The Stovebolt Site Forums The Shop Area Engine Shop 250 Engine question

Hi,

I purchased a 52 AD several months ago and it came with a 250 engine and TH 350 tranny. The engine runs just fine but I noticed that whoever did the engine swap didn't bother to hook up the vacuum advance. He also put on an aftermarket aluminum valve cover without a hole for the pcv valve. It just has a breather cap and the pcv hose was plugged with a bolt and was laying on the intake manifold. I just finished installing a firewall mounted brake booster from Classic Performance products and decided to use the unused pcv hose for my vacuum source for the power booster.

I have two questions:
1. Is it ok to run my 250 without any vacuum advance? As I mentioned, it runs just fine as it is without the advance hooked up.

2. Is it ok to have just a breather on my valve cover or do I need to invest in a new valve cover that has a pcv hole in it?

If runs OK I'd leave the vacuum advance alone for now you can figure out what the PO did later. You do need to get the PCV valve working. Gas is collecting in your oil and could damage you engine. I would find a rubber grommet the right size for the PCV valve take the cover off and drill/cut a hole for the grommet. When you put it back together your idle mixture and speed will change so you will have to adjust them.

I second what Kedso said about the pcv. The lack of pcv will cause pressure buildup in the crankcase and can cause the oil seals to blow out. There is also a connection to be made from the oil filler cap to the air cleaner, allowing fresh air to flow through the engine.

While the engine will run good without the vacuum advance connected, it will use less fuel at speed when the vacuum is advanced. Another thing you can do that doesn't cost much is to put in an advance kit with lighter weights and springs in the distributor and an adjustable vacuum module. This will really improve your performance on the highway.

Thanks to FredT and kedso for the info!!
I will hook up the PCV asap.

Ummm! No Advance...No Power!!!! It will be like new bigger engine with advance hooked up. That's the first thing I would do. Just run a hose from dist advance to the carb on any lower nipple near base of it. Does it have that? plugged off?

Pvc, not so important, will be messsy, oily around engine w/out it. Most alum coverss have knock-outs or flat spots to put holes in for accessories like that. I suppose if you could figure what years, maybe there's a filler cap with a grommet for pcv like Phord had on their vehicles. STill need the IN hose though like someone else said. Even a filter vent just on cover is better than nothing. Race engine places have those bolt on breathers available for V-8's usually, but can bolt to anything you want.

Experiment with connecting your vac advance to ported or manifold vacuum and see which works best. Make sure your vac advance can is still good.

Some misguided mechanics, who are used to hacking on SBCs, will disconnect the vac advance and run the motor on full mechanical with lots of initial lead-in. Usually makes anything but a 327 race motor run like crap. Like your motor is runnin' 6 grand through the 1320 anyway. Recurve that distributor & check all vacuum lines, and it'll run better.

good luck

chip

OH, make sure the vacuum modulator from the TH350 is run to manifold vacuum.