whats my problem?
Thread Starter
Burning Brakes
Joined: Feb 2005
Posts: 977
Likes: 1
From: wash. dc
whats my problem?
i put new valve seals and installed headers on my 71 BB. i adjusted valves as per the shop manual. in my effort to tune it up i noticed the vacuum gage would idle at 19Hg then it would drop to 15 then go back up to as much as 22Hg b4 settlin back to 19-20. it also didn't idle very smooth. when i took it for a drive it kinda chugged until i got above 2000 rpm then it smoothes out. am i lookin for a vacuum leak or does this sound like i need to put bigger jets in. the timing is set at 16* and 36 total. carb is a qjet.
Thread Starter
Burning Brakes
Joined: Feb 2005
Posts: 977
Likes: 1
From: wash. dc
i was thinking that too lee, thats i went back and re-did them... tighten until i can't spin them with my fingers, then tighten 1/4-1/2 turn and set. am i supposed to be able to move the rockers when they're set or not.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Do the vlvs 1 more time but find zero lash not zero p-rod twist.
Originally Posted by 71redskin
i put new valve seals and installed headers on my 71 BB. i adjusted valves as per the shop manual. in my effort to tune it up i noticed the vacuum gage would idle at 19Hg then it would drop to 15 then go back up to as much as 22Hg b4 settlin back to 19-20. it also didn't idle very smooth. when i took it for a drive it kinda chugged until i got above 2000 rpm then it smoothes out. am i lookin for a vacuum leak or does this sound like i need to put bigger jets in. the timing is set at 16* and 36 total. carb is a qjet.
Since u gave those self locking nuts a workout they may no longer hold and should replace those too or at least use some thin hardware store back-up nuts to double nut the rockers.
U can read on this forum every week where a rocker nut comes lose Red.Never heard of 20"hg vac let alone 22" vac.
My Hanyes says for '71 tune up spec at idle (600rpm) the BB has only 12"hg vac. I would normaly think u are on the wrong carb fitt'n or even a bad vac gauge but check ur vlvs again first then i'll try to help with vac/dist adv if u request so. 
Hope this works.
cardo0
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
i just adjusted the valves tonight....when i do it the difference between 0 lash and resistance of spinning is only 1/16 of a turn...however you can still spin them in your hands at this point.....and after the valve is adjusted and you work on the other valve the first one will appear looser.....from the lifter bleeding off....if you have are waiting till the pushrods doesn't spin i think you are over tightening it
