1983 Mazda RX7 FB - Welding Practice

[Tepper]

I've had a bit of an itch for an RX7 for a while now, and having looked at a few I've settled on this one. Went to have a look at it today, paid for it and it'll be getting trailered over to my lock-up in a fortnight.

eBay pics:








She's pretty solid, there are a few small areas of rust but nothing too serious. It's been sat for 15 years and it runs if you hold the revs or if you pour petrol down the carb and there's no fuel coming out of the jets in the primaries so I think it'll need the carb sorting out. I'll probably order a rebuild kit and fully strip it down. Interestingly, it's got a Janspeed boost gauge and a plate riveted onto the bulkhead saying it was a Janspeed turbo conversion. The turbo is no longer there, but there's still a Janspeed exhaust on there as well as some weird ignition controller which I can only assume had something to do with the conversion. Someone in the past has removed the 'rat's nest' and fitted a blanking plate to the inlet manifold and it also has a manual choke, rather than the standard automatic.

Plans are to get it running and MOT'd, then go from there. I'm looking forward to getting stuck in!

[luckyseven]

Welcome to the dark side, lol

Towbar on an RX-7? That's just plain wrong Interesting that your car might have had an aftermarket turbo setup. What's the carb that's on it now, is it the stock four-barrel Nikki carb? Choke was always manual, btw. It has some little electromagnetic thing that's supposed to retract it when the engine warms up, though they rarely work well any more. A 12A-engined Series 2 like that wouldn't have had much in the way of rat's nest to remove, tbh, that only really came in on the big-engined 13B and fuel injected cars, none of which we got in the UK until the FC-model RX-7s. Check for rust in the rear seat pan and the plates for the axle arms, they're typical spots. These cars can hide quite bad rust quite well, sadly. Inlet blanking plate just means the emissions nonsense has been deleted at some point, and you're well rid of it, appalling rubbish. Judging by the previous turbo application, I'm guessing yours must be on headers now? Poor fuel flow might simply be a dodgy, clagged up fuel pump and/or filter, they're prone to it though the Nikki carb gums up easily too on stale unleaded. Sadly given the lay-up I fear you're right that it'll need stripping down. Good luck with that!


Lastly, may I point you towards www.rx7fb.com/ as the font of all 1st-gen RX-7 wisdom? Free to join, and all knowledge is there at your feet. Plus it's a nice place to be

[smurph323]

Aug 3, 2013 18:56:16 GMT Tepper said:

I've had a bit of an itch for an RX7 for a while now, and having looked at a few I've settled on this one.

i think thats how it started for all of us
welcome, bet you cant wait to see her arrive

[Tepper]

Cheers people, yeah I am a bit excited for it to turn up. Even with it running just by having petrol poured down the carb it sounded brilliant.

Luckyseven, the towbar has to go! I'll need to find out how it's attached, if it can just be unbolted I'll be happy but I fear it'll be welded on. It's running the standard carb, or something that looks exactly the same as one to my untrained eye. Headers? I don't know to be honest with you, I'll have to get some pics of the engine bay when it arrives and I'm sure you'll be able to tell me what's what. I think I might just try to find a secondhand carb, fit that then rebuild the one that came off. I'm already registered on the FB forum, I had a bit of a read up on there when I started thinking about buying an FB. Thanks for your advice.

[luckyseven]

Yeah, the original exhaust had a massive manifold chamber about the size and shape of an oven-ready turkey (called the Thermal Reactor!) which was supposed to merge exhaust gas with a fresh air feed from an airpump. There were also bypass valves and other rubbish designed at cleaning the exhaust emissions, which is where your blanking plates come in. None of this would have fitted or worked on a turbo application very convincingly, hence why I imagine you've got an aftermarket setup from the ports back.


If you're already registered on the FB forum, it'd be great for you to say hello. There's a fella called Dave Nock (Codge) on there who keeps an unofficial record of where all the 1st gen RX-7s are and he'd be extremely grateful for even a rough location. He's harmless, lol, not in a stalker sorta creepy way! In addition, I mentioned your car on there and general consensus is no-one's ever seen a Janspeed conversion running; a couple have surfaced with the turbo removed, like yours, but they don't seem to survive intact. It'd be really interesting if you could spare the time to take some pics for our curiosity when you get the car over?

