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OEM Cam Specifications

17363 Views 39 Replies 5 Participants Last post by  mysticj, 
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Below is the current and accurate data on the 6g72, 6g74, and 6g75 Non-MIVEC OEM Camshafts.


6g72 Camshafts
(Galant & Eclipse GT Model)
Intake Opens (BTDC) 15*
Intake Closes (ABDC) 53*
Exhaust Opens (BBDC) 53*
Exhaust Closes (ATDC) 15*
248* Intake Valve Duration
248* Exhaust Valve Duration
109* Lobe Seperation Angle
30* Valve Overlap

(Eclipse GTS Model)
Intake Opens (BTDC) 7*
Intake Closes (ABDC) 61*
Exhaust Opens (BBDC) 57*
Exhaust Closes (ATDC) 15*
248* Intake Valve Duration
252* Exhaust Valve Duration
115* Lobe Seperation Angle
22* Valve Overlap


6g74 Camshafts
(1997-2001 Model Years)
Intake Opens (BTDC) 9*
Intake Closes (ABDC) 59*
Exhaust Opens (BBDC) 47*
Exhaust Closes (ATDC) 21*
248* Intake Valve Duration
248* Exhaust Valve Duration
109* Lobe Seperation Angle
30* Valve Overlap

(2002+ Model Years)
Intake Opens (BTDC) 13*
Intake Closes (ABDC) 55*
Exhaust Opens (BBDC) 51*
Exhaust Closes (ATDC) 17*
248* Intake Valve Duration
248* Exhaust Valve Duration
109* Lobe Seperation Angle
30* Valve Overlap


6g75 Non-MIVEC Camshafts
(Galant Models)
Intake Opens (BTDC) 7*
Intake Closes (ABDC) 61*
Exhaust Opens (BBDC) 61*
Exhaust Closes (ATDC) 15*
248* Intake Valve Duration
256* Exhaust Valve Duration
115* Lobe Seperation Angle
22* Valve Overlap

(Endeavor & Montero Models)
Intake Opens (BTDC) 5*
Intake Closes (ABDC) 55*
Exhaust Opens (BBDC) 51*
Exhaust Closes (ATDC) 17*
240* Intake Valve Duration
248* Exhaust Valve Duration
111* Lobe Seperation Angle
22* Valve Overlap


As you can see the engines have the same intake valve duration, whereas the 6g72 in the Eclipse GTSm, and the 6g75 Non-MIVEC engines have a longer exhaust valve duration as well as less valve overlap. What is valve overlap? Overlap is where both the intake and exhaust valves are open at the same time on each cylinder (this occurs around Top Dead Center or TDC). Excessive valve overlap is something commonly found on racing engines, too much overlap also results in rough idle conditions. A lot of overlap favors higher RPM range performance ranther than lower RPM range. A certain amount of valve overlap is beneficial, without it volumetric efficiency of the engine is usually compromised.

Lobe seperation angle: a wider lobe-separation angle (overlap decreases) improves idle quality, idle vacuum and helps top-end power (say 112 to 116 degrees for example). A tighter lobe-separation angle (104 to 110 degrees) will produce a rough idle and better midrange torque but limit top-end power.



Valve Lift Specifications & Tech Information
I measured two sets of 6g72 cams, and a set of 6g75 Non-MIVEC cams using a Mitutoyo calipers. These were my own measurements, and to be as accurate as possible I had all lobes checked for each set of cams. I enlisted the assistance of two engineers who are high end machinists for 20+ years for a company called Sundyne. All of our measurements had no more than a +/- .002” variance.

Here is where we ran into conflicting information between our own measurements and those stated by RPW's measurements. RPW states a "standard Mitsubishi base circle of 1.180" being used for their camshafts. We even went as far as measuring the bare casting area between each cam lobe where the best measurement we obtained was 1.002" maximum between 3 different sets of the 6g7x series camshafts.

