Engine guru rebuild question

[xtinc]

Hi,

I'm in the process of rebuilding my motor, an L26 block and early E88 head. I purchased the block from a guy who gave up on his Z project, it had been rebuilt by a reputable shop, bored .030, polished crank, and balanced. I noticed the spec sheet indicated the deck had been shaved, but didn't indicate exactly how much. I'm assuming very minimal to clean the deck surface. The E88 came off my L24, I wasn't the original owner so not sure of previous head work, but the machine shop also shaved a very nominal amount to clean up head surface, timing components are new. I installed the timing set with everything at TDC, lined up the bright links with timing marks using the #1 setting, the timing notch lined up perfect with the cam plate. Now for the question. No matter what adjustment I make to the tension side guide, I cannot get the tensioner to pop out any less then 3/16". According to the manual tensioner should sit flush against tensioner housing. Is this due to the deck and head being shaved? and is this acceptable?

[Bambikiller240]

I'm no "engine guru" by any means, but I have assembled a few L24 engines.

Which manual are you refering to? I ask because I assembled my engines by following the How to Rebuild Book, and the Factory Service Manual and don't remember that statement. (not that it couldn't be there, I just don't remember it)

Have you counted the # of links between the timing marks on the gears? If everything is as it should be in terms of assembly, I think your next step is to have the head measured to see how much has been milled off of it, and same with the engine. You may have to shim the cam towers to compensate for the head milling. I do not know what you would do about the block milling, but if too much eas milled from the block you may have clearance issues with the valves and piston heads. Someone sells real thick metal headgaskets ($$$ Pricey) that may be needed to compensate for block milling.

*most shops around here will stamp the head with the amount of milling done so the owner and next machine shop will know what has been done previously.

BTW, our member "Phred" is an "Engine Guru", you may want to talk with him.

[xtinc]

I also used the How to Rebuild book, on page 131 it says "adjust so there is no clearance between the backside of the tensioner shoe and housing". I did count and verify proper link count between cam and crank timing marks, I also checked piston to valve clearance and it's good. Thanks for the reply an I'll try contacting Phred

[Bambikiller240]

Yeah, something isn't right. I remember that I had just barely enough slack in the chain to get the tensioner bolts started with the shoe fully compressed. Of course my block and head had not been milled at all. With as much gap at the tensioner as you have, you should also check the wipe pattern of the cam on the rocker arms per the Rebuild book to ensure that the cam is not running off the rocker pad.

Let us know what Phred has to say and the outcome of your project. This is the kind of stuff that can help other members down the road with similar issues.

[Phred]

Xtinc,

The gap between the plunger and body of the tensioner on your engine is not unusual if it has had the deck surfaces machined. To determine how much the head has been cut is easy. A stock L-series head is 4.250 thick, ( from cyl. deck to cam deck.) You must use a digital caliper or micrometer to measure it, then you'll know how much its been cut. Its harder to measure the block height when its assembled, and I can't remember off the top of my head how tall the stock block is anyway. Be carefull when (if) installing cam tower shims on an engine which has a used cam and rockers in it. The cam/rocker contact patch will change, and will require different thickness lash pads to realign the contact area. If you have the same cam/rockers as were used prior to your rebuild, and they are both stock, I would run it as is. The only other very minor consequence will be a slight increase in the wear on the bottom of the tensioner rubber, as the chain won't run smoothly againt the face of the rubber for the first few hundred miles. This will not degrade performance or engine life.

The only other problem I see from your picture is I don't see any washers under the heads of those bolts holding the tensioner or chain guides. Washers are important here, as they distribute the tporque load. Its not unusual to find broken chain guides in improperly assembled engines. Use a flat and a new lock washer on these parts, or just a flat washer with locktite and 7 ft. lbs. (or 84 in. lbs.) of torque.

[xtinc]

Phred,

Thanks for the info and peace of mind. The chain guides and tensioner do have flat washers installed, but I'm going to take your advice to locktite and retorque.

Tom