[Tepper]

I think the thermal reactor is still there, it does have some huge chamber for a manifold. Looks like any pipework into it has been welded up. As I've said on the FB forum, I'll gladly put some pics up when I get the car, I'm just as curious as everyone else regarding the Janspeed bits.

[Tepper]

Here she is!


When we got it off the recovery truck I stuck some petrol in and she fired up, the petrol in the inline filter looked pretty grotty... After the first start it actually just about idled, which I was quite impressed with. However, after a few starts, it now takes a while to fire up and won't idle at all. I reckon it's probably cacked up fuel. Would it run if I just gave it a gravity feed of fresh petrol straight into the carb or does it need pressure from the fuel pump?

There are a few obvious things that need doing, such as sorting out the leaking oil cooler, changing all the fluids, sorting out a headlight bulb and wipers etc. I'm after an electric window switch too if anyone's got one kicking about they might be interested in selling.

Pictures as promised:














Loads of dodgy wiring :roll:




This brass thing on the side of the carb looks like it should be connected to something, it was chucking out some sort of vapour when the car was running.














Some sort of bung in the exhaust looking from under the car:


Looks like there should be 2 belts here?


So there you have it. Thoughts? Comments? If you see anything in the pics that is obviously not how it should be, please give me a heads up! I think what I'm going to do is drop the fuel tank and give it a really good clean up to make sure the fuel getting to the carb is good then go from there. That inline filter needs changing and it's fitted the wrong way round as well. I didn't have a look underneath it today as I'm suffering with an almighty hangover and getting it into the garage was enough of a struggle... Oh and the clutch doesn't seem to be engaging properly, the car moves but even with the clutch fully out it doesn't feel like it's biting properly.

[spandelly]

That looks pretty good and love the pootie tang avatar. must admit though when I saw the spare pulley it just screamed supercharger conversion. If everything else is still there from its turbo days (uprated ignition etc) then it could prove pretty cheap too.

shada tae

[luckyseven]

Zoinks! Scary wiring is scary! Scotchlocks are never a good sign...

Interesting stuff going on there, it looks like when whovever it was stripped the turbo out, they put back a completely original theraml reactor amongst other things. The exhaust bung might have been an EGT feed or even lambda sensor for tuning air-fuel ratio? Wonder what the holes were for cut in the radiator shroud, it can't have been running an intercooler or it'd have been like a bomb ! (that corner there is where the expansion tank for the radiator ought to live, by the way, it normally mounts onto the radiator shrouding where those holes are. Can't see in any of the pics whether you still have one)

That pulley only has two belts when the airpump's still on, which yours isn't. Have to say I chuckled at the way the writing's worn of the igntion module; "Use only with MicroDynamics red....." What!? Red what, tell me! What am I missing !? lol

[Mark]

Any progress?

[Tepper]

Remember this? I've moved into a new unit and have started working on it again. I've taken a slightly different direction now and bought a (likely shagged) 13b turbo engine, gearbox, loom etc from a later RX-7 FC. This will be controlled by a MS2 with a brand new loom. I hope to run a Borg Warner or Holset turbo as the standard one is knackered and I will need to make a custom downpipe/manifold either way with supporting upgrades to the fuel system. At the moment I'm working on getting the shell stripped back and treated with POR-15, getting the polybushes fitted and cleaning up/sealing/modifying the fuel tank to accept an in-tank EFI pump. Once this is done I'll get the car back on it's wheels to free up the lift then I can start thinking about the engine - leaning towards rebuilding it myself with an Atkins kit and getting a small street port done by Era at Oldones. Pictures/descriptions copied from the RX7 FB forum:

Finally got a bit of an update on this, it's moving along slowly constrained by time/budget but it's nice to have things moving again. At the moment, the car looks like this:


I have almost finished stripping everything from the underside of the car - this is to check the condition of the shell and treat it with POR-15, install polybushes and check/paint suspension components. I will also need to modify the fuel tank to accept an in-tank FI pump, I am thinking about doing something along these lines: www.gearhead-efi.com/gm-ecm-pcm-conversion/in-tank-fuel-pump-conversion.html

The underside looks pretty good, I've only found one small hole in the sill so far:


The condition of the shell generally looks good:






Axle and fuel tank out:


Using a DIY puller to remove the suspension bushings, which thankfully all came out without too much of a fight:


Suspension parts ready for sandblasting/painting/polybushes:


