Intake manifold swap

[Paul G]

I Got everything back together now. Swapped the Edelbrock Performer 318 for an Edelbrock Performer RPM Air gap 340/360 intake manifold. This is on my mild built 360 btw. I re adjusted the curb idle and had to do something a little funny. Mixture screws were about 1 1/2 turns out +/-, each on the Performer manifold. I now have them about 3/4 turn out each. Had to make it a lot leaner. I adjusted for max vacuum idling in park. I had 16" with the old intake. Adjusted to 16" vacuum again. Just had to lean them out a lot. Any idea why? 

Side note. The engine pulls hard to 6k easily now. Used to fall flat just over 5k before. Still a tire fryer! Traction is a big issue. Also I have a little slight bog from idle to tromped full throttle. Normal driving is smooth as silk. I had that bog completely worked out with that old intake.     

[Ghoste]

No surprise that there is a bog with the better manifold.  Did you leave the acclerator pump setting as they were?

[Paul G]

Didnt do anything different with the carb other than adjust curb idle and idle mixture. Timing is about the same, 12 at idle, 38 by 2500 RPM.

[Ghoste]

Likelt needs a bigger shot from the pump.  What carb?

[Paul G]

Holley 750 vacuum secondary.

[Ghoste]

Then at least you have lots of adjustment available.  Seems like a lot of carb for a smallblock but that's only my opinion.

[elacruze]

Sounds like you may have had a slight vacuum leak on the old manifold. Obviously the engine is pulling harder on the jets, forcing you to lean out.
With that in mind, I'd consider that stomping it to WOT may be pulling the secondaries open too fast rather than not enough pump shot. You can tie the secondaries closed with a zip-tie and confirm or disprove the possibility.

[ACUDANUT]

Then at least you have lots of adjustment available.  Seems like a lot of carb for a smallblock but that's only my opinion.

I agree.  Holley 600 or 650 are better for small blocks.

[Paul G]

I checked float level last night. The primary side was good, the secondary side was a little low. Not even a dribble out the sight hole. Adjusted it up till it dribbled out. Went for ride. Seems better now. Gets good scratch going 35 mph and tromping the gas. Feels like it helped get rid of that flat spot.

[greenpigs]

If you could score a 650 Holley for cheap I would swap it on and see how it runs.

[ACUDANUT]

BTW I hate you.   I have 4 feet of snow in front of garage and won't be able to even start my cars until April. 

[Sixt8Chrgr]

If you could score a 650 Holley for cheap I would swap it on and see how it runs.

I agree

[nvrbdn]

where you at paul? if you were close id let you try my 650 for a trial. but i know there is snow here.

[greenpigs]

, Arizona....and he sucks right now because of that.

[Paul G]

I spent more than my share of days shoveling snow in bone freezing cold. But no more!  I really feel for you guys up there in the frozen north. BTW, they say we might see the 80's this weekend. 

where you at paul? if you were close id let you try my 650 for a trial. but i know there is snow here.

Surprise, Arizona. (Phoenix)

[Ghoste]

We get our revenge in the summer when you have 110 in the shade every day.

[Paul G]

But it's a dry heat.