looses power

Frank Castros · 10-25-2014, 09:56 AM

GT/HA '66 Plymouth Belvedere, 426 Street Wedge, 3,675 lbs.
2.77 first gear ratio, 4.89 rear gear, shifting @ 6,500 rpm, 7,500 rpm at the finish line.
1.44 60', 4.35 @ 330, 10.80 @ 122.00 mph.

Problem is it runs out of steam at the top of the first gear.

Running an Edelbrock Super Victor with a Carter AFB 585 cfm, fresh Product Engineering 9500 Fuel Pump and 4 port regulator.

What do you guys think?

Paul Precht · 10-25-2014, 01:37 PM

Quote:

Originally Posted by Frank Castros

GT/HA '66 Plymouth Belvedere, 426 Street Wedge, 3,675 lbs.
2.77 first gear ratio, 4.89 rear gear, shifting @ 6,500 rpm, 7,500 rpm at the finish line.
1.44 60', 4.35 @ 330, 10.80 @ 122.00 mph.

Problem is it runs out of steam at the top of the first gear.

Running an Edelbrock Super Victor with a Carter AFB 585 cfm, fresh Product Engineering 9500 Fuel Pump and 4 port regulator.

What do you guys think?

Hi Frank, Jim Hale could be very helpful with that combo but my thought is you're turning it too high, I would go with a 4.56 gear and back to a 2.45 first and advance the cam a little.

Lee Valentine · 10-25-2014, 03:09 PM

Try shifting 1-2 at 6000-6200 see if it goes faster.

Ed Wright · 10-25-2014, 04:19 PM

Quote:

Originally Posted by Lee Valentine

Try shifting 1-2 at 6000-6200 see if it goes faster.

I was thinking the same thing. I always have to get out of low gear much sooner than second.

Myron Piatek · 10-25-2014, 04:35 PM

Just to be on the safe side, if clearances and other factors allow it, try upping spring pressures a bit. It's better to have a LITTLE more than needed than a little less. Do some research on what your overall engine combo should like in springs.

Being a long stroke big block, it could work better with less rpm, as suggested.

Frank Castros · 10-25-2014, 08:36 PM

Okay, I'm good with lower rpm, but I'm thinking the intake has too much plenum and runner, agree?

Chris Hill · 10-26-2014, 08:02 PM

Quote:

Originally Posted by Frank Castros

GT/HA '66 Plymouth Belvedere, 426 Street Wedge, 3,675 lbs.
2.77 first gear ratio, 4.89 rear gear, shifting @ 6,500 rpm, 7,500 rpm at the finish line.
1.44 60', 4.35 @ 330, 10.80 @ 122.00 mph.

Problem is it runs out of steam at the top of the first gear.

Running an Edelbrock Super Victor with a Carter AFB 585 cfm, fresh Product Engineering 9500 Fuel Pump and 4 port regulator.

What do you guys think?

Everything seems ok. 1-2 shift sooner.

Don't go to 4.56 and 2.45 low gear. It won't leave starting line at all.

HTMtrSprt · 10-26-2014, 11:10 PM

I would agree that a large runner and plenum wouldn't cause a lack of power. Sprint cup restrictor plate motors (similar to the big motor, small carb setup) actually make power using the biggest runner size they can cut into the manifold casting. More likely a fuel delivery issue if it only occurs in low gear as that is when there is the highest 'G' loading on the fuel system.

10-25-2014, 09:56 AM	#1
Frank Castros VIP Member Join Date: Nov 2001 Location: The Lowcountry. Posts: 2,962 Likes: 2,554 Liked 2,712 Times in 954 Posts	looses power GT/HA '66 Plymouth Belvedere, 426 Street Wedge, 3,675 lbs. 2.77 first gear ratio, 4.89 rear gear, shifting @ 6,500 rpm, 7,500 rpm at the finish line. 1.44 60', 4.35 @ 330, 10.80 @ 122.00 mph. Problem is it runs out of steam at the top of the first gear. Running an Edelbrock Super Victor with a Carter AFB 585 cfm, fresh Product Engineering 9500 Fuel Pump and 4 port regulator. What do you guys think?

10-25-2014, 03:09 PM	#3
Lee Valentine Senior Member Join Date: May 2004 Location: Brookfield, CT Posts: 708 Likes: 13 Liked 319 Times in 68 Posts	Re: looses power Try shifting 1-2 at 6000-6200 see if it goes faster. __________________ Lee Valentine 1661 STK

10-25-2014, 04:35 PM	#5
Myron Piatek VIP Member Join Date: Nov 2001 Location: Florida Posts: 1,542 Likes: 34 Liked 138 Times in 51 Posts	Re: looses power Just to be on the safe side, if clearances and other factors allow it, try upping spring pressures a bit. It's better to have a LITTLE more than needed than a little less. Do some research on what your overall engine combo should like in springs. Being a long stroke big block, it could work better with less rpm, as suggested. __________________ LOCOMOTION Racing

10-25-2014, 08:36 PM	#6
Frank Castros VIP Member Join Date: Nov 2001 Location: The Lowcountry. Posts: 2,962 Likes: 2,554 Liked 2,712 Times in 954 Posts	Re: looses power Okay, I'm good with lower rpm, but I'm thinking the intake has too much plenum and runner, agree?

10-26-2014, 11:10 PM	#8
HTMtrSprt Junior Member Join Date: Oct 2007 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: looses power I would agree that a large runner and plenum wouldn't cause a lack of power. Sprint cup restrictor plate motors (similar to the big motor, small carb setup) actually make power using the biggest runner size they can cut into the manifold casting. More likely a fuel delivery issue if it only occurs in low gear as that is when there is the highest 'G' loading on the fuel system.