Bare EQ Magnum heads vs. machining stock Magnums?

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MopaR&D

MopaR&D

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Hey guys, so I have a pair of stock factory Magnum heads at the machine shop now which I plan to get cleaned up with a light mill, valve job, new guides, and light pocket porting to the intake bowls. The quote comes to around $700, which I just realized is about the same price as a pair of bare EngineQuest iron heads; I already have the valves and springs from my current heads so I wouldn't need to buy those. Is the factory valve job on the EQ heads any good, and how do the guides tend to fit? Also how would the flow compare to bowl-ported stock Magnums? Also the EQs are advertised at 62cc chambers, is this accurate? I know my stock heads came out to 66cc chambers when I checked them, might give a nice little compression boost since I'm using a stock JY 5.9L Magnum short block.

Just wondering if it's worth going with the new unmodified EQ heads vs. redoing my stock ones...?

EDIT: And no the heads I have aren't cracked, or at least they weren't when I got them; I put about 25k miles on them on my last 360.
 
The EQ valve guides will need to be reamed for your valves most likely (a long shot if all 16 valves fit with proper clearance), as well as need a valve job afterwards. Think of the bare EQ's as roughed-in, ready for the end users setting up. That was my experience, and have read of others with the same.
 
Maybe consider what you are putting money into, and if the budget allows a little more for going to new EQ heads.
Used Magnum heads are fine on a tight budget, but I personally would not spend that much for the work you are planning on them. If they were brand new stock castings I would not hesitate.
The factory Magnum valves are not worth spending money on either, although you did not specify if you had stock valves or good replacement valves and springs.
Best value for the long term success, is to contact a shop like IMM or a good local shop and have them quote a pair of EQ heads set up for you with good parts, and see if you can justify the cost.
EQ heads will outperform stock castings when equally prepped.
 
EQ's are the way to go. The guides will be tight but if your machine shop is decent this is ideal for them and you. EQ's will flow 237-238cfm as is OOTB. A stock Magnum will not crack 200 cfm totally stock. Do not hesitate to go with EQ's--they seem to make excellent power in any configuration. J.Rob
 
^^^ Seems like a no-brainer if the budget supports it. Good/bettter head breathing is the bedrock of any performance engine.
 
That's the thing, I'm not sure if the budget supports it... $700 is already pretty steep, I have a hard time going much over that. Sounds like it's worth it but I'm getting really tired of my Duster sitting in my garage with no engine, I'm gonna have to get creative with funds here... currently I drive for Lyft to make money as I'm also in grad school but it's summer now, no classes.

Anyway I need to call the machine shop pronto and tell them to not proceed, if they haven't already
 
Ok just talked to my machine shop, they haven't started on my heads yet so I'm gonna go with the EQs.

@RAMM they really flow that much? If so that definitely seems worth it for an extra 40-some cfm. Give me more reasons to be happy with my purchase, I want to feel good about dropping $1k-plus on just heads when the whole build is barely double that lol
 
Oh yeah, I also already have a Magnum Air-Gap manifold to use but I think I'm going to get the CH318B heads with the LA intake bolt pattern just because that opens up so many more choices. I'll probably just get another Air-Gap for LA heads but maybe some day I'll go crazy and get a tunnel ram:D
 
MOPEkidD-3 said:
Oh yeah, I also already have a Magnum Air-Gap manifold to use but I think I'm going to get the CH318B heads with the LA intake bolt pattern just because that opens up so many more choices. I'll probably just get another Air-Gap for LA heads but maybe some day I'll go crazy and get a tunnel ram:D
Click to expand...

That's what I did (CH318B)
The EQ's are thicker cast where the stock magnums tend to crack.
Every once in awhile you hear about the crack allowing a valve seat to fall out either hanging the valve open to the point the piston hits it, or breaking up and trashing the piston, cylinder AND the head.

How's that for a good feeling about the EQ's?:D
 
TrailBeast said:
That's what I did (CH318B)
The EQ's are thicker cast where the stock magnums tend to crack.
Every once in awhile you hear about the crack allowing a valve seat to fall out either hanging the valve open to the point the piston hits it, or breaking up and trashing the piston, cylinder AND the head.

How's that for a good feeling about the EQ's?:D
Click to expand...

I have heard a lot about stock Magnums cracking, seems like it's mostly minor though is it really that common for the seats to just fall out?

Also are the stock valves really that bad? What's wrong with them? I don't want to have to get new ones of those too if I can. .
 
MOPEkidD-3 said:
I have heard a lot about stock Magnums cracking, seems like it's mostly minor though is it really that common for the seats to just fall out?

Also are the stock valves really that bad? What's wrong with them? I don't want to have to get new ones of those too if I can. .
Click to expand...

I don't think the valves are bad, but the valve job could be better.
The springs the EQ's come with are pretty light (as in ok for stock cams) but not much better than that.
The EQ stock 1.092 valves can't take much lift unless you get the springs, locks and retainers set like Hughes sells. (200 bucks) and allows up to around .540 or so.

On mine the guides were real nice, but I did lap check the valves since I was swapping springs anyway.
Not that you want to do it now, but the EQ's can be bushed in the guides, have the spring seats cut deeper, longer stem 2.02 valves and really put down some flow later if you want.

I read a couple of places when I was researching the EQ about the valve seats falling out.
It's not real common, but has happened.
Apparently the common Magnum crack allows the seat pocket to get larger and in some cases it falls out.
 
