94 5.0 valve adjustment

[shorn]

What is the best way to adjust the valves on a 305 5.0. I have been told to adjust with #1 at TDC Exhaust 1-3-4-8 and intake 1-2-5-7, then roll the engine 360 and adjust the rest, turning each nut one full turn after the lash is removed. However, the machine shop that installed the valves says,
adjust both #1 valves at TDC, then roll the engine 90 degrees and adjust each cylinder according to the firing order continuing to roll the engine 90 degrees after each pair. Also he recommends turning the adjusting nut about 1 and 1/8 turns after removing the lash.

 

[leedub]

Re: 94 5.0 valve adjustment

You could adjust either way as you described, but just to be safe, I adjusted both valves on each cylinder when they're both closed. I just went cylinder-by-cylinder along the firing order until I was done.

Regarding valve lash, it seems like there are varying opinions among mechanics ranging from 1/2 to 1 full turn after lash is removed (I went 3/4). Seems like anything over 1 turn would be much too tight.

 

[John_S]

Re: 94 5.0 valve adjustment

Mercruiser Service Manual recommends one full turn after zero lash. Never seen anyone recommend more. I've seen less, usually from car engine builders.

Finding zero lash on a cold engine, especially if the intake is already on, can be tricky. Lifters may not be full of oil. I would recommend a follow up with the "hot" method with engine running. You will want a set of those rocker clips to do that.

 

[dan t.]

Re: 94 5.0 valve adjustment

GM built the motors not Merc, GM service manuals recomend 3/4 of a turn. I have been setting Chev engines at 3/4 for over 40 years with 0 problems.

 

[John_S]

Re: 94 5.0 valve adjustment

GM built the motors not Merc, GM service manuals recomend 3/4 of a turn. I have been setting Chev engines at 3/4 for over 40 years with 0 problems.

I can't tell you if it was Merc or what GM recommended for marine use. If volvo has the same spec, suspect it would have been a GM recommendation. GM designs marine engines: http://www.gmpowertrain.com/MarineEnginesControllers/Introduction.aspx Merc and volvo just have their versions of them.

Personally, don't think it makes much of a difference. The only advantage I can see, is that with the merc spec, you can have a little more cam and lifter wear before you need to readjust the lifters. Car guys use 1/4 or 1/2 turn, such that when they over rev and get some valve float, the lifter doesn't pump up too high, and cause damage as the rpms drop back down.

 

[joewithaboat]

Re: 94 5.0 valve adjustment

My experiences, others may differ...

The type of hydraulic lifter (who made it), cam size and spring pressure will have more to do with the best setting than Merc. or GM. Although GM actually makes it's own lifter. If the engine is rebuilt use the cam and lifter manufactures recommendations. It is generally best to get them from the same manufacturer. Although some cam companies sell you more expensive anti pump up lifters which actually are the same as there normal...with different preload recommendations... but that's a different story.

Finding true zero is nearly impossible unless lifter is new with NO oil in it. The only way to be on the true heel of the lobe is to set one lifter every 45 deg, takes two full revolutions of the crank. That's why racers use deg. tape or degree'd balancers.

All that being said smaller stock type cams and hydraulic lifter travel is why various methods work ok. But when someone sets them running or one every 45 deg it will make more power and run smoother. Hot and running is the best way for most. You still have to get them close cold.

1/8 to 1/4 turn after zero will work well with a hot cam, good lifters and springs. 1/2 to 1 turn for stock/mild stuff. The 1/8 to 1/4 essentially gives the lifter less ability to hold the valve open when pump up overcomes ability to bleed down at high rpm. You can generally see an extra 200 rpm if set this way & it will generally rev up quicker. It would take someone smarter than me to explain it well... but essentially you are changing cam timing events using the travel in the lifter by making the lifter taller or shorter.

When i had direct knowledge of it, cheap cam kits used re-manufactured lifters, that was 15 years ago. I'm sure they still are. By the way reman. in the lifter world means... surface the bottom and flush with fluid, no dis-assembly... yiks I don't know if they re-manufacture roller lifters. ????

I have found that a valve cover with the center cut out works better than the clips to set them running. Ive seen the clips pop off and wind up in the engine. adjust them slowly to give the lifter time to bleed down or pump up if you do it running.

