Is swapping a 7MGE Block for a GTE block a good idea?

[toyota.s]

I have a 87 Supra with a 7MGE with automatic transmission and I am rebuilding the engine. I am not adding any power, simply just a OEM plus build with MLS head gasket, ARP studs, rings, bearings ETC. I just want to drive this car daily and not race anybody; it can be done. The engine is disassembled and currently with my machinist, long story short my block has cracks all over, he says it looks like the head was severely over torqued and block needs to be replaced. He has a GTE block from a previous customer who had a check bounce and couldn't pay the bill. I asked if the block had oil squirters and it did confirming that it is indeed a GTE block. My machinist doesn't know if the GTE block is an 87 or not. My Cylinder head and cams are good, my question is is swapping a GE block for a GTE block a good idea?

He has a friend who is a Cressida guy and says he has some GE blocks. My first thought was to go with the GTE block but then I read similar post saying oil lines this, oil pumps that, oil sumps here, crankshaft there and had me spooked. Don't want to run into more of headache when I personally do the assembly and install it back into the Supra.

 

[Asterix]

From memory, the only difference is the GTE block has oil squirters and a second knock sensor. Pre-89 blocks typically had a 6M crank, 89+ a 7M crank with a slightly lower redline. Heads are the same between the two, but the cam shafts are not. Browsing around the EPC for a while will show other differences I don't remember.

If you're sticking with a GE but using a GTE block, I suggest blocking off the oil squirters. They aren't needed and reduce oil pressure quite a bit. The second knock sensor can simply be ignored.

Make sure your deck gets surfaced with the front timing cover in place.

Lastly, ignore ARP's recommended head stud torque of 90ft-lb. Torque to 75 and live a happy life knowing you didn't crush the head or crack the block.

 

[Bru]

The oil squirters would be overkill for a non-turbo application. They help to cool the bottom of the pistons, which gets hotter in a turbo engine. You could go either way depending on the cost. Something you're going to need to do is plug up the oil feed by the engine serial number for the nonexistent turbo and also block off the oil return return at the block. You might be able to recycle the block off plate from your non-turbo. Curiously, I have a block off plate to that is adjacent to the oil return in the block. It looks like the same size. If you are using the front timing cover from the turbo engine, you'll need to plug up the coolant ports that would feed the turbo. One is located near the thermostat, the other is located where the lower radiator hose connects.

 

[toyota.s]

From memory, the only difference is the GTE block has oil squirters and a second knock sensor. Pre-89 blocks typically had a 6M crank, 89+ a 7M crank with a slightly lower redline. Heads are the same between the two, but the cam shafts are not. Browsing around the EPC for a while will show other differences I don't remember.

If you're sticking with a GE but using a GTE block, I suggest blocking off the oil squirters. They aren't needed and reduce oil pressure quite a bit. The second knock sensor can simply be ignored.

Make sure your deck gets surfaced with the front timing cover in place.

Lastly, ignore ARP's recommended head stud torque of 90ft-lb. Torque to 75 and live a happy life knowing you didn't crush the head or crack the block.

yes that is a good tip, I'm asking my machinist to compare the blocks and have the squirters removed. Speaking of head torque I know we've spoken before and also to other users. What torque number would you start off with to get to 75ft ibs? 25-50-75?

 

[toyota.s]

The oil squirters would be overkill for a non-turbo application. They help to cool the bottom of the pistons, which gets hotter in a turbo engine. You could go either way depending on the cost. Something you're going to need to do is plug up the oil feed by the engine serial number for the nonexistent turbo and also block off the oil return return at the block. You might be able to recycle the block off plate from your non-turbo. Curiously, I have a block off plate to that is adjacent to the oil return in the block. It looks like the same size. If you are using the front timing cover from the turbo engine, you'll need to plug up the coolant ports that would feed the turbo. One is located near the thermostat, the other is located where the lower radiator hose connects.

yes, noted I have asked my machinist to swap any block off plates to the gte block. I plan to use my original timing cover from the ge block.

 

[Bru]

yes, noted I have asked my machinist to swap any block off plates to the gte block. I plan to use my original timing cover from the ge block.

The only issue with that is that after it's cut, they need to be on the same level. The best scenario would be if the front plate were equal or higher than the block before the cut. If the front plate is lower, and after the block is cut still lower, then that would be an issue. There would be a gap between the head and the top of the front plate. A workaround would be to use some Permatex Ultra Black silicone to seal the oil passage, but that's not an ideal solution.
Here's a link to another Supra forum with an article about timing cover bolt length for your reference. Click here to go there. I always put fasteners in zip lock bags marked with a sharpie, or use a cardboard box lid to keep them in order.

 

[Nick M]

Redline change is from the cam profiles. As noted, the blocks are different in terms of having oil squirters, turbo oil supply and drain, etc. The later blocks have more ribbing and a little "meatier".