1977 coupe deville 425 dies under load....

[poppo2_4]

Hello guys im new to this forum and so far its great........

just reently My car loss power, and dies when i put it in drive now i changed every

new holley car
fuel pump
alternator
intake cleaned and new gasket
cleaned fuel tank
checked vac lines
new distrubitor and super coil
new 10/40 oil
etc im loss now

im guessing fuel pressure or lock up convertor but the car tries to stay running when i put it in drive and give it gas JUST NO Power

[DFBonnett]

If in neutral or park, what happens if you suddenly floor it? Does it bog?

[poppo2_4]

Whats up , its great in netural and park but once i put it in gear and i hit the gas it doesnt even want to do anything and stalls out, and if i floor it thats worst..........maybe the timing is set right cause if u think about it if it dies in drive , so if i floor it in drive the power from the motor should just go.............do u know the fuel pressure for these motors

[95 9c1]

I've had a few of theese cars still have one, fuel presure stock pump 5 to7 psi, in 77 they had thm400's no lock up tranny's.
What kind of vacum do you have at idle? it should be 15 to 18. I recently had this same problem it turned out to be a massive vacum leak.
Theese motors are very sensitive to timing,tyring to get more power by advancing the timing is not the greatist thing for theese motors they are also sensitive to retard also,I would go no more than 1 degree in either direction from stock setting
Also the tin intake manifold gaskets can fool you they have a tendency to split between cylinders and on the ends. although this is more common with the factory aluminum intakes, but i did have it happen on an iron intake [creates massive vacume leak that can be hard to find]
Good luck hope this helps a little

[maxwedge]

Disconnect the engine pipe from the manifolds, see if the Cat is blocked or even the muffler.