okay guys im about to go crazy trying to figure this out ive tried everything!

5.7L 350, stock internals with bolt ons


i went from a

holley 600 single line
vac secondaries
weiand stealth intake


to a

Holley 670 dual line
vac secondaries
Holley street dominator intake(ported)

The problem im having is that when i go to WOT the car will not pull.
It tries to just go slowly barely increasing in speed. Its so bad thats its hard for me to pass up traffic...

Before the swap the car was pulling good at WOT, it gave u the push back into ur seat feeling, but now it just feels like it dogs through the gear.

So heres what ive tried so far..
-Swapped vaccum diaphrams from the old carb to new carb-(still no pull)
-Swapped back to the old carburetor (600) -(still no pull)
-raised timing to 16* initial-(still no pull)
-lowered timing to 12* initial -(still no pull)


im running out of ideas, what else could it be? im 90% sure my dizzy is in right.. ive swapped it a few times enough to know where to point rotor.

This one really has me stumped, any help greatly appreciated.

 

Sounds like the timing isn't advancing or your HEI module is done (if you have an HEI). If those aren't the issue, I would be thinking fuel pump/delivery next.

 

What's your fuel pressure when this is going on?

 

yes i have a hei, the vacum advance is working when i check the diaphram but im not sure as far as the hei internals (never had one go bad) any way of troubleshooting it?

Dont have a fuel pressure gauge but i doubt thats the problem pump is mechanical, and seems to be pumping fine ill have to pick up a small gauge and test it

 

To check the mechanical advance, disconnect the vacuum advance. Run the engine RPMs up while watching the timing mark with a timing light. The timing should advance as RPMs rise.

Mechanical pumps are pretty famous for not keeping up with demand. Was your car carb from the factory, or TPI?

 

My first thought was timing since you obviously had to pull the distributor to swap intakes. Sure the timing light is accurate? Five7kid makes some great points as well.

 

car was factory carbed, im gonna test the advance. Only other thing i can think of is the secondaries not opening..

but on both carbs? kinda farfetched no?

 

Quick thought here... Is it downshifting right away when you punch the throttle? I see from your sidebar info you've got a 700r4, and I know mine was running like crap when I forgot to put the kickdown cable on with the proper bracket last time I had mine apart.

 

yeah timing light is good, ive tried dfferent timing settings and nothing.
Still cant get it to pull at WOT, otherwise drives fine and starts fine

 

you might be on to something, its not downshifting.

There is a little play on the cable because a piece of it broke off a while back, however prior to the swap it was downshifting fine even with the piece broken off, could be that maybe it got additional play during the swap? ill have to check that out. i always thought that as long as the cable was tight at full open throttle it would be fine.

 

Full opening and rate of opening both count. Do you have the linkage corrector for a Holley carb and a TV cable?

 

That would be this thing, bolts on with the throttle stud in the top hole, btw:

http://www.summitracing.com/parts/HLY-20-121/?rtype=10

 

this is how my set up looks

at WOT


normal


bracket

 

Does your old carb have an adapter like the one I linked to? I don't think you've got the proper geometry on the cable there, as my experience has been that these carbs only come with the proper geometry for a regular detent cable for a non-overdrive trans, and certainly not for a GM TV cable.

Nice bracket, by the way. It's not the prettiest thing, but I bet it didn't cost $40 like mine did.

 

As does the throttle closed position; there should not be any slack in the cable then either. The tv valve in the tranny should start to move via the cable, the instant the throttle does. If there's initial slack, you'll have to open the throttle further before the tranny decides it's time to downshift, if ever.

It will also cause the line pressure to rise later than required by the engine torque, so you've probably got short sloppy shifts to go with it. A clutch pack and band burner by all accounts - adjust the cable properly.

 

Might not be related, but your throttle cable needs to swivel throughout it's travel so that it is always in a "pull" position instead of twisting up. It won't last too long the way you have it, and when it gives way it might surprise you when it hangs up at WOT. Looks like you have a nylon lock nut on there, a simple fix might be just backing it off a little.

 

it actually looks like eseibel67 is onto something. That first pic of wot, is that you holding it open with your finger? it looks like your throttle cable is way to tight, and at the wrong angle, so when you wot it looks like it is pulling back on the cable. can you have someone get into the car and push the pedal and see how far the throttle is really going?
can you understand that? i know i am not very good at explaining things.

 

Oh, yeah, I totally missed that. Never ever ever use a bolt to attach a throttle cable. Holley sells a stud for using that carburetor on our cars, I can't look it up at the moment, but I believe it's part number 20-95, costs about $7.

 

thanks for the help everyone i finally fixed the issue.

Apperently the tv cable needed adjustment, i reset the cable then gave the linkage WOt and it locked itself into place, the car is running good now with the 600.

I tried putting the 670 back on but when the secondaries open the car just starts acting as if its redlining.. so i gave up on the 670.

the 600 carb is running good tho, downshifts fine when i go to WOT now.

You guys mentioned re adjusting my trottle cable? is there too much slack ?at wot? yes on the first pic i am holding the linkage from the engine bay.The tranny cable is nice and snug though

 

It's just that it looks like it's held on with a bolt and not swiveling like it should. That can cause improper throttle operation, cable damage, and the throttle sticking open. If you don't have one, you need to get one.

Just looked up the proper stud for this, it was Holley part 20-37. Here's the link from Summit:

http://www.summitracing.com/parts/HLY-20-37/