Hello all,
I’m a new member to this forum. I apologize in advance for all the information, but, it is better to have too much than not enough.
Had a 331 built 2 years ago for a 1991 Mustang GT and have not been able to get it running well. Finally gave up and took it to be chassis dyno-tuned. After many hours and an expensive bill they could not get it running either.
Everyone assumes the low vacuum was a mechanical issue. The whole engine was gone through again… re-ringed, heads rechecked, cam was sent out to verify the grind which was good. Valve lash is at 1 turn and are not sticking. Turned them back to ½ turn with the same results.
Sprayed carb cleaner around everything…No vacuum leaks on any components.
Running 24#/hr injectors with a 73mm C&L Mass Air and 24# sampling tube.
A9L computer, 5 speed with 3.73 gearing.
MSD coil and distributor
CompCams grind # FW 3632/3634
Duration @ .050 intake = 224
Duration @ .050 exhaust = 232
Lobe Lift Intake = .348
Lobe Lift Exhaust = .354
Lobe Separation = 112.0
Intake C/L = 108.0
Cam Advance = 4
Symptoms:
Very low vacuum. The needle is smooth, steady and hovers around 10 in-hg. (I was told it should be in the mid to upper teens)
Glowing headers. Cherry red at the collectors.
Loud popping at intake/air cleaner
Plugs are fouled and the tops of the pistons have an oily black residue (a wide band reader shows the air/fuel mixture to be correct according to the guy working on the dyno-tune)
Misfires at varying rpms.
No Power. Have to lightly press the accelerator (less than would be used for just casual driving). Otherwise, it falls flat and pukes.
I know my limitations, and know I’m not the “sharpest knife in the drawer”. But even the sharper knives I have talked to have some ideas to chase after, but nothing seems to improve.
If anyone out there has seen this before or has any idea what to look at, your input would be greatly appreciated. Thanks in advance.
If more information is needed, just let me know.
Dale
I’m a new member to this forum. I apologize in advance for all the information, but, it is better to have too much than not enough.
Had a 331 built 2 years ago for a 1991 Mustang GT and have not been able to get it running well. Finally gave up and took it to be chassis dyno-tuned. After many hours and an expensive bill they could not get it running either.
Everyone assumes the low vacuum was a mechanical issue. The whole engine was gone through again… re-ringed, heads rechecked, cam was sent out to verify the grind which was good. Valve lash is at 1 turn and are not sticking. Turned them back to ½ turn with the same results.
Sprayed carb cleaner around everything…No vacuum leaks on any components.
Running 24#/hr injectors with a 73mm C&L Mass Air and 24# sampling tube.
A9L computer, 5 speed with 3.73 gearing.
MSD coil and distributor
CompCams grind # FW 3632/3634
Duration @ .050 intake = 224
Duration @ .050 exhaust = 232
Lobe Lift Intake = .348
Lobe Lift Exhaust = .354
Lobe Separation = 112.0
Intake C/L = 108.0
Cam Advance = 4
Symptoms:
Very low vacuum. The needle is smooth, steady and hovers around 10 in-hg. (I was told it should be in the mid to upper teens)
Glowing headers. Cherry red at the collectors.
Loud popping at intake/air cleaner
Plugs are fouled and the tops of the pistons have an oily black residue (a wide band reader shows the air/fuel mixture to be correct according to the guy working on the dyno-tune)
Misfires at varying rpms.
No Power. Have to lightly press the accelerator (less than would be used for just casual driving). Otherwise, it falls flat and pukes.
I know my limitations, and know I’m not the “sharpest knife in the drawer”. But even the sharper knives I have talked to have some ideas to chase after, but nothing seems to improve.
If anyone out there has seen this before or has any idea what to look at, your input would be greatly appreciated. Thanks in advance.
If more information is needed, just let me know.
Dale
