MMS 3500 Stage 2 Pics and Flowsheets

[SappySE107]

Just starting off on checking these parts out, and seeing how they stack up to what I have been doing. The CNC ported heads are definitely CNC ported, but not much beyond that. Its what I expected, but my commentary really isn't necessary. Ill get plenty more posted so if you are interested, like and subscribe. ha ha ha ha ha ha ha ha

First off, the picture dump of the MMS Stage 2 3500 heads.

[SappySE107]

Here are the flowsheets for stock, WOT-Tech Stage 2 and Milzy Motorsports Stage 2. Also included are the port volume measurement to give you an idea of how much was removed from each compared to stock.

[dbral]

STAGE 2: - Full port and polish, port-matching the intake runners, D-shaping/re-angling of exhaust ports, significant bowl work, correcting the short side radius, polished cc-matched combustion chambers

• Race Valve Job (9-angle Intake, radiused Exhaust)
• CC-matched combustion chambers
• stainless steel swirl-polished under-cut valves in OEM diameter
• Comp Cams valve springs (128lbs at install height), Comp Cams retainers, and Comp Cams keepers
• bronze valve guide liners
• new Viton valve seals
• assembled and toleranced
• clearanced for safe lifts up to .560"
• milling up to .020 free of charge

From a customer standpoint, we would be curious to know if all of the above was performed as stated by MMS on the heads in your possession.

I'm currently running a set of MMS stage 2 heads on one of my vehicles. Should I be concerned that a portion of each valve guide was machined away? Have you ever tried that before? What is the advantage? In a picture from the list above (Top row, 6 over from the left) looks like the guide may have slightly shifted in its bore at some point after being machined? Could this procedure cause durability issues?

Thanks for posting the data and pictures!

[SappySE107]

I don't know what he was advertising them as when you got them, so I can't say for sure that you did or didn't get what you paid for. There aren't 9 angles on this intake valve and the valve itself wasn't even back cut. Undercut would be the stem, and thats a non issue since they are machined valves, not stock replacement versions that still have casting on the back side. CC matched chambers, probably. They are CNC done and touch most of the chamber. Its manley retainers, stock keepers as far as I can tell. That or Comp changed to the manley design. Comp doesn't used machined locks that I can remember so telling the difference between stock and comp locks would be difficult. Bronze liners? since when. These aren't, thats for sure and I don't recall them ever being listed as such. New viton seals, which are all you can really get these days. They are Felpro/stock style seat/seals.

Oh I skipped the top. Full port, no. Polished, no. Port matching intake runners, yes, its bigger than the intake gasket by a little bit but it doesn't hurt flow. D shaping? It was a D already. Re angled I guess....its totally hogged out. 20cc or something like that on the exhaust. Correcting the short side radius, he does change the short side radius. Is that corrected? Not a polished combustion chamber.

So that is comparing the description now to 2019 work. If your car has older MMS work, then its probably different heads. They were hand ported by high school kids in 2008. The set of heads and manifolds I had back then didn't look anything like what these cnc heads are.

Cutting the guides out of the ports like these aren't may or may not cause the guides to wear faster, but it 100% didn't help flow.

[SappySE107]

I do know he has had the 9 angle valve job listed for over a decade now. These heads got a 3 angle valve job. I also got the little spike that is dead center between both valves.

Between the valves



Exhaust Seat



Intake Seat



The seats are silver, which is impossible to discern angles from. Using the reflection of my finger, you can see it a lot better.

[dbral]

The Stage 2 description on the website has not changed to my knowledge since late 2017. Interesting pics. Looks a little rough but that may be normal under magnification? Did all of the valves seal on their seats? Do you notice anything concerning?

[SappySE107]

They all sealed. I don't recall him listing the bronze guide liners, but these heads don't have them. The manifolds are fully ported, the heads are not. I am very concerned about the sharp edges in the combustion chamber. They can create a hot spot and pre-ignition/detonation. We will find out on the dyno how much it matters. Both intake and exhaust appear to be the same valve job, and 3 angle.

[dbral]

Very curious about the dyno results. Will say that our Stage 2 does not knock and ping. Both sets of heads were ordered at roughly the same time but do not know what our heads look like compared to the set you have though. The car starts to pull pretty hard around 4k but is docile below that, esp under 2500 or so. The snappy-ish stock low end torque feel is gone. Still fun to drive though and these engines sound pretty good at high rpm and it has a lope at idle too.

Yeah, mms is a hot mess and not surprised that all of the boxes were not checked. It is worth mentioning that the previous owner of our car waited years too, only to get back a car that would not idle properly and stall out at low speeds....due to a very simple issue that mms overlooked I might add.



Off subject, but if you look at the stage 3 description it is listed as "Max intake flow is over 290 cfm". What kind of modifications does it take to hit this number? Would increasing the intake valve dia. 0.08" alone be enough or is there more work needed? What lift is usually considered max intake flow?

[SappySE107]

I have never seen 260 cfm on these heads. 290 would outflow LS1 and LZ9 heads. Max intake flow is whatever you want to call it. I think it was RSM that gave the flow of all 3 intake cylinders on the head open to .500". Yes, all 3 open at the same time. So its marketing bullshit at best. Bare none in fact. ROFL. The massive port sizes are probably to blame for the torque loss and lope. The cam shouldn't be that kind of powerband.

[dbral]

Not at all surprised to hear that either. Good to finally see honest numbers/comparisons. The port volumes are def. an eye-opener. I'm betting our car has the same cnc heads.

[SappySE107]

Measured the seat concentricity, and its fine. Intake is better than exhaust but both are better than I have seen from some machine shops before.

Intake


Exhaust