I'm gonna pull the engine......then what?

[saxart]

So, the engine (350 SBC) in my '70 has a leaky oil-pan gasket and leaky rear main seal. It also must have bad valve guide seals because it puffs smoke on start up. I believe it had a valve cover gasket leak before I bought it as the lower end of the engine and the top of the trans is coated in that thick, dry, old sludge you get when something "used to leak". They do not leak anymore however, so I think the PO replaced those gaskets.

Anyway....Long story short, I'm pulling the engine and tranny (4-speed, manual) out of the truck this winter so that I can replace the aforementioned gaskets as well as clean up the engine bay in the process.

Here's where your opinions come in... Should I pull the heads and replace the head gaskets while I have this engine out? I'm not seeing any signs of head-gasket deterioration, but I believe this engine is a 1974 vintage, and doesn't appear to have had any rebuild work done to it, so in other words, they're old. (If it has been rebuilt, it's been quite awhile ago.) Because of this, I'm thinking the head gaskets should be replaced "just because" as I'm guessing they don't last forever.

Any thoughts or opinions are appreciated...

[LongBox]

And then, with the heads off, do you do the lifters, because you might as well, and then the cam, cause lots of guys think they should be replaced together with the lifters, and then...

Well, you get the idea. It is hard to just "do the head gaskets", when there are other things that are mostly labour...

[saxart]

Originally Posted by LongBox

And then, with the heads off, do you do the lifters, because you might as well, and then the cam, cause lots of guys think they should be replaced together with the lifters, and then...

Well, you get the idea. It is hard to just "do the head gaskets", when there are other things that are mostly labour...

LOL! Yeah, a friend and I call that "mission creep". I'm not interested in going deep on this thing. I just want to replace the bad gaskets. No creepin' going on HERE!

[chevycheetah]

Personally, I'd go ahead and just replace them while you got it out. If you just want to do the gaskets then you'll be alright... if you decide to just do "one extra thing" (i.e. the lifters, then cam, then....) you'll have the engine out forever until you swap an LS in or god knows what else.

[MARKDTN]

I wouldn't do head gaskets unless there was a reason. If you pull it, I would pull the water pump and replace it unless it is very new. I would replace the timing chain and oil pump (and pickup). I would do new oil pan and timing cover gaskets and intake gaskets. If the lifter galley is fairly clean I would no go deeper. In my experience once you start blasting the gunk out of the lifter galley you will have gunk in the oil pan later that will clog the oil pump pickup. I have had that with 2 different 318 Dodge engines. If the lifter galley is all gunked up, then a complete rebuild is what I would do. Actually I would get a 1-piece seal core to rebuild instead of the original. The 1-pc seal engines and center-bolt valve covers cut out SO MANY leaks it is not even worth messing with the old stuff unless you need numbers matching.

[Coley]

Gaskets are cheap.
When you have the engine out do as many as you can while you have good access.
Just be prepared to possibly repair anything you find while/when its out.

C.

[GRX]

Same. Would not do the head gaskets unless there is a reason. Highly recommend you replace ALL the freeze plugs while it's out.

[davepl]

It's either a cosmetic or a mechanical project. So far it's a cosmetic (leaks and cleanup). I'd keep it that way. Otherwise, once you're into it for head gaskets, why not main bearings?

Know your goal, don't get sidetracked!

[In The Ten Ring]

Originally Posted by saxart

LOL! Yeah, a friend and I call that "mission creep". I'm not interested in going deep on this thing. I just want to replace the bad gaskets. No creepin' going on HERE!

"Mission creep," oh I love that! If my truck's fuel system was a bridge that needed to be blown, then mission creep turned into a full-on invasion of the Continent of Europe.

In my case I knew I had the time if not really the space, to allow mission creep. If you do not, then you may be able to stay focused. Good luck!

[GASoline71]

Trust me... once you pull that intake manifold off of a 40+ year old engine and look at the lifter valley... You might end up tearing it apart anyways.

Ask me how I know...

