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Discussion Starter · #1 ·
Hi!

So I need the Mazda 303-507 crankshaft timing peg, but I can only buy it from the USA and the shipping to Macedonia is $50 plus the already overpriced $40 for the peg and you can see how it's a lot of money for what is basically an M10 screw.

So would any of you kind people who already have the 303-507 peg please measure accurately the 4 points labeled A, B, C and D with a caliper and tell me the dimensions?

I will make a new drawing with the dimensions (both in millimeters and inches) and it will be here for people who wish to make their own timing peg. I have access to a lathe and I'm pretty sure I can make this peg no problem. I'll make more, actually, and I will give them away for free to whoever wants one. So, anyone? Please?

 

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The one good pic I knew of is gone now. I found a crappy one tho, and these should be your requested dimensions. I've also attached one for the cam tool.

A - 38.55
B - 5
C - 26
D - 12.55


The whole timing procedure for this engine is crappy and there are a dozen points in the process where things can go sideways.

There have been a few different arguments made about using just an M10 bolt ~60 mm long is better/worse/exactly same as using the 303-507 peg. The issue is that the tip diameter of the peg -vs- tip diameter of a bolt could alter true TDC, but I've seen very skilled mechanic with multiple rebuilds of this engine use a degree wheel and verify there was no change to TDC between the two.

I dunno- have no opinion here.
 

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Discussion Starter · #3 ·
Thanks TiGraySpeed6, you're the man.
Well, if the screw is the same dimensions as the peg then I don't see the problem. I think it's important that the tip of the peg is at a 90 degree angle. Maybe people make it rounded when they cut it, I don't know. I'll make a few pegs and report back.
 

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So you can have a sense of what's happening, here's a peg and a bolt in position







 
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Discussion Starter · #5 ·
Great, thanks! So I'll screw in the "SST" and then rotate the crank clockwise with a 21mm wrench until it stops, right? On the compression cycle of piston #1 .
 

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Yuppers-
slowly rotate and the spoke with the hole should end up at 6:00, lined up with the threaded hole in the timing cover which would be used with an M6 bolt to help hold the pulley while you torqued the crank bolt- which you don't need to do, but it's a way to double check.

You should also see the crank position sensor lined up with the 20th tooth on the pulley.
 
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Discussion Starter · #8 ·
So, I put together this image to make it clear how does the SST 303-1061 look in 3D.








Just to make sure, only these 3 areas need to be 5mm, everything else is 10mm, right?

 

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Yup.
Those are taken from the Mazda OEM plate, pic of oem plate below for reference.

I've also added a pic of a custom cut plate, in use, so you can see it situated for context. This one is all one thickness. Most important thing is that it's tight in the cams- you should have to literally tap it into place. I can't stress enough that you don't want them to move. Note that both outside edges, indeed much of the tool, rests on the head for support.





 
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Discussion Starter · #10 ·
Great info, thanks!

I'm collecting info, tools and parts to do the VVT and timing chain job :)

I'll post pictures of the 303-507 and 303-1061 when I make them.
 

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Discussion Starter · #11 ·
Update

I've been quite busy with work but I've managed in the meantime to make the special tools.

First, here's the 303-507 SST with metric and imperal dimensions, as promised :)



Now, here's the tools:

303-507






303-1061






Both


They turned out great.

Cost of timing peg - $40, it cost me $0.29 :grin2:
Cost of cam alignment plate - $80? I don't know. It cost me $0.00 because it was a leftover piece of T7000 series aluminum and I knew the guy with the CNC mill and lathe who made these for me for free.

Who want a timing peg for free? :grin2::grin2::grin2:


Thanks a lot, TiGraySpeed6, you've really helped me.
 

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The one good pic I knew of is gone now. I found a crappy one tho, and these should be your requested dimensions. I've also attached one for the cam tool.

A - 38.55
B - 5
C - 26
D - 12.55


The whole timing procedure for this engine is crappy and there are a dozen points in the process where things can go sideways.

There have been a few different arguments made about using just an M10 bolt ~60 mm long is better/worse/exactly same as using the 303-507 peg. The issue is that the tip diameter of the peg -vs- tip diameter of a bolt could alter true TDC, but I've seen very skilled mechanic with multiple rebuilds of this engine use a degree wheel and verify there was no change to TDC between the two.

I dunno- have no opinion here.
hi,
could you please check for me the dimensions of the 303-748 peg???
i didn't find it in google..

thank you a lot
 
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