Stock Magnum heads do not have seat inserts, just lightly induction hardened seats from the factory. All stock Magnum heads seam to crack eventually. In most cases, the cracks in stock heads are not a problem, and you can run them a long way like that. The problem is they usually have really worn seats with any real mileage, so you pay to install hardened seat inserts into heads that are good in stock form, but not really worth rebuilding when they are used.
Not sure if the common cracking has caused some of these replacement seats to loosen and fall out, but the EQ heads are better so I personally won't risk it.
As for your stock valves, just have your machine shop take them out and inspect them. The exhaust seats and exhaust valves are usually pretty badly worn. Your machinist can determine if they are still serviceable.
 
MOPEkidD-3 said:
I have heard a lot about stock Magnums cracking, seems like it's mostly minor though is it really that common for the seats to just fall out?

Also are the stock valves really that bad? What's wrong with them? I don't want to have to get new ones of those too if I can. .
Click to expand...

Bobzilla said:
Stock Magnum heads do not have seat inserts, just lightly induction hardened seats from the factory. All stock Magnum heads seam to crack eventually. In most cases, the cracks in stock heads are not a problem, and you can run them a long way like that. The problem is they usually have really worn seats with any real mileage, so you pay to install hardened seat inserts into heads that are good in stock form, but not really worth rebuilding when they are used.
Not sure if the common cracking has caused some of these replacement seats to loosen and fall out, but the EQ heads are better so I personally won't risk it.
As for your stock valves, just have your machine shop take them out and inspect them. The exhaust seats and exhaust valves are usually pretty badly worn. Your machinist can determine if they are still serviceable.
Click to expand...

Yep, sorry I got that wrong.
There are three Chrysler motors that the seats have fallen out, but the mags are not on that list.
 
TrailBeast said:
I don't think the valves are bad, but the valve job could be better.
The springs the EQ's come with are pretty light (as in ok for stock cams) but not much better than that.
The EQ stock 1.092 valves can't take much lift unless you get the springs, locks and retainers set like Hughes sells. (200 bucks) and allows up to around .540 or so.

On mine the guides were real nice, but I did lap check the valves since I was swapping springs anyway.
Not that you want to do it now, but the EQ's can be bushed in the guides, have the spring seats cut deeper, longer stem 2.02 valves and really put down some flow later if you want.

I read a couple of places when I was researching the EQ about the valve seats falling out.
It's not real common, but has happened.
Apparently the common Magnum crack allows the seat pocket to get larger and in some cases it falls out.
Click to expand...

Alright sounds good, I already have a set of the Hughes retainers and springs #1110 springs from my "old" heads. These heads I bought from a FABO member about 7 years ago and they were obviously reconditioned to some extent, they weren't just dirty junkyard heads someone pulled and shipped; I'd imagine the valves should be in decent shape.

So at the minimum I'd probably be looking at the cost of the bare EQ heads, plus a valve job, valve guide reaming, and prepping the valves themselves? I'm not gonna pay for pocket porting on these since they flow so much better OOTB...
 
MOPEkidD-3 said:
Alright sounds good, I already have a set of the Hughes retainers and springs #1110 springs from my "old" heads. These heads I bought from a FABO member about 7 years ago and they were obviously reconditioned to some extent, they weren't just dirty junkyard heads someone pulled and shipped; I'd imagine the valves should be in decent shape.

So at the minimum I'd probably be looking at the cost of the bare EQ heads, plus a valve job, valve guide reaming, and prepping the valves themselves? I'm not gonna pay for pocket porting on these since they flow so much better OOTB...
Click to expand...

The guides should be checked and probably only bushed if needed, but yea the valves will need done for sure.
Nice that you already have the springs and retainers.

The mag I have now had around 90k on it and looked really good inside, but man o man were the exhaust valves trashed.
I could turn them 180 degrees and see light around the seats they were so bad.
Besides the crack on all four corner cylinders that was the decision maker for getting the EQ's.
 
TrailBeast said:
The guides should be checked and probably only bushed if needed, but yea the valves will need done for sure.
Nice that you already have the springs and retainers.

The mag I have now had around 90k on it and looked really good inside, but man o man were the exhaust valves trashed.
I could turn them 180 degrees and see light around the seats they were so bad.
Besides the crack on all four corner cylinders that was the decision maker for getting the EQ's.
Click to expand...

I've heard of guys going through 5, 6, 7 junkyard Magnum heads with them all cracked; I didn't even bother with the heads that were on my 5.9 Mag short block, pulled them off the engine at the junkyard and immediately tossed them back in the truck's bed lol.
 
If the budget is tight, and the Magnum castings you have are in good shape, you could always run them the way they are for now since they have upgraded springs, then do a good set of EQ replacements later as an upgrade if you decide you want more power in a couple years. Check the valves and seats, and decide from there. Don't worry about even looking for cracks if the valves will still seal.
I am all for doing it right the first time but if the valves seal, you only have to buy gaskets right now to get it running.
 
Hughes engines says they put bronze guides in there new EQ heads right out the box, not sure if it's 100% necessary though.
 
With proper clearance and good valves, bronze guides are not required. They just do bronze right away instead of sizing the cast iron.
Think of it this way; how many high mileage Magnums are out there running the valves against cast iron, without bronze guide inserts, with no problems at all?
Proper setup is most important.
 
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