1988 Mercruiser 5.7 260 - which are intake and which are exhaust valves on the head

[Blueghost924]

Hi, I have a 1988 Mercruiser 5.7 260 Alpha 1, and was going to follow the shop manual with the valve adjustment. I removed the spark plugs and have rotated the engine by hand to the #1 cylinder TDC. This is where I paused, because the Mercruiser manual discusses adjusting certain intake and exhaust valves on both heads. I pulled the valve cover off the port head (for cylinders 1, 3, 5, 7) and for the life of me, I can't tell which valves are the intake and which ones are the exhaust (looking at them from the top).

Advice?

 

[alldodge]

Look at which ones align with the exhaust ports (exhaust valves), can do the same with the intake (intake valves). The green lines below show alignment with the exhaust valves. Also note that 1-3-5-7 are on the left bank, and 2-4-6-8 are on the right bank. Valve alignment on the other side is the same

 

[Bt Doctur]

Save yourself some agravation, rotate the engine until; the intake valve opens and closes. Now you on the compression stroke with both valves closed
Adjust both lifters for that cylinder. Then move to the next cylinder. Rotate motor untill that intake opes and closes, now your on the compression stroke for that cylinder, adjust those. 0 lash plus 3/4 turn more.. Try to do #1 cylinder last. Rotate motor untill the intake opens and closes. Continue slowly turning the motor untill the timing mark is at 0. Adjust valves. This will set up the timing so you can drop the dist in the block aligned with #1 piston.

 

[Scott Danforth]

As AllDodge indicated, EIIEEIIE.

as BtDoctur indicated, just go down the firing order. I personnaly like setting them with the motor running

 

[Blueghost924]

Great info...all makes sense. Thanks!

 

[G_Hipster]

As AllDodge indicated, EIIEEIIE.

I personnaly like setting them with the motor running

This, on stock lifters, as I've seen some hydraulics start to hold the valves open at less than 3/4 at idle. A couple of instances I've had the lifters wouldn't take that much pre-load.

 

[alldodge]

This, on stock lifters, as I've seen some hydraulics start to hold the valves open at less than 3/4 at idle. A couple of instances I've had the lifters wouldn't take that much pre-load.

Not saying this wasn't seen, but if this was happening then my first thought is there is something wrong with the lifter and it needs replaced

 

[gm280]

AllDodge, I see you have after market roller rockers. What ratio, 1.52 or 1.60? I also see an aluminum intake as well and of course the headers. That does bring back memories when I was building SBC engines. :thumb:

 

[alldodge]

That pic was just one off the web, I do have after market on my Cruiser's 502 and believe they should be 1.5

 

[Bt Doctur]

Many, many years ago we used 6 cylinder rockers on the V8`s because of the ratio. Made the SB`s think a cam was installed

 

[G_Hipster]

.
Not saying this wasn't seen, but if this was happening then my first thought is there is something wrong with the lifter and it needs replaced

Chebbies are easy, Set up a Mopar with shaft mount adjustables, fast bleeds you can hardly feel, and a dial indicator. lol

It happened with a set of Sealed Power replacement lifters I put in a fresh engine. Initially set them at 3/4, fired it and had one of those Omg moments. Rechecked the dist/ign a dozen times before I ended back up at the rockers. Head scratcher for sure. A second set on another acted very similar. I set up at 1/2 turn now on stock lifters.

 

[boatman37]

i built a 327 years ago with a Crower shaft mount rocker assembly. if i remember correctly it had 1.5's intake and 1.6 exhaust. had a full roller setup. definitely overkill for all the more that motor was but it was cool. i think the cam was a .625 lift or something like that. either way it ran 12.30s in a 3600lb '69 chevelle