Hi mopar lovers. I'm new to the forum even though I've read plenty of helpful post. Well I just got done showing my old boss at the machine shop my 440 promaxx heads and the grinding I had to do to clearance my 3/8 push rods so they didn't hit the head to line up with my Hughes 1.6 rockers. He was having a [censored] fit about how the geometry is way off and I'm going to waste valve guides. Now I'm no idiot and neither is he but I believe he is exaggerating a little bit. What do you guys think. Also the rocker tips sweep isn't directly in the center of the valve but Hughes recommends at least .040 between sweep and tip edge which I'm well with in. It's my 440 tube chassis duster with a solid roller cam. Sorry so long thanks for any help and experience

Mopar geo blows in general but if you could post pics folks could tell you if the semi norm or if its way off, there is a fella here that can help if its really "wrong".



How do the pro max heads look overall?

A good read on TD machine website.
Geometry on a shaft rocker is dictated by three items.
1 Shaft center to tip length
2 shaft height
3 valve tip height

TD makes their own stands and rockers for application. They have different length rockers as well as stands for those lengths. Plus shims to correct for valve height.

Lot of stuff not used on stock style stands. But, an educational read.

I've never seen the promaxx heads so I can't speak from experience there but unless the folks who designed that head really messed it up the geometry should be okay. Most big block heads will work just fine up to about 0.650 lift. After that you might need to do some machine work to move things around or try different rocker arms to see which fit the best. There is a big variation between rocker arms, some are long, some are short, some are in between.

No way I would run 1.6 on a mopar, why? Spec the cam for lift and duration you want running 1.5 rockers.

You will be a way ahead like your friend says/recommends Your not building a pro stock motor, way too many motors/heads/cams have been messed up with 1.6 rockers on mopars and some folk don't even know it when it happens to them. They blame everything else. You don't need 1.6s and they are more trouble than they are worth in your case. Too bad you spent so much time grinding those heads when you can run just as fast with 1.5s I promise.

Did you try shimming the rocker arms first to move them away from the heads to make clearance? I use 1.6 ratio on both stock and after market aluminum heads a lot and I have had to grind some on a lot of the aluminum heads to get clearance, not so on other brands I can't remember grinding on a stock head to clear 3/8 pushrods with 1.5 up to 1.7 ratio rockers The Edlebrock RPM and the Super Victor Max Wedge heads both needed grinding on them to clear, especially the Victor M.W. heads with both the Hughes 1.6 ratio rockers and then later with the 1.6 ratio Harland Sharp rockers I replaced the Hughes with

The promaxx heads seem really nice the installed height was spot on and they hand blend the bowls. I guess their sidewinder look a likes. I wasn't aware not to use 1.6 rockers. I had to buy new ones so I figure why not get more lift out of my cam which I bought new at the same time. So I very well could have made the cam bigger and used 1.5s. I just mocked it up to get all my clearances. If I shim the rocker shafts it throws the rocker tips even further past the tip center. My sweep patter is almost spot on. I'll try and get some pics up later. Right now I'm doing body work

I'm going to recheck everything this outer springs installed so I get a better idea of sweep pattern push rod clearance, geometry and p2v specs.

i would love to see some pics of the heads, bowls, ports and all that...

do you know if the valves and springs are the same as what is in the edelbrock heads?

If I could figure out how to load pictures. The valves say edlebrock ferrea on them so I'd have to say yeah

Promaxx same as Sidewinder etc Great heads for the $$ but Sidewinders available for way less--1.5's are pain in a@$% with 3/8ths most running a Smith or Trend etc 5/16ths pushrod to make life easy--1.6 is not faster in most Mopars just a real PAIN --Sidewinders and Promaxx worse than Eddys in that dept just run a 1.5 you guys!!!!! Getting them 10000% on paper is an exercise not a way to go faster or ??? Just keep it simple please!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Sidewinders are very wide at top of port and not suitable for 3/8ths unless you grind a lot ( more than Eddeys_ get some Smith 5/16ths they SWEAR are good for extreme pressure at the length needed for those heads and RELAXXXXXXXX

No production pushrod engine made in the last 30 years still uses 1.5 rockers, and certainly no race engine.
Why would the intake and exhaust sides need exactly the same cam lobe, lift and rocker ratio?
They don't - they're 2 completely different systems. It's just the cheapest way to make them, and it's a coincidence if it's still true when the engine has been modified.
Bigger intake rocker always helps if the cam isn't big enough (specially if the LSA is too large), but bigger exhaust generally does nothing.

Leon441's remark is correct but a bit short.
What is always present, but neither visible nor revealed by the manufacturer: exactly where do you put the rocker shaft hole WRT the pushrod seat and roller axle? Hint: it's not in a straight line unless your name is Miller, and how far away the line is "bent" determines the geometry. If this makes the roller tip do something you don't want it's not fixable.

