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Ripp'd 3.5L
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Discussion Starter #1 (Edited)
6G72, 6G74, and 6G75 FAQ.

Over the past few months I’ve been getting a good number of questions, some of which are asked over and over. So to make it easier for everyone. I have compiled a list of FAQ.

1. Q: What gains will I see if I swap out my intake manifold (6G72 GT mani) to a 6G74 intake manifold? Is it worth it?

A: It is worth the trouble. The 6G72 intake manifold (GT version) is a P.O.S. .I.M.O.. It actually chokes the engine at higher RPM’s. Buy yourself a GTS intake mani or a 6G74 mani. You wont be disappointed.


2. Q: Will the 6G74 throttle body bolt on to my eclipse without modification?

A: No. 2 items must be looked at. First item is the cruise control solenoid and its holding bracket. Both of these items hit the firewall. Short and simple solution is to remove the bracket and remove the cruise control solenoid. Second item to look at is the TPS socket. It is different from the connector that we got on our eclipse. Simple solution to that is to buy a TPS pigtail and install that in place of our stock TPS connector.


3. Q: I want to do the full 6G74 engine swap, how much will I be spending at a minimum if I do the swap myself?

A: A tight budget swap will run you at a minimum of about $750ish (assuming you find a 6G74 at $450 shipped). Account for the following: New belts (all), fluids (all), and a few miscellaneous items.


4. Q: After I did the swap, I got 2 SES codes; first being a cam position sensor malfunction and a crank position sensor malfunction. How do I fix this?

A: The one item that is tripping both codes is the cam reluctor wheel. Diamante’s distributors only came with a 1-pulse reluctor wheel. 2003 to 2005 eclipse’s have 3 pulse reluctor wheels. If you performed this swap on a 2000 to 2002 eclipse, you will not have this problem (assuming you USE the diamante distributor). Fix action is to tear down the distributor assembly, pull the reluctor wheel from both distributors and swap the 3 pulse wheel onto the diamante distributor assembly. Reset the ECU (disconnect pos terminal from battery for about 10 min) and your problem should be fixed.


5. Q: I want to try putting a 6G75 intake manifold on my 6G72. What problems need to be fixed in order to make it work?

A: There are 3 problems that I’ve personally seen. First problem and most difficult to overcome is the throttle cable bracket tie down (the screw holes which hold your throttle cable bracket in place). There is no tie down (6G75 equipped vehicles have throttle cable-less throttle bodies). You will have to drill and tap your own tie down. I’ve done it…..not really hard at all if you have the tools. Next issue is the fuel pressure regulator vacuum port. There isn’t one. You can do 1 of 2 things. Drill and tap a hole to insert a nipple into (so to speak) or just go out to your local car parts store and buy yourself a vacuum “T” so you can add a vacuum port to feed your fuel pressure regulator. Third problem is actually dependent on “which” 6G75 manifold you bought. If you bought a manifold from a Galant-non ralliart model (like I did), the throttle body mounting point is actually curved in towards the front of the engine bay (at approximately 60ish degrees. Your battery will be in the way once you mount the throttle body on. Fix action is to move your battery over towards the drivers side.


6. Q: Will the heads from my 6G72 fit onto the 6G74 block?

A: Yes. ALL cylinder heads within the 6G7x family will swap between blocks. Though they will bolt on, that does not mean that all coolant passages are in the same location/size (6G72, 6G74 and 6G75 have identical coolant passages).


7. Q: Do you recommend upgrading the stock clutch to a high performance clutch when doing and engine swap?

A: YES. I have personally used the stock eclipse shitty clutch with the 6G74 engine. Clutch slippage will occur.


8. Q: I did the 6G74 engine swap on my automatic tranmission 200x eclipse. My speedometer sometimes goes out (does not work) and the ECU throws the transmission into 2nd gear permanently till I reset the ECU, how can I fix this?

A: I personally do not have a automatic transmission eclipse….but I have helped swap engines on an auto tranny eclipse. Same problem did occur. Though I do not have a answer for this problem, I have a “theoretical” solution for it. That solution would be to pull out the cams from your 6G72 and put them in the 6G74 (use the 6G72 valve covers to time your cams!). Also use your stock distributor. Your ECU should not see any difference when metering RPM’s like it does when you use the diamante distributor and cams. Therefore it should put an end to your problem. (if anyone out there does this, please pm me and let me know if it has fixed the problem).


9. Q: Is it possible to install a 6G75 intake manifold on my 6G74? What problems will I have?

A: Refer to question number 5. WITH one additional problem. Plenum will not clear the hood. If you so choose to cut your hood, problem solved.


10. Q: Why can’t I just put my stock distributor on the 6G74? Doesn’t it fit?

A: Does it fit you ask? Yes it does. Does it work….yes and no. The 6G74’s cam timing is different than that of the 6G72. There for you will have the symptoms from question #4 with an additional problem. Your ignition timing will be all f*kt up. The car will run, it will just run horribly. Don’t be lazy, tear down the distributors and swap the reluctor wheels.


11. Q: You mentioned that you swapped the cams from the 6G72 onto the 6G74. Did you have to swap the reluctor wheel back? Did you have to swap distributors?

A: If you swap the cams over….swap BACK to the stock distributor (also use the stock reluctor wheel….the one your car came with).


12. Q: Do I need to swap the fuel injectors from the 6G74 back to the 6G72’s injectors if I decide not to tune the ECU for now?

A: YES! Not tuning and using larger injectors (270’s vs 210’s) will cause a number of problems. A few of them being; running extremely rich air/fuel mixtures, numerous SES codes, and poor performance from your engine.


