MG MGB and MGB GT Tech Talk
I was wrong about the adjusting screws, they are the same. Tom, sorry about wasting your time measuring the screws.
The answer is that the rocker stands are a 1/4 different!
Don't know which years the stands were shorter, but I originally had the taller stands on and couldn't adjust the clearances correctly so I changed to the shorter stands and that solved my problem.
I measured the stands as well. I didn't find any difference in their hight. There seem to be a slight difference in the distance from the center of the rocker shaft and the base of the stand. I suspect you got some midget rocker stands mixed up some how. The B rocker shaft would fit in them as would the rockers. They would also bolt up to the head, and they would be around 1/4" shorter.
Rockers are rockes are rockers...except for #4 pedestal oil difference...adjusting screws are adjusting screws are adjusting screws.....valves are a little different, there's double or single valve springs, single or double timing chains....
...unless I know everything that's in an engine was supposed to be in a B engine, i toss that boat anchor....any type rod can go on any crank so long as you use the correct piston for the rod (&, some of the pistons will interchange on different rods)....a cam is a cam is a cam; the grind doesn't affect how it goes together in the engine....a head is a head is a head; they'll all interchange....however, you can't mix & match push rods & tappets...
....what I think Gary has is a bastardized engine that somebody who doesn't understand B engines chopped up either before he bought it or while it was in the machine shop....were it mine, it'd be out by the side of the road for the garbage man to haul off...it & everything that had been bolted to it short blockwise....&, the head would get stripped & built with know MGB 1800 parts!
That is the American way!! I will take it to the scrap yard and get my $15.00!!! :o) Seriously, I doubt it is bastardized!! I think Tom nailed it when he posted last night!! Apparently he had a problem when he used newer style head and an older block and newer style lifters and pushrods!! I am just considering shaving the pedistals and seeing what happens!! I do have a couple of spare sets!! Anyway, see if this helps!! It was a newer block, older head and rocker assembly with the new style (bucket lifters) I still go back to asking anybody to measure the older and newer style lifter pushrod assemblies and seeing if there is even 1/8th of an inch difference!! Just try it Tony, you and I may learn something!! If there is not. what the heck!! then we learned too!! Right???
Mine is a 70ish block, pre-smog head, late lifters and pushrods, with 70ish rocker assembly pushing early valves.
I think whoever suggested maybe the valves just weren't set deep enough may have it.
That was Tom, but dammit!! The guy said he set them to 'specs' but nobody can tell me what the height is supposed to be above the head or bottom of the head!! They are damn near flush with the firing chamber, which to my way of thinking is waaaay deeper than a small block chevy which I am waaay more familiar with!! One old guy just told me 'hell, it's just a motor!!' but doesn't seem to be!! :o)
I'm sorry again, my dad measured the short part of the rocker stand against the taller part. I wasn't paying attention.
The short side is about 1 3/4 inches, right?? No problem Dave!! We appreciate the effort!!
I know that we changed something in the rocker assembly to make it work, but I just don't remember what!
This is Toms reply from last nite!!
Author: Tom Bedenbaugh (---.proxy.aol.com)
Date: 07-02-03 18:30
As I told you in one of my e mails. I had this problem once changing an early style engine with the heavier tappets to the later style. I ended up replacing the early rocker towers with the later ones and it solved the problem. The one thing you have to do is fill the offset oil grove with a brazing rod, and finisk it off flush. This is if you valves are seated properly.
No!!! This is the second guy!! I walked in with the head and he said 'hmm, older MG head???' I would assume that he knows what he is talking about, but who knows for sure???
The first guys really let me down!! I had never used them before, but apparently they do a lot of British cars!!
All three styles of towers are about 2 1/8". I can't help you with the pushrod lengths.
Good luck! I'm leaving.
"Date:Â Â Â 06-28-03 17:38
...Your seats may be higher now if the shop put in new valve seats.
Any chance you got the wrong valves (too tall of a stem)? As I recall, the earlier heads had a deeper combustion chamber than the later heads. I don't know if the two heads required different valve stem lengths or not..."
The old valves I've pulled out of old heads around here measure roughly anywhere from 4-3/8" to 4-1/2" tall. That 1/8th inch plus possible valve seating heights plus rocker stands (see D. Kiehna above) might all add up to your error. At any rate, if I were you I would shave my rocker pedestals ONLY as a last resort.
After getting burned, like you, with my first machine shop, I started doing a full assembly to check clearances, etc. before putting on any adhesives. If everything looks OK, then I take it back down & reassemble with LockTite, Hylomar, etc. It's a pain in the differential, but disassembly later is even worse.
David!! Very good point!! We do have the newer style valves in!! I know, 'cuz I had to find the keepers!!! Thanks!! You don't have the older lifter pushrod combo , do you??
