1980 Mazda 626 which ecomods first?

[Simonas]

I've read much on this sight, but finally decided to join. My car in a 1980 Mazda 626. It has been sitting for 8 years or so, but the overall condition is reasonably good other than the paint finish. It has minimal rust, which is a lot of the reason for me taking it. That and the fact that it was given to me for the cost of transferring it to my father's name (insurance costs half as much that way).

My plans are to get the vehicle going as soon as possible, and it has to pass inspection before the middle of this year because of a new law that would unregister the vehicle and that would cost all kinds of money and hassle to get back.

So... my planned mods are as follows. Some will definitely get done as some fluids will be replaced anyway, and the head needs to be milled and the head gasket replaced. Other things like the passenger mirror delete and antenna delete would happen mainly because I don't want to hunt for replacements.

I'm copying my list of planned modifications from my car "Mazda 626" in the "garage":

Compression ratio raised from 8.6:1 to 10:1 as the head gasket must be replaced anyway.

Front air dam, fan possibly disabled.

Rear (and possibly front) wheel skirts.

Vacuum gauge (possibly).

Alternator "off" switch.

Mud flap removal.

Passenger mirror removal (broken right now, so why not remove it?).

Antenna delete (no radio, no need for antenna).

Possibly speaker delete for weight reduction.

Smooth wheel covers (probably coroplast, as pizza pans are hard to obtain).

Aerodynamic grill block (possibly hooked into air dam)

Kammback (length: to rear bumper)

Carburetor fuel solenoid kill switch.

Ignition timing adjusted.

Synthetic transmission and differential oil.

Increased tire pressure to max.

Differential ring and pinion changed from 3.909 to 3.636 ratio assuming that I can find one. I'd need to find one off a 6-speed English Miata or a 2-liter RWD 626.

Disk brake pad return springs (homemade, and won't be a hassle as I have to remove disks for machining anyway.)

And most important of all--further adjusting of the nut behind the wheel: EOC, P&G.

The vehicle will be used mainly for mixed driving, i.e. driving 10km (6mi) to town and running errands. Over here gas is expensive, and I like older cars because I can work on them myself. My speed would never exceed 70km/hr (44mph)other than on our "autobahn", where I am allowed to do 90 (56) until I get two years of driving status. I can find most major parts for the car on ebay and have them shipped as most people here don't even know there was a first generation Mazda 626. I've never seen one other than the one that is mine.

So...What I am looking for is the experts opinion on what I should do first and what would benefit me the most. Keep in mind that I am planning ahead a lot, so these mods probably won't start happening until sometime in the summer. I just thought it wise to think ahead somewhat as to what kind of opinions and options you all have to offer.

Thanks to all who help me out with this. I'll welcome criticism that has a good attitude behind it, any relevant ideas are welcome. Thanks in advance.

I've included a picture of a car similar to mine.

[chefdave]

Hi
have not seen a mazada like that for years. from what i can renember were a stunning car but limited head room in back. should have a 5 speed box fitted as std. one i test drove was a 2litre 16valve beauiful engine. as for mods as all say on here front air dam rear would need some work. take photo of vehicle and use template on this site for tidying up rear end aero speaking. maybe a

[Simonas]

Many thanks for the quick response. Everyone else feel free to chime in with other ideas.

The head liner is in good condition everywhere except the back, where heads have previously rubbed. It also doesn't appear to have had rear seat belts, as I haven't found a place they should have been mounted to.

The European version with 1.6 engine got a 4-speed from '78 to '80, from '80-'82 they got 5-speeds standard. The interesting thing is that mine is the earlier version and it has a 5-speed. It could be that the transmission was replaced along with the engine, which the previous owner told me he had had replaced. At least, he said he had the block replaced.

My engine is a SOHC 1.6l 55kw, with a stock CR of 8.6:1 and points ignition.

As for the template, I used the second picture I posted and came up with the pictures below. The problem is that the car doesn't have one section of the roof that is the highest; it is all level. So does that mean I should use the center of the roof as the reference, or just fit the template to the car however makes the Kammback easier to build?

[chefdave]

Hi
i would go on first photo with template. others no doubt would give different/better advice. try going through the aero section on this forum and see what has been done to other saloon cars. one sticks is a scorin in black.

[mechman600]

Be aware that if you mill the head on an overhead cam engine, the cam timing (and ignition timing if it's driven off the cam) will become quite retarded, because the cam to crank distance will be reduced while the belt is staying the same. This could be beneficial if you want to go for a poor man's Atkinson, but I would modify the cam sprocket to be sure the cam timing remains the same. That way you can test the effects of increased CR alone and then adjust the cam timing if you want later.

[poomanchu]

That is incredibly clean for a 34 year old car! I would really enjoy seeing all those mods you have planned for it come into fruition and the results they would bear.

Originally Posted by mechman600

Be aware that if you mill the head on an overhead cam engine, the cam timing (and ignition timing if it's driven off the cam) will become quite retarded, because the cam to crank distance will be reduced while the belt is staying the same. This could be beneficial if you want to go for a poor man's Atkinson, but I would modify the cam sprocket to be sure the cam timing remains the same. That way you can test the effects of increased CR alone and then adjust the cam timing if you want later.

