Black Spark Plugs - Vacuum / Timing / Carb Adjustment ?

[azhighcountry]

I knew it was running way too rich even before we pulled the plugs. They where all very black and sooty when we pulled them to install the new TTI headers.

First question is how much vacuum should I be pulling? At 800 RPM in gear I was getting about 2"vacuum. I kicked the timing up to about 26 degrees and adjusted the 4 mixture screws as shown in a Holly video. Now I am getting around 8"vacuum at 800 RPM.

I have a vacuum pump for the power brakes so the only thing connected to the engine vacuum is the PCV valve. Should I be getting more vacuum with this set up? I don't know much about cams so here are the specs.

Cam -

Brand: COMP Cams
Manufacturer's Part Number: 21-226-4
Part Type: Camshafts
Product Line: COMP Cams Xtreme Energy Camshafts
UPC: 036584046769
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,800-6,800
Intake Duration at 050 inch Lift: 250
Exhaust Duration at 050 inch Lift: 256
Duration at 050 inch Lift: 250 int./256 exh.
Advertised Intake Duration: 294
Advertised Exhaust Duration :306
Advertised Duration: 294 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.519 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.524 in.
Valve Lift with Factory Rocker Arm Ratio: 0.519 int./0.524 exh.
Lobe Separation (degrees): 110
Camshaft Gear Attachment: 1-bolt
Computer-Controlled Compatible: No
Grind Number: CRB XE294H-10
Valve Springs Required: Yes
Quantity: Sold individually.
Notes: Single-bolt camshaft

I am running a Holly 850 Double pump, Edelbrock RPM manifold and Edelbrock RPM heads . Engine is .040 over with 10:1 compression.

[DynoDave]

Sept 12, 2014 16:22:29 GMT -5 azhighcountry said:

Product Line: COMP Cams Xtreme Energy Camshafts
UPC: 036584046769

I don't know the answer to that question. But a quick Google search on the cam information above found this vendor...

link

..which has the following description...

- Produces Top Engine Horsepower

- Delivers Increased Engine Vacuum

Both fairly vague promises, and things that would seem on the surface to be contradictory.

I also noticed a fairly small (1.5 pages) of responses from Google, and none of them from major vendors...none from Comp Cams, Summit, Jegs, etc. So I'm guessing this is an older upc #. If it's been discontinued, it looks like Comp doesn't have specs online.

[azhighcountry]

The UPC and information was taken directly from Summit today. I found the same info you did which tells me nothing. "Delivers Increased Engine Vacuum", increased over what? This engine was built less than a year ago and only seen 40 miles on the road. We are trying to get it dialed in well enough to break thing in without fouling plugs every time I drive it.

A couple more short trips to break in the rear end then back to the shop to have them change the oil and make sure all looks good. Then after about 500 miles it will go to a speed shop to be tuned on a dyno.

[DynoDave]

Yeah, with promises like that, they just can't be wrong, can they.

2 was certainly lousy. 8 is getting better. Just not sure what can be achieved with that cam. Let us know what you get come dyno day.