Well, I have decided to swap a fuel injected H.O. 5.0 into my 83 GS 5 speed. I am going to use a T5 transmission from the 5.0 and hope that my stockrear end lives (no slicks for me!). I have read all the info on Granny's (www.engineswaps.com), and have done a search on here that turned up some good stuff, but I have a few more questions.

First question-Wiring! How much wiring is involved between the Ford ECM computer and the RX7 chassis harness? Wiring will IMO probably be the biggest pain in the this swap, how much of a pain is it going to be?

Gauges- Is anyone with a motor swap using the factory gauges? I know the factory tach can be modded to work with a piston engine, how about the speedo hookup and oil/water gauges?

Engine fit- How tight is the engine bay with a Ford Windsor? I have seen pictures and it looks like the sides and front have clearance to spare, but the hood clearnace and firewall clearance is a little tight.

Exhaust- Anyone with a V8 Swap: is there room for true dual? How about long tube headers?

Performance-Any dragstrip numbers? If so what motor/mods?

Rearend- I'm thinking the stock 3.90's are going to be a little low for a 5.0. Any luck with the 3.30's or 3.60's (I think that's the other ratios I have heard are made for the RX7 rear.) Does anyway make ring and pinions other than mazda?

Last of all, how does the car handle with the V8 swap? Did you do anything to correct the weight balance? If so how much needed to be moved?

Overall this looks like a relative straight forward engine swap. I have a shop with an engine hoist, I can weld, and I've got a little fabrication expierience, so none of that should be an issue. Thanks in advance for the help guys, this should be a very fun car

 

Prepare to be flamed, MikelZ!
When wiring in the Ford EFI, I would recommend building a completely seperate harness, and just tie in the wires that need to interface with the car. Factory gauges work just fine, but you'll need to make your own adaptor fitting for the temp sender. It's a strange thread. You're absolutely correct about room around the engine... lots of room on the sides, a little snug everywhere else. I put duals on mine, the left pipe crosses to the right side under the trans tailhousing. There's room for 2 small oval mufflers in the stock location. I wasn't happy with the 3.91 gears, so I swapped to 3.63's. Rotsa ruck finding a diesel courier for the 3.31's, I couldn't come up with one. I couldn't find anything taller, but I really am happy with the 3.63's. I got the speedo working with a ratio adaptor box. I did a lot of work trying to beat the system, but I really didn't save much money compared with buying from Granny's. All in all, I love the results.

Kerry

 

I was doing a 302 conversion also. Lost interest. I am selling the motor mounts and trans crossmember if you are interested.

 

Hi, W8. I wondered what happened to you. Sorry to hear you're not going to finish it.

Kerry

 

Well, I have too many projects going on at once. And not enough funds to continue on with it. The car is completely ready for the motor. If had a place to store the car, I would finish it later. Thanks for all the help you gave me. MikelZ, keep in touch with Kerry. He is very good source for help.

 

just something that might help you, the rear-end off a GSL-SE would be a better choice since it's stronger and also it has LSD and Disc Brakes.

 

Sure have fun with the 4.10 ring & pinion that the GSLSE has. They are also not that strong Ive broken 2 with my modded 13B with stock ports.-rtyPWR

 

you can change the gear ratio, but between all the rear-ends from 70-91, the best one is TII and then GSL-SE. Now you breaking it might be some other problem

 

Thanks a lot for the help guys, this looks like it's a pretty straight forward swap.

A few more questions if ya don't mind..

What did you do for the cooling system? I'm guessing the stock radiator is laughably unsuited for the 5.0. Looking at the stock radiator I am thinking that Jeg's makes a generic dragster aluminum radiator that would slide right in, although I might have to fab some mounts, but that's no biggie.

Looking at the clearnance on the sides of the engine, I am thinking that longtube headers will fit just fine, how is clearance at the firewall? (I don't have my 12A out yet).

Oh and Kerry, what tranny are you using?

Once again, thanks a lot, I really do appreciate the help

 

I have seen a ford 9" shortened and modified to bolt into a first gen. I think it might have been on granny's web site. This would be the answer to your rear end problem. They are fairly inexpensive IIRC around $700. then you could use any gear you want and you would not have to worry about breaking it. If you plan to put more than about 250hp to the ground you will be snapping stock axles and destroying gears in the rear end. Just a thought.


Good luck,
Mike

 

All the discussion about braking diffs assumes an aggressive driving style. If you don't shock the driveline, you won't put nearly as much abuse into the diff. Get the car rolling, then punch it, ease back, shift, punch it again. Maybe not as much fun, but it beats laying under a broken car every weekend.

I used a radiator I had access to, it's not one I would recommend. I drive home from work in stop & go traffic, 100° heat with the AC blowing icicles, and it runs pretty warm until I get it moving about 45mph or so. Go with the most rediator you can possibly afford. The airflow out of the RX-7 engine compartment seems to be poor at low speed. (I noticed this with the rotary as well) If I had to do it over again, I'd seriously consider Granny's setup. It's pricey, but it's been proven to work. I spent an incredible amount of time mounting and ducting mine, and I have to run 2 electric fans and a 14" mechanical just to keep it reasonable. I'm using a T-5 trans with what I believe is the same clutch hydraulics Granny's sells. I managed to save all of about $20 by re-inventing the wheel, and it only took me 3 weeks. Never again. If it's available as a proven combination, spend the little bit extra and buy it from the guy who did the legwork. (geez, I sound like a salesman. I have no connection with Granny's) I have a lot of connections, have worked in the auto parts field most of my life, and have a decent amount of machining, fabrication, and welding skills. I couldn't beat the system (find/make it cheaper, I'm an incurable scrounge). That goes for clutch and radiator.

Long tube headers might work, but I think the ready-made Mustang headers will be too low. The lowest point on my car is the bellhousing, and I've sawn 3/4 inch off of it. It's now the lowest point because I also shortened the engine oil sump by 1 inch. If you can find a Mustang with long headers to look at, check ground clearance, make sure they are not any lower than the oil pan.

Good Luck,
Kerry

 

You could get by running an 8.8 diff, a 9" is overkill unless you plan to put down a lot of power.