In the Honda DOHC world it is common to mill the head. I really have never taken this into consideration! I thought the tensioner would adjust for any slack, but now that I actually think about it the distance IS changed. Whoa all these years...

For my Frankenstein engine (2000 Honda CRV Block, 1994 Integra dohc vtec head, 1999 Integra type r cams, hi comp pistons) I used adjustable cam gears to fine tune the timing. I wouldn't be surprised if someone out there makes a set for your car.

[mechman600]

Originally Posted by poomanchu

I used adjustable cam gears to fine tune the timing. I wouldn't be surprised if someone out there makes a set for your car.

Cheaper to elongate the bolt holes on the cam gear, loosen and tweak. Armed with a degree wheel, a few beers and an afternoon, you can get it bang on.

I wonder if FE gain from retarding the timing would be proportional to the amount of beer consumption.

[Occasionally6]

OK for the Honda but on the Mazda engine, the cam gear is located on a Woodruff key. Offset keys might be available though.

These engines are known for wear on the chain adjuster and loose timing chain tension so look for those with the head off.

10:1 may not be achievable with head machining. The limit is 0.2mm off the standard 109mm height. If it were a 1.8 or 2.0l, substituting a head from one of the smaller capacity engines might work to increase CR. Valve sizes are the same for all three. (Engine swap?)

The 1.8 and 2.0l have an 80mm bore vs 78mm for the 1.6l, so an over bore and swapping pistons might be possible if a rebuild was an option. That will also increase CR. I don't know if there is a difference in the block castings that would preclude that.

1.8 and 2.0l distributors have 2 stage centrifugal advance vs 1 stage for the 1.6l, and different vacuum and centrifugal advance curves. Auto. trans. have different vacuum advance curves to manual trans. distributors. It will be possible to play mix and match if the parts are still available. Filling and filing the slots, swapping the springs and altering the weights in the advance mechanism are also possible.

The carb tune can be played with - swapping or filling (solder) and drilling air bleed tubes etc. Concentrate on the primary venturi as that will what you operate with under light loads. You can make global changes by dropping the float level some (6mm between top of float and float bowl is standard). The idle fuel mixture position will affect light load FC a lot.

EGR was fitted to these engines in some markets.

There is (should be) a hot air intake flap in the air cleaner intake. Easy to play with that.

The same engine family was used in 'B' and 'E' series commercial vehicles (for parts).

The 2.0l 626 has taller man. trans. ratios than 1.6 and 1.8l.

The same trans. family was used in SI-III and SIV-V NA RX-7, early MX-5/Miata, and the 'B' and 'E' commercial vehicles ^.

[Simonas]

Thanks a lot for the advice.

The car in the pictures isn't mine. Mine is currently up the road a ways from our house, and I don't have the guts to walk all the way there and back with a camera in -15C and high winds. Taking the pictures isn't the bad part, it's walking there and back that would freeze me. That and the car is between a fence and a building, so there is not enough room for me to get decent pictures.

I hadn't really thought about the timing, but I could file off a bit of the Woodruff key and then lap the sprocket to the shaft, tighten it down pretty tightly and that might hold it. Of course, that assumes that the shaft has a taper, and I haven't gotten around to taking the engine apart yet.

The engine currently has 79mm Lada (Russian car) pistons in it. At least, the previous owner said that he had to put them in. I just assume they are 79mm because that is the standard size. For all I know, they could be overbore pistons and that would yield something like 79.4 or 79.8mm. If has 79mm pistons, I calculated that the compression ratio is now 8.8:1 instead of 8.6:1. The only thing is that I don't know how much of a dish the Lada pistons have. I plan to do further calculations when I get it the head off.

Currently a rebuild isn't an option, as I'm short on money, and the engine was rebuilt not too long before being parked. The engine oil is a light brown color, so I'm suspecting that that is the oil from the change after break in. The guy who gave/sold me the car was known for keeping his cars in good condition so I'm not super worried.

Yes, there is a flap, but the hot air intake hose is missing, so I'll have to find another one.

What I wish I could find is a 3.636 differential ring and pinion. Then the ride height could be lowered with smaller tires and the gear ratio would be better. According to my calculations, the engine would run at 2000rpm at 70kmh (44mph). Engine speed would be reduced by 7% or so if I could find one of those ring and pinion sets for a decent price. Like not much over $120 (€90) to get it to my house. I think UK Miata 6-speeds and Australian MX-5s had them...

For mechman800: I don't drink (alcohol), even if I'm old enough to. In this weather I'd much prefer hot tea to cold beer even if I did drink. My philosophy is that if you've never taken the first drink, you'll never drive drunk.

I've looked at various mods for sedans, so I'm not totally oblivious to the ideas. I'm thinking of making the kammback hook to the roof gutters on the top, have a hinge in the middle of it, and then be hooked to the back of the trunk so the trunk could be opened. I still have to make some calculations to get it to work, and as I stated earlier, the weather could be warmer and calmer.