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Thank you, Silvertune, for your outstanding comment.
Anyhow, I did see the chamber sizes differing by about 17cc, but what does that mean regarding the swap? I've tried searching the forums and have found a lot of info on full motor swaps, but not head specific swaps, and the ability to do so, or lack thereof. I'm incredibly new to this shit, and understand the frustration regarding senior members, but let's be honest. We all start somewhere.
 

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You appear to have the dexterity of mind to know that "we all start somewhere" so why don't you pick somewhere even slightly logical to start and that is the BASICS of how an engine works. If you want to cut to the chase of your current train of thought go google "compression ratio" and figure out what it does and how it's calculated so you may develop the ability to think for yourself rather than develop a habit of prompting the wrinkled teet that is this forum to spoon feed you.

Once you can think for yourself you can get engine specific. The 6g75s 65cc chambers are 22cc's larger than that of the 6g72. Since you have a GTS you have perfectly flat top pistons and so 43cc plus some clearance volume at top dead center now add OVER FIFTY PERCENT to that volume...

So you're talking about dropping the compression ratio more than two points even on the GTS motor which comes with 10:1 pistons compared to the GT's 9:1. You're talking ~7.5:1 which is below running threshold for an internal combustion engine. The engine would not even start and if it did it would run like absolute shit. You'd have to go wide open just to get away from a stop sign.

And no. You can't mill the heads down enough to compensate. Beyond the fact that you'd need adjustable gears to set the timing you'd bury the valves in the pistons before you even got enough compression into it to make the same power with 6g75 heads as you already were with 6g72 heads. Yes... the heads have the same bolt pattern. But I'm gonna guess you didn't stick random legos together as a child just because they stuck together. Clearly you're smarter than that. Which means you're just being lazy because all this information is readily available on multiple forums across the internet.

Besides. What makes the 6g75 heads better? Giant valves? More "flow"? Go read up on that term too for it is the single most abused word thrown around in automotive performance next to "back pressure" which I also encourage you to look up. Even if the compression ratio were to stay the same the 6g75 heads would LOSE power on the 3.0. The valves are TOO big, the reversion effects associated with big flow numbers at low lift levels relative to the displacement would defeat the volumetric efficiency of the engine entirely at the RPM's these motors operate at. The 72 does not move enough volume to create enough port velocity to keep air in the cylinders until a purpose defeating high RPM with the 75 heads and that'd apply IF they even worked.

If you want evidence to support my claims go look up the 3000gt all motor dyno sheets available on the web. They make worse numbers than our 3 liters do stock and the only significant differences are the head flow numbers. The turbo cars get away with it because they're turboed! The stock small valve heads are perfectly capable on the 3 liter and even the 3.5 when they're ported and matched with a cam designed for those breathing dynamics. If you want 3.8 heads go get a 3.8.
 

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What distributor do i need in my 2000 gt manufactured in sept of 99, but the motor was swapped with a motor from a post 4/2000. Both camshaft and crankshaft codes are thrown
 

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What distributor do i need in my 2000 gt manufactured in sept of 99, but the motor was swapped with a motor from a post 4/2000. Both camshaft and crankshaft codes are thrown

Should be single pulse wheel, not the 4 pulse wheel. Also depends on what rom you're running in the ecu. Also depends on the distributor- if it's aftermarket or re manufactured then it's anyone's guess.


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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.
Good stuff, question your quite knowledgeable in regards to our lovely pride and joys "eclipses" now i just put a used tranny in my eclipse 2002gt 3.0 automatic but have exghausted myself trying to troubleshoot my problem which is the tranny throws itself in to fail safe mode, ive changed in/out speed sensors, nuetral switch, checked wiring, etc. Im thinking now that they may have given me the same trans but out of galant. Could this be the problem????
 
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