I will go one step further and note additional creditable documentation that is easily found in the Factory Service Manual. Here I reference from the 8th Gen Galant FSM (Page 11D-58, under Service Specifications). Camshaft cam height (basically lobe height) is as follows;

8th Gen Galant – Page 11D-58
Intake Standard Value - 1.485"
Intake Limit Value - Minimum 1.465"
Exhaust Standard Value - 1.462"
Exhaust Limit Value - Minimum 1.443"

9th Gen Galant FSM - Page 11D-63
Intake Standard Value - 1.472"
Intake Limit Value - Minimum 1.452"
Exhaust Standard Value - 1.485"
Exhaust Limit Value - Minimum 1.465"

With that information taken into consideration below is what I have found for the valve lift on the stock camshafts. I first measured for the lobe circle, and then measured the lobe height. Now the measurements were as followed;

6g72 Galant & Eclipse GT
Intake Lobe Circle: 1.263"
Intake Lobe Height: 1.485"
Intake Lift: .305" (Per RPW base circle specs)
Intake Lift: .222" (Per my own current measurements)

Exhaust Lobe Circle: 1.263"
Exhaust Lobe Height: 1.470"
Exhaust Lift: .290" (Per RPW base circle specs)
Exhaust Lift: .207" (Per my own current measurements)


6g75 Non-MIVEC Galant
Intake Lobe Circle: 1.263"
Intake Lobe Height: 1.485"
Intake Lift: .305" (Per RPW base circle specs)
Intake Lift: .222" (Per my own current measurements)

Exhaust Lobe Circle: 1.263"
Exhaust Lobe Height: 1.470"
Exhaust Lift: .290" (Per RPW base circle specs)
Exhaust Lift: .207" (Per my own current measurements)


Actual Valve Lift -
I found the rocker ratio for the 6g7x series engines is apparently 1.6, so given what we have found for cam lobe height this is what the actual valve lift should be I guess;

Valve Lift = Lobe Height X Rocker Ratio

Our measurements;
Intake Lobe Height .222"
Exhaust Lobe Height .207"
.222" x 1.6 =.355" Lift (9.017mm)
.207" x 1.6 = .331" Lift (8.407mm)

RPW Spec (1.181" lobe base circle)
Intake Lobe Height .305"
Exhaust Lobe Height .290"
.305" x 1.6 =.488" Lift (12.395mm)
.290" x 1.6 = .464" Lift (11.786mm)


So what does all of this mean? Well that is the difficult part and I am still struggling with trying to find where/how RPW obtained the "standard Mitsubishi 1.181" base circle" specs given what we have found on 3 sets of highly used OEM camshafts. This base circle measurement, as well as the cam specifications we are getting as a result from different measurements.

The question that begs to be asked is if the RPW valve lift specs are actual valve lift, or lobe height? Let's take their Stage 3 cams with .343" advertised lift for example. As we know the Rocker Ratio plays a part in finding the actual valve lift so we will factor this in here as well.

.343" x 1.6 = .549" Valve Lift

If the .343" is actual valve lift, then let's flip the equation to find out for reasonable doubt;
.343"/1.6 = .214" Valve Lift

With that I think it is safe to say the advertised valve lift of .343" is just part of the lobe height measurement on the cam, and actual valve lift is really .549" (13.945mm) vs .214" (5.436mm).


Valve Spring Specifications/Tech

OEM 6g7X Valve Spring Demensions
Installed height is 1.74"
Seat pressure of 60lbs
Spring ID - .639" (+/- .01")
Spring OD - .981" (+/- .01")
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Silvertune
Thank you Matt. Time to crunch some numbers.

I do have one question (or two) though. The GT/GTZ cams cam with staggered centerlines correct? I've read before that front bank was 109 and rear was 112, any way to confirm that. Also the 75 cams have a symmetrical centerline, does that hold true for the GTS as well?
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Silvertune
And so the plot thickens. I'm trying to find a dyno sheet for an NA 24v SOHC engine that isn't 60whp/liter +/- 3 or so. That is to say, one that isn't cammed or MIVEC.
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Silvertune
You need to get that thing on a real dyno. When the MN crew went and all got dynoed at the same time some pretty weird numbers resulted. 72 with IHE and 74 top end made 175 180, those are stock motor numbers so far as I can tell. Stock as in zero mods. I don't know if the dyno was just reading low or what because then Matt went on and put down 232 251 which seems right in line with a well put together 75. Either way, still 60ish whp per liter.
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Silvertune
The Endeavor cams suck. :lol:
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Silvertune
So I hear this company RPW makes a set of high lift 262's and this random guy with a turbo has them in his car with great results. ;)

No but really. That SOHC 12v made pathetic numbers even with those cams, that motor is garbage. Granted there are some ever famed boost builds with it... I digress. Schofield, why exactly did the cam project not produce? You have the OEM specs and the RPW specs. Who needs custom stuff, why not just have Delta grind out some RPW replicas and call it a day. If I were still rolling stock cams I'd be more than happy with that.
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Silvertune
Please do.

