hotrodman

have 99 cobra DOHCeng. want to know if motor turns,, over backs,, when hooking air up to it will it bend vavle or not .im ready do it now so let me know soon

Black Horse

no it wont hurt it

Black Horse

remember first remove all the spark plugs first (so it'll be easier to turn the crank, and make sure your at top dead center on the compression stoke on the cylinder your testing...., remove you oil cap and coolant cap to listen for air ...and your set, you may also want to remove the air intake from the throttle body to listen for air from there also<edited><editID>Black Horse</editID><editDate>37999.830162037</editDate></edited>

hotrodman

you know sometimes when you bump it over and you think its on top dead ,,if its a little before it rolls the motor backwards,im doing a leak down because my compreesion was good 175/170/per. cyl.a guess thats good . but motor still smokes like a dog when i floor it or whlie crusing at a steady speed say 70mph in let off,blows smoke real bad 51,000 miles i know i run the crap out of it at the track, but it smoked before that ,found out that mac longtube headers had problems.had weld slag in pipes goes up egr tube and gets sucked in thougth intake,also the coating flaks off get in cyl.and glazes cyl.walls. got on another fourm it had all kinds of dohc motors messing up with these headers,,how much leak down is to much .my 83 351w has 2 percent but that a new motor with 20 miles on it.

Black Horse

no more than 10%... try putting it in gear so the engine wont turn when you pressureize it

hotrodman

okay im going to go warm her up and see what i got keep you posted on what a find.<edited><editID>hotrodman</editID><editDate>38010.2652662037</editDate></edited>

Black Horse

yeah

hotrodman

okay;; that broke my back! here is my results
#1-11%
#2-8%
#3-3%
#4-11%
#5-12%
#6-4%
#7-5%
#8-9% car has 51,000 miles no signs of oil on plugs??compression 170/175 per. cyl.car smokes when run hard?? also wnen letting off gas on interstate?<edited><editID>hotrodman</editID><editDate>38010.2661921296</editDate></edited>

vfast

valve guides!!!!! or seals

hotrodman

i need more input please!!!!!!!!!!!!!