Engine and Transmission Tech

Boy, I have really been snakebit on this project. All I was trying to do was swap intakes on my 5.0 MGB.

So I had an internal vacuum leak at the ports and had to pull the intake off. I found the right intake gasket and it seemed to seal up nice. Now when i start the car it has a terrible clacking noise. Sounds a lot like a diesel engine but louder. I think it is valve train related as when I rev the motor slightly it seems faster than the RPMs. Pulled the valve covers and nothing is hitting and there is good oil flow plus all the rockers are going up and down as they should.

I guess the intake is coming off again. First thing I will look for is trash in the lifters but I'm not really familiar with roller lifters. Anything else I should look for?

Pull the intake. If you don't see anything pull the heads. My first impression is something droppe3d down an intake port while the engine was open.

You could use one of those inspection camera's to look through the spark plug holes into the cylinders for debris and then if you find something use a magnet or vacuum to remove the debris. If there is debris in a cylinder, at the very least with an inspection camera you should be able to find the cylinder that has some damage.

If some foriegn object got in there damage has been done. About 40 years ago I dropped a 1/4" steel washer down the intake of a 2 liter Ford engine. The noise on startup was bad but quickly got softer and the engine began to have a slight miss.

I had no idea what I had happened but eventually took the head off. The washer was gone but the top of the piston had many little dents. The intake valve seating surface had been nicked and that cylinder was losing compression.

5 liter heads aren't that hard to pull. Better safe than sorry.

I'm afraid that Donald is probably right.
Some trash likely dropped into one of the ports and is now inside a cylinder.
I'll assume that the valve train wasn't disturbed when you changed the gaskets.
Pull the plugs and see if any are damaged. If you find one then that head has to come off to assess the damage.
If the plugs look ok then see if you can look into the plug holes while turning the motor over by hand. If you're lucky you will find a piece of gasket or something else that is soft.
Like Steve said, a borescope or inspection camera makes this much easier. (they are very cheap these days. And come in handy for all sorts of stuff.)
If it all still looks ok, then have a look at the valves and rockers. Do any of the valve stems look lower than the rest when they are closed? Do any of the rockers feel loose when closed? If so then remove the intake and peer down the ports to see if something is stuck in the valve. If nothing is found then check the valve carefully for bending.
If all of that checks ok then you may just have some lifters that have bled down.
If you have nerves of steel you can start the motor and let it idle for a few minutes to pump them back up. (The risk of further damage is high).
But if you aren't 100% sure.
The best bet is to pull the heads to check.

I hope it all goes well.

Cheers
Fred

Sorry guys, I've been away for awhile. This is some kind of lifter problem but I cant figure it out. I put a brand new set of lifters in and after running a few minutes everything was fine. Then I began hearing a loud lifter tap from the area of the number 4 cylinder. Since there is no way to adjust valve lash on these motors I'm at a loss.

Adjustable pushrods maybe?

You said that you have oil flow at the rockers.
What about pressure?

I had something similar happen to me shortly after building my motor. Turned out one of the roller rocker lock nuts loosened up and then the adjustment nut began to back off. I had painted them all (silver sharpie marks) during assembly to make sure I torqued each one. I called the manufacturer and they said that occasionally (very rarely) on new builds they have seen this happen.... I re-torqued them all and miraculously nothing was damaged. Mine is a roller 5.0 block with AFR upgraded valve springs. 7/16" valvetrain studs, Scorpion 1.6:1 roller rockers and my cam is fairly high lift too so the stress are much higher than stock.