Gary

[In The Ten Ring]

Originally Posted by GASoline71

Trust me... once you pull that intake manifold off of a 40+ year old engine and look at the lifter valley... You might end up tearing it apart anyways.

Ask me how I know...

Gary

That's how it is! When I first started on my truck in 2013, I thought "I'll have her going in 3 weeks." Well, it's been three years and she's still in pieces all over!

My motto, "well, while I have this off I might as well.....

[69chevytrucker]

if you are pulling the engine the gaskets come in a kit so do them all. but like others have said you could open a can of worms. if you do then you save cause if the worms are there get them now cause do you want to put the engine back in just to find out it is full of worms and then have to pull it again?

[saxart]

Originally Posted by davepl

It's either a cosmetic or a mechanical project. So far it's a cosmetic (leaks and cleanup). I'd keep it that way. Otherwise, once you're into it for head gaskets, why not main bearings?

Know your goal, don't get sidetracked!

Thanks for ALL of the thoughts so far guys. I really appreciate it. I think Davepl hit the nail on the head. This is strictly a COSMETIC project. I don't plan on getting wrapped up in any mechanical repairs unless something looks truly ugly after opening it up.

I'm fortunate from the stand point that I've already gotten sucked up into projects in the past so I know how easily it can happen. Case in point... Here is a 1969 John Deere 140 garden tractor I used to own. I spent hundreds of hours and way too much money on it!

[69chevytrucker]

Originally Posted by saxart

Thanks for ALL of the thoughts so far guys. I really appreciate it. I think Davepl hit the nail on the head. This is strictly a COSMETIC project. I don't plan on getting wrapped up in any mechanical repairs unless something looks truly ugly after opening it up.

I'm fortunate from the stand point that I've already gotten sucked up into projects in the past so I know how easily it can happen. Case in point... Here is a 1969 John Deere 140 garden tractor I used to own. I spent hundreds of hours and way too much money on it!

i work for JD thats nice we have a guy at work that does that to old tractors good job

[Mike_The_Grad]

I attempted the same "cosmetic" refurbishing as my 72 c10 sat in my driveway for about 8 years with no hood and no tarp.(tarps start getting expensive...) started with fuel system,drop and clean tank,new sending unit,new rubber hoses,new fuel pump,new filter,rebuilt the original q-jet. New battery and the damn thing fired up. So, I said "hey it runs, why not clean it up,replace a few gaskets and repaint it,drop it back in?" So thats what I did. New freeze plugs,oil pan gasket, timing cover gasket, and that's when my plan suddenly became the unplanned... I had about 1/2"-3/4" of play in my timing set. (Engine ran like a top.) OK, new double roller timing set for $35, continuing with the plan. Pulled intake and found 20 years of carbonized oil in the sheet metal shield riveted under the intake.(that was a lot of fun to clean without removing those rivets.the rivets can be removed and replaced I found out way to late.) New valve cover gaskets,water pump was replaced, exhaust header gaskets, new no-name HEI distributor,plugs,wires, and a chevy orange paint job done in my shed to finish it off. I didn't touch anything inside the block,didn't touch the heads. I got 4,000 miles out of it and blew a head gasket... I guess letting the truck sit all that time exposed to the elements with plain Ole tap water sitting in the block and then trying to breathe new life into it was a little too much for those 20 year old head gaskets...lol. so I had a new plan. "Replace head gaskets and be back on the road by the end of the week." Sure. "Unplanned" became a frequently used word in my vocabulary from then on out. Long block-short (see what I did there? 16 months later I have a .04 over bore block that was also decked, a Comp Cam RV kit, reman 882 heads, new valve train with roller tipped rockers,and a corvette oil pump. All assembled by myself in my garage with only my tools,service manual,YouTube,google (mostly this website), and a "heck, if someone else can do it,I can do it"-attitude. 15k miles later it still starts and goes down the road.(also rewired the entire truck headlights to taillights with an American autowire kit myself.) What I'm getting at is, consider what would happen if it didn't go as planned. Could you afford (time and financially)to do it twice if something were to happen? Luckily I was able to,being unemployed and having some money stashed from the previous job coincidentally was the only way I could. I wasnt happy about it either. But I did learn alot.

