Holley carb tuning using emission computer

[HSSS427]

Have a Holley 750cfm model 4150 - 9379 on a 427 so. I decided instead of guessing that I'd take it somewhere and have them adjust it. Went to Carburetor Specialists in Marietta, GA and they basically took the emissions inspection computer and used it to tune the carb. Stuck the sensor up the side pipes and then ran the numbers for:
HC - Unburned hydrocarbons
CO - Carbon Monoxide
CO2 - Carbon Dioxide

When we first set it up we were getting roughly the following readings:
HC - 7000
CO - 7%
CO2 - Don't remember, but they were mainly adjusting using the HC and CO numbers

When they finished the numbers were:
HC at idle = 3200
CO at idle = 4%
HC at cruise (3300 rpm)= 650
CO at cruise = 5%

Wanted to know if other folks had used similar services and what results you got.

All I know is that the car idled and ran a lot smoother as I apparently had a mixture that was really rich. It also cut down on the backfires I was getting.

Other thing they recommended was to install a PCV and take the oiled K&N filter out and go with a higher flowing paper filter (with a note to change it frequently). Said the vacum level and richness was pulling oil past the rings and also mixing fuel into the oil.

Appreciate any comments and thoughts on this.
Thanks!

[Michael C Henry]

When I got everything inorder in Washington state .Emmissions said I had high hydrocarbons due to a lean missfire conditionn.The emmissions repairer found one bad spark plug but adjusted the idle mix richer.that brought down the HC but CO went up.The emmissions referee said at the last testing he would have goe somewhere between where we started and where we ended up,signed off on it and issued a waiver.

[HSSS427]

I'm lucky as the car is titles as a 1965 AC Cobra, even though it was built in 1996. As such I don't have to pass emissions here. But, the tuning they did sure did make it run better.

However, I installed the PCV valve on the rear breather port and connected to the vacum outlet on the rear of the Holley 750. It ran like crap...was sucking oil into the cylinders and smoke was coming out of both pipes. I took the hose off and plugged both ends and its running like a charm again. Not sure why the PCV was pulling so much crap through the carb. Do I have the wrong PCV valve maybe? Right now I'm going to put the breather back on and just keep the oil changed on a regular basis.
Thanks!
Scott

[Michael C Henry]

Mine came from Nevada It was built in 1984. and was titled as a 1965 Cobra replica . In 2000 , Washington state changed it to Kit-V but kept the date of manufacture as 1984. The date of manufacture also affects emmissions first five years no testing if registration hasn't changed hands then testing every other year (even years on even years and odd years on odd years)until after 25 years . My arithmetic 2008 will be my last go around

[trularin]

The draft side of a PCV system should be baffled sop it does not draw oil from the head. Oil sprays up from the rocker, push rod and valve spring assemblies as part of the lubrication process.

A baffle should be placed over the PCV valve port opening so only the air is drafted from the crankcase.

A breather provides fresh air to replace the drafted air.

As a matter of economics, it is least expensive to vent the rocker cover to the filtered air at the carburator air horn. Most use a pipe or hose connected to the base of the air cleaner and run that to the rocker cover. Then the PCV valve is installed in the other valve/rocker cover and it is connected to the 3/8 to 1/2 inch barbed fitting at the base of the carb.

Just my $0.02

[HSSS427]

Trulain
Thanks - that makes sense now that you explained it. I put the PVC on a plate on the rear breather port on the intake and I know it was getting all sorts of stuff splashed on it.

Right now I don't want to cut the valve covers as they look too nice in original configuration. I guess I'll look for a baffle of some kind. Any ideas if there is some kind of off the shelf product for this?
Thanks!

[trularin]

Most covers have stand-offs or posts for baffles.

However, you cane construct a couple of post with 10-32 threaded rod and used chrome acorn nuts as fasteners. RTV smears are okay for shock absorbers.

Hope this helps.

[bobt427]

Weirhouse you need to find one of the old ford baffled intake plates for the back of your intake manifold. The ones I have seen have metal like an S.O.S pad ,or steel wool in a little baskit as a baffle.

[Big-Foot]

I agree with the others that there needs to be some form of baffling before the PCV. Another thing is to make sure that your PCV is sealing well. Your PCV valve should have a nice metallic rattle to it. If you not, it is defective.

[HSSS427]

Thanks all. Bobt427 - any idea on a part number for that Ford baffled intake cover as I am becoming baffled (couldn't resist that pun)
Thanks!

[HSSS427]

[1 R.B.]

Weirhouse, Because I had removed the baffle inside the valve cover to gain enough clearance for the roller rockers my PCV valve was sucking the oil up and sending it to the carb. Needless to say I was getting oil comming out the end of my side pipes. I purchased a baffled breather grommet from Jeg's and no more problem. The part number is 720-5425 and the price is $5.99 for two of them. I hope this helps.