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Had the engine apart to replace a head gasket. This is a 1987 Mercruiser (Chevy) 350 w/ Thunderbolt IV electronic ignition (yes it has electronic advance). Also replaced spark plugs with same plug number, but an updated (looked a bit different), AC Delco MR43T.

Put it back together as per SELOC manual
-> adjusted valve lash by tightening until play was gone in the pushrod (couldn't rotate the rod by hand), then tightened another 3/4 turn
-> set timing to 8* BTDC with engine idling (as per spec). Tach on the dash read around 500rpm, but difficult to read. I adjusted the idle as far down as it would go w/o the engine stalling, then set timing.

Took it out on the water, and it started making a clicking noise around 3000rpm. Retarded the timing (without a light) and it got better, but started clicking around 3500rpm. Continued to retard timing until clicking was gone completely. Haven't had a chance to check what it is with a timing light. My guess is it's now around 4* BTDC.

Runs around 4000-4100rpm...max power is 4600rpm.

I'm not too familiar with what spark-knocking or bad valve lash sounds like, but if I had to guess what bad valve lash sounds like this is it.

Maybe the valves only make noise at high power and retarding the timing is just stealing power but not really fixing the problem??
 

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I would go thru that valve adjustment one more time just to be sure but they usually make noise at no load and low rpm. I use the method I found at centuryperformance.com . Hyd lifters are a bit tricky until you get a feel for them. I never get them right the first time. Spin the pushrod with your fingers until you feel a resistance then crank the rocker down to spec. In other words not really tight. If you get them to tight you are actually compressing the plunger in the lifter and could have valves that wont close when the lifter has oil pressure with the engine running.
Timing marks are not always accurate either. The pointer can be easily bent and the outer part of the balancer can creep because its rubber mounted.
Hope this helps
 

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Horsepower Junkie
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When you adjust your vavles adjust the intake valve when you see the exh. valve just start to open. Do the exhaust when the intake valve has gone past full open and is about 2/3 of the way closed.

Frank
 

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It sound like you might have your valves to tight not turn push rods means with light pressure with your finger tips. and the go 3/4 of a turn this set the plunger in the lifter where it need to be. I think you might be too tight just hope it wasn't enough to hit a piston and bend a valve good luck and keep us posted
 

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Horsepower Junkie
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Also check your timing to by reving around 3k. Verify you have your initial + what you module put's in. A V8-24 module put's in 24deg on top of you initial. So if your initial is 8 then you should have 32deg timing total with a v8-24 module.
 

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not sure how much ambient (ie open exhaust, etc...) noise you're dealing with, but if a lot and it is hard to tell on clicking, could be a slight exhaust manifold leak... can sound like ticking sometimes... I once didn't get the manifold on one side torked doen all the way and had a small leak that sounded for the life of me like lifter / valve noise... felt like an idiot once I figured it out!
 

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Heck, I would adjust it with the motor running. Thats how I do them. Easy as pie. Start motor and back off on each nut until it clatters, then tighten till it stops. After that go to the next one. Once done turn all of them 1/4-1/2 turn . Dont rev it when the valve covers are off. Kinda gets messy.

I once had a set of trick flow heads and boy they loved to chatter at high RPM and timing. Found out 29* total was what they liked and they were quiet. I am guessing you have 217 cast heads so thats not an issue. I run the same heads and an initial of 12* and a 22* module on 87 octane and have no problems.
 
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