rithsleeper

Still pretty new to the rotary scene. I drive a 1979 12a in ITA. This weekend just kept getting worse. I knew going in my rear rotor was really low on compression and the front is acceptable on a good day. I changed my plugs before the race weekend. All weekend the engine kept getting weaker and weaker then staeted hesitating. I think it was fuel filter clogged cause I removed and back washed it and the hesitating stopped. By that time I was down about 2 additional lap seconds....

Got the car home and pulled the plugs. Both leading plugs looked like they were burnt up a brown color and the contacts were melted a bit and deformed. However the trailing plugs looked perfect other than a bit of oil.....

What's the deal? Is it normal for one to get burnt up and others to stay good? I just got an engine with 30k on it ti swap in and if its a carb or fuel supply problem I don't want to ruin this engine also....

Where should I start, I'm sure the carb hasn't been touched in at least 15 years but its run really hard all the time so I doubt any corrosion could build up.

misterstyx69

iTrader: (142)

what part Number of plugs were in it?

rithsleeper

They were same ngk I've been running br8eq14.

Can someone else tell me where to find steps to put a 83 12a into a 79? They look a lot different...

diabolical1

iTrader: (3)

a few possibilities to explore ...

1. the type of plugs you were running - (as inquired above)
2. timing (may need more or less)
3. you mentioned fuel starvation ... that sounds like "lean moments" to me

diabolical1

iTrader: (3)

getting the engine itself into your car is not an issue. you'll want to pay attention to the clutch though. I think the year they changed was 1982, but for the life of me, I always forget. either way, with the '83, you'll have to get the matching clutch for it. the only other differences I can think of are emissions-related, and there's not much you can do about that because housings and exhaust ports are involved. however, if you're racing the car, I doubt much of that means anything to you.

rithsleeper

Holy crap that was a ton of crap on that engine. I got it all off and they look the same now. Now just have to get the huge socket to get my flywheel off.

What plugs should I use if not these. I'm pretty sure it would be fuel starving. I just don't want to burn up the seals in this new engine. How would you check for a lean condition without o2 sensors? Just keep pulling the plugs till they are black?

diabolical1

iTrader: (3)

just so you know ... the flywheels are not interchangeable. they are balanced differently. i'm not sure if that was your reason for removing it, but that's the deal.

I have had good results running B_EV-type plugs. I ran 7s for lead and 8s for trailing. they have since been superceded with like 3 different types (based on material), but I would need to get my reference to tell you what they are and I don't have it with me at the moment.

you will need a gauge of some sort. you can track AFR or EGT, but since AFR is what you actually want, then it would probably make more sense to get that.

rithsleeper

So if I can't change the flywheel over what do I do? Can I transfer my clutch plate? It looks like the 79 flywheel is a lot lighter and way less material but looks like the gear sits the same distance from the engine. I have the clutch from the new engine but I'm not sure the shape it is in... can I use a 79 clutch assembly on the 83?

diabolical1

iTrader: (3)

I think you can use the '79 disc in the '83, but I've never tried it myself.

maybe this thread will make it somewhat clearer: https://www.rx7club.com/1st-generati...estion-984008/