As the title states. The motor breaks up around the 1000' on the 1/4 mile track. I let out of it as soon as the motor began to break up. Pulled to the pits and pulled out the plugs. All plugs looked lean, plugs from cylinders #1 and #7 were completely destroyed. Beyond mangled. Running a 130 shot on a mildly built TBI motor. Any insight? I'm thinking inadequate fuel supply because I'm running the stock pump.

 

you're on the right track with the fuel pump. how much timing are you taking out?

 

Guess you dont have a wideband air fuel ratio monitor? Probly very lean and overheating the plugs. Ditto on how much timing you running? Also, did it ping at all during the run?

How much colder of a plug are you running?

 

run a separate fuel pump for the n20. holley blue is good. use the regulator that comes with it. set the psi to 6psi by plumbing and wiring the system and activate the soleniod while holing the plate over a bucket to catch the fuel. retarding timing can be tricky because it has to be set right to begin with and thats in another book. try one level cooler plug. ac delco R44T should work

 

no wideband a/f monitor in the car. Just a few degrees of timing taken out. Running AC Delco 44 plugs. I think the car is just leaning out on the fuel side. No real pinging, just breaking up around the 1000'. Plumbing its own fuel system or putting a new motor (bigger and faster) in it is the next step.

 

go down to a 43. i run r42ts's in my car and leave on a 100 shot (at about 2K rpms, and no i don't recommend it) and the plugs are still sharp with a decent timing mark when i pull around.


forgot to mention thats without pulling any timing

 

You are running out of fuel. I had the same problem with my old 84. I was running a 175 shot and it melted the #5 plug. On the dyno my Fuel pressure dropped from 7psi to about 4psi then started to miss.

I also agree you should be running the R43's You should have about 6 degrees of timing pulled out also.

 

i am currently running a stock TBI pump. Will a 255lph pump be enough to supply my setup?

 

I would say yes. I have a couple friends that running wet shots, 200 being the biggest, on a single 255 pump with out problems. The guy running the 200 did use the kenne bell boost-a-pump though. I would say a 130 hit wouldn't be to much for the pump. My 84 was a carb setup and I was running a holley red, didn't have any problems on the 150 shot, just ran out of pump with the 175.

 

thanks for you input. can anyone else chime in on the 255 fuel pump being enough for a 130 shot on a tbi setup? I feel as that it is more than enough

 

whats the fuel pressure on a TBI setup?

I ran a walbro 255lph i think it was for a 150 wet shot on a 383 that already made 400whp and I had no problems at all. Fuel pressure was around 46-48 psi. I had a hot wire kit tho, which gave it almost an extra volt to the pump. A smaller TBI motor making less power than my old 383 should beable to handle a 130 shot or so on a single pump easily, even with stock wiring

 

the tbi is running factory pressure at ~13psi. Sounds like i just found the solution to my problem. thanks for all of the info guys.