SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: 90ultra21lx on July 25, 2017, 11:31:33 AM
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So after my BBC stock original 454 not running right we just did a compression test, #5 read at 87-90 and the rest were in between 110-120, so I'm told I need a valve job, my main question is is it not smart to just do a valve job and not rebuild the rest of the motor? It's a stock 454 and at this time I'm not trying to have anything other than reliable nice cruiser.. trying not to break bank but also don't want to regret not doing something when it was torn apart in 6 months... also ballpark what am I looking at for shop like very basic ballpark, $1k, 2k more? Less? Thanks guys I appreciate it very much
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The part that scares me-"I'm told I need a valve job"
With just a compression test. Was that dry or wet test?
I'd do a leak down on the suspect cylinders.
If it is just a couple of leaky valves, I'd just hand lap them in.
A pair of head gaskets and an intake set (summit 91 bux) valve grinding compound (summit $4.99, lol) and a weekend, Bam done.
Dan'l
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I should've been more descriptive sorry lol my buddy is a car mechanic for years we just did a dry test and now the shop I go to wants to do a wet test and leak down, and another test to isolate the problem before jumping into it. I guess I just figure it needs a valve job considering it's 27 years old and never been opened up? Is that not accurate statement?
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I should've been more descriptive sorry lol my buddy is a car mechanic for years we just did a dry test and now the shop I go to wants to do a wet test and leak down, and another test to isolate the problem before jumping into it. I guess I just figure it needs a valve job considering it's 27 years old and never been opened up? Is that not accurate statement?
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Those will help isolate whether it is leaking from top or bottom end. If you decide to do a valve job... while the heads are off, you can visually inspect the cylinders for wear beyond what the leak down and wet compression test shows... also can take a peek at cam and lifter wear... that way when you bolt the heads on, you know if there is anything else thatneedz to be addressed. As for a valve job... we get 240.00 for a complete valve job both heads (disassemble, clean, buff, magnaflux, check guides, check valve stems wear, grind valves, 3 angle grind seats, check and set valve stem heights, check valve springs pressures open and closed height, set valve spring install heights, and reassemble)... Plus 90.00 to surface and cc match both heads.
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A quick and easy test to help narrow in on the issue before you tear it down is to put some wd40 into the low compression cyclinder and see if the compression numbers temporarily jump up. If they do, its usually a sign of worn rings, If the compression numbers remain low than you can more than likely assume its a valve sealing issue and go from there.
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Well it's bad news, all bad news... took it to mechanic today did another compression test same #5 was low, so go to pull the valve cover off, then notice a crack going all the way thru the indomar exhaust manifold, after getting the valve cover off and he determined it does need a valve job, we find metal shavings in the oil... so it looks like bearings and all that goes with it will be getting done as well.. good news I'll have a like new motor lol. My question is do u guys think I'm not smart for telling them just leave it stock just make it like new again or should I add some mild things since they're in there? TBH I'm happy doing 55-60 top speed and cruising at 45-50 and knowing it starts every time and doesn't give me problems, it's my first boat and I got 2 young kids so not gonna have much opportunities to go much faster anyway... also anyone know where I can get a nice used set of water cooled exhaust manifolds? Also u guys would agree it's not good idea to weld n fix the cracked manifold right? Thanks in advance everyone!
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