[SPD_FRK]

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")

 

[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?

 

[SPD_FRK]

I will have to check all of that. Had to edit the original posting, GTS numbers and 75 numbers were off. FSM shows GTS cams as a 248/252 duration, took a little digging to find it but got the number straightened out and added the valve opening/closing timing as well.

 

[Drunkoffjuic]

I will have to check all of that. Had to edit the original posting, GTS numbers and 75 numbers were off. FSM shows GTS cams as a 248/252 duration, took a little digging to find it but got the number straightened out and added the valve opening/closing timing as well.

Yeah I was right in the middle of posting that as well:

Using this tool I got a different result.

The GTS i have as being 248/252 with these specs:

I dont have the specs for the non-mivec and I was unsure as to what to use for the Mivec specs as it is listed as such:

 

[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.

 

[SPD_FRK]

Yeah I was right in the middle of posting that as well:

Yea I pulled the stuff off GT where I had originally posted it back in 2011, went back through my Tech Resources on the MEDIC here at work and double checked it all, found GTS was wrong by a couple degrees lol.

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.

I am still running the stock GT motor...well I was LOL. I have this virtual dyno graph (for whatever it is worth if anything), from back in January when the car was bone stock with the exception of the CAI that was already on the car;

 

[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.

 

[SPD_FRK]

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.

Yea I haven't gone to any dyno places out here and usually stay away from them for a few reasons of my own.

Just updated 74 Cam specs with this;
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

 

[SPD_FRK]

Update to the 75 Non-Mivec Cams, differences between Galant and SUV motors to be aware of people;

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

 

[Silvertune]

The Endeavor cams suck. :lol:

 

[SPD_FRK]

The Endeavor cams suck. :lol:

Indeed they do, but check these out;

Intake Opens (BTDC) 19*
Intake Closes (ABDC) 59*
Exhaust Opens (BBDC) 59*
Exhaust Closes (ATDC) 19*
258* Intake Valve Duration
258* Exhaust Valve Duration
110* Lobe Seperation Angle
38* Valve Overlap


:eek3:

 

[M-Rod]

^ What the heck are those out of?!?!

 

[SPD_FRK]

^ What the heck are those out of?!?!

Another one of the Mitsubishi V6 motors
:agreed:
:corn2:

 

[M-Rod]

Time to do some digging around Mitchell. Whatever the hell they are, it has to be more cost effective than the $1000 that RPW wants for cams.

 

[SPD_FRK]

Time to do some digging around Mitchell. Whatever the hell they are, it has to be more cost effective than the $1000 that RPW wants for cams.

Sad thing is we can't even use those cams. They were the camshaft that Mitsu used in the 97+ 3000 GT SOHC motor which unfortunately was only a 12v and not the 24v head :rant: :rant: :rant:

 

[M-Rod]

Aw come on

You had me digging through every 24v SOHC trying to come up with some kind of confirmation.

/boner

 

[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.

 

[SPD_FRK]

Justin that was the plan and I still try and recommend people to do the same but as you know very few pony up cash. I just didnt push through the stuff because I couldnt justify putting the funds into it whe. I was still trying to finish that damn galant lol. I was planning to swap in the set of 75 cams and get some numbers from that before getting the new cams ground from delta.


I have some interesting valve lift stuff I will add to the original post tomorrow.

 

[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.

 

[SPD_FRK]

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.

Don't hold me to this 100%, but if I remember right it was something like $200 for a set of cams to be done. I could be off a bit on that, but I don't believe its much.

A lot of people were "scared" of running regrinds thinking they were weaker, but many of those people didn't know how the entire process was done either. I believe the guy's name was "ItalliGrasso" or something like that who had a set done for his 3000GT build and swore by the work and strength. A lot of people praise the work Delta can do.

For obvious reasons given the cost for us to buy a set of billet cams vs having a set ground to our own specs I was planning to have Delta do a set of cams for myself once I decide what profile I want to use. The benefit of posting all the information I have collected and pieced together for the OEM cams, I believe this thread will be helpful and a great resource for others to go to Delta and have a set made to their own specs, or run off a set of specs already submitted.

I will have time tomorrow to compile more of the data I have for the valve lift of the cams. I did a lot of measurements and had a couple engineers working with me as I was running into conflicting information/specs with what I was finding on 3 sets of cams and what RPW had listed for OEM specs on their site. It is interesting stuff and will probably gather some more technical interest on the subject here.