347 power problem

[4lug]

I just installed a new 347 the following E cam stock heads with roller rockers stock upper and lower manifold with 1 inch spacer 24 lbs injectors 155 fuel pump adjustable fuel regulator set at 39 psi 24lb 76 mm c&l mass air meter and k&n cone 65mm throttle body.When i get to 3 grand it goes flat no power i have to back off to get power. Could it be vacuum or computor problem

 

[Matt90GT]

Vacuum will usually show up as a bad idle + you could have a stiffer brake pedal.

Most likely it is in the MAF sensor. Try turning that about 30* to see if it helps.

Also is the fuel with or w/o vaccum?

 

[86T-Top]

I'm no expert, but I think the fact that you are running stock heads and stock intake is killing you. I don't think it is a vaccum problem since you didn't state that the car was idling poorly or running rough. You need an intake and heads that can flow more air for the 347, you are running parts that were designed for a 302, and they are restrictive for a 302 at that.

Mario

 

[NeQX]

Is this serious?

 

[Matt90GT]

You can run stock heads and intake on a 347. Ford did it with the 351s. That is not the problem.

Seriously look into the MAF first. Did you get the right sampling tube installed?

 

[bluelx347]

It could also be a fuel problem. You might be running out of fuel when you get to 3 grand. I am just in the midst of building one and i've hurd you need at least 30 lb injectors. hope this helps