Mopar Performance R/T Head Fiasco

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DionR

DionR

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Plenty of people have bolted Magnum heads on their early blocks, with virtually no problems (with the right lifters and pushrods). I should have known better than to think it would work that well for me.

I ***umed that because the factory heads bolted on fine, the aftermarket MP cast iron R/T heads would also.

Picked up what I thought was a good set for a reasonable price to make the conversion about a year ago. Decided in December to get them checked just to make sure they were ok, ended up that 4 of the valves were bent because the guides had been knurled and the stems seized in the heads. $280 and (4) new valves later, I have a good set of heads. That should have been my first clue this wasn't going to go well.

Set one of them on the motor yesterday, and dropped a couple of pushrods in to check the length of the MP conversion pushrods. Length checked out ok, but the heads don't have sufficent clearance for the pushrods (top or bottom). :(

Parts016.jpg


Parts017.jpg


I'd heard rumors about it, but hadn't seen it before, so I wasn't entirely surprised. Doesn't look like something that you can fix with a drill bit, either.

In addition to that, the exhaust flange doesn't have sufficent material around the port on the bottom to seal to the manifold and allow me to run the 340 freeflows I had on the car.

Parts018.jpg


If I spring for the roller lifters and cam, I can avoid the pushrod problem, but I'm not sure what to do about the exhaust. I could run a right side Jeep mainfold, but the left needs to be the A-Body specific one.

My buddy had a set of production magnum heads, so set one of those on the block, and neither of these issues exists with those heads. Just the MP R/T heads. Figures.

Just figured I would share, in case I saved someone else the same grief.

Anyone want a set of 1.92/1.625 cast iron R/T heads, ready to run? Only $700 plus shipping. ;-)
 
Its not that far off, both problems. Those push rod holes could be opened up. I would not use a drill, the hole just needs opening on one side. A rat tail hand file could do it if U don't mind spending 100 hours filling, lol. Really a good machine shop should be able to do it and going up U should not hit water.

As for the exhaust ports, how does the manifold fit?? The gaskets some times are larger than the ports. U can lay the gaskets on the exhaust manifolds and see. The 273/318 engines use smaller exhaust gaskets, so no problem there. I got a feeling the smaller gaskets will seal and U might luck out and get an 1/8, even a 1/4 inch seal. With some rtv and free flowing mufflers it should seal ok.
 
dodge freak said:
A rat tail hand file could do it if U don't mind spending 100 hours filling, lol. Really a good machine shop should be able to do it and going up U should not hit water.
Click to expand...

Not sure I want to take them to a shop again, and I know for certain I don't want to work all of that cast iron with a rat tail file. :)

dodge freak said:
As for the exhaust ports, how does the manifold fit?? The gaskets some times are larger than the ports. U can lay the gaskets on the exhaust manifolds and see. The 273/318 engines use smaller exhaust gaskets, so no problem there. I got a feeling the smaller gaskets will seal and U might luck out and get an 1/8, even a 1/4 inch seal. With some rtv and free flowing mufflers it should seal ok.
Click to expand...

The R/T ports almost match the 318 gaskets, only a bit wider. The problem is, the gasket I showed in the picture matches the port in the manifold. Basically, the bottom of the port in the manifold starts where the sealing surface on the head stops. The only hope I have there is, I didn't put some bolts in the holes in the gasket, and check to see if I had any slop to push the gasket up. If so, I might be able to scoot the manifold up a skosh and get maybe a 1/16" of an inch of overlap between the head and manifold. Pretty thin, though.
 
Dion, what is the pushrod thickness? Could you use a skinnier pushrod?

I'm sure there is a different gasket (Exhaust) that could work for you.
 
It would be cheaper to run 1.65 or a 1.7 rocker to avoid the pushrod issue than a whole roller setup. But this is an easy fix, just get in there and make the room for the pushrod. A file will work, and it really doesnt take that long. Geat a good new sharp file and it will be done in no time. Elbow grease if free.

As for the old manifold on the new magnum heads, they are going to be a problem. If you are willing to spend the $ for a roller setup, I think you would be better off going with a set of headers instead.
 
MRL, being that the pushrod has a interfearance at top and bottom, ya think it would be cheap (From your point of view and cost) to have it machined instead of a file?

HOw much are the 1.65 rockers?

Still wondering if thinner pushrods would work. If those are 3/8's P-rods, then the 5/16 should clear I think.
 
If your on a budget, there is nothing wrong with filing it. Doesnt really matter if you pay some machine shop to do it, or do it yourself. Those are 5/16 pushrods in the pic. This is the issue running a Mgnum head with a flat tappet cam. You dont need a ton of room for the pushrod, .020-.030" will do.
 
