Funny gray rod next to the camshaft!? (86 or newer Engine?)

[DanT]

PLEASE HELP BY 4 PM TODAY...

I am selling my '85 T4 wagon at 4 PM on Monday... but I have the cam cover off right now... and I am afraid to put the cover back on or to drive the car ... unitl I find out how to re-connect that funny gray rod that I see next to the cam shaft. (I have never pulled the cover before, and wonder if I disconnected something.)

To be a nice guy I bought a new cam cover gasket to stop a small leak for the new owner (85 gasket does not fit this cam cover.) After lifting the cover I now see a funny gray rod next to the camshaft... that appears to be disconnected at the location of the fuel pump/camshaft lobe area. I am not sure how it is suppose to be connected. Too late to take pictures with my cell phone/no flash, but will post tomorrow when I have light.

I know this is a replacement engine and it is obviously not an 85 (have downloaded the 85 FSM). My guess is it must be an 86 to 88... or newer? Engine serial # 3A 2966294.

The cam cover has a series of extra wiggles on the carburetor side... along with this funny gray rod that apparently moves 4 pivot points back and forth... but the assembly is not connected on the end that is close to the fuel pump/ cam of the camshaft... and it is not clear to me at all how to connect it. Have tried for an hour to find a newer T4 FSM or information on this... and am just stuck.

Anybody know what to do with that funny gray rod connection?

Thanks.

Dan

[tercel4wdrules]

Sounds to me like this is a JDM 3A-SCV (swirl control valve) engine. It will have a 3A-SCV tag on the side of the valve cover as opposed to either '3A' or '3A-C'. From what you're describing it has the "wavy" valve cover. You will likely have to get a valve cover gasket for a Corolla with the 4A-C engine with the wavy valve cover (I don't remember which years had this engine). There were two styles of valve covers - the straight type, which is the one that our cars came with, or if it has a JDM engine, then it will have a wavy valve cover. Perhaps someone else here on the forums with this JDM replacement engine can have some info on the rod from that vacuum doodad.

[DanT]

T4rules,

I think you nailed what is going on. Thanks. The previous owner, who lived in Washington State, said she had put in a "Japanese Engine" with 30 k on it... about 40 k ago. The cover is wavy just like you said. Unfortunately the spot where the "3A" always shows is missing the decal... but this almost certainly would say "3A-SCV" if it were visible.

Much less concerned about changing the gasket at this point then just driving the vehicle tomorrow without concern for damaging the head... because I did not understand what that rod is suppose to do... and was concerned about why it was disconnected on the back toward the firewall side.

Feeling less concerned about that now, and I am starting to suspect that rod was intentionally left hanging... when the JDM engine was installed into this T4. I did a search on this list and found a thread that you were in on for this engine back in March of 08. 71 posts to that thread, so obviously a lot of information... but only read a few bits so far. Post title:

Newb looking for a bit of info on 3A scv

The following text from sdoan from that post is of great interest, as this "swirl control valve" is the gray rod that puzzled me. ( However, in my situation, unlike having a vacuum can at the back of the cam it appears they simply left that vacuum can off entirely, blocked the hole at the back of the head, and left the "swirl control control rod" with no connection whatsoever.)

The swirl mechanism has vanes that stick into the intake tracks in the head just before the intake valves. The vacuum can on the back of the head pulls on a rod that is connected to the 4 vanes causing them to angle into the intake stream setting up the swirl. I don't know if lack of vacuum reduces the angle to minimum, but that would make sense - but you should check. You can see the mechanism to move the vanes by pulling the valve cover. You can see the vanes by pulling the intake/exhaust manifolds. The whole mechanism can be removed (I considered this) from under the valve cover. The fittings that the vanes fit through would have to be removed and replaced by very large bolts with gaskets. As I remember the hole for the vacuum can at the back of the head is easy to block, but I can't remember if it needs a bolt and gasket or a plate and gasket.

Perhaps this might explain why this vehicle runs too rich??? I told the new owner to get the carb adjusted or to get a new carb. Right now it looks like that rod could swing around and adjust the angle of those 4 vanes inside of the ports. Am I correct that those vanes should either be fixed at some angle, or removed if these vanes are not being adjusted with some mechanism that is linked to the engine performance?

Dan

[larry mcgrath]

I ran a 3a scv engine for 8 years with the linkage dis-conected didnt afect the performnce from what i could see.

[DanT]

Larry,

That is what I was hoping to hear from someone. Thanks! Attached are 2 photos of what this assembly looks like on this vehicle. Clearly the thing is unattached.

Correct me if my thinking is wrong, but the logic used to disconnect the SCV might go like this:

The vanes are free to float inside the intake ports with this arrangement. The 4 vanes are linked with that rod on the top, so they all move together and pivot at the same angle. The air/fuel mixture coming in would create significant "air flow" across each vane. If the vanes were free to float... like a weather vane in a strong wind... then the vane would simply line up with the flow... and not inhibit the process.

I am ready to let this rest at this point... and to just drive the vehicle as before. It seems like this might be the most common approach to placing a Japanese "JDM 3A -SCV" into an American Tercel.

Thanks for the help!

Dan

[Petros]

it will not harm a thing to have it disconnects. the idea with it, that was popular with all engine manufacturers at the time, was that you can accelerate the air/fuel mixture at part throttle conditions to improve part throttle torque and economy. If left on it will harm max hp output. The early 4age had the TVIS (toyota variable induction system) with two intake runners for each cylinder, one closed off with a throttle like plate at low rpms. It actually works, but I guess benefit was marginal and later EFI engines accomplished the same thing by other means using the ECM.

Likely with US federal emissions the power out put was so low they eliminated it in USDM cars.