The correct plugs for small upgrades?

35th

Registered User
90 thunderbird SC 5speed what kind of spark plugs should I be running it is mostly stock with a BBK throttle body and 10‰ od SC pully wondering if I've got the wrong plugs in it I belive I put ngk iridium.
 
Non gapable iridium wondering if that's where that same old studder comes from although it has gotten better after I did throttle body gasket
 
This car is driving me insane

So today for the first time ever if your acceralting at aprox half throttle it backfires and a large cloud of black smoke I haven't done anything to the car in weeks other than drive it about 150 miles in a month its driving me crazy it'll start up and idle then about 10-15 seconds the tach will just drop and then start working but it's not just the tach the entire engine stumbles to thr point that it'll shut off if you hold the acceraltor at about 1500 rpm for 20 seconds or so it stops dropping off but while driving obvious lack of power too much throttle will cause back fire and blacksmoke....
 
So today for the first time ever if your acceralting at aprox half throttle it backfires and a large cloud of black smoke I haven't done anything to the car in weeks other than drive it about 150 miles in a month its driving me crazy it'll start up and idle then about 10-15 seconds the tach will just drop and then start working but it's not just the tach the entire engine stumbles to thr point that it'll shut off if you hold the acceraltor at about 1500 rpm for 20 seconds or so it stops dropping off but while driving obvious lack of power too much throttle will cause back fire and blacksmoke....

Do you have a code reader? That is the best way to find out whats going on.
 
Codes aren't pulling anything that would be consistent clutch switch code low fuel circuit code that's been there for 2 years but I think I sorta have a clue what is going on I believe that I have 2 separate issues one is electrical which is the tach on engine stumble for an issue the other is I'm loosing coolant but can't find where not on the ground under the car not in the oil and not white smoking but enough is getting lost its running hot cause it to run really bad... Any suggestion on the coolant issue I feel like I need to find that first then the stumble /tach issue
 
Anyone have any sort of ideas for what to look for 90 SC 5sp antifreeze boiling in the rad. New rad water pump thermo Stat upper and lower hoses drivers side heater hose water pump bypass hose once the engine gets warm you can see air bubbles coming up into the overflow tank but not when it's cool also new sending units on both the gauge and to the computer fan works but once it gets to the "r" on the gauge you can see the gauge starts getting jerky it'll go up to the m and back down to the r but very erraticly not a smooth transition at all its at that point you see the bubbles in the overflow
 
Sounds like at least one of the head gaskets let go.

Get your hands on a combustion test kit you can use on the expansion tank. AutoZone around here rents one, or, you can invest in your own.

Oh, and tach bouncing is usually cam sensor. Search here for detail on how to troubleshoot, etc.

Good luck.
 
It's a new cam sensor and when the tach does that the whole engine stumbles with it I think that's the engine overheating but as far as head gasket wouldn't I see bubbles all the time not just when motor is warm nearing overheating and I'm gonna get a compression tester just to see compression what numbers are standard for this car?
 
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