[saxart]

Originally Posted by Mike_The_Grad

I attempted the same "cosmetic" refurbishing as my 72 c10 sat in my driveway for about 8 years with no hood and no tarp.(tarps start getting expensive...) started with fuel system,drop and clean tank,new sending unit,new rubber hoses,new fuel pump,new filter,rebuilt the original q-jet. New battery and the damn thing fired up. So, I said "hey it runs, why not clean it up,replace a few gaskets and repaint it,drop it back in?" So thats what I did. New freeze plugs,oil pan gasket, timing cover gasket, and that's when my plan suddenly became the unplanned... I had about 1/2"-3/4" of play in my timing set. (Engine ran like a top.) OK, new double roller timing set for $35, continuing with the plan. Pulled intake and found 20 years of carbonized oil in the sheet metal shield riveted under the intake.(that was a lot of fun to clean without removing those rivets.the rivets can be removed and replaced I found out way to late.) New valve cover gaskets,water pump was replaced, exhaust header gaskets, new no-name HEI distributor,plugs,wires, and a chevy orange paint job done in my shed to finish it off. I didn't touch anything inside the block,didn't touch the heads. I got 4,000 miles out of it and blew a head gasket... I guess letting the truck sit all that time exposed to the elements with plain Ole tap water sitting in the block and then trying to breathe new life into it was a little too much for those 20 year old head gaskets...lol. so I had a new plan. "Replace head gaskets and be back on the road by the end of the week." Sure. "Unplanned" became a frequently used word in my vocabulary from then on out. Long block-short (see what I did there? 16 months later I have a .04 over bore block that was also decked, a Comp Cam RV kit, reman 882 heads, new valve train with roller tipped rockers,and a corvette oil pump. All assembled by myself in my garage with only my tools,service manual,YouTube,google (mostly this website), and a "heck, if someone else can do it,I can do it"-attitude. 15k miles later it still starts and goes down the road.(also rewired the entire truck headlights to taillights with an American autowire kit myself.) What I'm getting at is, consider what would happen if it didn't go as planned. Could you afford (time and financially)to do it twice if something were to happen? Luckily I was able to,being unemployed and having some money stashed from the previous job coincidentally was the only way I could. I wasnt happy about it either. But I did learn alot.

Great post Mike! This post not only describes some of what I've already done, but also some future plans for the truck. Ironic! You make some great points here. (I'll certainly research how to remove those intake sheet metal rivets) Your story pretty much nails down why I feel like head gaskets need to be a part of this whole process. You've also confirmed that all bets are going to be off (and fingers will be crossed) when I do open up that engine. Who knows what I'll find inside!

Thanks again for ALL of the posts to this thread. This really is a great resource for these old trucks!

[chevytruckguy70]

I'd stay away from removing the heads of any sbc with more than 20,000 miles on it. The pistons rings are only designed to seat once. Removing the heads and then retorqing them again during install will change the roundness of the cylinders. The rings will not conform and it doesn't take long to start seeing smoke AFTER the initial valve seal puff once started.

If the heads come off, the cylinders need honing (at least) and the rings replaced.

And if you're doing that you may as well .........

[saxart]

Originally Posted by chevytruckguy70

I'd stay away from removing the heads of any sbc with more than 20,000 miles on it. The pistons rings are only designed to seat once. Removing the heads and then retorqing them again during install will change the roundness of the cylinders. The rings will not conform and it doesn't take long to start seeing smoke AFTER the initial valve seal puff once started.

If the heads come off, the cylinders need honing (at least) and the rings replaced.

HUH???? I'm certainly no engine expert, so you certainly may know more than me, but how does torquing the head back on "change the roundness of the cylinders"? I can see that one would need to replace the head-studs because they stretch, but I don't get how the entire block could be pulled into a different shape.