As well as the chassis side of things I have been doing bits and pieces to get the TII engine ready. Blanking plate for some of the emissions kit made redundant by the Megasquirt made up and fitted to upper inlet manifold:




Dodgy old alarm and redundant emissions/ignition wiring traced through the engine bay loom and removed, to be replaced with new DIYAutoTune loom:






And finally on a work trip away, I couldn't bring the car but I could bring a soldering iron and a Megasquirt MS2 kit with a Zeal daughterboard and boost control modkit. JimStim & MS assembled and tested:








That's more or less up to date, things have been happening in a slightly strange order due to time/budget/lift availability but I'm trying to chip away at it when I can. If anyone needs any ignition stuff stripped from the old 12a please feel free to give me a shout, also I'll be ordering some bits from the US in the near future and would be able to shove some more small/light bits in the box, so if anyone needs anything let me know!

[nitrosurf]

Did you ever consider putting it back to Janspeed spec, considering the apparent exclusivity of what you've got? Probably completely impractical and what you're doing will result in more quickly quickly zoomzoom, but a 'one of xxx0' official Janspeed RX7's would be cool.

Good luck with the project, I'll watch with interest!

[Tepper]

Aug 2, 2017 12:34:58 GMT nitrosurf said:

Did you ever consider putting it back to Janspeed spec, considering the apparent exclusivity of what you've got? Probably completely impractical and what you're doing will result in more quickly quickly zoomzoom, but a 'one of xxx0' official Janspeed RX7's would be cool.

Good luck with the project, I'll watch with interest!

I did think about it, but it would've been a nightmare to source all the right bits, would've (I imagine) been harder to get running consistently safe AFR's and would ultimately put out less power. Also the scarcity of good 12a parts put me off, it would be a shame to wreck an engine that someone else who valued it's originality could've made use of. I know there was a guy on the FB forum building a Janspeed car, I actually sent him the plaque from mine but I don't know how he's getting on.

[Tepper]

That is a nice setup indeed, I came across it when I was looking at my options but it is quite expensive. I'll grab one of the GM ones from the US to have a play with because they're so cheap it's got to be worth a look! P38 Range Rovers have a similar setup I think - a bit like the internal swirl tank concept?

Got a bit done on the 7 today in between a Hyundai Trajet :roll: and my brother's E36:


Pulled the back seat to check for rust... and found some! Looks worse than it is, I chipped the loose stuff away and had a good stab with a screwdriver but it seems solid. Will need to be ground back to see what we're working with, this rust is the same on both sides and has taken hold where a rubber bung seals a threaded hole through the suspension mounting plate.






Rest of it looks pretty clean, some broken glass under there supporting my theory that the car has been broken into/nicked at least once:


Also removed the secondary throttle plates/linkage from the FC throttle body, holes plugged with grub screws, an idea nicked from Ian:


And wire brushed the front control arms ready for POR-15 - the rest of the suspension stuff is going for blasting/powder coating next week but the balljoints on these seem fine, so will keep them:


Plenty more work to be done but should have it back on it's wheels before too long which will at least free up the lift for my workshop mates.

[yoeddynz]

Wow - you've been really lucky getting an FB without any real rust issues. Good thread and glad to see you're using MS as well.

Does the daughter board fit inside the standard MS case neatly?

[Tepper]

Aug 8, 2017 20:54:12 GMT yoeddynz said:

Wow - you've been really lucky getting an FB without any real rust issues. Good thread and glad to see you're using MS as well.

Does the daughter board fit inside the standard MS case neatly?

I consider myself very lucky indeed, especially considering I didn't really know what I was doing when I bought it (and still don't ).

The daughterboard fits pretty well, it would fit better if I'd soldered the wires from the main PCB to the other side of the daughterboard so it sat with the components facing downwards but it sits in there fine as it is, just pretty tight against the processor.

Suspension parts and the exhaust heat shields have been dropped off at the powdercoaters, should be done in about 2 weeks. All the suspension stuff is going satin black, the heatshields are just getting blasted then I'll paint them with some kind of silver high temp paint. Anyone used this stuff?

[Tepper]

Got a few bits done up at the unit this evening - slow progress, but I'm hoping to finish getting the underside of the car stripped back to bare metal on Sunday then should be able to finally get the POR-15 on next time I have a full 12hr day available for paint.