How much were they quoting you for regrinds? There's no way in hell they're as expensive as RPW's, in which case they'd really be quite fairly priced when considered among aftermarket camshaft options for other cars.
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Silvertune
I know at least one galant owner who'd be more than happy to get a set of knock off RPW's for 200$. That is pennies on the dollar, now I just have to find the exact specs on these things. I've got two sets of spotless cams sitting in a sealed container I could send in.

This begs the question of valve springs though, particularly for the 75 guys because they're the ones who float real bad with boost or higher revs. RPW's springs aren't exactly expensive relatively speaking but it's so effing hard to order from them anymore it's ridiculous.
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Silvertune
Who said the Evo springs fit our heads? They aren't even close. I bought one years ago to compare and it won't even sit in the base circle. They're wider and shorter and according to a tension measurement I read up on once they're softer than ours too.

When I talked to RPW years ago as well they told me the spring tension wasn't the issue for us (this was prior to any real headway on boosted 75's where float started coming up). It's that the stock springs bind under high lift circumstances and that's what the RPW springs have to offer is that they can compress for the required lift. They made a high PSI set and a basic set, the high psi settling in at 100 psi seat pressure. However that option was dropped last year because it was unneccessary for anything short of insane boost numbers. I've put 17 pounds through the basic springs at 7k and had no issues.


Thanks for the lift specs. I was wondering when a pattern in their cam grinds was going to emerge. Since they use identical springs for all the motors I figured there had to be some reason behind it; all the lifts are the same for stock cams. I talked to an Aussie guy once awhile back about the SOHC cams since custom regrinds were big there for awhile. Told me you can get away with a lot more duration on the stock springs at stock lift levels and extend the powerband to the 6-7k range where the numbers start to look really good. The problem then becomes combatting the choke from long runner manifolds but my work with XG's takes care of that.

A 70mm tb option that isn't me customizing ford products would be sweet too. I've got one going on a 75 this spring that I'm excited to see perform. I know the Evo stuff bolts up and plugs in but the IAC housing is on the top and I don't believe that will clear the hood on a 75 manifold.
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Silvertune
Well I'll be, I must've been sent the wrong spring. That's quite annoying.

Okay so the springs at least sit on the heads but what about retainers? Needless to say our retainers don't fit on the Evo springs and we have a thinner valve stem so I doubt the Evo retainers will work with our valves.
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Silvertune
That doesn't address my question. The Evo has a 6.5mm stem, ours is 6. You need to see if the eclipse locks on the eclipse valve fit the evo retainer the same way the evo valve and locks do.
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Silvertune
Parts #'s mean nothing to me if there are no words to label them. Why don't you quite beating around the bush and actually prove something.

Valve locks don't just jam into a retainer. They have to fit the valve and retainer like a glove. Evo locks will not fit our valves because our valves have a smaller stem. On the same note I have a hard time believing that our locks and Evo locks share the same external dimensions in which case we needs springs that fit our retainers. Based solely on imagery our retainers aren't going to sit on top of the Evo springs because they're tapered.

The requirement becomes either custom springs or custom retainers. I'd rather buy custom springs rather than evo springs and custom retainers, it'd be cheaper and easier. Though at this point you might as well order RPW because that will ultimately be cheapest.
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Silvertune
I am aware of the locations..

Taunt as you might, seeing as that I work until 9 tonight and again at 7 tomorrow morning I will request that you find it in your soul to explain yourself so that I may rest easy.
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Silvertune
I have real RPW stuff so I don't even know why I bother. Serves this community right for leaving cam options in the hands of the likes of you. I digress.
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Silvertune
If you knew jack diddly about my car you'd know why those springs aren't coming out unless prompted to do so by a cloud of smoke preceded by a loud bang and some fire. Granted I will be stripping the engine down to the heads in a couple weeks, I don't have a compressor to get the springs out. That said, they matched the stock springs perfectly, the difference being the taller coils to allow for more compression.

Alas, I didn't write all this down but I suppose I should so that when the shade of the passing whims of Matt Schofield's heart begin to change he can't put a choke hold on this endeavor. I'm going to see about this Delta business and hopefully try a set on a local car this spring. That is, once the all stock motor record is thoroughly shattered for the 75. I want to see 12 seconds NA.
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Silvertune
I'm too lazy to open the sheet on my phone. I guess it doesn't matter though, that company can make them regardless. I've got three sets in a drawer, I'll have to hit up my shop come spring and see what they can hook me up with. I'd like a see a 75 with some radius cut valves and a good stage 2 RPW grind.
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