351W swap PCV

[KyleQ]

I'm in the middle of swapping in a 351W with BC's manifold adapter and I'm wondering about the PCV system... The car lower has a PCV boss in the back of the intake and the 351W does not... I've got a breather tube off the oil filler neck that feeds into the throttle body - is that going to be enough?

I'm worried about the motor sucking up oil.. any thoughts? Experiences?



Thanks-

Kyle

 

[tasker]

buddy, give me some encouragement....my 351 kicked my ass tonight. I should of looked at everything better as far as what was missing and such. Yours looks freakin awesome in there!

 

[KyleQ]

What are you doing for PCV or does your intake have the boss for it?

 

[tasker]

carb'd, has the boss can check tomorrow at work (Ford parts guy)

 

[DirtDonk]

Since you're also running the non-351 valve covers, you have to put the valve in the back of the manifold, just like a 302.

On the manifold, there would normally be a metal screen, a rubber grommet, then the valve. The valve gets a 3/8" hose plumbed directly to an appropriate vacuum port (usually on the underside) in the upper manifold.

On the valve cover, the hose fitting simply plumbs to the fitting on the throttle body or intake tube. Like you mentioned.
The only real requirement here is that it must be between the throttle body and the MAF sensor. Can't be on the vacuum side of the TB, or the filter side of the MAF. This way it's still clean, but the air gets measured by the sensors. It's all just one big happy loop.

And yes, that's it. the tube on the valve cover is for filtered return air into the crankcase, and the valve is for pulling the contaminated air out and ingesting it through the intake manifold.

Paul

 

[ilovemaui]

Since you're also running the non-351 valve covers, you have to put the valve in the back of the manifold, just like a 302.

On the manifold, there would normally be a metal screen, a rubber grommet, then the valve. The valve gets a 3/8" hose plumbed directly to an appropriate vacuum port (usually on the underside) in the upper manifold.

On the valve cover, the hose fitting simply plumbs to the fitting on the throttle body or intake tube. Like you mentioned.
The only real requirement here is that it must be between the throttle body and the MAF sensor. Can't be on the vacuum side of the TB, or the filter side of the MAF. This way it's still clean, but the air gets measured by the sensors. It's all just one big happy loop.

And yes, that's it. the tube on the valve cover is for filtered return air into the crankcase, and the valve is for pulling the contaminated air out and ingesting it through the intake manifold.

Paul

What he said. There are ways to work around using the pcv valve but I would recommend doing it the way ford intended.

 

[KyleQ]

So what happens if I've got no pcv, will the intake just stuck some misty oil?
Will it blow a seal somewhere?

 

[Ranchtruck]

Since you're also running the non-351 valve covers, you have to put the valve in the back of the manifold, just like a 302.

On the manifold, there would normally be a metal screen, a rubber grommet, then the valve. The valve gets a 3/8" hose plumbed directly to an appropriate vacuum port (usually on the underside) in the upper manifold.

There's no provision for a PCV hole in the 351w efi truck lower intake or in a carbed intake. No casting boss, nothing. So it can't be done like a 5.0l.

The PCV system needs to be a loop, and you want to have a baffle plate where it's sucking out of the valvecover or it will slurp up a mist of oil coming off the rockers.

I'd recomend drilling the other valvecover for a PCV grommet and riviting a baffle to the inside of it like a stock valvecover would have. May not be what you want to do with those nice covers though.

 

[75junebug]

I run the ford motorsports alum valve covers with the PCV valve on 1 valve cover. The filler cap is one of those cheap Oriellys cap plugs with a filter in it. Been like that for almost 10 years now with no issues. This set up was with both carb and Mustang factory efi(with BCB adapter).

 

[KyleQ]

I ran the Bronco hard all weekend without a single issue, other than tearing a tire off a wheel


I'm running, what I think are, Mustang valve covers. The pass side is baffled and that vent line off the oil filler neck runs back into the throttle body - a sealed system. Do I need to do anything else? The PCV is just a one way valve - I'm not loosing any metered air...

I've got another set on my other built 351W that I can take a picture of - I'll also pop off the throttle body and see if I'm sucking and oil... I never did check my oil level all weekend, I had 30lbs of oil pressure at 200* & 850 RPM. On any throttle I would constantly see 60psi.

 

[ilovemaui]

There's no provision for a PCV hole in the 351w efi truck lower intake or in a carbed intake. No casting boss, nothing. So it can't be done like a 5.0l.

The PCV system needs to be a loop, and you want to have a baffle plate where it's sucking out of the valvecover or it will slurp up a mist of oil coming off the rockers.

I'd recomend drilling the other valvecover for a PCV grommet and riviting a baffle to the inside of it like a stock valvecover would have. May not be what you want to do with those nice covers though.

