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MGB 78 MGB crankcase ventilation

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Paul Slice

Paul Slice

Jedi Hopeful
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Hello all,
I know this horse has been beat to death but I have not seen this question on the topic.My 78 MGB has had the emissions removed,Weber DGV carb with Pico header and exhaust. I installed a Piper fast road camshaft along with new rings and rod bearings to the 80000 mile motor along with a new WP and oil pump also oil pressure regulator(stock volume).The dist. was replaced with a eurospec one from Bob at Brit-tec.I used hydromar sealent on all the gaskets and packed grease into the inner rings of front and rear seals. The crankcase pressure is vented to the Webers air breather but I also tried the ventura hanging hose trick. The motor still seeps oil around most gaskets as well as a slight drip around the rear main seal area. I also have a 80 Spitfire that has received the same treatment and does not leak or seep any oil.The trick on the Spit is to vent from the fuel pump blocking plate as well as the valve cover. This involves venting the pressure thru a small hole in the plate up thru a 1/2 inch hose to a hanging K&N filter mounted on the back of the valve cover. Will this also work on my MGB which has a blanking plate also, instead of installing PCV valve in the intake?
thanks Paul
 
Paul: I installed a Weber DGV on a 73 that I owned several (10!) years ago, and I had similar problems with the PCV system. In short, it will not work correctly with the hose from the front side cover connected to the underside of the aircleaner. Many Detroit made engines use a similar looking setup, with a PCV valve in the rocker cover that closes under high vacuum. I tried various combinations of hose sizes and PCV valves in an attempt to provide some restriction, but to no avail.
In the end I retro fit a Smiths mushroom type PCV (as used from 64-68) on the Pierce manifold at the power brake booster vacuum take-off point. That set-up worked great and provided real Positive Crankcase Ventilation. You need to have a vented oil filler cap, or on the later cars, ensure that the line from the valve cover to the charcoal cannister is clear, or provide a small air cleaner on the end of the hose if the charcoal cannister has been removed.

[ 10-15-2003: Message edited by: Andy Blackley ]</p>
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Paul Slice:
<SNIP> I also have a 80 Spitfire that has received the same treatment and does not leak or seep any oil.The trick on the Spit is to vent from the fuel pump blocking plate as well as the valve cover. This involves venting the pressure thru a small hole in the plate up thru a 1/2 inch hose to a hanging K&N filter mounted on the back of the valve cover. Will this also work on my MGB which has a blanking plate also, instead of installing PCV valve in the intake?
thanks Paul<hr></blockquote>

Wow, so thats why my Spit is dribbling oil out the rear seal! Do you have any pictures of this set up? I have dual webbers and a hot cam and ever since I did these mods I've been living with oil leak problems! I would be forever in your debt if you can show me how to implement a fix!

Basil
 
Basil, this is the kit that I used and it works great. I also have their billitt adjustable shocks on the front of my Spit. I can e-mail you some pictures of the setup if you would like them. Paul
pri vent kit
 
Guys:

I read this with interest, because I did the same thing on my 1500 Midget engine (really, a Spit engine). The car is a racer, and was a blowing a bit oil into the catch (overflow) can.I built the "vented blanking plate" similar to what's described above.
On my car, it blew more oil than ever! (if it had fixed things, I might have mentioned it here). I can't speak to the effect it would have on a street car....mine "lives" above 4500 RPM at all times. Maybe it would be an improvement with moderate use, but it didn't help me.
I finally "fixed" my car by carefully positioning a hose to the valve cover vent that was under constant suction (in a homemade carb intake plenum). It's really pretty similar to the original PCV system. Car ran a 2 hour race after this "fix" and didn't loose a drop of oil.
 
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