Having taken the engine hat off to hunt for the mysterious tappet noise, I bolted a dial gauge on and checked number one exhaust for when it shut.

 

I noticed that one of the notches in the FRONT rim of the crank pulley was almost lined up with the timing mark on the cam chain cover. As I checked the max opening of the rocker I saw the other mark on the front rim was lined up, so I measured the distance across the chord between the two notches.

 

A little bit bit of geometry showed me that the angle between them was the exhaust duration between max opening and closing. One came up a little out on the cover timing marks (15deg) but that is a Crow cam so it is a bit out from stock in closing.

 

Coincidence or purpose? Does anyone know what they were put there for??

Edited May 30, 201115 yr by altezzaclub

Having taken the engine hat off to hunt for the mysterious tappet noise, I bolted a dial gauge on and checked number one exhaust for when it shut.

 

I noticed that one of the notches in the FRONT rim of the crank pulley was almost lined up with the timing mark on the cam chain cover. As I checked the max opening of the rocker I saw the other mark on the front rim was lined up, so I measured the distance across the chord between the two notches.

 

A little bit bit of geometry showed me that the angle between them was the exhaust duration between max opening and closing. One come up a little out on the cover timing marks (15deg) but that is a Crow cam so it is a bit out from stock in closing.

 

Coincidence or purpose? Does anyone know what they were put there for??

 

Alttezza

Have you got a pix of the pulley, I would like to see the marks ?

Thanks

Andy

Remind me at the end of the month Andy, I'm in NZ working on my Mum's house until then.

 

cheers

Actually, now I photgraph it all, they are slots more than notches, cut into the front face of the front flange of the pulley. The TDC timing notch is cut into the edge of the rear flange of the pulley. Maybe they show valve opening and closing.

Edited May 30, 201115 yr by altezzaclub

Altezza

This is interesting.

I have the same on a pulley, I assumed some one cut the marks in to check dissy timings at 10 deg intervals, I was wrong.

 

 

my 4age has a similar mark... wondering what this is for also.

i had the same problem with my 4k when i was timing it up. set the other notch to 0 (according to the cover) go to start it and nothing. cracked the shits and pulled number 1 plug out and stuck a screwdriver in the bore to feel it come tdc and it lined up with the other mark?

 

set it to the other mark and it ran fine.

 

thanks toyota for the mind f@$k!

LoL Evan..

 

Next time you're setting tappets, check those front grooves against valve opening & closing on #1 cyl. Then again, I don't expect you to have a stock cam anyway! :laff:

stock cams are for whimps! :lolcry:

stock cams are for whimps! :lolcry:

 

Ahhhh But you need a stock cam to get reground into something better.