Popping out of the inlet?

[wiggman2030]

Hi guys.

I've had trouble getting my rx7 to run properly when warm. I only recently bought it (as a non runner). I got it running but once it's warm it wont idle or start up without pumping the throttle. I have a replacement carb coming as I have given up on the current one. (lots of stuff has been removed and it looks like it's been played with).

Anyway I noticed that there seems to be a popping noise. Which sounds like it's firing out of the intake. Could this be carb related or do I have another problem on my hands?

Cheers.

[Steve-A]

Hiya. Welcome to the forum

If you got some pictures up of the current carb set-up we might be able to help you diagnose whats been removed from the carb. There's lots of the 'rats nest' of vacuum tubes and solenoids that can be removed as they were carryovers fro, the american emissions laws. Most of the time the carbs are fine and just require a good clean out inside

Are you able to get a quick video of the sound it's making? If it is firing out of the inlet that's normally a sign that the ignition timing is way out, there's a chance the trailing plug leads could be on backwards or something I suppose?

Have you got a standard exhaust? Some of the thinner aftermarket exhaust manifolds can amplify the sound of the flame front hitting the exhaust at idle sounds kinda popping or like it's blowing a bit.

[wiggman2030]

Thanks for the reply,

I will check the timing. I can't seem to find any marks though. I noticed a small mark just behind the bottom crank pulley but nothing else?

I will also check the leads. Im changing the carb soon so once i've done that ill let you know how i got

Thanks

[Steve-A]

There should be two timing marks on the lower front pulley. They are on the rear edge of the pulley, closest to the engine. The marks are for TDC and 20 degrees ATDC. The reference marker is a little metal rod directly above the lower pulley.

The front leading plug should be at TDC at 900rpm idle, and the front trailing at 20 ATDC. The rear plugs 180s degrees out from that. It's also worth checking the plug leads are on the dizzy in the right order. The cap is marks with L1 for front leading, L2 for rear leading, T1 for front trailing, T2 for rear trailing, T for the trailing coil and L for the leading coil.

Seeing as you cant get the car to idle, you can also pull the vacuum advance lines off the dizzy and you an advancing timing light to measure the advance at 4,000rpm. It should be 24 degrees BTDC on the front leading plug.

[ian65]

Hi Craig,
It's may be best not to mess with the timing or ignition system until you have changed the carb. The Nikki carb and rats nest that I have sent you is spot on and perfectly set up. I've used it on 2 of my 1st gens and I know it's fine. Once you've installed this onto your engine, you will know that the carb / fuel side of things are working A1...... if you still have problems, then follow Steves advice and adjust the timing but do the carb first other wise you might mess up your ignition timings for no reason.... one thing at at time!
If it's popping back through the inlet/carb, it could be running lean..... swapping to my carb will sort out your carb settings...fuel /air mixture.

[Steve-A]

Yeah Ian right, if you've got a carb coming it's worth bolting that on first to see if it fixes it

[myatt1972]

Years ago I had a car that would only start with a tow and wouldnt idle, I ran through a load of stuff to try and sort things in the end it turned out to be low compression on the rear rotor.
I hope you have better luck than me

[mullins]

I'm putting my money on a dead engine, sorry. I've also had this popping before and it ended in a tear down

[wiggman2030]

right ok, I changed the carb and it's not popping any more. Jut misfires a fair bit.

Im changing the plugs and leads soon but at least that's sorted now

[mullins]

I assume from the wanted ad, this did end in a dead engine??