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Emissions 318 cylinder head question #1447546
06/04/13 02:52 PM
06/04/13 02:52 PM
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North Central Florida
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eightlitermopar Offline OP
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I have a basic question regarding production 318 cylinder heads being used on older, non-emission engines.

This is a picture of a 318 head, casting 4027593 (production run 1977 to 1984)

The arrows point to holes which I assume is part of the emissions system (air pump or something?)

If I were to use heads like this on a motor with older exhaust manifolds or headers, how would I block off these holes? If not blocked off, it appears it would be an exhaust leak?

Just curious. Thanks!

Eightlitermopar

7730758-318head.jpg (4712 downloads)

Mopar or no car
Re: Emissions 318 cylinder head question [Re: eightlitermopar] #1447547
06/04/13 03:17 PM
06/04/13 03:17 PM
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Iowa
burdar Offline
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I did this on the heads I was going to use for my 318. The holes are easily tapped and plugged with set screws.

Re: Emissions 318 cylinder head question [Re: eightlitermopar] #1447548
06/04/13 05:03 PM
06/04/13 05:03 PM
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Florida
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scratchnfotraction Offline
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most times used they are plugged with carbon.

but when a VJ and cleaning are done,the ports can be tapped and set screws used. make sure the are counter sunk a little for the header/manifold gasket/flange seal.

when I find them pluged with carbon and doing a home VJ on them. I run a drill bit in a 1/2" or so, then fill them with the Copper RTV or JBWeld.

i have also run a drill bit all the way thru to clean the passage,then use brass round stock to hammer into the hole. then brad the end over and file flat with the gasket flange.

most times I just hit them with the copper rtv,I run headers and coat both side of the header gasket with the copper RTV for no exhaust leaks.

if youhave a roller cam block and run roller lifter/PRs you need to enlage the PR holes in the early LA heads.

LA heads got the large PR holes in 85 whhen the 318 went roller cam.

Re: Emissions 318 cylinder head question [Re: burdar] #1447549
06/04/13 05:05 PM
06/04/13 05:05 PM
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North Central Florida
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eightlitermopar Offline OP
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Ok, cool! Seems easy enough.

Also, to hijack my own thread here:

These heads are pretty low mile heads, but I have 2 valves that leak just a little.

Can I lap just those two leaky valves or should I just lap all of them? I have never lapped valves before. I figure, "if it ain't broke don't fix it" but I might be wrong here.

Ideas?

thanks!

eightlitermopar


Mopar or no car
Re: Emissions 318 cylinder head question [Re: scratchnfotraction] #1447550
06/04/13 05:08 PM
06/04/13 05:08 PM
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North Central Florida
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eightlitermopar Offline OP
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Quote:


when I find them pluged with carbon and doing a home VJ on them. I run a drill bit in a 1/2" or so, then fill them with the Copper RTV or JBWeld.




I was wondering about JBweld as opposed to tapping them and using a set screw. Any problems with the JB weld not holding up over time?


Mopar or no car
Re: Emissions 318 cylinder head question [Re: eightlitermopar] #1447551
06/04/13 05:13 PM
06/04/13 05:13 PM
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Lincoln Nebraska
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RapidRobert Offline
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I'd suggest tap em then screw in some studs with thread lock. JB weld may or may not hold (cleaning is the key) but it'd sure be a pain if you had to redo em. I'd lap all the valves while you're at it


live every 24 hour block of time like it's your last day on earth
Re: Emissions 318 cylinder head question [Re: eightlitermopar] #1447552
06/04/13 05:14 PM
06/04/13 05:14 PM
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dogdays Offline
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"leak just a little"
That's a can of worms!

Sure, go ahead and lap but if after 20 or so seconds if you don't get good contact patterns on each side they need more attention.

Keep in mind that as valves heat and expand more than the heads, the lapped areas will probably not be in contact with each other any more.

The holes are for AIR injection. Mopar ran the air into a separate passage in the exhaust manifold, then into the head exhaust ports through those holes. I drilled them out, tapped for 1/4-20 threads, then screwed in some junk screws and cut off the heads. Done. Use thread locker? Hardly necessary. But when threading, use plenty of lubricant. I managed to break off a tap in one of the holes. That one I plugged from the inside with some goop I had around.

Seeing how easily they plug with carbon I am sure just filling them with JBWeld would suffice in blocking them off.

R.

Last edited by dogdays; 06/04/13 05:20 PM.
Re: Emissions 318 cylinder head question [Re: dogdays] #1447553
06/04/13 06:38 PM
06/04/13 06:38 PM
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North Central Florida
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eightlitermopar Offline OP
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Quote:

"leak just a little"
That's a can of worms!

Sure, go ahead and lap but if after 20 or so seconds if you don't get good contact patterns on each side they need more attention.

Keep in mind that as valves heat and expand more than the heads, the lapped areas will probably not be in contact with each other any more.

