The V8 Owners Forum -

Car is a P6 3.5 with Edelbrock 500 carb, Edelbrock valve covers which allow push in breathers.
It has a crank case vent at the rear of the block.
Currently passenger side valve cover is connected to the carb Vac port via a pcv valve, passenger side is connected to air filter base via the push in filter.
Rear crankcase vent is connected to a small catch tank which has a filter on the top.
Does this setup sound ok?
Just checking a car over before road tuning.

The rear crankcase connection is an air intake, and normally connected to the air filter case, so it gets filtered air at near atmospheric pressure. The rocker cover vents connected to the high vacuum side of the throttles. The idea being to keep the crankcase under a slight vacuum.

Thanks, not a million miles away then.

On my 3.5, there rear breather is not connected to the inlet system - it just has a filter that is like a fuel filter in it.

garrycol wrote: ↑

Tue Sep 01, 2020 10:36 am

On my 3.5, there rear breather is not connected to the inlet system - it just has a filter that is like a fuel filter in it.

Thinking back to my first RV8, there was filter in that feed too. But connected to the air filter body, before the air filters.

garrycol wrote: ↑

Tue Sep 01, 2020 10:36 am

On my 3.5, there rear breather is not connected to the inlet system - it just has a filter that is like a fuel filter in it.

What he said.
An inline fuel filter will suffice.

Thanks for the above guys , helped me out a bit too.
What about the small thing on the rear of the left valve cover, some sort of breather but so small.....can I do away with it and plug the hole .

The engine is modified so who knows.

My take is that there is a pipe on the right hand rocker cover that goes to the inlet manifold or the carb some where - this is the sucker that takes internal engine fumes into the intake - but this system needs and inlet to let air into the internal engine - I think that filter is where air goes into the engine/crankcase and with engine fumes is sucked out the hole in the right hand rocker covers.

On the original twin carb engine, both carbs have suckers that are piped to take fumes from each rocker and air gets in at the back of the engine through a fuel filter type filter - the subject of discussion above.

Mc Tool wrote: ↑

Sat Sep 05, 2020 2:38 am

Thanks for the above guys , helped me out a bit too.
What about the small thing on the rear of the left valve cover, some sort of breather but so small.....can I do away with it and plug the hole .
IMG_20200105_124108.jpg

Sounds like you have an EFI rocker cover on a carb block. That tiny hole is the air intake on EFI engines. They have only one breather, from the other rocker cover, at the front. A flame trap fits into a hole same as the oil filler.

Old storey Dave , spent ages sanding and polishing early 3.5 round rocker covers and as soon as I finished I saw some efi square covers.....had to have them . I do have the flame trap on other cover, probly put an efi manifold ect on it as I want to sell it to finance a 3.9 serp motor build...heaps to polish on that too

Mc Tool wrote: ↑

Sat Sep 05, 2020 2:38 am

Thanks for the above guys , helped me out a bit too.
What about the small thing on the rear of the left valve cover, some sort of breather but so small.....can I do away with it and plug the hole .
IMG_20200105_124108.jpg

Same setup as my 3.9 in a Tvr.
Left hand rocker as you look at photo is the breather for air in and the other side is piped to plenum for extraction.
Not sure blocking it is the way forward.

DaveEFI wrote: ↑

Sat Sep 05, 2020 8:40 am

Sounds like you have an EFI rocker cover on a carb block. That tiny hole is the air intake on EFI engines. They have only one breather, from the other rocker cover, at the front. A flame trap fits into a hole same as the oil filler.

Well not all EFIs - 3.5s and 3.9s I think. Other EFIs such as Thor do not have this and have a 3.5 carb arrangement with their rocker covers with a large pipe in each Rocker. The left rocker pipe goes to the throttle body and the right rocker pipe goes to the inlet manifold cross over pipe.

Sorry to hijack the thread but I have a similar problem....
My engine came with no interconnecting pipes on the engine and no carbs.
I now have an twin SU inlet manifold and need some help identifying the ports...
1) there is a small tube from the top of the carb mounts which I presume is the vacuum advance for the dizzy - should this be connected internally to both ports?
2) There is a banjo bolt type arrangement on the top of the manifold connecting to one of the inlets towards the rear. This is a large bolt and hole but it comes out as a connection for a small pipe
3) There is a fitting connected on top of the manifold connecting to one of the inlets towards the front - the fitting is not just a fitting as it is not straight through - it ends in a relatively large pipe connector

I've labelled them up using the above numbering in the two attached photos
Your thoughts, as always, would be much appreciated.
2022-12-22 14.20.05 by Chris Marsland, on Flickr
2022-12-22 14.20.44 by Chris Marsland, on Flickr
Thanks
Chris

1. This is part of the cooling system. It is at the highest point of the system and should be connected to the expansion bottle / header tank / top of radiator to allow any air to escape.
2. This goes to the automatic transmission to give an indication of engine load (engine load being about equal to manifold depression)
3. This goes to the brake servo. The feature inside the fitting is a one-way valve.

Chris.

Thanks Chris, I get 2 and 3 but I only half get 1
So to help me get my head around it - where does the vacuum for the dizzy advance get taken from if it’s not 1 and are you saying there is water circulating round the inlet manifold that high up?
Chris

PS I guess the fact that 2 exists means the manifold is from an auto car then? Does this give me any issues using it on a manual (other than having to block up the port)?