Maybe it's just me but are the head locating dowels drilled too low in the head? (head too low on deck)
 
I guess you'd better drive them over to Coeur d'Alene and drop them off. I can tell that you don't want to fight with them anymore.
 
Mr Hemi said:
Maybe it's just me but are the head locating dowels drilled too low in the head? (head too low on deck)
Click to expand...

It looks like the front of the drivers side head is about a 1/16" too low...???

He has the dowels in correct??
 
The pushrod issue is a simple fix. I had the same problem and I borrowed a rotary cutter that you use with an electric drill. (dye grinder) I had plenty of room in about 15 minutes.

Jack
 
MRL Performance said:
This is the issue running a Mgnum head with a flat tappet cam.
Click to expand...

I tried a set of production Magnum heads, and neither of these issues exist. This is a problem because I am trying to use the R/T heads.

The pushrods are 5/16", so that wont fix it.

Not clear on the rockers, are you saying that a different ratio will fix this? I'm already bumping up against the issue of not enough retainer clearance, so that might be a different issue.

Not sure what is up with the head on the block. I noticed it when I bolt the head on, but wasn't worried about it. The block has the dowels, and they haven't been re-located. The head had a couple of bolt in it, too. As far as I know, the head hasn't been milled, but who knows. Hopefully there is still sufficient clearance for the intake to bolt down.
 
Coyote Jack said:
The pushrod issue is a simple fix. I had the same problem and I borrowed a rotary cutter that you use with an electric drill. (dye grinder) I had plenty of room in about 15 minutes.

Jack
Click to expand...

You're running R/T heads?
 
For the exhaust issue, I have heard of people who were planning on using dakota manifolds.
Unfortunately I havent heard back from any of them...anyone know?

I know they will work on the head, but will the exit clear?
 
The passenger side isn't an issue, a stock Magnum manifold would work fine.

There is a thread on here where a guy got one to work on the left side by shimming the motor on the driver's side, grinding a notch in the manifold, and trimming the column sleeve, all in an early A-Body. Not something I want to do.

I've thought about an 1/8" plate sandwich between the head and manifold, with the hope that it create enough overlap to seal the port.
 
damnimcooltom said:
I guess you'd better drive them over to Coeur d'Alene and drop them off. I can tell that you don't want to fight with them anymore.
Click to expand...

You're right, I should just bring them over. Heads are free, but gas is gonna cost you about $700 for me to get them to you. :grin:
 
U could open up the bolt holes on the exhaust manifold to sneak it up a bit. A thin bead of rtv on both sides of the gasket and it should hold. If it does leak, it won't be like loud as heck. I try it and see and go from there.

A new file can do wonders. At least you didn't bolt the heads on
 
DionR said:
The passenger side isn't an issue, a stock Magnum manifold would work fine.

There is a thread on here where a guy got one to work on the left side by shimming the motor on the driver's side, grinding a notch in the manifold, and trimming the column sleeve, all in an early A-Body. Not something I want to do.

I've thought about an 1/8" plate sandwich between the head and manifold, with the hope that it create enough overlap to seal the port.
Click to expand...


Gotcha. I know I remember this being mentioned, but never heard how it worked out. Now I know!:iconbigg:
 
DionR said:
You're running R/T heads?
Click to expand...

I have the stock magnum heads with lots of work done on them. The issue is the same on either head. I didn't have the issue until I went to roller rockers. I only had 4 that were touching but I opened up all of the pushrod holes a little. You are only talking a few thousands to get the clearance that is needed.

Jack
 
Coyote Jack said:
I have the stock magnum heads with lots of work done on them. The issue is the same on either head. I didn't have the issue until I went to roller rockers. I only had 4 that were touching but I opened up all of the pushrod holes a little. You are only talking a few thousands to get the clearance that is needed.

Jack
Click to expand...

I tried a set of stock heads the same day and had plenty of clearance with that set. They were pretty much wide open in the pushrod area, while the R/T's are almost cast completely closed, and then drilled for the pushrods.

Must be due to the rockers, I am using stock stuff there.
 
DionR said:
I tried a set of stock heads the same day and had plenty of clearance with that set. They were pretty much wide open in the pushrod area, while the R/T's are almost cast completely closed, and then drilled for the pushrods.

Must be due to the rockers, I am using stock stuff there.
Click to expand...

I just happen to have one of my heads off right now. I will see if I can get a pic of it tonight. If I remember correctly, my heads were not opened up much at all. But I could be wrong.

Jack
 
Here is a pic of one of my heads. It's hard to see the pushrod area though. Yes, those are 2.02 valves.

Jack
 

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