I have found the source of my engine noise, as I think I talked about earlier along with some head gasket problems. When I first put my mufflers on my 255 flathead I became aware of a very loud tappet noise, this is when i took the heads off to find my head gasket issue and to check the clearances on my adjustable lifters. I had found 2 lifters screws that were backed off completely so I assumed that the rebuilder had forgotten to do these 2. Not the case, assembled everything and I had the same noise,(I read on one thread that the engine sounded like a thrashing machine, exactly like one). Removed the center head and found 2 more adjusting screws backed completley off. These are new lifters and they do not have enough torque to hold them in place, they were purchased by my rebuilder who says they came from a company in the southern US, maybe southern China. Now to fix this properly the valves should come out and the lifter's either replaced or fixed, I do not want to remove the valves at this point. I have screwed the adjusting screws out as far as I can, cleaned with brake clean and applied a top quality high temperature thread lock, adjusted them right away, checked them twice and will button everthing up and try again but I am not sure about long term.
This is a pain in the block and it is a warning to everyone with adjustable lifters in a fresh rebuild to check this before and fix it before the valves are installed. My rebuilder says Oh well, here is some locktight.

 

If the lifters are either going to stay put or go in the trash (i.e., no warranty), I'd set them with Loctite, then take a punch and mess up the threads so they can't screw in. There is no way to replace them without removing the valves....

 

I talked to my guy again and he is going to replace them, just need to find a good set. I thought about peaning them but decided to fix it right. The heads are off again and the valves are coming out. I don't want to deal with this later when the truck is complete and it is harder to work on. Before I took the heads off i checked my compression with the new copper head gaskets, all 135 - 140 lbs. Thats a little high but goes along with my calculated compression ratio.

Keep you posted

 

My buddy, who has a machine shop & builds flat heads, has seen these lifters flatten out a cam as well. Be careful on which lifters you get and be sure to use the proper oil and an additive when you break it in.

 

Red's Headers sell the good ones, from what I've heard. I think they are made in Australia.

 

isky or reds , and flathead jacks are the only ones i trust for 'em . found a nicely priced set on an evil bay store here not too long ago and inquired about if they { hollow ones too } were the crap made in china . guy sent me an email back berating me for asking about them and that he has no problem with them .... yet . to me that meant ... YES THEY WERE . i might suggest if they haven't been replaced that you check the valve springs too . mine had a " knocking " noise which is part of the reason it's still sitting apart , and it turns out i had a spring go soft and was letting the whole guide and valve assembly slap up and down . it was so worn i can pull the keeper off with my fingers !!!!!!!!! still trying to get my hollow adjustables , i keep buying other stuff and getting sidetracked ........................ geuss i've been living with blondes to long ...............

 

I thought about the springs, they are new but I should check them. As far as the oil for break in, I have struggled with this as the zinc additive is gone in most oils. I found out that here in Canada that the SAE 30 oil still has the zinc and that the flatheads like the straight 30 weight oil. Also that "high mileage" oil still has the additive as well.

 

Regardless of the oil used, I would still smear everything liberally with a good pre-lube (cam, lifters, etc). Machine shops have a good assortment of Michigan Bearing pre-lube, etc. I have used some green stuff successfully for years.