EQ magnum heads rocker question

-
2

2times

Member
Joined
Oct 30, 2010
Messages
9
Reaction score
2
Location
VIC
Hi Guys, i'm new to this forum looks like a great place to ask some questions and get some help, I'm building a 360 using EQ magnum heads and i've purchased roller rockers to suit, the question is standard magnum rocker studs are 5/16 into the head and 3/8 to the rocker assembly and i'm not sure if it's gonna be strong enough to support the cam i'm running. cam specs as follows:

Comp solid flat tappet
258@50 intake .608 lift with 1.6 roller minus lash
264@50 exhaust .620 lift with 1.6 rolers minus lash
106 lobe sep.

should have max rpm of 6800rpm and sring pressures will be around 135-150psi on seat and approx 320-350psi on nose depending on spring (looking at using a single bee hive style spring)

Do you think the 5/16 stud into the head will be strong enough with the lift duration and spring pressures?
or should i drill and tap the head for 3/8 studs?

The car will mainly see street use and the occasion 1/4mile trip maybe 8-
10 times a year

Thanks in advance!
 

A more cost effective solution would be to use the Chevy rockers and have a (GOOD) shop drill and tap for the 3/8 studs and yes, ues polylocks. The Jomar's that Hughes sells ARE a Chevy part. At 6,800, I sure wouldn't be using a 3/8 to 5/16 "adapter" stud.

That's what I'm planning to do. Not knocking the Hughes stuff, but the Chevy stuff makes for a cheap and fairly reliable setup with even some pretty stout springs...you'd only need the stud girdle if your going to use a STIFF spring. I know plenty of bow-ties that run rollers without a girdle and they're okay.
 
I think you will have a hard time finding a spring that fits the EQ installed height and pocket, and has the pressures the cam needs. If you do, yes, I think you will have issues shearing the studs when you rev it. You're at the performance level where I would have suggested the RHS LA-X Magnums so you could run the LA shaft rockers too.One way or another I think you will need to spend to make it reliable at that level.
 
moper is right as rain. Even big block chevys with hardened 7/16" rocker studs have trouble at high RPM at those spring pressures required. Thinking you can match the shaft mount system for strength with a stud or bolt mount is a mistake. "But so and so runs them no problem" Well, so and so runnin them with no problem is just like somebody ridin a motorcycle. Either they have had a fall, or they are going to. People runnin studs at those lift and valve spring pressure levels have either broken a stud or bolt or HEAD, or it's in their future. Ain't no gettin around it. Unless of course you run a shaft mount.
 
Chevy stuff relaible? Did you just say that? chevy stuff is weaker than stock Hemi stuff in the valve train department and that's sayin sumthin cause the stock Hemi valve gear SUCKS. Just like the stock big chevy valve gear. The chevys are known for burnin pushrod ends, smokin holes through rocker arms, breakin rocker studs and droppin the occasional valve. I've done way more than my share of expensive machine work to upgrade chevy heads. Even with upgrades, without a stud girdle connecting the rocker studs in similar fashion to a shaft mount, they are still way inferior to the stock Chrysler LA rocker system. I have seen people run STOCK 273 iron rockers at .650 lift without a failure. Is it smart? No, but you cannot run that much lift and spring pressure with a STOCK chevy valve train. AIN'T gonna happen. You buys run all the chevy valve train crappola you want to. I don't want my stuff to BREAK.
 
ehhh, he did say "Fairly" in which...welll, I'll just not repeat what you said. But it is cheap/inexpensive part that will work well.

Mad, I thinking more spring pressure with that cam. 100/300 seems light....but, WTF Do I know, LOL. What ever the grinder says, that's what's run.
 
I'm running a Hyd cam that's got close to the same lift as yours, slightly less, but still over .600. Open pressure on mine is right around 325#, seat pressure at about 130#. I'm running the EQ heads (sold as "Iron Ram" from hughes) with the 5/16 studs and the Jomar stud girdle. I'm running 1.65 roller rockers (not the shaft mounted ones). No problems so far, and makes good power (see signature). I would like to get the shaft mounted rockers eventually, and a bigger cam. I really wouldn't go any bigger with the small studs.
 
