what is the best proformance setting? it's on an 84 2.8 carbed. with minor changes so far. let me know if ya need to know what I did.

 

play with it in 2* increments and see what works "best" for your combo. there is no hard set number since every engine is differant

 

Yep... I generally don't go over about 14 initial, though... running 12 here.

 

12 is good for mildly modified and I'm sure you can run **** gas on 12 degrees without problems. If you try to run higher though, I'd switch to high octane. At 12 degrees, the car *might* run better on mid-grade though.

 

ok see I heard 6 to 7 for best over all

 

I'm not sure the kind of base timing the carbed motors are supposed to run....but the V8's are generally timed at about 6 degrees. The v6's tend to have more advance. A fuel injected 2.8, and a 3.1, both have 10 degrees stock. But again, yours is carbed so I can't be sure.

 

well the service manual from the factory says 0. sadly enough I think that was wrong. I might recheck it cause thatmight have been just to get ti running and adjust

 

there should be a sticker on the hood telling you the base timing you should set it to if the motor is original.

also, if you bumped the timing wouldnt it make little or no difference switching octane? if the actual spark is occuring earlier then i dont think a slower burning gas is going to help.

 

87 octane can withstand a certain amount of timing advance but once that's exceeded, the car starts to ping, which is the sound of detonation. Upping to a higher octane will keep that from happening.

 

how will using higher octane help tho? its the early spark causing the detonation not high cylinder head temperatures. all higher octane means is it will burn at a higher temperatrue/slower.

 

Octane is a chemical in fuel that makes it burn slower. Pinging is caused by overly advanced timing, high compression, high temperatures, or a hot spot in the combustion chamber. If you add octane, it keeps the fuel from pre-igniting and pinging. if you add advance to your timing, but lower your compression, you won't ping if it's in the right combination. I run 14* of advance on my motor with 87 octane. On the stock 10* I had to downshift going up hills for a while, but with the 14* of advance, I can let cruis control do it by itself and I can stay in 5th gear.

 

You can get away with 14* on 87 octane? Dang.. I'm running 14 degrees (my 5.0 has the same base timing as the 2.8's/3.1's) and I'm pumping premium. Anything less and the car runs 'funny'

 

What's the compression on your car, i bet it's a little higher than 8.1:1, right. Proably somewhere around 9:1 or so. If so, that's the difference, but yeah, I run 14* with 87 out of Arco. No knocking or anything. No my fiance's car is another story. It's a 1983 Volvo with a 2.3L FI motor, after 20 years it has some carbon build up and unless i run 89 in it, it pings like a mo' fo'.

 

Good point, I forgot about that. My compression is supposed to be 9:1, but that's rated with heads with larger combustion chambers than mine, so I'm betting my cr is closer to 9.5:1

 

If the car is running presently, Then crank it advanced 2 more degrees and look for knock(predetonation), or it flattening out on power in the top end. If either of these happen, then back it down a degree until it feels better- its that simple.

 

Octane is a rating.

Toulene is the chemical.

I went to 14, before the turbo, and found much better pull in the upper middle range of rpms - especially in 3rd. I still ran 87, but went to 93 anyway (only .10 more/gal here at teh BP station on 441 )

Our engines have 8.9:1 cr, 3.1 has 8.5:1 cr. Nixon, you also have to factor in things like chamber characteristics, when it comes to pinging.

I think I was able to do 14 on 87, due to a stretched timing chain.

 

That's what I meant...spent a lot of time on the phone today so i got used to the damn numbers being different. Stupid non-standard numbers.

 

Wow. The compression numbers are great for adding high psi blowers.

Akshay

 

Yeah they are. The 3.1's got even better #'s, at 8.5:1.