cjwalker81

i own an 83 rx7 and need help with a certain issue that has been causing me great grief and costing me lots of money. The original engine turned its last spark some time ago so i purchased another streetport 13b to replace

the last but ever since installation havent had any success with it. the engine willrun fine coasting along at 110 - 120kmphr but accelaration is very rough and hesitant. the tacho jumps alot so theres no doubt that its spark. the coils are brand new echlins, new leads, new plugs, rotor, dizzy cap and even tried a whole different dizzy. Ive also tried replacing the oringinal modules with the bosch version and still nothing. can someone please offer any advice.

HELP

Racer X

Seems like you replaced everything that provides spark to your engine.Are you sure it's not the fuel system????Might be the fuel pump or a bad fuel filter.Are you running EFI or carb setup?Another thing you can do is check the condition of your plugs.If you're not getting proper spark it might show on your plugs.Are they a bit fouled?If it's hesitating due to improper spark there should be some signs on the old plugs you had before you changed them.Check in the back of a haynes manual to see the plug conditions and reasons for the plug looking the way it does.

cjwalker81

plugs seem to be burning cleanly. im running the stock nikki and had a guy tune it. he said that he traced the problem to the pickups in the dizzy so i got the other dizzy but no luck. he got the engine idling alright but even at idle you can notice the engine jumping slightly.

Racer X

You're running a Nikki on a 13b?Are you using a adapter plate?Has the carb been rebuilt at all?Are the vaccum lines all good.You might have a vaccum leak.

Racer X

Oh I forgot to mention a nikki is not a stock carb unless you have a 12a rotary.13b's came Fuel injected.Well the 6-port ones did.The 4 ports are carbed but I can't remember what carb they had.

cjwalker81

Oh I forgot to mention a nikki is not a stock carb unless you have a 12a rotary.13b's came Fuel injected.Well the 6-port ones did.The 4 ports are carbed but I can't remember what carb they had.[/quote]

yeah its a 4 port. it is running the stock carb. have to check to see if it is a nikki but im pretty sure it is. my dad owns an rx2 capella with 12a and my carb is very similar to his but not quite the same. ive also heard that the 12a carbs are better and that ive been advised by a certain mazda mob to make the swap with an adapter plate. would an air leak make the tacho jump, i have checked all hoses but anything is possible. the trailing and leading vaccums on the dizzy join together at a tee and then lead to the carb (or manifold too dark to see right now) would this be right do you know or does it not really matter. thanks for your help

the carb had been rebuilt bythe place that did the engine as far as i know

Racer X

Oh I forgot to mention a nikki is not a stock carb unless you have a 12a rotary.13b's came Fuel injected.Well the 6-port ones did.The 4 ports are carbed but I can't remember what carb they had.[/quote]

yeah its a 4 port. it is running the stock carb. have to check to see if it is a nikki but im pretty sure it is. my dad owns an rx2 capella with 12a and my carb is very similar to his but not quite the same. ive also heard that the 12a carbs are better and that ive been advised by a certain mazda mob to make the swap with an adapter plate. would an air leak make the tacho jump, i have checked all hoses but anything is possible. the trailing and leading vaccums on the dizzy join together at a tee and then lead to the carb (or manifold too dark to see right now) would this be right do you know or does it not really matter. thanks for your help

the carb had been rebuilt bythe place that did the engine as far as i know[/quote]

That sounds right.Hows the fuel pump and filter?Are they both good?Sometimes a pump might not be feeding enough fuel for good acceleration.

cjwalker81

new pump (carter) and pressure regulator (holley red) and two new filters (under hood and at pump) c how its pissin me off.

Racer X

Damn sounds like everything is new and the engine still ***** up.Where is mike or felix when you could use thier help on this.Is all the wiring the same as before???Did the old engine run good???

Wooffinn

Hey CJ, what a **** of a problem. I've had plenty of ignition problems with customer's cars over the years, but it sounds like you've covered the bases. I've had a couple recently with worn ignition wiring curcuits/switches.[by this I mean your ignition switch inside] .Just start it and give the whole key and barrel a bit of a wiggle. I find 'wiggle tests' as I call them are quite useful.however care should be taken obviously around the secondry ignition system[ie leads/plugs]when it's running. You may have accidently damaged or squashed a loom when doing the swap. I've found from experience, mazda looms do become quite brittle with age, so sometimes even moving it out of the way can cause a break.

Just check that the carb hasn't been removed as I have found,certainly over here, that there are different types of four port 13b carbs. Also some of these carbs have a very fine guaze filter inside the banjo bolt on the top of the carb[where your fuel lines go in]. Basically just remove it to check for any junk in it.Even if it doesn't look too bad, just clean it out anyhow. I've seen that cause many a problem.Good luck.