Newbie 318 questions

[Flathead38]

Hi all, I am a newbie trying to help my brother return a '69 Charger to the road for his son (see my intro). I have some basic 318 questions I was hoping to get some answers on...

We are tearing into the original 318 to fix a leaky left head gasket (I hope that's all it is). The engine has not been apart for 40 years, and has an Edelbrock LD4B intake manifold. When I pulled the intake, a couple of questions came to mind... The heads will come off in the next day or two, and then I'll probably have more questions...

1) The block has 4 coolant passages (2 on each bank) that mate with the intake, in the very front, and in the very rear. The Edelbrock manifold has corresponding openings only for the front pair. Why are the rear two passages disabled/blocked off?

2) Unfortunately there is considerable corrosion at the coolant ports in the aluminum intake, but it's in good condition otherwise. Is it feasible to weld them to restore the ports?

3) In the very center of each head, there is a port that mates with the intake, whose purpose is not obvious to me... In our case, these ports, right and left, are almost completely plugged with carbon. What is their purpose, and what would cause the excessive buildup? Blow by from a forty-year-old engine (although it doesn't really smoke much when running)?

To head off the "dump the 318 and stab in a big block" comments, I am helping my brother's high-school age son get this running, and that's not viable option for him for now...

 

[WileE]

Probably best to provide pix for your first 2 queries. The heat crossover passage you refer to is a common problem with carbon build up.... clean it out.

 

[Flathead38]

I might have a clue on question 3. Looks like the original factory manifolds had manifold heat control valves that must have connected somehow to these passages...? Our car has headers, and so I presume the original manifold heat function was just disabled. Am I on the right track?

 

[Flathead38]

In response to WileERobby, here are pictures of the gasket surfaces of the head, our corroded intake, and a NOS intake. You can see that the head has two coolant ports, but the intake has only one...

 

[RemCharger]

In response to WileERobby, here are pictures of the gasket surfaces of the head, our corroded intake, and a NOS intake. You can see that the head has two coolant ports, but the intake has only one...

View attachment 1437970

View attachment 1437971

View attachment 1437972

That's the way smallblock chevy, ford and dodge are. Big block chevs n ford's too

 

[451Mopar]

The heads are a single casting so they can go on either side of the engine. That is why there is water passages on each end.
The basic cooling flow is from the bottom of the radiator into the pump, then the pump pushed the water into the block. The head gasket covers the holes on the front of the block (you will see if you pull a head) and forces the water to flow from the front of the block to the rear of the block where the water then enters the rear of the cylinder head and flows toward the front. Then into the intake manifold to the thermostat, and back to the top of the radiator. There are some small block to head holes in the head gasket to get air out and equalize the cylinder head temps.
The center hole is the exhaust cross-over. It actually goes into one of the center exhaust ports. When it is cold, the exhaust manifold heat riser closes to force the passenger exhaust to flow through the crossover to the drivers side to heat the intake manifold. This heat also helps speed up opening the manifold mounted choke assembly on a stock intake.
Later years it also provide EGR. For performance you don't want the exhaust heating up the intake manifold, and the aluminum intakes heat up pretty easy anyhow.
The carbon build up is not a problem if the passenger heat riser valve is Open/remover, or your running headers. Really only a issue with the stock exhaust when the car is cold, after that the heat riser valve opens (if it is not stuck.)
Fel-Pro sells three different intake manifold gaskets where the crossover is blocked off. I think the small port 318 is Part # 1243?

The open horseshoe around the crossover is not sealed and is exposed to the air. I think it allows for the thermal expansion of the crossover?

The aluminum intake can be tig welded (maybe even epoxy repair) if the rust is that bad, As long as it seals, it's not a big deal what it looks like.

More than likely the leak is the core plugs in the cylinder heads, not the head gasket, but pretty much need to remove the head to get at the rear core plugs anyhow.

Check the valve guide seals, they likely need to be replaced too.

 

[69Bee]

When you reassemble the intake, do NOT use the cork end pieces for the valley rails, but rather only use silicone (I like/use Permatex Ultra-Grey). The bolt torque is also about 25 ft/lbs and not 40 ft/lbs as that is for an iron manifold. The cork end pieces will not allow the manifold to seal the water passages and dump water into the engine, could crack the manifold if you try to go to 40 ft/lbs, or both.

 

[PurpleBeeper]

These guys are all correct. I would suggest, even on a budget, to remove both heads and have a basic valve job, valve guides/seals and resurfacing done (basic head rebuild)...both heads. I would also inspect the camshaft/timing chain/lifters while in there.

