Even more 454 problems

Well I'm back... if anyone recalls I have a 454 that had eaten up some lifters. It's a PCM 454 in a 1988 Supra Saltare ski boat.

I pulled the engine and have it completely disassembled. I haven't found any evidence of oil starvation, and all of the cylinders and valves LOOK good. How can I test the valves? Do I need to just assume that the heads need to go to the machine shop before re-installation?

I didn't find any milky oil in the pan, and there is no evidence of oil starvation anywhere in the engine. This brings me back to the original problem... what caused the lifters to fail? I have received a recommendation from comp cams on a cam that they recommend ... another question is whether i need the whole kit they sell (Camshaft, Lifters, Matched Valve Springs, Valve Spring Retainers, Valve Locks, Valve Stem Seals, Timing Chain Set, Assembly Lube) or whether I can just get by with lifters + cam?

Since I have the engine out and disassembled I'm going to do the bearings on the bottom end, but I have no idea how -- does anyone have a web page or a write-up that explains the procedure?

Thanks for any help.

Rob

Reply to
Robert C. Bosworth
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Your local library usually has the engine rebuilding books, even specific to that marine engine.

Cheap manuals like Haynes have all the specs and clearances and torque settings at least. They are pretty good for a beginner. The Chiltons assumes you know a bunch.

For the bottom end, you need to plasti-gauge it to see if it needs touching first. Basically you can buy the gauge at auto supply shops. It is a plastic rod that you stick between the bearing and the crankshaft. You remove a main and a rod bearing cap and stick the rod in, then you tighten the bearing cap back on with a torque wrench. Then open it and see how flat the gauge got. They come with a chart so, so flat means it has so much clearance. If that clearance is within specs and the bearings look nice, you leave them alone.

Otherwise you need the book to see where the over and under sizes are stamped on the engine. Usually around the oil filter. You then need to look for marks on the crank and on the back of the bearing shells to see what size they are. Bearings can be over and under sized and if the engine was played with already, that crank is likely already at it's limit. Then things start getting expensive.

If everything looks pretty and the gap is a bit big according to the plasti gauge, you can sometimes get away with just putting new bearing shells in at the same size that came out or .0001 or 2 or something like that oversized if the plastigauge allows.

Good luck!

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"Robert C. Bosworth" wrote:

Reply to
Mike Romain

oil starvation would wipe the lifters. The question is what? I think the BBC uses splash oiling from the heads to oil the lobes like a SBC does. If so, do you have plugged drainback holes in the heads?

You need the cam and lifters. The lifters don't have to be comp, but they need to be new. You really should put in new springs to go with the new cam - same thing - they don't need to be comp, but you need to match the specs (pressure) or you might get valve float - my buddy's Nova felt like it picked up 50hp at 5000 rpm with new springs vs the stock springs - they were too weak for the new cam - his stock cam and stock springs were only designed for 4000... you also run the risk of coil bind if the new cam is bigger than the old one. IOW, get the springs.

FWIW, the price of the kit is usually cheaper than buying it all separately. The only thing you don't really need is the timing chain, but you should probably put a new chain in anyway, so I'd probably do it.

I just did bearings on a SBC 307 for my dirt car, and I have one piece of advice - get a ridge reamer and a ring compressor and pull the pistons. It's a real PITA reinstalling the crank with the rods in the way. And if you've gone that far, a set of rings is cheap insurance you won't have to do it again...

And you cannot be too clean. Consider spending the $30 or whatever it costs to get the block hot tanked. It's much nicer than scraping off layer after layer of pennzoil frosting. The stuff on my 307 took multiple attempts to get through with a pressure washer. It needs to be spotless inside (especially inside) and out - you don't want crud in your new bearings, do you?

I'd also recommend taking your oil pump and replacing it with a high volume one with a welded on pickup.

And yes, at this point you've pretty much rebuilt the whole thing. It can be done, but take it slow, clean everything, and measure everything. Or pay a pro and farm it out. 20+ hours to disassemble, clean, measure and reassemble is probably a low #...

Ray

Reply to
ray

It is always a good idea to have them checked for guide wear, reseat them and install new seals.

