how does milling the cylinder head affect the valve timing??

907mge · 03-25-2011, 03:04 AM

The 7mge is a non interferance motor to begin with, so no. The only thing it will do is raise the compression a bit.

btwilson86 · 03-25-2011, 07:24 AM

The teeth on the timing belt most likely would not perfectly align due to the shorter gap between cams and crank, so to get timing set perfectly you should use adjustable cam gears. I'm assuming at most they will be a degree or two off, so it may not be very noticeable if you ran without the adjustable cam gears.

El_supracabra · 03-25-2011, 09:41 AM

I see what you are saying....hmm...well, wouldnt you be able to "take up" the extra slack with the idler adjustment?

when i put it in time, i rolled it over 360* and it seemed to line back up perfectly. Would that cause it to completely fall on its face at 4000rpm and spit and stumble? It will BARELY make it to 6000. and only if i HOLD it to the floor.

El_supracabra · 03-25-2011, 09:43 AM

see the thread "the unfixable mystery problem". lol EXACT SAME problem

thanks!

907mge · 03-25-2011, 09:52 PM

I would think that that little amount would not throw off the belt that much. After all it is only 2/100ths of an inch. I would think you probably have another problem.

cre · 03-26-2011, 01:14 AM

A non-interference engine is only such as long as the distance between the piston crown and the valves isn't reduced beyond a given point. I don't remember how much room you've got on the 7M before that safety margin is gone.... But, that has absolutely nothing to do with timing.

No, even with slack being pulled up by the idler the timing is still skewed.... You're not removing the slack evenly, just on one side.

BT's right though, the difference is negligible and in most cases not a concern.

El_supracabra · 03-29-2011, 05:37 AM

Thanks a lot guys! that is a bit of a relief about my timing. Ill still keep it in mind though...

so far i have Ohm tested the TPS (tested good but needs adjusted), the ISC valve, the MAF, the primary coil, igniter, all 3 pickup coils, the fuel pump relay (for S&G's) and voltage tested all of my VSV's. Im thinking that i may need to replace my fuel injectors or replace my ECU....

pishta · 06-04-2022, 05:49 PM

Quote:

Originally Posted by 907mge

The 7mge is a non interferance motor to begin with, so no. The only thing it will do is raise the compression a bit.

Wrong...the cam timing will be retarded because the cam cog will be closer to the crank cog and will roll CCW a smidge. You can only mill an OHC about .02mm before you need to cut and use a "head saver" shim. these are usually .020" an allow a .020 cut on the head or block to preserve factory valve timing.

03-25-2011, 07:24 AM	#2
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	The teeth on the timing belt most likely would not perfectly align due to the shorter gap between cams and crank, so to get timing set perfectly you should use adjustable cam gears. I'm assuming at most they will be a degree or two off, so it may not be very noticeable if you ran without the adjustable cam gears. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

03-25-2011, 09:41 AM	#3
El_supracabra Intake Join Date: Feb 2011 Location: South of Columbus, Ohio Posts: 45	I see what you are saying....hmm...well, wouldnt you be able to "take up" the extra slack with the idler adjustment? when i put it in time, i rolled it over 360* and it seemed to line back up perfectly. Would that cause it to completely fall on its face at 4000rpm and spit and stumble? It will BARELY make it to 6000. and only if i HOLD it to the floor. __________________ 86.5 Supra NA: milled head .020, decked block .007, .5mm+ pistons, port & polished intake manifold and cyl head,OBX header, 3-angle, cold air intake, Cometic MLS HG. ALL NATURAL! CHEVROLET- Cracked Heads, Every Valve Rattles, Oil Leaks Every Time FORD- Flipped Over, Rebuilt Dodge DODGE- Dirty Old Dust Gathering Engine I'd rather drive a Toyota, than push a ford.

03-25-2011, 09:43 AM	#4
El_supracabra Intake Join Date: Feb 2011 Location: South of Columbus, Ohio Posts: 45	see the thread "the unfixable mystery problem". lol EXACT SAME problem thanks! __________________ 86.5 Supra NA: milled head .020, decked block .007, .5mm+ pistons, port & polished intake manifold and cyl head,OBX header, 3-angle, cold air intake, Cometic MLS HG. ALL NATURAL! CHEVROLET- Cracked Heads, Every Valve Rattles, Oil Leaks Every Time FORD- Flipped Over, Rebuilt Dodge DODGE- Dirty Old Dust Gathering Engine I'd rather drive a Toyota, than push a ford.

03-26-2011, 01:14 AM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	A non-interference engine is only such as long as the distance between the piston crown and the valves isn't reduced beyond a given point. I don't remember how much room you've got on the 7M before that safety margin is gone.... But, that has absolutely nothing to do with timing. No, even with slack being pulled up by the idler the timing is still skewed.... You're not removing the slack evenly, just on one side. BT's right though, the difference is negligible and in most cases not a concern. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

03-29-2011, 05:37 AM	#7
El_supracabra Intake Join Date: Feb 2011 Location: South of Columbus, Ohio Posts: 45	Thanks a lot guys! that is a bit of a relief about my timing. Ill still keep it in mind though... so far i have Ohm tested the TPS (tested good but needs adjusted), the ISC valve, the MAF, the primary coil, igniter, all 3 pickup coils, the fuel pump relay (for S&G's) and voltage tested all of my VSV's. Im thinking that i may need to replace my fuel injectors or replace my ECU.... __________________ 86.5 Supra NA: milled head .020, decked block .007, .5mm+ pistons, port & polished intake manifold and cyl head,OBX header, 3-angle, cold air intake, Cometic MLS HG. ALL NATURAL! CHEVROLET- Cracked Heads, Every Valve Rattles, Oil Leaks Every Time FORD- Flipped Over, Rebuilt Dodge DODGE- Dirty Old Dust Gathering Engine I'd rather drive a Toyota, than push a ford.

03-25-2011, 03:04 AM	#1
907mge 20psi boost Join Date: Dec 2009 Location: Harrisburg Posts: 759	The 7mge is a non interferance motor to begin with, so no. The only thing it will do is raise the compression a bit.

03-25-2011, 09:52 PM	#5
907mge 20psi boost Join Date: Dec 2009 Location: Harrisburg Posts: 759	I would think that that little amount would not throw off the belt that much. After all it is only 2/100ths of an inch. I would think you probably have another problem.

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