 

[Davefinan]

These guys are all correct. I would suggest, even on a budget, to remove both heads and have a basic valve job, valve guides/seals and resurfacing done (basic head rebuild)...both heads. I would also inspect the camshaft/timing chain/lifters while in there.

^^^^^100%^^^^^^

 

[Flathead38]

Thanks to all for your expertise. A couple more details to share with the left head off. First, the head gasket failure that was causing the "whoosh" sound every time cylinder #7 came up on compression... Easy to see why I initially diagnosed this as an exhaust gasket failure. No erosion in the head or block deck, so I think a new gasket would fix it, but...

The third picture shows what I'll call an "occlusion" at the very top of #7 cylinder. There is also some additional minor pitting. Not sure what would cause this. My three guesses are:

1) casting defect in the block or sleeve (haven't looked yet to see if it previously was sleeved), or
2) corrosion from a water jacket into the cylinder about to wreak havoc, or
3) something corrosive in the cylinder when the car was parked for a long time, causing corrosion from the cylinder out...

We had it running and driving, and no evidence of exhaust getting into the coolant, nor of coolant forming steam in the exhaust. I presume the right way to fix this would be to sleeve the cylinder, which means total rebuild... The cylinder walls otherwise look pretty good. Would I be playing with fire to ignore the occlusion and slap it back together with new gaskets and crude valve job?

BTW, based on block and head casting numbers, pretty sure this engine is original to the car (I haven't uncovered the stamped engine # yet), but not sure that means much for a 318 car...

Thoughts?

 

[Flathead38]

The heads are a single casting so they can go on either side of the engine. That is why there is water passages on each end.
The basic cooling flow is from the bottom of the radiator into the pump, then the pump pushed the water into the block. The head gasket covers the holes on the front of the block (you will see if you pull a head) and forces the water to flow from the front of the block to the rear of the block where the water then enters the rear of the cylinder head and flows toward the front. Then into the intake manifold to the thermostat, and back to the top of the radiator. There are some small block to head holes in the head gasket to get air out and equalize the cylinder head temps.
The center hole is the exhaust cross-over. It actually goes into one of the center exhaust ports. When it is cold, the exhaust manifold heat riser closes to force the passenger exhaust to flow through the crossover to the drivers side to heat the intake manifold. This heat also helps speed up opening the manifold mounted choke assembly on a stock intake.
Later years it also provide EGR. For performance you don't want the exhaust heating up the intake manifold, and the aluminum intakes heat up pretty easy anyhow.
The carbon build up is not a problem if the passenger heat riser valve is Open/remover, or your running headers. Really only a issue with the stock exhaust when the car is cold, after that the heat riser valve opens (if it is not stuck.)
Fel-Pro sells three different intake manifold gaskets where the crossover is blocked off. I think the small port 318 is Part # 1243?

The open horseshoe around the crossover is not sealed and is exposed to the air. I think it allows for the thermal expansion of the crossover?

The aluminum intake can be tig welded (maybe even epoxy repair) if the rust is that bad, As long as it seals, it's not a big deal what it looks like.

More than likely the leak is the core plugs in the cylinder heads, not the head gasket, but pretty much need to remove the head to get at the rear core plugs anyhow.

Check the valve guide seals, they likely need to be replaced too.

Thanks for taking the time to give me a very thorough answer. This all makes perfect sense to me now.

 

[Dako]

If the owner is cash limited and you are trying to get the kid on the road...assemble and run it.
Best case, they drive and enjoy the heck out of it...as is. (Most likely)
Worst case, it doesn't hold up and you fix what fails. You will have bought two gasket kits.

Don't over think it. Get that kid on the road!

 

[Flathead38]

If the owner is cash limited and you are trying to get the kid on the road...assemble and run it.
Best case, they drive and enjoy the heck out of it...as is. (Most likely)
Worst case, it doesn't hold up and you fix what fails. You will have bought two gasket kits.

Don't over think it. Get that kid on the road!

I really appreciate the perspective. I have a tendency to be a perfectionist with all things mechanical, but my brother and I chatted tonight, and we are leaning towards doing exactly this.

 

[JR_Charger]

I agree with Dako - don't let yourself get bogged down in any particular area, or this will drag on for years. Bottom line, the car in stock condition is still 100% functional on most public roads at legal speeds. There could be some unlimited speed roads in Montana where the 318 will struggle, but mine was good to cruise at 75 at least. You don't have to win a drag race with a Tesla. Just being in a 69 Charger will make you the coolest guy pulling up to an intersection 99% of the time.

 

[1STMP]

318 questions? Where's the list ?