Timing Belt Trouble

[RoarinE21]

Also it's expected that every time you use a part thats not OEM, everything has to be checked/rechecked and than checked again. A simple glance at those two gears side by side would have prevented this.

Definitely glad thats what I ended up doing before trying to start this thing. Guess it still woulda saved me about 3-4 hours of work and a head gasket

[ForcedFirebird]

Appears it was bolted together in the wrong position.

[zaq123]

Fuckin amen. Moral of the story is dont buy anything ebay/amazon without checking everything about the product out first
Or just dont in the first place:nice:

Also it's expected that every time you use a part thats not OEM, everything has to be checked/rechecked and than checked again. A simple glance at those two gears side by side would have prevented this.

[RoarinE21]

shit gears are shit

Fuckin amen. Moral of the story is dont buy anything ebay/amazon without checking everything about the product out first
Or just dont in the first place:nice:

[digger]

shit gears are shit

[RoarinE21]

Alright am pulling the head and going back to to one gasket this weekend. Also found my old oem cam gear and compared it to my second aftermarket one and it looks like I was right! the timing marks were inches off! the one I made with my sharpie was only one tooth haha. Not sure wtf they were thinking when they made these and advertising them for m20s besides destroying everyones valves. Well guess that solved it! thanks everyone for the feedback, sure ill be back soon with some other problems!

heres a pic of the oem vs aftermarket cam gear, you can see the actual timing marks circled in red and the ones put on by aftermarket guys in blue:

https://farm5.staticflickr.com/4750/40027853371_99787878e8_m.jpg

[zaq123]

I couldnt figure out what the M20 valves are all supposed to look like at tdc so if anyone knows or has a picture of that that would be great[/B].

At DTC for cyl 1: if you look at cam lobes for that cyl, they should be pointing down at the same angle from the center line. Very roughly speaking, IN lobe will be at 4 o'clock and EX at 8 o'clock position. Basically, the same position when you can measure the valve clearance properly

[ForcedFirebird]

First off, you don't need two head gaskets on an m20. You just gave yourself something silly like 7:1 compression - don't even know if you will be able to get it to fire as you will be dangerously close to 100psi cranking. the m20 came from the factory with 8.8:1 which is perfectly fine to boost, or even raise compression and boost.

What is the sharpie line in your pic? You need to put the crank at TDC, then use the tick mark located on the outside of your cam gear. The marks inside the gear are for advancing or retarding the cam.

I suggest you take the head off, put a single head gasket back on, put the stock cam gear back on, then attempt to work on it. If it's a stock engine you are going to turbo, toss that cam gear aside. I have been putting turbos on bone stock motors for years with great results. Just o-ring the block (or stock thick .070" MLS head gasket), and put ARP studs in and the engine will easily make 400 in a daily driver and last many years so long as you don't botch the tune.

[zaq123]

Also anyone know where you can rent the a leak down test kit?

You can build your own. Use the spark plug adapter hose from the compression tester, quick connector, 2 gauges and 4-5" tubing in between two gauges. Epoxy/JB weld a restriction inside the tube and drill 0.04 hole once epoxy is dry. All part can be found in HF or HD store for under $20.

if you are concerned about bent valves and don't have a tester, you can just TDC a cylinder and pressurize it thru a spark plug hole with the compressor (still need a comp. gauge plug hose). If you can hear/feel the air from IN/EX, valve aren't sealing. Just make sure you can hold the crank nice and firm, the breaker bar will want to smack you with all that pressure in the cyl.

Honestly, I'd just pull the head if you meet any major resistance during the rotation. M20 should rotate very easy even with HD valve springs and 12" bar. It will obviously resist slightly when v. springs are compressing but it will be still smooth.

Did you ever tried to find TDC with a piston stop? If so, even with a gentle rotation you will feel when pistons meet the hard stop. Don't know how else to describe it....when overcoming valve spring pressure you will feel some a resistance but it will be very smooth (spark plug removed obviously).

