Mercruiser 470 valve clearances

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mcwinfrey8

Seaman Apprentice
Joined
Feb 7, 2006
Messages
30
I've had the head off my 470 engine to re-cut the valve seats and was wondering the procedure to re-set the valve clearances. I sort of remember the rocker nuts simply being down tight allowing the hydraulic lifters to do all the work, and have read something about a go-nogo gauge and shortened push rods?!? Could i not simply install a means of locking the rocker nuts, enabling me to back them off the required amount to compensate for the shallower seat? <br />Thanks guys, Ben
 
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DHPMARINE

Captain
Joined
Dec 16, 2003
Messages
3,688
Re: Mercruiser 470 valve clearances

Ben,check the manual.As I recal,valve lash is measured with the lifter collapsed.I would think this would give the +/- tolerance quite large,and you may not need to do anything.<br /><br />Other than that,the adjustments ARE made with different lenghth push rods.<br /><br />Trying to cobble up something to deal with rpm ranges and temps may be difficult.<br /><br />At anyrate you have to measure first to see what has to be done.<br /><br />DHP
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: Mercruiser 470 valve clearances

DHP is correct.<br /> there is a tool to fully collapse the lifter to check valve clearence. its easier if you remove and bleed the lifters first. if the oil in the lifter is thick its almost impossible to collapse it.<br /> which is why I reccomend a good machine shop with experience on this motor. a good shop will measure the installed stem height and record the average and then after cutting the face and seats will cut the stems to achive the same average as previously recorded.<br /> but other than pushrod changes there is no other factory reccomended lash adjustments. lots of other oddities on that motor as well. you really really need the factory service manual. the head must be properly aligned or the intake will leak oil .<br /> best I remember that head surface has no alignment pins and must be properly oriented before torqueing the head bolts.<br />if I get a bit of energy ill look out in the shed for the manual.
 
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Capt Ken

Commander
Joined
Jul 30, 2002
Messages
2,269
Re: Mercruiser 470 valve clearances

Makes ya wonder why Mercruiser quit building them.
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: Mercruiser 470 valve clearances

not at all, what a pain in the rumpus.<br />but if and when they ran they were stout little beasts, about the time they got most the bugs out of them production ceased<br /> however I wont work on them anymore.
 
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Trent

Captain
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Nov 17, 2001
Messages
3,333
Re: Mercruiser 470 valve clearances

Wondering why Rodbolt does not work on this engine anymore... ? Its made money for alot of techs..!! :)
 
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DHPMARINE

Captain
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Dec 16, 2003
Messages
3,688
Re: Mercruiser 470 valve clearances

Trent, <br />(I'm certainly NOT speaking for rodbolt,just for me)<br />Making money is why we are in business.That's why I say support your local dealer.You may need him someday.But sometimes we have to draw a line in the dirt and not step across.<br /><br />Compare it to the newspaper machine on the corner.You can put in $.50,open the door and take ALL the papers.Blind man on the corner,put $.25 in the cup,and take ALL the pencils.<br /><br />Someone with a no win boat,even though I can make $$$$ working on it,he's still a no win,and I just can't do it.<br /><br />DHP
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: Mercruiser 470 valve clearances

Trent<br /> I am in the biddness to make money, I make more than most techs and there is a reason.<br /> not only am I good at what I do I have learned many hard and valuable lessons over the years.<br /> one of the lessons is to learn when the old salty beast is just no longer viable to have at your dealership.<br /> quite a number of the parts are NLA on that rig and others are outragously expensive.<br /> I turned away an 83 wellcraft a few months ago with twin 470's. a ten minute survey and some quick mental calculations came up with a repair bill of 7K or so and thats was just correcting obvious problems and catching up on some of the maint.<br /> boat was not worth it, if I touched it i would own it and anything that went wrong after that big a bill would be my fault.<br /> after 30 some odd years of dealing with machinery I can look at a boat and tell you if its a POS or a viable craft.<br /> I wont work on a POS. its not worth my time or reputation nor the dealers I contract for.<br /> I turned away a 27 albermarle last week with a pair of saltwater cooled 5.8L volvos. took me less than 20 min to rack up over 18K in repair work and I never got past just using a flashlight or starting either pile of rust.<br /> so thats mostly why I normally wont work on old stuff, not that I cant, I have made more money off that 3.7L than most techs. but its still an oddball open deck block design that parts are harder and harder to get.<br /> getting back to that 27.<br /> the guy was indignant that I would not touch it so I showed him why, time I was done I had about an hour of my time in it but told him if he took it away by the end of the week there would be no charge.<br /> that was about the best I could do for him.
 
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Rod Holder

Petty Officer 3rd Class
Joined
Jan 17, 2002
Messages
98
Re: Mercruiser 470 valve clearances

You will be well within the lash tollerance if you tighten the rocket nut while rotating the pushrod tube until you "feel" there is no longer gap between lifter and rocker arm. From there, if another 3/4 turn brings it to complete stop, you are locked and loaded. If it takes more than 3/4 turn, you can add shims between pedistal and rocker (Summit Racing) http://store.summitracing.com/partdetail.asp?part=CRN-99170-1&N=115+4294848747&autoview=sku <br />and if it takes less than 3/4 turns (which I doubt), you might need longer tubes.<br />Hope that helped.....RH
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: Mercruiser 470 valve clearances

mcwinfrey8<br /> you really need the tool. the rockers on that motor are 1.73 to 1 ratio so a little bit of valvestem installed height makes a difference on the other end. what your looking for is a lifter plunger preload of about .05"-.08".<br /> the bolt torque is 20 ft pounds, DO NOT use the turns down method. this valvetrain is a ford derivitave. the distance for tappet clearence with the lifter collapsed is .110 to .210"<br /> most will depend on the machist that cut the valves, I used one for years in Clebure TX that when you got the head back all the valvestems were the correct height and about equal within couple thousanths, another shop in Ft worth sent stuff back with 20-30 thousanths difference. there are 4 different pushrod lenths availible, your engine may have had any combination of them, thats why its a good idea to keep them marked., if you dont have the tool you can guess by measuring the distance from the plunger to the plunger retainer with the valve closed and the rocker bolt torqued. you will find that lifter is very difficult to collapse unless you remove and dissasemble and clean them as per the service manual.
 
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Rod Holder

Petty Officer 3rd Class
Joined
Jan 17, 2002
Messages
98
Re: Mercruiser 470 valve clearances

Good point, It would be a good idea to verify the tappet clearance after using the "turn down" method. I did on mine, and it was well within spec.<br /><br />If it is not, at least you know where you are at in regards adding shims or using different tubes.<br /><br />RH
 
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