348 PVC Installation

[chuckl]

I have a heated-up 61 348, Tri-power. It has tons of torque and runs like hell. The timing is spot on. I want to install a PVC set-up through the draft tube opening in the intake manifold. I have power brake vacuum and the distributer vacuum advance teed off the center carb. This arrangement seems to be perfect for max power, fuel efficiency and braking.

Originally, the vacuum advance was piped through a drilled stud in the rear carb base into the manifold. I installed a 1/2" phenolic block to reduce carb temp, so the original stud is way too short.

How can I plumb the PVC with out messing any thing up? I can add one, an even longer, stub; but drilling that long of a stud and then turning it down for the vacuum hose is impractical. Chuck

 

[boxerdog]

Can you tap a hole in the phenolic block somewhere and add a fitting?

 

[61BUBBLE348]

I did this.

 

[chuckl]

I did this.
View attachment 52603 View attachment 52604

If I plumb the PVC hose into the current "T," will anything change if I install a second "T" into the PVC hose, for my vacuum advance? Since all three are manifold vacuum, will one interfere with the other(s). Just don't want too much monkey motion or garbage up the engine too much. Thanks

 

[Don Jacks]

The "Calibrated Air Leak"[pcv] will likely effect your power brakes and vacuum advance when using the same port.It may not be too noticeable since that little 0950 cam makes so much vacuum anyway,especially if your vacuum advance is adjustable.

 

[chuckl]

The "Calibrated Air Leak"[pcv] will likely effect your power brakes and vacuum advance when using the same port.It may not be too noticeable since that little 0950 cam makes so much vacuum anyway,especially if your vacuum advance is adjustable.

Thanks Don. I really do know the difference between PVC and PCV. I have been installing about 3,000 feet of PVC on the farm. I even checked my spelling to make sure I had it correct. Yeah, right! Old age, I guess.

 

[skipxt4]

Poly, Crankcase, Vinyl Positive, Chloride, Ventilation.

 

[427John]

Chuck,you may want to consider replumbing your vacuum lines with the PCV going into the center carb and vac. advance and power brakes going into the front or rear carb.The vac.adv. and power brakes just require a vacuum source and entail minimal airflow while as Don said PCV is a calibrated air leak and will be best equally distributed from the center carb.Also use care in selecting the PCV valve itself they are tailored to original application(high perf big cam=lower vacuum,low perf small cam=higher vacuum)so if you use a PCV valve from a high perf application with a weaker spring or larger orifice in an engine that makes lots of vacuum you will get lots of extra air that you will have to tune for and if you go the other way you may not get the ventilation you are hoping for.Hopefully you can get access to one of the old PCV system testers its a simple little tool that plugs into the fresh air source to the crankcase and measures airflow and has red,yellow and green zones to indicate how well it is working.

 

[chuckl]

Chuck,you may want to consider replumbing your vacuum lines with the PCV going into the center carb and vac. advance and power brakes going into the front or rear carb.The vac.adv. and power brakes just require a vacuum source and entail minimal airflow while as Don said PCV is a calibrated air leak and will be best equally distributed from the center carb.Also use care in selecting the PCV valve itself they are tailored to original application(high perf big cam=lower vacuum,low perf small cam=higher vacuum)so if you use a PCV valve from a high perf application with a weaker spring or larger orifice in an engine that makes lots of vacuum you will get lots of extra air that you will have to tune for and if you go the other way you may not get the ventilation you are hoping for.Hopefully you can get access to one of the old PCV system testers its a simple little tool that plugs into the fresh air source to the crankcase and measures airflow and has red,yellow and green zones to indicate how well it is working.

Thanks. I'll probably use the rear carb, if I have enough room.