The holes are for AIR injection. Mopar ran the air into a separate passage in the exhaust manifold, then into the head exhaust ports through those holes. I drilled them out, tapped for 1/4-20 threads, then screwed in some junk screws and cut off the heads. Done. Use thread locker? Hardly necessary. But when threading, use plenty of lubricant. I managed to break off a tap in one of the holes. That one I plugged from the inside with some goop I had around.

Seeing how easily they plug with carbon I am sure just filling them with JBWeld would suffice in blocking them off.

R.




I know, I am debating how much I want to mess with this. My original 1969 castings are at the machine shop right now getting checked out, but it will be another week before he even looks at them. His "to do" list is lined up on the shop floor around the corner!

I thought I would look at these due to the hardend seats.

So, in the mean time I am just puttering around with what I have.

I am done spending a lot of money on this motor, and I am just ready to get it back on the road.

I know I can get a set of done, ready to bolt on 302 castings for $430 a pair. Perhaps I'll eventually go with that.

I'm just looking at all my options right now.


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Re: Emissions 318 cylinder head question [Re: eightlitermopar] #1447554
06/04/13 06:57 PM
06/04/13 06:57 PM
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Florida
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scratchnfotraction Offline
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I would take that 430$ and get a used engine with a 90 day warranty.

rolling the dice you have crapped out with mag heads,looking at worn heads,waiting on old heads.

I bring a JY engines home,strip and clean them,change all gaskets exept head gaskets,3 cans of plasticoat hemi orange and they look new.

300$ for a 91 318,I just swaped in my lunati roller cam/comp 901 spring with heads on engine.

picked up another 88 roller cam 318 for 300$ used with 90 day warranty.fixin to pop a roller whiplash in this one and let it rip rollin the dice for 800$

less time & $$$ in the long run with lots more fun wearing/breaking used junk along the way for me.

even the 440 in my sig pic was a 300$ engine I built the truck around,70,000 miles on the clock and runs great.

give you local JY a call while you wait and see what they have on the cheap.

I feel your pain with all that has gone wrong on your project latly.


Last edited by scratchnfotraction; 06/04/13 06:59 PM.
Re: Emissions 318 cylinder head question [Re: eightlitermopar] #1447555
06/04/13 07:01 PM
06/04/13 07:01 PM
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dogdays Offline
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Mess with them, what do you have to lose?

On my 302s the factory valve job is one angle, as far as I can tell. I spent about a day home porting them, I hope they flow better. I also cut down the guides for more retainer to guide clearance. Done in 15 minutes after I had the tool. I kept the same OD, 0.625" so I could use the stock stem seals.
Valve springs from the roller cam heads are stronger than stock springs on your heads.

But one could do the plugging in an hour, easily.

R.

Re: Emissions 318 cylinder head question [Re: scratchnfotraction] #1447556
06/04/13 07:06 PM
06/04/13 07:06 PM
Joined: Mar 2005
Posts: 1,630
North Central Florida
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eightlitermopar Offline OP
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Quote:

I would take that 430$ and get a used engine with a 90 day warranty.

rolling the dice you have crapped out with mag heads,looking at worn heads,waiting on old heads.

I bring a JY engines home,strip and clean them,change all gaskets exept head gaskets,3 cans of plasticoat hemi orange and they look new.

300$ for a 91 318,I just swaped in my lunati roller cam/comp 901 spring with heads on engine.

picked up another 88 roller cam 318 for 300$ used with 90 day warranty.fixin to pop a roller whiplash in this one and let it rip rollin the dice for 800$

less time & $$$ in the long run with lots more fun wearing/breaking used junk along the way for me.

even the 440 in my sig pic was a 300$ engine I built the truck around,70,000 miles on the clock and runs great.

give you local JY a call while you wait and see what they have on the cheap.

I feel your pain with all that has gone wrong on your project latly.






Thanks scratchin' I have learned a lot from trying to do this magnum build. The heads are currently stripped in the scrap pile. Now that I know what to look for, the seats were pitted, worn to one side and possibly cracked. The machine shop didn't think it would be worth it to try to redo....and I agree.

So now I have 3 sets of LA 318 heads I can work with. The short block is fresh and ready to roll. I have all the parts except for worry free cylinder heads.

Now, if the motor runs like crap with new heads, I just may scrap the whole stupid car!

This is all part of learning though, right?

Which reminds me...scratchin, you are close to clearwater cylinder head. What do you know about the work they do? Good, bad, avoid? It was their heads I was scoping out on ebay.

eightlitermopar


Mopar or no car
Re: Emissions 318 cylinder head question [Re: eightlitermopar] #1447557
06/04/13 11:13 PM
06/04/13 11:13 PM
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Florida
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scratchnfotraction Offline
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Florida
yes, i hear good things about them. and they are about 30 miles or so from me in clearwater.

check out odessa cyl heads here in fl they are 30 the other way from me.

IIRC,clearwater cylheads have the EQ heads that have the magnum chamber ports with the LA intake bolt pattern

these seem to be the best heads now days they are good up to 450 HP

i was looking at a pair moparts member Goldmember has when I was at his place a few weeks ago.

I will be doing a set of the EQ heads soon myself.

let me know if you need anything on this end with them.







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