My 408 began life in a 1995 Bronco the original 351 lower had PCV in the back just like the 302's. I'm running a 351 GT40 lower and it has the same PCV setup. I considered eliminating the PCV on the lower but in the end I kept it stock. I'm running Trick Flow valve covers. I had to cut a hole for the oil filler neck and vent to the TB.

 

[70_Steve]

I'm running a GT40 lower, and even with a larger baffle installed still had problems sucking major amounts of oil up the PCV valve. I'm running the stock 5.0 cast aluminum valve covers, so I bought an extra set, then modified the oil fill on the new set to accept a PCV valve and grommet. The valve cover with the oil fill is the only one that has the baffle. Since moving the PCV valve to the valve cover I haven't had the first problem with oil consumption or oil being sucked up the PCV valve.

 

[KyleQ]

Good to know - got any pics of that? My other motor has a PVC equipped GT40 lower and I don't want oil in that tubular upper... Running the funny filtery baffle thingy under your PCV?

 

[70_Steve]

Good to know - got any pics of that? My other motor has a PVC equipped GT40 lower and I don't want oil in that tubular upper... Running the funny filtery baffle thingy under your PCV?

Yeah, got pics on my home PC. I'll post some when I get home tonight.

The pics I have aren't that good. I didn't take any as I was modifying the valve cover, so all I have are a pic or two looking down the length of the valve cover between it, the upper intake and the hydroboost... The modification isn't all that complicated. I cut the oil fill tube down to about an inch or so. Then made a steel bushing about an inch long, so the OD would fit inside the tube and the ID was the correct size for the PCV grommet. Then just soft-soldered the bushing into place.

Are you asking about that mesh cylinder that goes under the PCV valve? I tried that with the PCV valve mounted in the rear of the intake. I didn't make provisions for it when I moved the PCV to the valve cover.

 

[br0nc0xrapt0r]

For carbed engines is there any issue with hooking the vent from the oil fill neck on the valve covers to the PCV port on the carb?

 

[70_Steve]

For carbed engines is there any issue with hooking the vent from the oil fill neck on the valve covers to the PCV port on the carb?

Only thing that comes to mind is there would be no PCV valve. But that can be resolved also. The LS1 in my 98 Camaro SS has an "in-line" PCV valve that lays horizontally along side the valve cover and is just spliced into some 3/8" tubing. I suspect that should work for your proposed install.

 

[KyleQ]

I guess I could just run a catch can between the oil fll tube and the throttle body. My concern is built up gasses inside of the motor - do the crankcase gasses make it up to the cylinder heads where it can be relieved or is it just sitting trapped in the oil pan? I'm guessing that air can travel up through the drain holes in the top of the block, through the pushrod holes and into the cylinder heads where the PCV can sit and prevent misty oil from flowing directly back into the intake. If I run a catch can that should prevent the intake from gumming up, correct?

 

[ilovemaui]

I'm running a GT40 lower, and even with a larger baffle installed still had problems sucking major amounts of oil up the PCV valve. I'm running the stock 5.0 cast aluminum valve covers, so I bought an extra set, then modified the oil fill on the new set to accept a PCV valve and grommet. The valve cover with the oil fill is the only one that has the baffle. Since moving the PCV valve to the valve cover I haven't had the first problem with oil consumption or oil being sucked up the PCV valve.

I installed a sponge type thing from Autozone that fits in the oil filler tube for about $2. It is supposed to catch the oil before it goes into the TB but allows the air to flow through. I only have about twenty miles on the 408, so I don't know how well it works. If it doen't work out I'll probably install a catch can. I had a catch can on my C6 vette that worked pretty well.

 

[DirtDonk]

So what happens if I've got no pcv, will the intake just stuck some misty oil?
Will it blow a seal somewhere?

Not likely to blow a seal as long as there is a vent in some capacity. Which you have on your valve cover.
But what will still happen over the long-haul is that your internals will build up with mucho contaminants from burned oil and unburned fuel finding it's way and staying in the crankcase. Not to mention the constant buildup of moisture from condensation when drive times are not long. This keeps the oil from building up enough heat to evaporate the moisture in the first place,
And that condensate mixed with the oil and other combustion byproducts creates acids and all sorts of mean and nasty things that you really don't want inside your engine. Ever.

And yes, it will probably drool oil all over the place. Wherever you have an opening. It might not blow seals, but it sure will look like it sometimes!

Paul

 

[DirtDonk]

There's no provision for a PCV hole in the 351w efi truck lower intake or in a carbed intake. No casting boss, nothing. So it can't be done like a 5.0l.

The PCV system needs to be a loop, and you want to have a baffle plate where it's sucking out of the valvecover or it will slurp up a mist of oil coming off the rockers.

I'd recomend drilling the other valvecover for a PCV grommet and riviting a baffle to the inside of it like a stock valvecover would have. May not be what you want to do with those nice covers though.

Since he said "351 with the BC manifold adapters" I assumed he was running a 5.0 intake setup.

Paul