this monday i will be speaking to a Jaguar engine rebuild specialist shop and i would like to gather some suggestions as to what to ask the proprietor concerning a 3.4l engine that they have already rebuilt and is for the most part, ready to go. IOW i'm expecting to replace, entirely the short block in my current 3.4l engine, if not the head too. i'm very familiar with the rebuild process as regards engines from the era. so i can speak intelligently (my assessment!) to them, generally, about their rebuilt engine, i think. ...just fearful i will leave something out.

questions i should ask concerning the rebuilding a head would also be helpful, as i may decide to have that done too.

thanks in advance for any and all insights.

 

Ask if the water ports on the head where the coolant flows from the block into the head are not all corroded away at the edges.
Some times it is possible to add aluminum and cut the edges back to speck _ this requires the head to be re-surfaced of course.
If the ports are really bad, then the rest of the aluminum on the inside is just as corroded, failure can happen around the valve seats.

Are the valve seats still serviceable ? Machinists will cut them too much so you can't find shims thin enough to get the correct valve clearance.
When this happens some material has to be ground off the end of the valve stem to get enough clearance _ this is a very bad practice. (you may ask my why later if you want)

A bad machinist will "deck" the head with out straightening it first, while this may seem OK, it still leaves the rest of the head warped.
This causes the camshaft to bind on its bore, and the cam covers not fitting properly _ the cam covers will always seep oil as no amount of tightening will correct this.

Are the lifter buckets lose, this is common if the car has been over heated badly ?

Lose valve guides and wear on them ?

All heads have to be pressure tested, even if the car wasn't using water, it's just a given.

There should be a work order as to what has been done, and everything should be documented.

 

thanks! i will ask them.

 

Have the sludge trap plugs been removed from the crankshaft and the sludge and solidified muck thoroughly flushed from the traps and oilways? To be sure he's actually done it, ask him how he removed the plugs. They are staked in place and total b...s to extract.

You need to read up on body language and look the rebuilder in the eye in the discussion. The fact is that if he's good, he's probably done everything well; and if he's not, he'll most likely respond yes to all the questions anyway.

Apologies for my total lack of faith in human nature.

 

apologies unnecessary, ...i've found that it's an unfortunate "occupational hazard" of the aging process.

 

Ensure the bores are correct for size, taper & ovality for your oversize pistons. I don't know what oversize you are boring to as the 3.4 can go up to 60 thou being un-sleeved. The 3.8 only 30 thou. though & you re-sleeve. The 3.8 has Brivadium sleeves.

 

yes, good idea, i hadn't thought of that. i'll ask.

 

Refresh page for edit.

 

There's a current thread that started with the crankshaft rear oil seal. Everything point in that is relevant from the seal to skimming the deck of the block with the (new) timing cover in place.

 

For performance and reliability, some of the key things I have had done on different heads for engines of many brands are: upgrade the intake/exhaust valves to larger sizes for performance, or at least upgrade to a more modern materials for valve seats (nickel/bronze, etc.) to run on newer fuels, and do either 3-angle, 4 angle, or full radius on the valves for better flow. For more power consider having the heat ported so that it provides smoother and better flow. For reliability look at better quality components (rockers, springs, valves, guides, etc.)

For the bottom end even for more stock/street for reliability as well as power see what the cost difference is if the engine was balanced and blue-printed where they take more care in the machining process, etc. Also look at better quality forged internals such as pistons, crank, and overall better quality parts, bearings, rings, etc. Any rebuild is a big expense and time for the job so try to stretch your budget on the internal quality of the parts and how it is rebuilt so it will last longer.

 

thank you for your assistance. i'll surely be asking about balancing. when i rebuilt my mga engine many years ago, having the crank, rods, pistons flywheel and clutch balanced made a world of difference. most noticeably, was how quickly the engine would rev.

 

What reputable machinist wouldn't balance an engine, isn't that a given, especially a long stroke engine from a Jag ?

 

Absolutely Jeff. My crank, flywheel & clutch assembly was way out of balance before we corrected.

 

The crank should be balanced by itself first, then the other parts. Which connecting rods to use? Many upgrade to the later series 3 XJ rods as they are stronger. But they are also I believe heavier. I'd stick with the early Le Mans winning rods with all their oilways unless I had the odd 2000 spondulix to splash on a set of lightweight H section.

 

My rods & pistons were weight matched.

We balanced crank & flywheel separately and then as a unit including clutch.

While videos of the plant balancing crankshafts looks impressive they did not do a very good job of it in reality. We re-balanced every crankshaft they sent to SA on top, new equipment for the era.

 

just got back from builder in idaho. they've worked up an estimate on rebuilt block and head using a contemporary block and its matching head from roughly the same time. ...same displacement too, 3.4l.

see new thread "...does this look reasonable..." for details.