The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners

  • Join the Community!

    DSMtuners is a massive archive of DSM information - but more importantly, it's a COMMUNITY! Join in and participate with other DSMers, and invite all of your DSM friends to make this place their home. Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice. ;)

Please Support Feal Suspension
Please Support ExtremePSI

4g63t tolerance guide?


Proven Member
Oct 11, 2007
I have been searching to find what the most popular engine specs reference is. I used to hear alot about Chilton's but never got one and Ill be tearing my built motor down soon to measure everything and rebuild via my own measurements.

I have a blueprinting book from Amazon on the way but I also will need a great 6 bolt service book as well! Let me know whats available as Im not clear on what manuals will be thorough enough for me with service limit tolerances and all.


Proven Member
Jan 16, 2008
Wisconsin, Wisconsin
The chiltons and Haynes manual claim to be a full teardown and rebuild...The books at the local auto parts stores are now 25$+...


DSM Wiseman
Aug 16, 2004
Columbia, Missouri
There really isn't a universal set number for any spec in the engine. It depends on whether you are making stock power, using stock internals, making big power and so on. Many people build them differently. A good rule of thumb is the more power you are making, the looser you want the engine.

Mr Peepers

DSM Wiseman
Oct 16, 2005
Janesville, Wisconsin
It will vary pretty wildly with the different parts you use. Cast vs forged pistons, power goal etc. With a stock bottom end you would basically want to run looser ring gaps and on the higher end of the piston to wall clearance to keep things from making contact with more power/heat. .020 and .022 ring gaps and .002" PTW clearance worked well for me, but that's much tighter than you would want to run a forged piston.


Proven Member
Oct 11, 2007
Okay I bought this motor slightly used which was built by a known 4g63 shop so I guess I have to tear it down first to see what forged parts I have.

What do people tend to say about machining a block for a second time with 650hp goals? This motor has been running like 525hp and I'll surely start a build thread upon ripping apart and measuring my clearances pre-machining..


Proven Member
Jul 1, 2009
Pensacola, Florida
Measure your clearances as you tear the engine down.

Ring gap, bearingss, PTW ect


Proven Member
Nov 17, 2008
Manheim, Pennsylvania
If you are reading books that are 4g63 specific and don't like what they are telling you, maybe you should consider letting a shop build your motor. I'm not trying to be rude, but places like Bushur and AMS charge you good money to rebuild motors, because they have tried different things and they know what works, and more importantly, what DOES NOT work! I used pretty much the same spec's Matt gave out (Mr. Peepers) for the PTW and ring gaps (stock pistons). I have built many 4g's that have survived for years using the "Haynes" manual spec's for main and rod bearing clearances, and other torque specs.

Bottom line: If your not sure you can do it right, can afford to do it twice?


Proven Member
Oct 11, 2007
Well Im a pro tech with my dad in our own shop and Ive done everything other than the bottom end to this car, my shep rebuild will be done by me as im confident with these standard trans's especially.

This now is currently the second build motor and im sick of people not doing theyre work properly, id rather take the time and money to get my own tools which are all on their way to spec everything BEFORE machine this way I can tell the machinist what the specs NEED to be so that there is no chance of some small taper or anything slipping by the blue print work, balancing will be done by me as well.

Its much more reliable to take the 4 hours to entirely check EVERY bore on the block both vertical and horizontal for so that the block can be minimum machined to fit my new crank and bearings. This way if everyone does they're job right, once the parts come and I DOUBLE check even the bearings thickness to make sure they are what they are advertised to be, then if my clearences have been researched enough there should be no issue.

The most important part to me is a virgin block/tolerances of machining commands/balancing so if I can get a virgin block which someone did a nice job of ripping me off on here already, then my motors should go from lasting 10k to 20k between builds!

AMSOIL Dlr #352885

Proven Member
Dec 1, 2020
Grimesland, North_Carolina
For Everyone's Information (FEI) reading this...

Perform Clearance Inspections on every item you can measure before teardown.
Just like checks for build.

I always use the Piston Manufacturer's Specified clearances for Pistons and use the rings/brand/type suggested also.
Bore measurements are very critical as well as the Crosshatch honing stone grit finish.

1) Pressure wash block, REMOVE all oil Galley plugs, water jacket plugs. HAVE STEEL Block hot tanked. BE CAREFUL on aluminum compatibility with vat chemicals.
2) Get a quality Dial indicator and stand for endplay inspections, Quality Micrometers, Check accuracy before and during use!
3) inspect /Take all measurements for any thing to determine engine health before you tear down.
4) Match mark Everything bolted to block, main caps, rod caps, piston/cyl # to rods & front direction, flywheel location clutch cover to flywheel
KEEP ALL PARTS that wear/match together -TOGETHER!!! Match all wear parts to location removed from.
5) Bag and TAG/Mark all hardware location use etc.
6) clean oil galley bores w/ rifle bore cleaning brushes
7) Wash w/ tide until cylinder bores wipe clean... lube w/ anti-rust protection, cosmoline metal parts...
8) Wash with tide until bores wipe clean after all machining work again...Keep bare metal oiled to prevent rust/corrosion etc...
9) Did I say KEEP the Environment you are working in clean everything so cleaned up you can eat off it?...
10) If reusing pistons, check ring land clearances...IF USING NEW PISTONS RE-Check ring land clearances, behind machine shop
11) If reusing pistons, check piston to cylinder clearances, IF USING NEW PISTONS Recheck Piston/Cylinder wall clearances, behind machine shop
12) Measure ring gap on old rings, measure ring end gap for EACH NEW rings, Measure Ring end gap after machine shop bore or honing. ONCE SATISFIED Mark location for each cylinder.
13) BAG COVER tightly every time you walk away from it for any amount of time & when not working on it.
14) Plastigauge is your friend, use it!
15) Clean all internal/external threads with thread restoring kit
16) Inspect & Use Quality Hardware
17) Adhere to Proper Torque methods with a Quality Calibrated Torque Instruments.
18) Follow precise torque specs for wet, dry and Plastic Region bolt torque.
19) Don't reuse plastic region head bolts or USE ARP Stud/nut set.
20) Use Lubricant supplied w/ ARP Hardware or buy it.
21) Did I say check/measure any/everything measurable....
22) Don't forget piston pin bushings or condition if reusing pins...
23) Did I say clean everything...
24) Now let's talk about the Cylinder head, valves, seats, lifters........


Nov 14, 2013
Independence, Kansas
I agree with this and only want to add this one VERY IMPORTANT ITEM on my builds, once you see pictures, you will see why. Thanks to Dale @BogusSVO from way back. It's a thing that I always point out!
My only difference from the above is I wash my cylinders with ATF until a white paper towel comes out with NO grey, all RED on them. This takes me 5-6 times, washing each cylinder with my palm of my hand and ATF (a detegent). :thumb:


DSM Wiseman
Jun 9, 2003
M-Town, Michigan
The bench mark for engine specs/tolerances would be the OEM service manuals. There are plenty to be found on ebay.


Nov 14, 2013
Independence, Kansas
Good point Nick! I have a FSM for every car that I own! Invaluable. I can't imagine owning a DSM and not having one. I have the 90 set, 92 set and a 98 set. Well worth whatever I paid for them! I also have a Saturn FSM, a Honda Accord FSM and a 1996 Impala SS FSM. If I work on it, I have it.
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Feal Suspension Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications OHM Racing Raven Fabrication RixRacing RockAuto RTM Racing SouthBay Fuel Injectors STM Tuned VR Speed Factory

Latest posts

Build Thread Updates

Latest Classifieds