Project 6G74 Blackout

[M-Rod]

The 6G75 heads will lower your compression slightly as a forewarning.

But as far as making them work, all you will need to do is remove the cover where your distributor sits on the rear head. Make sure both engines are at TDC on cylinder 1 if you want to make your distributor install as easy as possible. Once you have that done, remove the distributor from your 6G72/74 head, as well as the studs, then install them both onto the 6G75 heads.

One other thing you can do, that isn't necessary, but would clean things up, would be to remove the cam sensor from the front head, and bolt in the cover from your 6G72/74 head.

[jmath99V6]

I thought I read somewhere that the 75 pistons 95mm. So would it be worth it to but a set of 75 pistons and have my 74 bored? I need to do a little more research about the math that goes into the compression ratio. I know there's a thread about the the cr with a 74 bottom and 75 heads, but I don't remember if I saw it here, on galanttuners, or club3g. It's all running together lol

[M-Rod]

It all depends on what you want to do. I was stuck at that point with mine as well when I found out I needed new pistons. At that point I figured it would cost roughly the same whether I was going to rebuild my 74 or just buy a low mileage 75 and drop it in. And the decision to go with the 75 was the evident way to go. Plus it eliminated a bunch of unnecessary time and labor.

[jmath99V6]

I talked to some local shops and it looks like I could get the blocked bored for under $150 and they have NPR piston and ring sets for the 6G75 (95mm) on ebay for like $210 ( I did a little research and they seem to be decent). So, my question is, how would I figure the compression ratio for that?

[jmath99V6]

not the best picture, but that's my 5 spd.

Only 70k mi. and got all the other stuff (master and slave cylinders, pedals, shifter, flywheel, intermediate shaft, etc.) for only $350 - needless to say I'm pretty geeked

[Galantfan88]

Looking good man, keep up the good work

[beam514]

did you grab the center console too?? lol

[jmath99V6]

did you grab the center console too?? lol

lol yeah. maybe I'll use the shifter boot.

[M-Rod]

nice find. You will be happy with the M/T

[SPD_FRK]

Project has come along nicely man, good to see you picked up the 5spd swap too.

The 6G75 heads will lower your compression slightly as a forewarning.

Doing a 75 head swap onto a 72/74 will drop the CR drastically. Consider this, the 72/74 is only a 9:1 CR for both IIRC wheras the 75 is a 10:1 CR. Now the 74 heads have 43cc chambers (72 is likely same if not less), and the 75 heads have 65cc chambers. If you swap over the 75 heads to an engine with 9:1 CR, you will probably see a final CR in the range of 8.5:1 if not lower, good for high boost maybe but certainly not N/A.

You could certainly swap in a 75 crank though to make the 74 a stroker without boring the block. Personally for as far as the V6 platform has advanced so far, the full 75 swap is the best option when it comes to the dollar spent and performance gained.

[jmath99V6]

Thanks. Maybe I'll just stick with the stock heads for now then. Ran into another snag though. I just realized I didn't pull the bolts out of my 72 before I sold it, so I need a set of bolts to connect the engine to the transmission. I know they're M12s but does anyone know the lengths or where I can get them? I called the local dealership but the parts guy said he needed the vin #??? not sure why.

[jmath99V6]

BTW, I haven't seen anything about them on this forum but THMotorsports is pretty decent. I got a injen cai for $175 with free shipping. Customer service was pretty good too. I ordered a clutch kit sut the price was wrong and they fixed it immediately. The refund actually showed up before the charge on my card statement.

[jmath99V6]

Getting pretty close. I got my shift cables and clutch pedal installed yesterday. I put the engine back together on Wednesday and Thursday. Got the transmission bolts I needed at the junkyard. I'll be in jersey this weekend, so won't probably put the engine and transmission back in until next week. Is there a specific procedure for starting an engine after it's been rebuilt?
I'll post pics soon.

[jmath99V6]

I put the fenders back on to line up my new radiator support. Everything looks good, just need to weld it in place


Shifter base and shift linkage installed (yes they are the most annoying thing ever)


Almost ready to drop the 74. I'm pretty excited


I know i should have saved up and got some rpw headers, but that'll have to be a spring project


Painted front calipers, they didn't turn out half bad, but I don't know why i went with silver

[beam514]

good choice on the valve cover colors *thumbs up*. For a second I was like what the hell is that thing on the left of the engine?? haha I forgot because I removed my PS pump. And silver is good for the calipers. Low key

[M-Rod]

good job so far. Can't wait to see another engine swapped V6!

[jmath99V6]

Alright, so engine is in, but I'm running into a few problems. on the 74, the injectors are all tied into one plug, but on the galant it looks like the wires run from the wire harness directly to the injectors ( i'll post pictures to clarify later), and the speed sensor connectors from the galant doesn't fit the one on the transmission, anbody else run into that or am i doing something retarded?

[jmath99V6]

anybody have Dimante service manuals?

[M-Rod]

the injectors will be fine with the original wiring that your 3.0 used. As far as the transmission goes, I believe only one existng pigtail connects to the M/T. It's the speed sensor. The pigtail is similar to that of the tps and map sensors. Hope this helps. Good luck.

[beam514]

on some of the manual transmissions, there is a speed sensor conversion harness. Dunno why they did this but its a blue plug to a red plug (the red plug is similar to the MAP sensor plug)