I would like to thank Tony Mawad for saving this info that took me a very long time to type out. Had he not saved it, it would have been lost when the site crashed in March of 2005.
SPECIFIC 7MGTE REBUILD TIPS PART 1
This is intended to serve as a guide and to share the lessons that I've learned through the thousands of dollars I've spent. If you plan on rebuilding your 7M, please consider what I have to say. This isn't an all-inclusive guide or "everything you need to know". This is only intended to be supplemental information. You still need to familiarize yourself with basic engine maintenance techniques available in any Haynes or Chilton's manual. See also http://www.cygnusx1.net/
PAY ATTENTION!
When selecting your machine shop, look at their operation. It would be in your best interests to select the machine shop that has the cleanest setup and the newest, most accurate equipment. Many machine shops cannot correctly machine components for our engines.
The 7MGTE oil system is a high-flow, low-pressure system. At idle, the stock specification from toyota for oil pressure is 4.3psi. Yes, I said 4.3 psi, NOT 43 PSI! From the factory, the 7MGTE has rod clearances of .0008 to .0021, total thrust washer clearance of .002 to .009 (thats the clearances of both sides added together) and crank main bearing clearances of .0012 to .0019.
Check your oil pump drive shaft clearances:
http://www.cygnusx1.net/supra/libra...M/em/EM_84.html
Also -ensure your camshafts have the correct clearance. .0014-.0028 for the number 1 and .0010-.0037 for the rest of the journals.
Clearances too large will contribute to low oil pressure.
In additon, you should keep in mind that with such tight clearances it is possible for the measurements to change significantly with a change in temperature. If you take home your crankshaft, pistons, etc and re-measure them in your 0 degree garage, the measurements will probably change from the climate controlled readings of the machine shop. (And vice versa) Keep everything the same temperature for the whole process.
And, keep in mind that your mic might read different than your machinist - compare notes. Bring your mic in to check it out.
Many machine shops feel that it is necessary to make the clearances larger on these motors for "high performance" applications because thats what they do for the V8's. This, quite simply, is not the case. I learned this when I lost my first motor. Clearances that are too large will lead to a significantly lower oil pressure at idle and take out your bearings.
So, with that being said, BUILD THE ENGINE TIGHT. And always, I repeat always double check ALL measurements for yourself with a micrometer. Check your crankshaft, rods, piston bore, etc. etc. Dont trust the machinist to make sure that they are all correct. You will have a lot of time and money in this - dont let it go to waste.
PISTON FITMENT TIPS
Any reputable machine shop will wait until they have the pistons before they bore the block. If they want to bore the block before they have the pistons walk away with your engine because they are RETARDED!!
If you coat the pistons with any type of thermal barrier, consider the fact that they might not expand as intended from the manufacturer. Add .001 of clearance if you moly-coated the skirts.
HKS used to sell 85.5mm pistons - which are actually quite larger than the stock bore. I would limit any custom piston size to that.
MACHINING AND PREPPING THE BLOCK
Ensure that the rear timing cover is bolted to the block when you mill the top. If it isnt, your head will be held up by it and not seal correctly against the block surface.
Ensure that your machine shop gets it smooth. The first block I had done still had pits in it. My machinist insisted it would be "fine". Fuck him. Ill talk more about surfacing for your head gasket later.
A good machine shop will paint the block exterior, and ensure that all of the oil and coolant passages are clean upon the delivery of the block. If they are full of rust and debris when you blow out your oil passages before assembly, be sure to bring it up to your machinist.
CLEAN OUT THAT ENGINE!!!! Keep it clean - your oil passages should be spotless before assembly. Get a drip pan under your engine block while it is on the stand and blow it out with WD-40, air, with a final rinse of engine oil. Remove the piston oil squirters and ensure that they arent stuck open for some unknown reason. Ensure that they are clean and move freely. They have a check valve in them that shouldnt allow oil past at lower psi. Once you get the block clean, reinstall and torque to specs.
Check your oil filter housing. There are two relief valves in the housing - one bypasses oil to the oil cooler and the other bypasses oil in the event that the filter clogs. Ensure they are clean and installed in the correct DIRECTION.
Tap out all of the bolt holes and follow up the tap with a gun bore brush. You will make things easier on yourself.
And always, always cover it up when you're done for the day. Avoid dust-kicking drafts in your work area at all times. A trash bag with the little yellow handles that sinch it up works well.
CLEAN YOUR CRANKSHAFT OIL PASSAGES - same as above. If your crankshaft has a groove worn in the ends from the oil seal, you can purchase a repair sleeve that will fit right over the end.
ASSEMBLY OF YOUR SHORTBLOCK
Measure and set your ring-end gaps.
Use plenty of moly-based lube on your bearings during assembly.
I dislike plastigauge, my personal belief is that a good set of mics are far more accurate. However, plastigauge can be a good indicator of where you stand with your clearances - just dont rely on it.
Use ARP hardware - the new main stud kits have been changed. (The Supra community can thank me for that.) The old kits used to hit the pickup tube for the oil pump. Be wary if you have picked up an old kit.
Get a quality torque wrench.
PREPPING AND ASSEMBLING THE HEAD
The first thing you should do, before doing ANYTHING to the head you plan on rebuilding, it have it inspected and cleaned by a competent machinist. But be wary! I once had a machinist bead blast my journal surfaces He thought that bearings were supposed to go in there.