Before TB change, do you recall how it felt when you were rotating the engine to TDC?

[RoarinE21]

Also anyone know where you can rent the a leak down test kit?

[RoarinE21]

Maybe once you get the belt on right you should do a leakdown test instead of directly going to pull the head. You have a small chance you didn't bend a valve but it's worth a shot if it means you don't have to pull the head.

Was planning to do just that! its a project engine so I haven't started it yet (only hand cranked), plus I have double head gaskets for lower compression because boost, but that should also allow for more valve clearance.

Also for the slack people, it was only when I was setting the belt but then it quickly goes away once your crank it clockwise.

So today I took out the spark plugs and was also browsing pictures of m20 cam gears at TDC online, specifically was looking at how that little metal thing for the distributor is sittinf/facing. I then set my cam using that stratedgy to some random tooth on the gear. First I notcied both the rockers for cyl 1 were movable so that was a good sign, I the put on the belt and it cranks all the way beautifully no problem, what the fuck. Do you guys think its just some stupid chinese gear they messed up the lines on? It has the pin on the back like the normal cam gear so its sitting properly on the cam, then im pretty sure the distributor thingy is sitting in there right because theres that little divot thingy in the ring it goes into. Had an extra one of the aftermarket gears so I took some pics. Thankyou guys! Please keep up the feedback I think were figuring it out!!

https://www.flickr.com/photos/142582707@N02/39242574634/in/dateposted-public/

https://www.flickr.com/photos/142582707@N02/28173067239/in/dateposted-public/

https://www.flickr.com/photos/142582707@N02/25081453337/in/dateposted-public/

https://www.flickr.com/photos/142582707@N02/39920730972/in/dateposted-public/

Any other ways to confirm my valves are at tdc?

[vtechnik]

Maybe once you get the belt on right you should do a leakdown test instead of directly going to pull the head. You have a small chance you didn't bend a valve but it's worth a shot if it means you don't have to pull the head.

[zaq123]

Let me know if you guys think of anything

You didn't answer the question. Are you certain that your crank is in TDC for cyl #1? How did you verify that. Just because TDC marks on the crank aligned, it doesn't mean TDC for cyl #1.
Also as someone mentioned, there should be no slack if your tensioner was set correctly. You could experience some slack when not being careful in rotating it CCW but it will go back to normal once you get it going in CW direction.

"made up TDC line for slack" etc is a very wrong approach when dealing with TB and interference engines. They do not forgive.

The correct approach is to find true TDC for cyl#1 with a piston stop, install degree wheel and zero it out based on found TDC (disregard factory mark). Install head with cam at TDC for cyl 1. Install TB and set the tension, lock the tensioner. Install dial indicator on the rockers and verify that valve timing is where it needs to be based on the degree wheel on the crank. Adjust the cam gear (if adjustable) accordingly. If not adjustable, decide if you can live with what you get out of stock cam gear. If not, get an adjustable cam gear.


Based you your description of events, I would strongly recommend to pul the head and verify that valves didn't meet pistons. I know it sucks...

[uturn]

At TDC the two rockers for cyl 1 will have play because the valves will be closed. Are the threads holding in your tensioner stripped. If they don't lock in then everytime you spin it backwards the slack will get you out of time. Why are you even spinning it backwards?

[ForcedFirebird]

Compress the tensioner and tighten the bolt to keep it back. Put the belt on the crank first and pull up tight. Then wrap it around the oil pump, the the cam, making sure the right side of the belt is very tight. Then go around the cam while keeping it tight on the crank and slip it on the tensioner last.

I actually back the crank up one belt tooth so that as I put the belt over the tensioner, I turn the crank up to TDC. Then before releasing the tensioner, rotate the engine and make sure the cam lines back up.

also if you arent already crank it over with no spark plugs in

Also, this. When a piston is on it's compression stroke, you will have resistance. Take the plugs out and see if there's change.