Zero compression on rebuilt engine

sailaholic · Postby **sailaholic** » Wed Jun 18, 2014 1:21 pm

Tdc comes up twice though. Once for compression and once for exhaust. If you've got the cam gears pointed right but put them on the dowels the wrong way (done it) then you'll have no compression.

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CM sport · Postby **CM sport** » Wed Jun 18, 2014 2:35 pm

Read sailaholics post he is correct google the service manual for the engine and all the info you need should be in there if you don't already have one.

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Nevyn72 · Postby **Nevyn72** » Wed Jun 18, 2014 4:08 pm

This might be a bit of a strange one but is it possible to have the cam shafts arse about? ie. Inlet where the exhaust should be and vice-versa?

plohl · Postby **plohl** » Wed Jun 18, 2014 4:14 pm

^No.

One cam has the slotted end for the Crank/Cam angle sensor.

Russellb · Postby **Russellb** » Wed Jun 18, 2014 6:23 pm

sailaholic wrote:Tdc comes up twice though. Once for compression and once for exhaust. If you've got the cam gears pointed right but put them on the dowels the wrong way (done it) then you'll have no compression.
TDC IS TDC Don't mater what stroke your on ( other than Ignition )

plohl wrote:^No.

One cam has the slotted end for the Crank/Cam angle sensor.

But it's A NB SE so there are NO slots ECT on the back of the cam
Trigger it is done on the cam wheel

Ok now the NB SE has 2 different cam gears
one is the STD nb Exhaust wheel and the other is different ( cant find a photo now )
But saying that if the Cam Lobes point to the outside ( exhaust right and inlet Left ( from front of engine bay ) ))
And you have done TDC with the Screwdrive down the No1 plug hole then time to look at Valves ECT

speed · Postby **speed** » Thu Jun 19, 2014 9:18 pm

Reading about someone with zero comp saddens me.
Hope you sort it out soon!

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plohl · Postby **plohl** » Fri Jun 20, 2014 12:51 am

Russellb wrote:But it's A NB SE so there are NO slots ECT on the back of the cam
Trigger it is done on the cam wheel

my bad

project.r.racing · Postby **project.r.racing** » Sat Jun 21, 2014 2:03 pm

plohl wrote:
Russellb wrote:But it's A NB SE so there are NO slots ECT on the back of the cam
Trigger it is done on the cam wheel

my bad

exh cam is longer and doesn't fit in the in cam location due to slots.

my guess is incorrectly timed engine.

plohl · Postby **plohl** » Sat Jun 21, 2014 3:28 pm

^I'll remember that

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project.r.racing · Postby **project.r.racing** » Sat Jun 21, 2014 6:01 pm

do a in/ex cams swap, and you gotta cut 20mm away from the ex cam. how do i know? i just with 2 heads and 3 sets of cams today.

and1 · Postby **and1** » Sun Jun 22, 2014 2:36 am

Looks like I found my problem!!

I seem to have no clearance between lifters and the cams. I couldn't even fit my 0.05 mm feeler in between any of the lifters.

I think this could be due to the mix-match of my old cams and new (second hand!) head. I can't remember off the top of my head whether the lifters are from the old head or the new head. Could I swap in the old lifters and have the problem solved?

If not, what would be the most cost efficient way to change the shims on the lifters? Bear in mind I have no way of checking what the current clearance is as there is none :oops:

Anyways I took some photos of the timing while I was at it. Due to angle of pics, EX gear looks off but is actually on the marks.

IMG_1887 by AndyPhan123, on Flickr

IMG_1889 by AndyPhan123, on Flickr

Postby **Okibi** » Sun Jun 22, 2014 3:18 am

Too many teeth?

From here:
http://www.mazda-speed.com/forum2/index.php/topic,26758.0.html

the yellow mark is at the 10 and the white mark is at the "T"

Checking shims on the NB head
http://www.miataforumz.com/how-40/how-c ... -head-331/

project.r.racing · Postby **project.r.racing** » Sun Jun 22, 2014 9:01 am

No clearence between the lifters would do it. But if you have just used oem parts, then I fail to see how this could have happened. Unless you have used 1.1mm longer valves that are available aftermarket?

The teeth issue brought up might be an issue. But being 1 tootk out in timing isn't gonna bring the house down. Just make it idle like a rotor and maybe loose power in higher rpms. But still investigate it.

and1 · Postby **and1** » Sun Jun 22, 2014 2:10 pm

project.r.racing wrote:No clearence between the lifters would do it. But if you have just used oem parts, then I fail to see how this could have happened. Unless you have used 1.1mm longer valves that are available aftermarket?

The teeth issue brought up might be an issue. But being 1 tootk out in timing isn't gonna bring the house down. Just make it idle like a rotor and maybe loose power in higher rpms. But still investigate it.

Standard valve train. Head only had a reseat done. So I'm assuming the reseat was enough to put the clearances out of spec?

Where's the cheapest place to purchase shims? I guess I might have to buy a couple of different sizes to see if I get the required clearance.

I'll double check the timing while I'm at it..

greenMachine · Postby **greenMachine** » Sun Jun 22, 2014 4:35 pm

and1 wrote:If not, what would be the most cost efficient way to change the shims on the lifters? Bear in mind I have no way of checking what the current clearance is as there is none

Easy, but time consuming. Take out the shims (you have 'shim-on-top-of-bucket', I think), you may have to take out, or at least lift up, the camshafts to do this, and measure the clearances. Measure carefully, and write them down so that you not only know what your clearances are, but can identify what clearance is where. Subtract your desired clearance, and that gives you the shim thickness you need. Make sure that when you do this, the camshaft is fully tightened down or the clearances may not be accurate.

Then check all 32 of your shims and see how many you have that match, how many can be ground down to fit, and how many you need to buy. There is a firm in Melbourne that sells them, so you are in luck there.

Last time I did this it was a 'shim-under-bucket', and a real PITA, but it was surprising just how few shims I needed to buy.

:mrgreen: