OMP Blockoff Question...
 

I searched quite a bit and never found a direct answer.

To remove the OMP on my 12A, do I just need a blockoff plate? Or do I need more? I've read just a plate is fine and also read you have to blockoff the jets too...so which is it? Right now I removed the OMP, bought a plate and have it ready to install, but don't want to put it on if it's going to hurt my engine since I didn't mess with the jets either. I also capped off the two lines to the carb.

Second question, with the plate, I bought a gasket, should I use some sealant as well to prevent leaking?

Thanks! :icon_tup:

As I recall you need to put a cork in the tube that goes to the ACV valve as well and yes a little sealant wouldn't hurt.

Just take it off and put on the plate and gasket. You could use sealant, but I don't think it's mandatory. IIRC, I think I put a penny behind the plate over the cam hole as well, but it's been a while, so I could be making this up.

this is much easier if you bought the plate and opened the hood.

you remove the pump, install the plate with a new gasket. sealant is optional. cap off the lines at the carb, add oil/premix to the gas and you're done. took longer to type that than to do it

You should probably re-read my post before making a smart remark.

Excuse my "noob" question, what's the ACV? Is it just the large hole, first thing I see in there after I remove the OMP? lol

For the record for the other poster, I have removed my OMP and have a blockoff plate, was going to install it yesterday but remembered a few posts mentioning blocking something else off behind where the plate goes, so wanted to be sure before I seal it up and risk damaging the engine.

Thanks for the replies!

ACV is the air control valve, it gets lost when you put on the block off plate.

Then there's some plumbing you need to do, here's what I did:

http://carphotos.cardomain.com/ride_..._large.jpg?v=0

http://carphotos.cardomain.com/ride_..._large.jpg?v=0

https://i259.photobucket.com/albums/hh308/grgreen/r.jpg

Attachment 725065

Hmmm that must already be removed I don't have that. :blush: lol

I wouldn't advise lashing out at the elders on this forum. Most of us were modifying these cars before there was an internet to ask questions on. We just got out in the garage and figured it out.

The old metering system is pretty simply on the 85 and older cars. You have a metering pump that is driven by a shaft that passes thru the front cover. This shaft is geared internally and driven off the e-shaft.

There is a linkage that connects the metering pump to the throttle shaft on the carb. This triggers flow as the throttle is increased.

There are a pair of tubes that carry the oil up and into the intake via two nipples.

When the metering pump is removed you will see there is an oil supply hole in the front cover along with the shaft that drives the pump. The block off plate will cover these.

The other end of the system is the twin supply tubes to the intake manifold. When removing these you will have a pair of open nipples on the intake manifold. These nipples should be blocked off with some vacuum caps.

The ACV is part of completely different system. This was removed and a block off plate added back when the car was originally prepared I am sure.

Sorry Simon, I completely missed the "OMP" part of your question, I thought you were asking about the ACV block off, which is a bit more complicated.

For the OMP block off, yes, it's as simple as J9 says, just buy it and put it on.

But being the Cconservative type, I would also put a dab of that non-hardening hylomar sealant on there, just for good measure.

And if it's a daily driver, I'd hold on to that OMP, doing the premix routine at the gas stations gets kind of old.

Not trying to highjack this thread, but this is in the same area: What if one wants to retain the OMP but swap carbs to a holley? can one fabricate some linkage to connect to the throttle of the new carb or is there more involved then this?

I wasn't trying to be rude, I wasn't just asking without looking though as I took the pump out, plugged the carb, and bought a block off plate but decided to ask first because I read a few things about having to block something else off as well.

I guess I just need to bolt the blockoff plate now, thank you sir! :icon_tup:

No problem! Thanks for the help! :icon_tup:

Yes, a linkage from carb to OMP can be fabricated to work. Some people also use a bicycle brake cable to do this.

-billy

the only place you can put the jets on a holley setup are below the carburetor on the intake manifold. you can simply drill and tap the manifold for the jets but if you do so you should probably use the 2nd generation oil metering jets since they were designed to sit in a vacuumed environment where the stock carbed system the metering jets were before the throttle plates. the FC metering jets have check valves internally to keep the vacuum from emptying out the line under hard decel and nothing to push under heavy loads.

I believe I heard that you should not re-use the original bolts when installing a blockoff plate. They are too long.

They are indeed, I have some that fit I'll post the size in a few for anyone doing the same thing and curious.

Much appreciated Simon. I may be doing this myself before too long. :)

Yes, you should be able to just remove the OMP, install the blockoff plate with the gasket (sealant optional) and shorter bolts, remove the arm and tubes and be good to go.

Personally I'm going to be going this route:
http://www.rotaryaviation.com/oil_in...p_adaptors.htm

One of those adapters, a small oil tank mounted on the passenger side shock tower, and an OMP modified to always run in "full open" mode. Then I just have to keep the two-stroke tank filled and not worry about mixing when I gas up.

Those are cool, this is a race car though so it won't be a hassle to pre-mix.

Well, went out to throw the plate on and one of the holes is stripped, took the thread out of the actual block hole...now what?? lol

It's the lower bolt, the upper one was fine, this one is tighter than finger tight but not tight. Any ideas? How much pressure is behind the plate? Think some ghetto weld (JB Weld) around the outside of the plate (like gasket maker) and installing the two bolts would be enough to keep any leaking away?

It could start to leak when you aren't looking (like out on the track) and constitute a serious engine oil leak, probably not a chance you want to take with a 12A.

A more permanent solution would be to re-thread the hole to the next larger bolt size. You may need to ream out the bolt hole on the block off plate a bit too.

I'd try a tap of the same size as the current hole first.

For the aviation oil pump resevior, it would be easy to install a level sensor and run it to a light on the dash.

Helicoil...

I guess I have no choice but to re-thread it, I started it up put back together with the bolt as tight as I could get it without it loose again and it leaked. Not cool, I need it done by the 14th and work almost every day. :icon_tdow :(

Is this what I need? I'm pretty sure that's the size bolts I bought but is this the typical kit to fix these types of things or does it require extra items?