You will have to look at the specs on you stock springs, etc. IIRC, the stock springs in the BBC are a bit on the iffy side in a hard working stocker. If the new cam has more lift or the duration makes for more aggressive acceleration ramps, then valve float and damage can be a real problem. My experiance with CompCams is that they will not steer you wrong with a particular cam. It may be that they have a less aggressive cam that will allow you to use more of the stock components. My experience with boats is that if 300HP is good enough for a ski boat, then 400HP will be better and 500HP is very satisfying - until you can afford more. That is where their recommendations come in - to keep you from going past the point of reliability with good performance. If the BBC marine setup is like some of the automotive engines I've replaced cams in, you are in for one pleasant surprise when you push the throttle up the first time even with a mild cam upgrade.

That would be wise if you go forth with the cam setup. You are going to need an engine stand so you can roll 'er over. You are going to need a good torque wrench and a shop manual for the BBC. It's not a real toughie since you are going to have the front end off if you install a new cam. One of the most important things to do while you are working in this engine with the cam out is to check and maybe replace the cam bearings since you have the cam & lifter problem. That is a job for an automotive machine shop. It may be that your engine actually needs very little other than a new cam, lifters and push rods. A new set of rod and main bearings is no big deal since you have it down. Just make sure there is no evidence of crank journal grooving or oil starvation. If that has happened, you are in for a total rebuild. A new oil pump would also be a prudent and inexpensive insurance replacement right now just in case the problem was a sticky pressure plunger. Be sure you get the oil pump properly oriented when you install it so the distributor is where it should be. We used to drop the pan on our short track Chevies every 2 weeks just to replace the bearings if nothing else. At 9K RPM, they needed to be good.

Lugnut

Reply to
lugnut

Reply to
Shep

Ray --

Thanks for the reply. I think I'm just going to continue with the disassembly. I've got plenty of room and time to work, and have the engine on a stand and stripped down to just the short-block. The cylinders are fresh enough that there isn't really a ridge at the top and there is still cross-hatching visible on the cylinder walls. Regardless, I might strip it and just have the block boiled for good measure.

Tonight I'm going to go out and see if I can find a manual. Are valves something you can do yourself or is it work for a machine shop?

I'll start looking for a new oil pump.

Thanks,

Rob

Reply to
Robert C. Bosworth

drainback

springs - they

disassemble,

Valve jobs are DIY ~IF~ you have a set of valve guide tools to replace the guides (if needed) Then a valve seat grinder to re-cut the seats in the heads. Then you need a valve face grinder to cut the seat on the valve itself and possible true up the tips of the stems. Then a lapping tool to lap the new valves into the new seats. So if you have those tools go ahead. If not then send them to a machine shop.

Sounds like you may as well do a complete rebuild since you have it apart. Have the block hot tanked AND have new cam bearings installed. That will clean out the iron filings left behind from the cam failure.

You wondered about that failure. A camshaft is not really a hard to damage item. It only has a hardened surface that is about 3-4 thousands thick. Under that is just cast iron. The base of a lifter is a hardened piece of cast steel. All it takes is a small piece of crud to block an oil passage and score that lifter base, OR a lifter that stops rotating on the cam. (They rotate to equalize wear on the cam/lifter) Either one will damage that hardened area and then it is only a matter of time. Usually not long though. Doesn't take any other failure to do it.

As for the Comp Cams kit. I would use the entire kit to eliminate possible problems with mix and match parts, ESPECIALLY if you don't have a lot of experience rebuilding engines.

Reply to
Steve W.

You can change the valves yourself with a valve spring compressor, but to measure the valve guides for wear and replacing them - I'd go with a machine shop. (You can do it at home if you have the right tools and specs, but I brought my heads in to have them checked when I broke one of the rocker studs and they found the valve guides had been installed too high (and all over the place for height) so they cut them down.)

Call a machine shop and talk heads with them - they might be able to give you a good deal on disassembly, hot tanking, checking and reassembly. When I did my first set of springs it probably took about 2 hours to do both heads - it's slow going to dismantle, clean, inspect and reassemble x 16.

My quick and dirty test for valve guide wear - with the spring off, how much lateral play is in the valve if you wiggle the stem? I dunno what the spec is, but if you can hear it or feel it "click" then you need new valve guides. There should be almost no side-play in the guide. Then, if you pop the valve out, the seat area shouldn't be burnt or warped or anything - there should be a nice clean area about 1/16" of an inch.

See

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While you're going this far, if you have a die grinder, now is the perfect time to clean up casting flash in the ports... don't go too crazy, just a little polishing. :)

Ray

Reply to
ray

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