Oil Restrictor Tube
 

Can anyone tell me how the restrictor tube is removed from the head? I have a feeling that mine is the older style with the "too large" hole, but I need to check it out. Hoping this is the cause of #5 being a dead hole...

I used an easy out and threaded it into the restricter. Then pulled it out. Don’t go crazy on the easy out.

Does it matter which way the hole in the restrictor faces in the head?

Pulled the old one out last night and it is indeed the .125", making a new one now.

No, it can be set in any direction, as long as the metering hole is within the galley/pocket your good.

Good deal, thank you. I made a new restrictor and installed it yesterday. I did notice when I had it apart that the HLA's on the exhaust side of 3 and 5 were taller than the other 10. Ended up bleeding all of the HLA's and firing it back up. The bad news is that the miss is still there. You can hear a "puff" in the exhaust so I'm afraid that the hanging HLA's may have burned a couple of exhaust valves. By the way, the cam and followers showed no signs of extra wear or scoring. Luckily, there was a seller on Ebay that had two NOS GM valves # 9786805 so I've got those coming. What do I need to look for after tearing it apart to know if I need to take it to a machine shop or if I'm able to just lap in the new valves and call it a day.

What oil pressure are you seeing?

It's 30-32 at cold idle, 32-34 at around 2500 while cruising and about 20-24 at warm idle.

That is within spec, so pressure is not the issue. Most likely the restrictor tube as you surmise. Let us know what you find out.

I'm hoping that's what did the damage. Won't know until I tear it down for sure, but waiting on the new valves before I pull the head. I'll report back when I've got parts in-hand.

I was able to do an air test last night and confirmed that the exhaust valves on #3 and #5 are leaking. Just waiting on parts before I tear it down to try and fix the issue.

I finally got everything taken care of. It turned out to be a burned exhaust valve on #3 with #5 not far behind it. Ended up replacing both of those valves and re-lapping the other 4. She's now hitting on all six again and running like a top. I'm guessing that the larger hole in the restrictor tube was allowing too much oil to the lash adjusters and ended up holding those valves open a little bit causing them to get too hot and eventually burn up. Hopefully, the new restrictor that I made will fix this going forward.

:thumbup:

Hi I have had a problem with exhaust smoke since I rebuilt my Sprint. The cylinder pressures are good and the smoke happens after the engine has been run a while. Could this be the restricter?

No that sounds more likely to be a valve seal issue.
The restrictor only handles internal flow pressure.

Do you know what seals were used on your build?

Either valve seals or rings have not seated yet.

Rings, smoke on load
seals, smoke on start up and deceleration

What dimensions did you make your oil tube to? Oil galley orifice .078* . Center of.tube .125"?

I sell new oil restrictor tubes.

The problem is, I'm in Canada. Plus, the owner already had a new made up. So if you sell new ones, can you confirm the dimensions please?

Thank you

.078” & .160” are the dimensions of the ones I sell.