 

[Don S]

Re: 94 5.0 valve adjustment

Why don't you just follow the manual. I can't imagine how your engine will run when you do a little of what one person says, and a little of what another person says, and soon you have an engine that doesn't run because what one person said conflicts with the others.

Below is a file on valve adjustment from the OEM Manual for your engine.

There are two things that normally causes problem for those new to building engine.
1. You MUST start your valve adjustment on #1 TDC of the Compression stroke. Do that, like this. http://forums.iboats.com/showthread.php?t=427081

2. Finding Zero Lash. When you are moving the push rod and tightening the nut to find zero lash, when the push rod stops moving, you are at zero lash. STOP. Do not recheck, as it will be loose again. Do this one time on each valve, and one time only or the valves will be to tight.
After you get zero lash, add the additional amount stated in the manual.

 

[joewithaboat]

Re: 94 5.0 valve adjustment

Why don't you just follow the manual. I can't imagine how your engine will run when you do a little of what one person says, and a little of what another person says, and soon you have an engine that doesn't run because what one person said conflicts with the others.

Below is a file on valve adjustment from the OEM Manual for your engine.

There are two things that normally causes problem for those new to building engine.
1. You MUST start your valve adjustment on #1 TDC of the Compression stroke. Do that, like this. http://forums.iboats.com/showthread.php?t=427081

2. Finding Zero Lash. When you are moving the push rod and tightening the nut to find zero lash, when the push rod stops moving, you are at zero lash. STOP. Do not recheck, as it will be loose again. Do this one time on each valve, and one time only or the valves will be to tight.
After you get zero lash, add the additional amount stated in the manual.

Don, as usual, is giving good advice. Most folks I wind up helping with adjusting lifters have gotten them too tight. Engine will run but not well. Finding zero is a crap shoot for most people, by just reading about it. You really need to watch someone do it that knows what they are doing.
If i am assembling a fresh engine, i set with intake off (so you can see) no oil in lifter. Prime via oil pump before start of course.

 

[John_S]

Re: 94 5.0 valve adjustment

I have found that a valve cover with the center cut out works better than the clips to set them running. Ive seen the clips pop off and wind up in the engine.

I have used the cut-out valve cover on the older perimeter bolt style heads. You could tighten them up, and have both hands to work with. Also, on those heads, the ridge was lower and oil could spill over and onto exhaust. I went with clips with center bolt style, like what the OP should have. Either you have cut mutiple holes or always use one hand to hold the cover in place, or hope gravity is good enough. If you have a spare from the boneyard and access to a torch, might be worth it. The clips were cheap, held tightly in place for me, but don't remember if I checked to see if they could physically fit through the drain back holes. If one feels loose, check to see if it was bent or broken. Engine only needs to idle. No need to rev it with the clips on.

 

[joewithaboat]

Re: 94 5.0 valve adjustment

I have used the cut-out valve cover on the older perimeter bolt style heads. You could tighten them up, and have both hands to work with. Also, on those heads, the ridge was lower and oil could spill over and onto exhaust. I went with clips with center bolt style, like what the OP should have. Either you have cut mutiple holes or always use one hand to hold the cover in place, or hope gravity is good enough. If you have a spare from the boneyard and access to a torch, might be worth it. The clips were cheap, held tightly in place for me, but don't remember if I checked to see if they could physically fit through the drain back holes. If one feels loose, check to see if it was bent or broken. Engine only needs to idle. No need to rev it with the clips on.

Agreed, I have a box full of cut up valve covers. Two types of clips. Admittedly, i usually just wing it without either. Most of the time stuff im messing with has a roller tip or full roller rocker arm and you cant use clips. The little white plastic part of the two piece clips will go thru the oil returns in the ends. Luckily it stopped in the valley and I was able to get it out with one of those spring arm tentacle things you use once or twice in your life.

 

[John_S]

Re: 94 5.0 valve adjustment

FWIW: Here are the ones I used: http://www.jegs.com/i/Mr.+Gasket/720/1015/10002/-1 No plastic parts.

Even with clips I took extra precautions to make sure oil wouldn't spray on carpet, vynel, or myself. A mess under a car hood is much easier to clean up then a boat.

 

[joewithaboat]

Re: 94 5.0 valve adjustment

I have those and the two piece shown in the merc manual above. I like the ones you are showing better. The others are the ones that came apart, but i have used them and lent them out a bunch.