Rx7ner

This is my first post in this section so I hope I am doing this right. I have a 1980 Rx7 the engine is running real rough. It has been sitting up for around a year. I changed the fuel and filter. I put 93 octane with some fuel additive. Thinking it would help get out any trash out of the carb. I checked the plugs, wires and distributor and is getting fire. The header is glowing red on the back rotor and the front is getting hot but is not glowing. When i get it started and let the Rpm fall back down to idle I cant save it under 1500 RPM (itll just die) Then I will have to start over again. The highest RPM I can get is 5000. So I dont know if it is what yall call carbon lock or do you think it is in the carb? Any help would be apreciated. Thanks, Byron In Alabama

mortiky

rotary engines like low octane gas. higher octane actually burns slower allowing more time for the flame front to be exposed to the internal engine components for longer which gives the internals more time to absorb more heat from the combustion of the air/fuel. plus being as rotaries are lower compression than a conventional reciprocating engines, they (rotary engines) will not run as well on higher octane because they don't need the added resistance to detonation that higher octane fuels provide. so this could be one reason why you are having drive ability issues. also your carb could use an overhaul since your jets maybe gummed up, not allowing enough fuel to get in causing you to have a lean condition or lean misfire condition...... a anyone else got any ideas?

DivinDriver

iTrader: (15)

Rotaries prefer lower octane... but any commerically available gas will run them OK - - not cause symptoms like this.

Inability to low idle & high RPM starvation is usually indicative of a vacuum leak or fuel delivery problem, causing you to run too lean. When sitting for long periods, carburetors will gum up internally and do all manner of unhappy things.

You probably need to look at rebuilding your carb, but you should check carefully for vacuum leaks first - they are usually easier to fix.

The good news is, it won't be a shutter valve problem, as the 80's did not have them.

Does the car have any modifications? You said "header," what else is non-standard?

Rx7ner

Basically thats the only mod I have done except to take the air pump off. Ill check my manule on how to rebuild the carb. Thanks for the help.

DivinDriver

iTrader: (15)

If you pulled the thermal reactor (putting on the header) and the air pump, did you also remove & block off your ACV? Could be the source of your troubles, if the one of the ACV diaphragms cooked due to lack of airflow from the air pump.

Without an air pump and with a header, it serves no useful purpose.

RustyRacer

Check your timing.

Sounds almost exactly like the issue I had. https://www.rx7club.com/1st-generation-specific-1979-1985-18/cut-off-problem-1980-sa-only-when-hot-921771/ my solution to finding my timing.

Kentetsu

The glowing header tells us that either the timing is severely retarded, or you are starving for gas. The fact that only the rear is glowing, would imply that you have a restriction in the carb that is starving the rear rotor.

When you checked for spark, did you check both the upper and lower plugs? Loss of leading (lower) ignition could also cause something like this.

If no major/severe vacuum leaks are found, then I would suggest that you rebuild the carb. A great site for info on your stock Nikki carb is www.sterlingmetalworks.com






.

zaridar

iTrader: (3)

/\/\ agreed good advice he knows what hes saying

adding_lightness

i've been having a similar problem, no header to glow, but either does not idle at all or idles around 1.5-3k depending on how badly I need to get where i'm going, and wont go over 5k rpm unless i'm in neutral (will go about 6k for a few seconds there) are you also having to drive with the acceleration pedal ~half down or less to avoid killing the engine and have the engine start dropping off while driving (turning key off then back to run while still at speed temporarily fixes this for me)?

Kentetsu

You, sir, have clogged fuel jets. Time to rebuild the carb, or at the very least pull the jets and clean them out.

adding_lightness

glad that is all it was, I was looking for an excuse to clean/rebuild the carb when I pull the rat's nest anyway. Thanks for the help

DivinDriver

iTrader: (15)

IMHO, unless you're running a stripped carb, it's much easier to pull the whole carb & work on it on the bench, than it is to pull and reinstall the rear jets with the carb in place.

Access to the rear side of the carb in situ is a miserable backbreaker & prone to mis-aligning/crossthreading of tender little parts. Or dropping things in bad places.

Only hard part of removing/installing the whole device is that somewhat nasty rear-left mounting nut.

Kentetsu

I have to try to keep in mind that not everybody has an engine bay and carb that is stripped to the point of bare-nakedness It makes working on things sooo much easier!

DivinDriver

iTrader: (15)

Yeah, I wish I could play along, but my fascist state government says "Nein!"

adding_lightness

Will be rebuilding the carb in the morning as soon as it gets light enough to see, was wondering if there is anything else besides sterling's write up that I can read (or even better, look at pictures) to make it easier on myself, as this will be my first rebuild.

also, would it be a better idea to take out the rats nest while I have the carb out, or should I wait to be sure the carb is working before I start messing with it again?

Kentetsu

Get the carb sorted first. No sense in compounding your problems.