We aren't using new modern engine science we are using a block and heads designed in the 50's for 250 HP and most of the cheapo heads hate 1.6 ratio because the pushrod hits the intake port so WHY fight city hall-- run a 1.5 on these Dinos and keep on melting tires without the hassle is my point when is an easy 500-550 HP not enough for a fun street engine? Answer--Never unless you just read too much

I agree, pushrod clearance has to be dealt with, and if you can't fit a 3/8" pushrod using 1.5 rockers and a bigger cam is the answer.
A 5/16" pushrod isn't going to make it, no matter what un-obtainium and .150" wall thickness - the stiffness is 90% in the diameter.

Guess that must be a problem with the chinese junk heads. The Trick Flow heads that I have work just fine with 1.60 or 1.70 rocker arms and they'll even accept 7/16 diameter pushrods right out of the box.

I had already bought the promaxx heads and then trick flow came out with theirs. But in reality for the price of the tfs I'd buy indy. This is going to be a bracket motor not reving past 6500 with 105 ic 255 duration at .050 and .615 lift with the 1.6

It ain't Junk if they are quality casted aluminum with quality bronze guides that make easy 500-600 HP at half the price of some that are better
That is not an opinion--that is a fact
Or to put it another way Charlie Buck built an engine that went 3.52 in 1/8th last month---while that is an awesome deal it is not what most of us need--most of us needed a cheapo head that would make 500-600 HP for cheap--It took a Sidewinder to shoot down the truly crappy Stealth--The Steven produced Sidewinders ( or if you buy enough you can name anything you want) are that head--Get a CNC to write your name on them and work to send out heads with quality parts and valve job and you have Promaxx, Sidewinder,and maybe some yet to come but the fact is they are as good or IMO better than the Eddy for a killer price--they are quality castings something that can't be said for Stealth
They are sold for the most part by Mopar parts vendors that STRIVE to take care of customers and send out good parts not corporate folks that could care less--they are made by new wave enterprising folks that put it all on the line to make a buck and be part of the march forward to more for less--that is the way the world economy is heading--now more power to the enterprising USA makers too--I really like the Summit head--I do--and will use anything I can over an Indy but fact remains that the imported castings on the Promaxx and Sidewinders are far better than the previous import choices --much like other import things like rods etc that have improved a ton over time--
R&D on a 550 HP build Mopar street engine is funny--ya don't need any just build it and have some fun! That is what this was all about--Building the 700-1000 HP units for street is just an ego trip--so what's next 1400 HP pump gas engine? Who cares? The meat of the market is a guy that wants a classic Mopar body, cam sound, and melting tires with an orange lump under the hood Sidewinders meet that need and leave him some extra Loot so he can treat his date right.
AND... If Smith Bros say that a 5/16th will do the job--buy it and relax--yea it will not win the Spintron contest but I have plenty running around with street rollers and they seem to be doing fine

I love this idea that Mopars are so outdated, that you should only run 1.5 rockers. If that were the case, I could make the argument that you should only run a flat tappet cam, because big blocks never came from the factory with a roller cam. A roller cam has the ability to increase area under the curve with the same seat timing, which is exactly what a higher ratio rocker does. For that matter, the dinosaur Mopar engines never had roller rockers from the factory, so you shouldn't be running those either. Forget about aluminum heads and manifolds. Headers, no way!

I almost never use a 1.5 ratio rocker on my Mopar builds, and I don't seem to be hurting for power, reliability, or stabilty. I put the shafts in the right place, and it makes the rocker to valve geometry correct. There is no roller rocker that can be bolted to the cast in stands, and have proper geometry, no matter how much they are marketed as such. Do a Google search for Mopar rocker geometry. There are some good tech articles available, as well as some not so good. Use logic and common sense to separate the two.

As far as pushrods are concerned, you can get away with less pushrod when the rest of the valvetrain is stable. A smooth stable valvetrain puts less of a pounding on its individual parts.

In response to Polyspherics comment about Miller, if you study his (Millers) explanation of geometry, he tells you that even though the pushrod side may not be correct on other rocker brands, and is difficult to change, the valve side is far more important. So, if you don't correct the valve side, you lose twice. Also, I'll share a little secret. Miller's patent expired over 20 years ago.

Run the 1.6s with the shafts in the right place, and you won't have excessive guide wear or instability issues.

Since it is not a easy deal or economical for the OP to move his rocker shafts on his budget heads, don't you think he should run 1.5 if he wants to keep the cost down and make it reliable as possible without spending big bucks to run 1.6?

Believe it or not, with the reduced lift from the 1.5s, his effective geometry would be worse. Depending on the approach, moving the shafts is not that expensive, and might save some grinding. Also, he already has the rockers, so replacing them would be an additional cost.