Zole

Hello guys...can i ask a question regarding a 7.4 mercruiser carb i'm having a problem with idiling...so the engine is shaking a lot on idle..the carb is ok because i have a nother one and works the same...distributer,cables,firing order, ewerything check fine...so i go to the valves..the "mechanick" that asembold the engine told me that the valves are not adjustibal???.i'm pritty shore that he does not now what he is talking about so i wanted to ask you guys.he told me the hidro lifters don't have a roler(they are flat at the botom) and that you dont have to do preload.i've looked on the internet for them but the only video i could find is a gm 6 cilinder engine with that kind of lifters and they did the preload on them..if somone could spare some time and teach me on how to do this properly i would be greatful..thank you ewerybody

articfriends

iTrader: (1)

So deciphering what your asking,
1.you have a gen 4 or 5 454
2. it has a hydraulic, flat tappet cam and I assume stock rocker arms.
3. your mechanic says they do NOT have adjustment (possible)
4. he also says they do NOT need/have preload??? incorrect
You MAY have non adjustable valve train, if so, the pushrod length, valve height, etc needs to be very close to stock or you will not have correct preload. Most time any changes are made with cam, valves, etcs, rocker arms are converted to adjustable.
most run of mill hyd lifters will work fine between 1/2 turn of preload to about a full turn, fwiw, Smitty

Zole

thanks smitty...i knew that all valves need som kind of adjustment..seadly i did not asemble the engine so i dont know what kind of cam,valves and other stuff was don to the engine.I'll take a pic of the valves maybe then you will know beter what im talking about.It is not somthing that needs to be done righ away so i have time.You see now what kind of people do engines around here.Im wery sorry for my lack of knowlege but im triying my best to learn from you guys.I'll do some more reserch then i'll get back to you.Newer the less thank you for your time

xlint89

What engine do you actually have? Pictures might help

Getting a repair manual for your engine would go a long way for you to better understand and maintain the engine yourself.

mcollinstn

Some 454 heads do not come with adjustable valvetrain. They have "bolt down" rockers. Others have adjustable rockers.

FROM GM -
Mark IV motors are all pretty much hydraulic flat tappet. Gen 5 and newer have provisions for hydraulic rollers and dogbone roller retainers. Some Gen 5 are still hydraulic flat tappets. All Gen 6 and newer are dogbone style hydraulic roller lifters.

BUT you can put (retainer bar) roller lifters in ant BBC regardless of which series.
And you can put flat tappets in any of them as well.

We have no way of knowingkwhar's in your motor.

F-2 Speedy

iTrader: (6)

Thought you posted a pic of a roller rocker on your engine in your other thread ? those require adjustment

Build engine - Page 5 - Offshoreonly.com

Zole

yes that are rockers on my engine...the other engine that was making truble is a 7.4 mercruzer but that is not mine i was trying to help another guy...he went away with the boat so i can't take a picture...

F-2 Speedy

iTrader: (6)

Ooops my bad

Zole

newer mind your hart was in the wright place...i hope you had fun on 4 of july...i called my frend with the 7.4 mercruzer to se if he fixed the problem yust a minute ago....he told me his engine died and send me this foto



.You see the crack going all the way to the intake valve.

F-2 Speedy

iTrader: (6)

ya, thats not good