SPECIFIC 7MGTE REBUILD TIPS PART 1
This is intended to serve as a guide and to share the lessons that I've learned through the thousands of dollars I've spent. If you plan on rebuilding your 7M, please consider what I have to say. This isn't an all-inclusive guide or "everything you need to know". This is only intended to be supplemental information. You still need to familiarize yourself with basic engine maintenance techniques available in any Haynes or Chilton's manual. See also http://www.cygnusx1.net/
PAY ATTENTION!
When selecting your machine shop, look at their operation. It would be in your best interests to select the machine shop that has the cleanest setup and the newest, most accurate equipment. Many machine shops cannot correctly machine components for our engines.
The 7MGTE oil system is a high-flow, low-pressure system. At idle, the stock specification from toyota for oil pressure is 4.3psi. Yes, I said 4.3 psi, NOT 43 PSI! From the factory, the 7MGTE has rod clearances of .0008 to .0021, total thrust washer clearance of .002 to .009 (thats the clearances of both sides added together) and crank main bearing clearances of .0012 to .0019.
Check your oil pump drive shaft clearances:
http://www.cygnusx1.net/supra/libra...M/em/EM_84.html
Also -ensure your camshafts have the correct clearance. .0014-.0028 for the number 1 and .0010-.0037 for the rest of the journals.
Clearances too large will contribute to low oil pressure.
In additon, you should keep in mind that with such tight clearances it is possible for the measurements to change significantly with a change in temperature. If you take home your crankshaft, pistons, etc and re-measure them in your 0 degree garage, the measurements will probably change from the climate controlled readings of the machine shop. (And vice versa) Keep everything the same temperature for the whole process.
And, keep in mind that your mic might read different than your machinist - compare notes. Bring your mic in to check it out.
Many machine shops feel that it is necessary to make the clearances larger on these motors for "high performance" applications because thats what they do for the V8's. This, quite simply, is not the case. I learned this when I lost my first motor. Clearances that are too large will lead to a significantly lower oil pressure at idle and take out your bearings.
So, with that being said, BUILD THE ENGINE TIGHT. And always, I repeat always double check ALL measurements for yourself with a micrometer. Check your crankshaft, rods, piston bore, etc. etc. Dont trust the machinist to make sure that they are all correct. You will have a lot of time and money in this - dont let it go to waste.
PISTON FITMENT TIPS
Any reputable machine shop will wait until they have the pistons before they bore the block. If they want to bore the block before they have the pistons walk away with your engine because they are RETARDED!!
If you coat the pistons with any type of thermal barrier, consider the fact that they might not expand as intended from the manufacturer. Add .001 of clearance if you moly-coated the skirts.
HKS used to sell 85.5mm pistons - which are actually quite larger than the stock bore. I would limit any custom piston size to that.
MACHINING AND PREPPING THE BLOCK
Ensure that the rear timing cover is bolted to the block when you mill the top. If it isnt, your head will be held up by it and not seal correctly against the block surface.
Ensure that your machine shop gets it smooth. The first block I had done still had pits in it. My machinist insisted it would be "fine". Fuck him. Ill talk more about surfacing for your head gasket later.
A good machine shop will paint the block exterior, and ensure that all of the oil and coolant passages are clean upon the delivery of the block. If they are full of rust and debris when you blow out your oil passages before assembly, be sure to bring it up to your machinist.
CLEAN OUT THAT ENGINE!!!! Keep it clean - your oil passages should be spotless before assembly. Get a drip pan under your engine block while it is on the stand and blow it out with WD-40, air, with a final rinse of engine oil. Remove the piston oil squirters and ensure that they arent stuck open for some unknown reason. Ensure that they are clean and move freely. They have a check valve in them that shouldnt allow oil past at lower psi. Once you get the block clean, reinstall and torque to specs.
Check your oil filter housing. There are two relief valves in the housing - one bypasses oil to the oil cooler and the other bypasses oil in the event that the filter clogs. Ensure they are clean and installed in the correct DIRECTION.
Tap out all of the bolt holes and follow up the tap with a gun bore brush. You will make things easier on yourself.
And always, always cover it up when you're done for the day. Avoid dust-kicking drafts in your work area at all times. A trash bag with the little yellow handles that sinch it up works well.
CLEAN YOUR CRANKSHAFT OIL PASSAGES - same as above. If your crankshaft has a groove worn in the ends from the oil seal, you can purchase a repair sleeve that will fit right over the end.
ASSEMBLY OF YOUR SHORTBLOCK
Measure and set your ring-end gaps.
Use plenty of moly-based lube on your bearings during assembly.
I dislike plastigauge, my personal belief is that a good set of mics are far more accurate. However, plastigauge can be a good indicator of where you stand with your clearances - just dont rely on it.
Use ARP hardware - the new main stud kits have been changed. (The Supra community can thank me for that.) The old kits used to hit the pickup tube for the oil pump. Be wary if you have picked up an old kit.
Get a quality torque wrench.
PREPPING AND ASSEMBLING THE HEAD
The first thing you should do, before doing ANYTHING to the head you plan on rebuilding, it have it inspected and cleaned by a competent machinist. But be wary! I once had a machinist bead blast my journal surfaces He thought that bearings were supposed to go in there.
