Help with cobra 347

[redmoneypit]

Hi, after 160,000 miles I recently rebuilt my 95 cobra 5 spd motor adding a 347 rotating assm, GT40X heads, and a b303 cam and shorty headers. Everything else is pretty much stock except for not having the EGR hooked up. I tried using the Fordfuelinjection.com EGR delete kit but it still throws codes..
My car runs pretty good wide open but in part throttle mode is seems to miss and buck. My guess is it is running a little lean due to the extra cubes. Is there any tricks to richen this thing up?

 

[94GTCoupe]

adjustable fuel pressure regulator?

 

[1TallMF]

Did you have the ECU tuned with the new 347? And do you have a means of checking your actual A/F ratio? Did you change anything else like injectors, MAF, TB? I just fixed my part-throttle bucking for a second time, and both times it ended up being a bad or loose plug wire on the #4 cylinder. Its worth a look, but my best guess for you would be something's not right with the EGR delete.

 

[1TallMF]

Also, does it ping at WOT?

 

[redmoneypit]

No pinging at all. Right now I have no means of checking my A/f ratio so just guessing. I did put all new plugs wires and cap on the motor.. Ford stuff.
Had flat-top pistons so i am est.. 10-1 or so on compression. Did not change Maf, injectors 24lb, or TB
I have not tried cranking up the fuel pressure...

 

[final5-0]

Your load is off ... way far off ... with the 50 additional cubes

Load is what our pcm's are all about btw.

You might ... but I don't think so .. be able to tune it with the fuel pressure and dizzy twisting.

Even if you get it running half way decent ... the tune is still not gonna be all that close to optimized IMHO.

Make sure all connections are good and you don't have any v leaks. Do a pcm reset and see how much the pcm can help you ... you have no other choice but try that.

If it don't work ... you or a Pro is gonna have to tune it.

Good Luck and keep us informed about your progress.

Grady

 

[redmoneypit]

thanks, I guess I will be looking for a tweecer and try to give her he tune then...

 

[final5-0]

You said most of the other stuff is stock.

If you still use stock inj's and pump, I'd not be all that comfortable beating on it.

You could be more than ...... a little lean

Maybe you could give more detail for more replies

Grady

 

[redmoneypit]

Thanks, well it does have a MSD fuel pump a little better than stock.. I am surprised their are not more folks out there running 347s with the same problem.. 24lb injectors may be ok with a little tuning but this is a street engine. never race it just get on it now and then for fun...

 

[final5-0]

Musta been having a senior moment

You plainly said Cobra
but
I was thinkin 19's all this time

You most likely are not as lean as I thought at first

Still ... the extra cubes will throw the tune off more than someone who did the same mods with just a 302-306.

I think about a 347 often and maybe some day

Grady