Pressing in the new Energy Suspension polybushes with a hefty screw press that's probably older than the unit itself:


Some of the suspension components back from the powdercoaters. The finish looks pretty good, unfortunately some of the old rubber was not removed by the blasting process as I hoped it would be, so I had to use a wire brush to get the last of it off. If I had to do it again I would make sure it was all gone before sending it off! Hopefully it proves to be durable, which is my main concern:


One of the exhaust heatshields back from blasting, painted with silver stove paint. Will see how this looks when it's dried fully before I do the rest:


I also spent some time thinking about the fuel pump setup. I picked up these Corsa D assemblies at the breaker's just to have a play, hoping that I would be able to use the housing and upgrade the pump itself:




Having had a mess about with them, I don't think they'll work for a few reasons:
- They're set up as a returnless system; this looks like a neat way to do it but from doing some research it seems this is not ideal for a high performance application, although a return could be added
- They're too big! There's no flat area on the tank large enough to fit them, so welded modifications would be needed.

At the moment, I'm tempted to go with this, the Aeromotive Phantom:


It's pricey, but seems like it's going to be the neatest, quietest way to ensure reliable fuel delivery. The installation instructions call for a 3 1/4" mounting hole, which should work fine on this tank:




I think the flat under the spare wheel well is probably going to be the best location and I it should be possible to make an access panel in the well, and/or modify it for clearance if required. Any thoughts/suggestions would be gratefully received.

[Tepper]

Have had some time to mess around with the RX7 over the last few weeks and have also taken the plunge and had the underside of the car sandblasted. Money well spent I reckon given how much time it would've taken to do it with a wire wheel. Fortunately no rust was found - the guy who did the sandblasting said he couldn't believe how clean it was:













Result! I had the axle, front crossmember and fuel tank blasted as well while he was there:




Today I was working on the fuel tank, stripping the stonechip that the sandblaster wouldn't touch:


Condition of the fuel tank is pretty good, it's a bit thin in places and I've found one pinhole but I think it should be fine after the full POR-15 treatment inside and out:








Finally, I've drilled the holes ready for the new fuel pump setup, which made it easier to get all the rubbish out of the bottom of the tank:


Not a massively exciting update, should have paint on the underside of the car soon - waiting for the next free full day. Also, the paint is supposed to adhere better to light surface rust, so it shouldn't do at any harm to sit exposed for a while.

[Tepper]

Tank sealer in after drying the tank for a few hours with a hot air gun (the tank was cleaned/prepped a few days ago):


Hopefully it seals the tank as well as it has been able to seal the ends of my fingers - the fingers of my gloves were torn and I only realised afterwards. This stuff does not come off in a hurry.

It appears to be thick enough to seal the pinholes, so long as it sets alright it should be good to go. This is where it has seeped out a bit, you can see how thin the metal is:


This was only done as I had time between other stuff, still waiting for the big paint day.

[DavidB]

Aug 3, 2013 19:18:39 GMT luckyseven said:

Welcome to the dark side, lol

Towbar on an RX-7? That's just plain wrong Interesting that your car might have had an aftermarket turbo setup. What's the carb that's on it now, is it the stock four-barrel Nikki carb? Choke was always manual, btw. It has some little electromagnetic thing that's supposed to retract it when the engine warms up, though they rarely work well any more. A 12A-engined Series 2 like that wouldn't have had much in the way of rat's nest to remove, tbh, that only really came in on the big-engined 13B and fuel injected cars, none of which we got in the UK until the FC-model RX-7s. Check for rust in the rear seat pan and the plates for the axle arms, they're typical spots. These cars can hide quite bad rust quite well, sadly. Inlet blanking plate just means the emissions nonsense has been deleted at some point, and you're well rid of it, appalling rubbish. Judging by the previous turbo application, I'm guessing yours must be on headers now? Poor fuel flow might simply be a dodgy, clagged up fuel pump and/or filter, they're prone to it though the Nikki carb gums up easily too on stale unleaded. Sadly given the lay-up I fear you're right that it'll need stripping down. Good luck with that!


Lastly, may I point you towards www.rx7fb.com/ as the font of all 1st-gen RX-7 wisdom? Free to join, and all knowledge is there at your feet. Plus it's a nice place to be

Do you know of what happened to this Elford Turbo, if it ever got back on the road?

forum.retro-rides.org/board/12/readers-rides?page=2