Again, I'm not claiming to be an expert, so I'm not trying to shoot you down, just want to be fully informed.

[chevytruckguy70]

Originally Posted by saxart

HUH???? I'm certainly no engine expert, so you certainly may know more than me, but how does torquing the head back on "change the roundness of the cylinders"? I can see that one would need to replace the head-studs because they stretch, but I don't get how the entire block could be pulled into a different shape.

Again, I'm not claiming to be an expert, so I'm not trying to shoot you down, just want to be fully informed.

When the cylinders are bored and honed the block is not under any stress from the head bolts. As the heads are tightened the stress causes the sides of the cylinders to pull slightly. That's why there's a pattern to follow as you tighten. The rings will wear into the slightly out of round (.003" or so) during the break in period of the engine. They are designed to do this once. By taking off the head the cylinder relaxes. Reinstalling it will cause the cylinder to stress again, but not the same as before. The old rings can't wear in to the new shape. It doesn't take much to cause an oil ring to allow oil by.

Anytime anything metal is torqued it changes shape. Even it it's minor. It's easy to see when heads are put on and a cylinder bore is checked through the bottom of the engine without Pistons installed.

I'd just recommend not doing it
Posted via Mobile Device

[saxart]

Originally Posted by chevytruckguy70

When the cylinders are bored and honed the block is not under any stress from the head bolts. As the heads are tightened the stress causes the sides of the cylinders to pull slightly. That's why there's a pattern to follow as you tighten. The rings will wear into the slightly out of round (.003" or so) during the break in period of the engine. They are designed to do this once. By taking off the head the cylinder relaxes. Reinstalling it will cause the cylinder to stress again, but not the same as before. The old rings can't wear in to the new shape. It doesn't take much to cause an oil ring to allow oil by.

Anytime anything metal is torqued it changes shape. Even it it's minor. It's easy to see when heads are put on and a cylinder bore is checked through the bottom of the engine without Pistons installed.

I'd just recommend not doing it
Posted via Mobile Device

Thanks for the quick reply. I certainly understand the CONCEPT, I guess I just don't "buy" the thought that bolting down a head will move a cylinder block. I've rebuilt enough small engines to understand how tight of a tolerance the rings have with regards to sealing (compression) but this is the first time I've heard of something like this. How can a head stretch an engine block? I could see the HEAD bending slightly, or the studs stretching, but the block?? I'm doubtful....

Again, please don't think I'm "dissin'" on your knowledge. It sounds like you have more experience than I do.

Has anyone else heard about this kind of thought?

[69chevytrucker]

Originally Posted by chevytruckguy70

When the cylinders are bored and honed the block is not under any stress from the head bolts. As the heads are tightened the stress causes the sides of the cylinders to pull slightly. That's why there's a pattern to follow as you tighten. The rings will wear into the slightly out of round (.003" or so) during the break in period of the engine. They are designed to do this once. By taking off the head the cylinder relaxes. Reinstalling it will cause the cylinder to stress again, but not the same as before. The old rings can't wear in to the new shape. It doesn't take much to cause an oil ring to allow oil by.

Anytime anything metal is torqued it changes shape. Even it it's minor. It's easy to see when heads are put on and a cylinder bore is checked through the bottom of the engine without Pistons installed.

I'd just recommend not doing it
Posted via Mobile Device

i have never heard that before i have pulled a lot of heads and never had a issue i would really have to say that sounds a little crazy

[LongBox]

Actually, I have heard that racing engine builders will put a plate on the top of the block, torque it to spec, then hone the cylinders. The theory is that the cylinders will then be round when the head is torqued during the build.

Back to the OPs question: I still believe that this is about peace of mind, and convenience. I don't know what options are on his truck, but on my 69, with no power brakes and no power steering, everything is pretty accessible when the engine's in the truck. I do think it is worthwhile to do the timing set and the head gaskets, and to "play it by ear" on the rest of the motor, depending on what you see when you lift the manifold off the valley.