When my fox was completely stock (with 2 exhaust leaks, 1 in the exhaust manifold and one after the cat), i was running the 1/8 mile at an average of around 10.6. I recently added a 75mm throttle body with a matching egr spacer, c&l 73mm MAF, bbk shorty headers, new spark plugs, new valve cover gaskets because one was leaking, new intake manifold gasket because I had to take off the upper intake to get the valve covers off, bbk pulleys, and cleaned the air filter. I just went back to the track today and I'm running a 10.8, .2 seconds slower with all those upgrades and seals. My battery doesn't want charge normal at idle, even with the stock alternator pulley on and the engine keeps allowing down the idle is it idles too long down to close to 500 rpm. Any ideas why that could be? I'm leaning towards the belt I put on being to tight but I haven't gotten thechance to check it yet. There is no check engine light on and seems to run fine with normal street driving except at idle. Any ideas? I want to fix this problem ASAP.

 

what size was the other throttle body?

 

1.2 tenths could be many things, weather, off the line, etc. but let go this way.. is your motor set up other than the above stuff ?

2. If you look in the tech section in the stickies there is way to test the alternator circuit.

3. These cars do not always show a check engine light when there is a code. there could be code present and have no light on, do the KOEO test for codes.

 

The above is all I have, i haven't gotten a tune for it yet and the weather/ temperatures was pretty close to the same (this is san diego, the weather doesn't change much) and before, i only got a 10.8 once, every other time was 10.6 and below, now I can't seem to get under 10.8, and as for the alternator, I'll check it and I'll look to see if there's any codes popping up.

 

Does it seem to be charging if you hold it to 700-800 rpms? You may be able to bump the timing a bit. You really may need to with the new parts anyways.

 

The TB =
http://www.allfordmustangs.com/forum...fi-intake.html

to gain some back bump your timing... pull the spout connector and bump it to 12* then drive it if you hear no pinging then bump it 2 more degrees keep going until it pings then back it down 2 degrees. I wouldn't really go anymore than 18* I run 16*. every motor is different.

you also should look into gears.

A tune is going to do nothing on stock motor! you may clean up the A/F ratio slightly but for the cost it aint worth it nothing is going to happen. wait until you do more work and I mean heads, cam, intake which in trun means new injectors and fuel pump and then a tune will be needed.