Video Log Of The Restomodding Of My '76 RX-5 Cosmo (New Vid Jan 5/2023)
11-15-10, 10:13 AM
#102
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It's a consumer grade Campbell and Hausfield 40 gallon compressor rated at I think around 7 CFM @ 90 PSI. I've added another 20 gallon tank to it on the bottom drain fitting. It seems to handle the sand blasting fine and doesn't seem to mind running 2-3 hours continuously. I really only use air for blasting, the little air gun, and occasionally the big impact or a grinder.
11-15-10, 10:57 AM
#103
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hmm I have a 60 gallon tank thats rated at like 10.2 cfm at 90. I might need to invest in a sand blaster then. Since i need to blast my RX2 that way I can just take my sweet old time with it.
11-17-10, 05:06 PM
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Just watched all the videos and man i learned alot from them. When do you think you're going to put the engine together (if you haven't already)?
and which cosmos came with a 20b?
and which cosmos came with a 20b?
11-19-10, 09:26 AM
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Seriously though, once you have a blaster, you'll wonder how you ever made do without it. Instead of spending 20 minutes wire-wheeling a part, it takes 1 minute of blasting.
The Mazda Eunos/JC Cosmo, sold in the early 90s Japan-only was equipped with the 20B
some more inspiration for body work http://japanesenostalgiccar.com/foru...pic.php?t=4426
in case you ever need it that is...
in case you ever need it that is...
11-20-10, 10:30 AM
#113
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It's pretty easy if you have some mechanical experience and skill. I'll be posting the video of the rebuild within 30 days I think, so you'll find out soon. 
11-21-10, 10:21 AM
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Baking soda (actually, remember that the industrial version has far larger grains) is also nice because it has a natural anti-corrosion effect. Soda blasted parts can generally hang out in bare metal for a few months without worrying about rust.
I'll be applying a zinc-rich weld-through primer on panels where the backside will be hidden after they are welded in. Then after all the work is done, there are several products with long nozzles designed for rust coating hidden spaces like frame rails and rocker panels. On surfaces that have both sides exposed, I'll use POR-15. The interior floor, since it rotted from the inside out, will get a full coating of POR-15. The underside is for the most part already well undercoated. I'm just trying to decide whether to give the engine bay the whole POR-15 treatment or to just give it a shot of some high quality black paint (POR-15 "Hardnose" black, or rocker guard).
I'll be applying a zinc-rich weld-through primer on panels where the backside will be hidden after they are welded in. Then after all the work is done, there are several products with long nozzles designed for rust coating hidden spaces like frame rails and rocker panels. On surfaces that have both sides exposed, I'll use POR-15. The interior floor, since it rotted from the inside out, will get a full coating of POR-15. The underside is for the most part already well undercoated. I'm just trying to decide whether to give the engine bay the whole POR-15 treatment or to just give it a shot of some high quality black paint (POR-15 "Hardnose" black, or rocker guard).
11-21-10, 02:56 PM
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11-24-10, 09:58 AM
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Yes, the porting will be shown. But as I mentioned, it isn't the typical porting job. It is very conservative, only bringing the exhaust ports just shy of stock 2nd gen timings and only moving the primary ports down a little to boost midrange. The secondary and aux ports aren't touched at all.
waiting for the port job..
12-04-10, 03:31 PM
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Part 7: My 76 Mazda RX-5 Cosmo Restoration - Intake and Exhaust Porting
Has it been nearly a month since my last episode? Wow, time does indeed fly. I've been quite busy preparing to build the engine. So in part 7, I cover the intake and exhaust porting. The engine is being built with GSL-SE 6 port plates and the Cosmo rotor housings as the basis for a 6 port turbo setup. This port job is fairly conservative, only opening up the primary ports a little and bringing the exhaust ports close to 2nd gen RX-7 specs. The goal is to maintain fuel economy, low and midrange torque, and idle quality. This episode covers everything involved in porting including: marking out the new ports, grinding the port shape, smoothing the bowls, smoothing port to runner transitions, smoothing the runners, grinding and blending the exhaust ports.
http://www.youtube.com/watch?v=y1Gy5sVMK3o
http://www.youtube.com/watch?v=y1Gy5sVMK3o
12-05-10, 10:22 AM
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I use the grinding stones on the irons to get the port shape and runner transitions all worked out. Then I just use the sanding rolls to polish out any roughness left over from the stones and to adjust all the ports and runners so they match, if necessary.
The housings are a little more complicated because they are a mixture of a steel sleeve and aluminum casting. Truthfully, I dislike porting rotor housings for this reason. Generally I start with a grinding stone to quickly bring down the chrome/steel to as close to the final port shape as I can get it, then switch to a rotary file to eat away the aluminum. It usually takes several bit swaps between a grinding stone and a rotary file as the aluminum has to be ground away, then the steel/chrome again, then the aluminum, then the steel/chrome, etc. Then when the port shape is finalized and the runner transition is done, I follow up with the sanding roll to smooth everything out and make any final adjustments to both ports.
The housings are a little more complicated because they are a mixture of a steel sleeve and aluminum casting. Truthfully, I dislike porting rotor housings for this reason. Generally I start with a grinding stone to quickly bring down the chrome/steel to as close to the final port shape as I can get it, then switch to a rotary file to eat away the aluminum. It usually takes several bit swaps between a grinding stone and a rotary file as the aluminum has to be ground away, then the steel/chrome again, then the aluminum, then the steel/chrome, etc. Then when the port shape is finalized and the runner transition is done, I follow up with the sanding roll to smooth everything out and make any final adjustments to both ports.
