Makes sense. When Im on the compression stroke both valves will be on the same level? Also what if I didnt rotate the engine at all when it was taken apart, can I just adjust them now? Or its a must to have every cylinder ATDC compression stroke?Yes
And to be clear at top dead center on its compression stroke
Ayuh,.... it doesn't matter whether you rotated the motor, or not,....When Im on the compression stroke both valves will be on the same level? Also what if I didnt rotate the engine at all when it was taken apart, can I just adjust them now? Or its a must to have every cylinder ATDC compression stroke?
Agree up/down not turn, does not matter if you can turn it then it may be in the right spot but may also be just past it, based on how hard your turning. It can always be turned unless it's too tight alreadyI don't like the idea of turning the pushrods to find 0 lash, I gently lift 'em up, 'n down to find 0 lash, then tighten 3/4s turn tighter,....
Thanks for the advice ESG, will do.Dan,
Congrats on your accomplishment! I was looking over this long thread b/c I recalled there was more do and if you go back to post #4 and 7, you will see there is. That includes routine maintenance items as well as tracking down what looks to be a rich running situation. And recall that while possible the head gasket just let go, its not likely unless something caused it, like an overheat.
My suggestion:
- Get the timing done, this is an important next step
- Start a new thread titled something like “New to me boat, what maintenance items should I do?” And you will get a lot of good advice on what needs to be done. Note the lack of routine maintenance could have easily led to the overheat condition, so getting this done is an import step as well.
- Post the maintenance run the motor on the hose at idle for an extended period (like 30 min, perhaps more) and monitor temps. If anything unusual (hot) shut down and investigate. If all good, get the boat on the water and under load while monitoring temps and if all still good great, else investigate.
Thanks Lou, I've done the timing on it, set it to 2° ATDC as it said on the carburator air filter(Before doing timing, I checked the mark on the crank wheel and it was WAY back my guess about 25° BTDC at idle...) Ive also set the idle RPM to about +/- 750RPM. I than plugged the wires I bypassed back together and revved it to about 3000-3500RPM and the timing advanced to about a very steady 12° BTDC. From what Ive looked up and researched thats how it should be. Also the carburator looks to be brand new and its OEM so I dont think I have a problem with the carb. After doing the timing it starts like an EFI engine lol.Great work! I did a similar job on my '88 4.3 V6 back in '17. The cleaning and parts inspection are important, as is keeping everything organized. I would consider cleaning the carb, I think with your compression test results as consistent as they are now, it should idle smoother. Also, be careful about setting timing, make sure it's right, these engines are susceptible to detonation and that's one of the main causes of blown head gaskets. I do think yours may have been done before, because I don't think Fel Pro is the OEM on a Mercruiser. Beyond that to avoid another blown HG, make sure your boat is propped correctly, in that it reaches the specified WOT RPM at full throttle. And, despite what Merc says on an engine known for blown head gaskets and detonation, use at least midrange fuel, meaning, 89 octane instead of 87. So, the things to keep in mind to avoid a recurrence:
proper timing
use good fuel, 89 octane or better
engine must be properly propped and reach the specified WOT RPM as per Mercruiser's spec
inspect spark plugs for proper mixture, you don't want the engine running too lean, that also contributes to this problem