'64 Barracuda 273
'74 Duster 414 Stroker
512 HP @ 5800, 525 lb/ft @ 4400
Click to expand...

Yea...I think we have a pumpin street car here........ :)
 
First, springs pads must be cut to get any kind of spring height. Don't know the max you can run as cast, but it won't be enough to support that cam. I would think your installed height is going to be somewhere around 1.80". Beehive springs are the ticket to controlling the valve without excessive spring pressures.

Second...StrokerScam settle down. I never said the Chevy stuff was superior to the shaft mount rockers. In fact, many big spring Chevies have to use those TD and Jesels shaft rockers for valve train stability, right? What I'm saying is that for the dollar, the 3/8 stud/Chevy rocker and moderate spring pressures will be fine. And yes, the investment in a girdle is cheap insurance. And YES, I prefer the LA-style shaft mounted rockers too, but the OP's question was related to making what he has work.

By the way, what does burning push rods tips and smoking holes in rockers have to do with a stud mounted rocker??
 
I sure like the hughs rockers. I think you'll be miles ahead using those simply because Hughs has done a smart thing by dividing up the shaft like that. Makes changing out a failed rocker pretty easy and also seems to me the spring pressures would be handled better this way.
 
I'm running 224/230 hydraulic roller with the stock Dodge pedestal junk on my EQs. :)

I wouldn't run that cam with 5/16 - 3/8 studs. Also - I've bought a set of the comp studs and some 1.5 chevy roller rockers for mine and there is something hinky with the geometry. Hinkier than usual with small block Mopar I mean.
 
As I recall you can't cut the spring seats much. But you can use a longer valve. I've seen those heads as cast make serious power, so it's really only the valvetrain setup that gets me itchy.
 
LXguy said:
I'm running 224/230 hydraulic roller with the stock Dodge pedestal junk on my EQs. :)

I wouldn't run that cam with 5/16 - 3/8 studs. Also - I've bought a set of the comp studs and some 1.5 chevy roller rockers for mine and there is something hinky with the geometry. Hinkier than usual with small block Mopar I mean.
Click to expand...

LX - "hinky"? Have you mocked them up??
 
WOW! Great info thanks guys!!
Yes the seats will be cut and longer stem valves will be used so no issues with the spring rates and retainer clearance.

64physhy, thanks for your experience and good to know these EQ heads can make good power!
How long have you have your engine running for? any quarter mile abuse yet?

I'm looking along the lines of drilling and tapping for 3/8 studs just to give me some piece of mind.

Thanks guys8)
 
I just got it going again about a month ago. The first time I built it, I flattened the cam, so I took it to IMM to do it right and dyno it. Haven't had it to the track yet, but haven't been gentle with it, either.
 
rumblefish360 said:
ehhh, he did say "Fairly" in which...welll, I'll just not repeat what you said. But it is cheap/inexpensive part that will work well.

Mad, I thinking more spring pressure with that cam. 100/300 seems light....but, WTF Do I know, LOL. What ever the grinder says, that's what's run.
Click to expand...

When I originally posted the cam specs were not there or his intended spring pressures. The OG post has been changed!
 
You must log in or register to reply here.
-

Similar threads

E
Valvetrain Geometry
5 6 7 8 9
Replies
200
Views
6K
Earlie A
E
M
In 2025 are the replacement stamped steel Rocker arms good?
Replies
1
Views
182
junkyardhero
J
DionR
Could use some help identifying some roller rockers
2
Replies
41
Views
794
Illahe
I
Mojoe9955
Thoughts on used Magnum heads.
Replies
24
Views
1K
Slantsix64
Slantsix64
matt030305
What stall converter for my 408 stroker
2
Replies
37
Views
3K
autoxcuda
autoxcuda
Back
Top Bottom