds to me like all of this is related.

Do you think I really need to do main and rod bearings and rings, or do you think I can get away with just gaskets and seals?

Thanks again!

[hemi43]

Originally Posted by vancelot69

hemi43:
Yeah, that makes sense. Thanks for the education.

So, it wasn't WOT, but it felt to me like I was hammer down and it was revving pretty high (without having a tach to know for sure) when I drove it last, with an SM465 doing 60-ish, 33s, not sure of the diff gearing, I assume stock, and the SPID plate says 3.73. Another thing last time I drove it, it was about a 35 mile trip, 80% on highways. About halfway through, while on the highway, it started losing power and slowed down to about 52 and was running rough. After a moment, it straightened out and was ok the rest of the drive... And, I've been hearing an almost constant lifter or valve chatter. Sounds to me like all of this is related.
Do you think I really need to do main and rod bearings and rings, or do you think I can get away with just gaskets and seals?

Thanks again!

It sounds like the engine is old and tired. Putting seals and gaskets on it will be like putting lipstick on a pig.
For $hits and giggles, do a leak-down test to see what shape the cylinders are in. Even if it passes, I would be concerned about all the valve train noise you mentioned in your last post.
Here's what I'd be doing ----->https://www.summitracing.com/int/parts/hpe-hp291p

[cleszkie]

I would bet dollars to donuts that your aftermarket valve cover on the driver side has no oil baffle beneath the PCV valve port. When this is the case, the engine is able to pull an amazing amount of oil through the PCV valve and into your carb where it is sent into the engine to be burned along with your air/fuel mixture. Get a set of valve covers with the proper oil baffles in place and you will find that your oil consumption issue goes away. This exact thing happened to me, but I was running a brand new custom built engine. I wanted to use some cool old cast aluminum valve covers that had no oil baffles. The engine went through oil like nobody's business. I swapped on a set of valve covers with oil baffles, and oil consumption disappeared.

Also note that your plugs are probably really fouled at this point. So after you fix the oil baffle problem, clean your plugs or get a new set.

[vancelot69]

one thing I am addicted to with FB - being able to "like" posts. Thanks for all the replies.

[vancelot69]

cleszkie: can I tell if the valve covers are baffled without removing them, or do I have to take them off to tell?

[hemi43]

Originally Posted by vancelot69

cleszkie: can I tell if the valve covers are baffled without removing them, or do I have to take them off to tell?

remove the PCV valve, and look into the valve cover. There should be a sheet metal baffle which will prevent you from seeing the rockers.

[vancelot69]

ok, I pulled the PCV valve off looked in the cover and I can see the rockers...

So, short of getting "new" valve covers right this second, would it be ok to remove the PCV, cap off that line going into the carburetor, and put a breather on the driver's side valve cover for now? I want to drive it this weekend to an off road event, so if I need to get valve covers right now, would valve covers off a 70's or 80's 350 from a junk yard fit?

[hemi43]

Originally Posted by vancelot69

ok, I pulled the PCV valve off looked in the cover and I can see the rockers...

So, short of getting "new" valve covers right this second, would it be ok to remove the PCV, cap off that line going into the carburetor, and put a breather on the driver's side valve cover for now? I want to drive it this weekend to an off road event, so if I need to get valve covers right now, would valve covers off a 70's or 80's 350 from a junk yard fit?

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[hemi43]

Originally Posted by hemi43

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You can't plug off the pcv hose going to the carb. If you do your engine will run way too rich. What you could do is make an improvised puke can. It may take a bit of screwing around, but what you need to do is get a canister or even a jar that won't collapse under a bit of vacuum. Run a hose from the valve cover to this can, then another hose from the can to the pcv valve. The idea is to trap the oil in the can and preventing it from being sucked in the intake. This is a trick we use on turbo cars to prevent oil ingestion. As far as rocker covers, they will all fit until the late 80s when GM came out with the hold down bolts that went through the top of the cover. I actually machined some of the tooling that went into making the progressive die that stamped these "new" rocker covers back in the 80's.
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[vancelot69]

Went to my dad's this weekend to see if we had any valve covers laying around, and we did, but I only found 3, and, having been over 20 years since I did any engine work to any of our Chevy's out there, the 3 valve covers I found all look identical, that is, none of them have an oil filler cap, and right now I'm at work and can't look at my engine, but I don't think it has a separate oil filler neck. I can go back down when I have more time and dig in the garage and see if I can find any more covers.

It would look dumb, but maybe for now, I put one of those baffled valve covers on the driver's side and vent the passenger's side but leave the chrome cover on and see if that helps with the oil consumption.

He also had this old set of non-PCV valve covers sitting out there!

[cleszkie]

Please let us all know if your oil consumption dramatically drops when you swap on a valve cover with oil baffles. It seems like such a minor detail, but makes such a big difference. My new engine was going through quarts of oil too until I made the fix.

Oh yeah - don't forget to check your plugs. They will be VERY fouled at this point. Your performance will certainly improve with cleaned or new plugs. You will notice that the plugs that have the closest intake runners to the PCV port on your carb base will be the most fouled.

[Walter White]

interesting read. earlier you said the bell housing is dry--how wet is it elsewhere?

i think i would pressure wash it, take it for a drive, park it on cardboard then visually look for leaks. if it comes home dry it would be safer to assume it's burning the oil.

have you looked at the plugs yet?