The Great RX-7 Rally Car Build!!!
10-20-09, 03:16 AM
#28
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I rebuilt the carb!! It actually wasn't that hard.
I will get some more pics up soon. Now, I just need to get a fuel pressure regulator and try it out. Will be cool if it works right away...but I'll probably have to do some tweaking to get it running.
Once it's up and running, it's time for the rollcage
I will get some more pics up soon. Now, I just need to get a fuel pressure regulator and try it out. Will be cool if it works right away...but I'll probably have to do some tweaking to get it running.
Once it's up and running, it's time for the rollcage
10-23-09, 03:15 AM
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10-23-09, 05:29 PM
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Alright, I FINALLY got to hear it run for the first time since I bought it!!
I have the stock Nikki hooked up with a fuel pressure regulator and dead-headed. I tried to start it up and it ran on the first try! It doesn't seem to smoke either!
It runs rough, though, it idled around 1-1.5k and then sank to 700 for a while, then went up again. It's definitely not getting the correct A/F mixture..I can rev it and it seems like it's struggling. It also sounds like a streetport.........BRAP BRAP BRAP.
I then noticed the secondary barrels were filling up with fuel (at idle), so I disconnected the fuel pump until it died. I let it air out for a while and started it again. It ran rough (and sounds bad too), but the barrels filled up again so I killed the pump again. The levels in the float windows were each at about 1/3 full. I'll have to figure that out later. Here are some more pics:
Rebuilding:
12A carb on the 13B:
View from the other side:
Carb closeup:
Here is a pic of the secondaries flooding. As you can see, there is a pool of fuel sitting on each secondary throttle plate....anyone know that's happening?
I have the stock Nikki hooked up with a fuel pressure regulator and dead-headed. I tried to start it up and it ran on the first try! It doesn't seem to smoke either!
It runs rough, though, it idled around 1-1.5k and then sank to 700 for a while, then went up again. It's definitely not getting the correct A/F mixture..I can rev it and it seems like it's struggling. It also sounds like a streetport.........BRAP BRAP BRAP.
I then noticed the secondary barrels were filling up with fuel (at idle), so I disconnected the fuel pump until it died. I let it air out for a while and started it again. It ran rough (and sounds bad too), but the barrels filled up again so I killed the pump again. The levels in the float windows were each at about 1/3 full. I'll have to figure that out later. Here are some more pics:
Rebuilding:
12A carb on the 13B:
View from the other side:
Carb closeup:
Here is a pic of the secondaries flooding. As you can see, there is a pool of fuel sitting on each secondary throttle plate....anyone know that's happening?
10-23-09, 10:17 PM
#36
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Yeah there is a holley "blue" fuel pump on it. I think it's probably overpowering the $30 regulator I bought at autozone. I have that regulator set at 2psi.
10-24-09, 05:16 AM
#37
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Sounds like the floats are sticking. A couple of whacks to the top of the carb with a plastic hammer, or something similar that won't cause damage, should set it straight.
10-26-09, 08:23 AM
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OK, now it wont start. I whacked the carb a couple times with the plastic end of a screwdriver. Both floats sit at 1/2 full. They used to be 1/3 full, but now it's not pouring fuel into the secondaries anymore .. It's also not starting anymore 
.
I pulled the plugs, they were wet. I cranked the motor w/o leading plugs, but no mist came like like it usually does...just the normal loud psst, psst, psst sounds. I cranked the engine with the ignitor plug wire detatched, but in close proximity to its respective coil and both coils are sparking. The batt is new and it cranks hard. I don't get it! It was just running the previous day!
If someone is cranking over the engine, would I be able to see fuel coming out of the jets with my naked eye? (I haven't been able to look as I am working on it myself)
The current set up is:
Tank -> cheap $3 new filter -> Holley Blue pump -> FPR, set at 2psi -> stock rebuilt Nikki which IS deadheaded and has the vent solenoid powered by (+) 12v -> GSL-SE 13B motor -> Racing beat headers.
.. It's also not starting anymore . I pulled the plugs, they were wet. I cranked the motor w/o leading plugs, but no mist came like like it usually does...just the normal loud psst, psst, psst sounds. I cranked the engine with the ignitor plug wire detatched, but in close proximity to its respective coil and both coils are sparking. The batt is new and it cranks hard. I don't get it! It was just running the previous day!
If someone is cranking over the engine, would I be able to see fuel coming out of the jets with my naked eye? (I haven't been able to look as I am working on it myself)
The current set up is:
Tank -> cheap $3 new filter -> Holley Blue pump -> FPR, set at 2psi -> stock rebuilt Nikki which IS deadheaded and has the vent solenoid powered by (+) 12v -> GSL-SE 13B motor -> Racing beat headers.