13. Q: I’m in the middle of doing my engine swap and I have a problem, or 2…. My alternator wont line up and my power steering pump will not line up also. How can I fix this?

A: Make sure to use the alternator bracket that came with the 6G74 and also make sure you use the upper power steering bracket that came with it too.


14. Q: I read that you are using the crank pulley from the 6G72 on the 6G74, any benefit to that? Also what about the timing marks on the crank pulley’s, are they on the same spot on both?

A: For rotational weight reduction I chose to use the 6G72’s crank pulley (1.5 LBS lighter). Contrary to what I posted before, both crank pulley’s have the timing marks on the exact same location.


15. Q: I noticed that the housing where the thermostat is at looks different from our stock one. My heater hoses are too long. What do I do?

A: Cut the hose’s length to fit.


16. Q: I noticed my ECU is reading higher water temperature readings since I did the swap. Is this normal? If it is not, what can I do to fix this?

A: Re-use the stock 6G72 thermostat. It reads a few degrees cooler than that of the 6G74’s thermostat. That should solve your problem.


More to come....when I have more time. Hope this helps.
 

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Resident Asshole
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2. Q: Will the 6G74 throttle body bolt on to my eclipse without modification?

A: No. 2 items must be looked at. First item is the cruise control solenoid and its holding bracket. Both of these items hit the firewall. Short and simple solution is to remove the bracket and remove the cruise control solenoid. Second item to look at is the TPS socket. It is different from the connector that we got on our eclipse. Simple solution to that is to buy a TPS pigtail and install that in place of our stock TPS connector.
The proper answer is that only certain configurations have issues w/ the cruise control bracketry. I am using a 100% stock 74 TB on my car with ZERO fitment issues and only modification necessary was the new pig tail. This is with a Diamante manifold and a 72 engine.
 

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Ripp'd 3.5L
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Discussion Starter #6
The proper answer is that only certain configurations have issues w/ the cruise control bracketry. I am using a 100% stock 74 TB on my car with ZERO fitment issues and only modification necessary was the new pig tail. This is with a Diamante manifold and a 72 engine.
I think you may be right on that one. One of the 2 TB that i've seen would probably clear the fire wall...if mounted on a 6G72 block. If and only if you try and bolt either one to a 74 block, you will have fitment issues.
 

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FearIsTheMindKiller
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I thought it was the IAC pigtail and not the TPS on the diamante T/b.
 

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Generally Bitter Admin
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Thanks for the FAQ. All readers, please add anything relevant to engine swaps in this thread.

Stuck.
 

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Resident Asshole
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I think you may be right on that one. One of the 2 TB that i've seen would probably clear the fire wall...if mounted on a 6G72 block. If and only if you try and bolt either one to a 74 block, you will have fitment issues.
The only issue should be w/ the stock strut bar.

I thought it was the IAC pigtail and not the TPS on the diamante T/b.
You are correct. It's the 6 wire IAC that needs to be rewired. If you manage a pigtail from a Diamante you just match the wires. The color coding is identical.
 

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Strat190
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What is the benefit from swaping out heads/cams? Are the 6g72's better flowing than the 6g74's? What I have heard is that the 6g72's are better for high end horsepower and the 6g74's are better for low end torque. Someone correct me if I'm wrong.
 

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Hi

Thanks for all that info man u rock!! One question though I'm thinking of swapping my 4G64 engine 01 spyderGS with an 6G72 03-05 spyderGTS, for uniqueness do u think it will be worth it as far as everything goes since this is my first engine swap on my first car?? Anymore advice would be greatly appreciated!!
 

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Resident Asshole
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What is the benefit from swaping out heads/cams? Are the 6g72's better flowing than the 6g74's? What I have heard is that the 6g72's are better for high end horsepower and the 6g74's are better for low end torque. Someone correct me if I'm wrong.
The heads are identical. Only cam profiles are different and honestly the difference is not big enough to make a major difference.
 

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DJ, the transmission housings are different from the 4g64 to the 6g72, so in order to do that swap you'd have to swap your tranny too. You'd be better off just getting a gt/gts or turbocharging the 4g64. Or if you really want to do an engine swap, find yourself an Evo 7 engine.
 

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Ripp'd 3.5L
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Discussion Starter #15
The heads are identical. Only cam profiles are different and honestly the difference is not big enough to make a major difference.
Not a major difference....though there is a big difference. Stock 6G74 cams choke the engine at about 5600ish, using the 6G72 cams let your engine breath pretty damn well up to about 6500ish. There is some additional power, not much though, what really does change is where the power is made (rpm wise).
 

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Not a major difference....though there is a big difference. Stock 6G74 cams choke the engine at about 5600ish, using the 6G72 cams let your engine breath pretty damn well up to about 6500ish. There is some additional power, not much though, what really does change is where the power is made (rpm wise).
Dang it feels really good to talk about cars that can do dang near 7000rpm. I saw where someone said look for an EVO 7 motor... Well those drop straight in and what mods need to be done?

Where dragon said "not much though". Beleive me, 1hp can make a difference in winning or losing... at least that's how I see it. Power is power ;):yesway:
 

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sludging it up
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Can i do a direct swap of a 6g74 crank into my 72? or will i need other mods to make it work. I read the 3.5l swap discussion thread but with 45 pages it would take me a week to read though it all
 

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Ripp'd 3.5L
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Discussion Starter #20
Can i do a direct swap of a 6g74 crank into my 72? or will i need other mods to make it work. I read the 3.5l swap discussion thread but with 45 pages it would take me a week to read though it all
no direct swap...you'd have to buy some custom main bearings in order to get that specific swap to work (due to the different main journal sizes) IPP would be the place to find those main bearings...than again, the price would just not be worth it.
 
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