10-26-09, 09:19 AM
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Try dumping an ounce or two of Seafoam down the carb, then see if she'll start. Sounds like she's just flooded, which would be understandable considering the nature of the carb issue you were having. You still have good spark at the plugs, right?
10-26-09, 09:41 AM
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Well the plugs were in the car, and the spark was arcing across the ignitor to the wire that goes to the distributor.
The spark seemed a little weak, but it's been so long since I've looked at a 1st gen for spark that it could just be normal. Could the "weak" spark be because the plugs are wet? Wouldn't any spark at all ignite the (correct) mixture? If it's sparking up there, it has to be sparking at the plug end to make a circuit.
The spark seemed a little weak, but it's been so long since I've looked at a 1st gen for spark that it could just be normal. Could the "weak" spark be because the plugs are wet? Wouldn't any spark at all ignite the (correct) mixture? If it's sparking up there, it has to be sparking at the plug end to make a circuit.
11-01-09, 02:03 PM
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OK I have checked all the spark plugs and wires and they are all sparking blue.
It used to run at 700-1500 when started and then die after a minute or two, but the secondary barrels would flood. I took the plastic end of a screwdriver and tapped the top of the float tanks a few times and now the floats are both at 1/2 full and the barrels don't flood out anymore.
BUT, it won't start. I can get it started on 2 capfuls of seafoam and it'll run for 2-4 seconds.....then it dies, regardless if I am holding the throttle down or not.
What's going on here? Is it possible the fuel isn't getting from the float tanks to the venturis anymore?
It used to run at 700-1500 when started and then die after a minute or two, but the secondary barrels would flood. I took the plastic end of a screwdriver and tapped the top of the float tanks a few times and now the floats are both at 1/2 full and the barrels don't flood out anymore.
BUT, it won't start. I can get it started on 2 capfuls of seafoam and it'll run for 2-4 seconds.....then it dies, regardless if I am holding the throttle down or not.
What's going on here? Is it possible the fuel isn't getting from the float tanks to the venturis anymore?
11-01-09, 02:16 PM
#43
Great build.
There is a Mk2 Ford Escort rally car in the UK running a carbed 260bhp PP 13B and it can run in the 1.3 litre n/a class here- that makes about 100bhp more powerful than anything else in the class
There is a Mk2 Ford Escort rally car in the UK running a carbed 260bhp PP 13B and it can run in the 1.3 litre n/a class here- that makes about 100bhp more powerful than anything else in the class
11-15-09, 09:50 PM
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I guess a step-by-step conversion of a stock RX-7 to a race car in detail with lots of photos and troubleshooting a rebuilt carburetor aren't tech-related... 
ANYWAYS, I FINALLY GOT IT RUNNING!
I decided to just do a bunch of stuff and cross my fingers. First, I took a pipe cutter and made a fresh cut on the aluminum fuel return line and hooked that up to the carburetor. I then had to drop the tank and run a return line to it. I also replaced the supply line and capped the 3rd one (it was previously run back into the return one ???).
I double checked for vacuum leaks, didn't find any. I took off the accelerator pump nozzle and ran a guitar string through it just to make sure it wasn't partially clogged.
I put in all new NGK spark plugs. I poured an ounce of oil down the carb to help build compression (just in case).
I cranked it over....no start. I sprayed a some carb cleaner down the primaries....cranked, started, ran, ...kept running! It held idle around 1250RPMs and stayed there all by itself. I moved it around the driveway (don't have it insured yet), revved it up a few times, parked it, let it warm up, then shut it down.
I haven't tried it again, but I'm just very happy it can just run on gasoline again! Now that that's over, I can get to some fine tuning and then putting in the rollcage!
ANYWAYS, I FINALLY GOT IT RUNNING!
I decided to just do a bunch of stuff and cross my fingers. First, I took a pipe cutter and made a fresh cut on the aluminum fuel return line and hooked that up to the carburetor. I then had to drop the tank and run a return line to it. I also replaced the supply line and capped the 3rd one (it was previously run back into the return one ???).
I double checked for vacuum leaks, didn't find any. I took off the accelerator pump nozzle and ran a guitar string through it just to make sure it wasn't partially clogged.
I put in all new NGK spark plugs. I poured an ounce of oil down the carb to help build compression (just in case).
I cranked it over....no start. I sprayed a some carb cleaner down the primaries....cranked, started, ran, ...kept running! It held idle around 1250RPMs and stayed there all by itself.
I moved it around the driveway (don't have it insured yet), revved it up a few times, parked it, let it warm up, then shut it down.I haven't tried it again, but I'm just very happy it can just run on gasoline again! Now that that's over, I can get to some fine tuning and then putting in the rollcage!
