Engine build advice needed please

Hi guys

I have a question, but first some background to answer the anticipated "why the hell would you want to do that?"

Greetings from Cape Town SA! We do have Jeeps here, including a number of well loved XJs (please see www.xjsociety.co.za for your personal edification). However they are not NEARLY as prolific as on your side of the 'pond'. So 2nd hand spares are not so easy either, and we have the inconvenience of our currency that devalues rather alarmingly.

OK, so I bought a really tidy 98 XJ with a stripped-with-some-bits-missing engine, and other parts, due to a dishonest mechanic. I now have all I need to put her together, except a motor.

I got all happy, because I can buy a 2003 TJ sub-assembly with 60k miles on from a friend for a really good price + my engine block which he wants as a spare for the 4.8 stroker motor he's built. But now having done my research here, I see that 2000+ TJ block into an XJ is a bad idea.

So here's my question - what about me stripping his sub, balancing everything, with new rings and bearings and refitting to MY 98 block, with my 98 head? I can then return his original block to him as a spare, and I have no issues with missing parts. Or did the internals also change and make that a dumb idea??

Please let me know what you think!!

Thanx and cheers

Steve

I would think his complete block with your head should be ok?

Unless I'm forgetting something, you should be able to throw your top end on his bottom end and be off and running.

Hi Cal

Thanx for your quick reply!

Well that was precisely my plan, but then I saw this thread:

www.naxja.org/forum/showthread.php?t=1101266&highlight=motor+swap

So I think I'm screwed. Even if I modify the block or mounts, I'm not exactly giving him an identical block for a spare, which is part of the deal :-(

Have you compared the mounts yourself visually?

Does your friend still have the internals that came out of his running motor when he built his 4.8L stroker?

The engine mounts won't work nor will most of the accessory mounts on the TJ block.

Your idea is sound, providing everything checks out. The one thing I would pay particular attention to is the pistons. I would keep your stock cam and lifters though.

Ok, so will the internal 2003TJ stock components all be compatable in my 1998XJ block?

I'd like to use its cam and lifters too, as the 98 cam is rusted and the lifters missing.

The cam from the TJ most likely won't work in the 1998 block. The TJ camshaft uses a retaining plate. The 98 doesn't. However, I would still check the 98 block because the holes may be already there (doubtful) or the wings at least and you can just drill and tap the holes. If the 1998 cam is rusted what do the lifter bores look like?

Thanks Talyn, that's the type of info I was looking for.

To be honest I haven't checked, that's a good point, thanx! The rust is very much surface, but I'm a bit anal when it comes to these things, so I'm not sure I want to use the cam like that, even if I clean it up, I'll be worried about the followers/cam surface degrading...(?)

Guess it's time for me to strip it down completely and check everything properly. (Our bandit mechanic bolted the some of the bits together to make it look like the rebuild was on track)

I wouldn't use a rusted cam either, but I would also be concerned about the block having rust.

Re: Engine build update

Hi Guys, I'm back with news - Talyn: spot on with the difference with the cams - no retainer on mine! Thanx!!

I stripped my motor at my friend's workshop over the weekend, with him available for advice. Seeing as folks send him their Ferraris from all over the country to sort out, and he's always been spot on with his advice, I seriously value his judgement. So the plan was to see what I've got and what I haven't and decide from there regarding the best way forward.

The good news is I have most of what I need, the big end caps I scratched out amongst piles of nuts and bolts in the rogue's workshop match my rods and the motor seems to be in pretty good nick, especially considering it has nearly 300 000km under its belt. The rust on the cam was more dirt than rust and it cleaned up perfectly, and the follower tubes are still fine.

Giorgio has sourced all the parts for me at his cost price, even the missing sprockets - he can get me a timing chain kit with everything in, all at an excellent price, so it looks like I'm gonna be rebuilding my motor!

One thing is bothering me though - what sort of wear / tolerance is acceptable on the valve guides??? Both Giorgio and I were convinced that the wear was excessive due to the sideways play on the valves. Yet the engineering shop is saying that the head is perfect, play is within specs.

If someone can help me with advice on this one I'd appreciate it immensely!

Cheers
Steve

0.001 to 0.003 in. is stock spec on the valve guide to stem clearance. Unless you have developed a feel for it (some machinists have and some think they have) you need some specialized measuring tools to check it.

You can check it indirectly though. Pull the valve about 3/8" off the seat. Use a dial indicator and set it against the valve margin and as inline with the valve stem as possible. Push the valve away from the dial indicator and while holding it 0 the indicator. Then pull the valve toward the indicator. Stem to guide clearance will be roughly 1/2" of the measurement on the dial indicator.

Thanx Talyn, that's the type of figure I thought they should be. I'm wayyyy off that, and don't need a dial guage to see it! There must be at least a mm side to side rock on the valves, which translate to 0.02 inch play, if my maths is right.

I see the head doesn't have loose guides. What's the best solution, to fit guides or other valves? Or both? The valves actually look great, except one which is bent - probably from lying around the workshop.

If the guides are that worn out it most likely has some other issues. You will need guides and a a valve job at least. The guides can't be replaces w/o doing a valve job.

I reckon the issue is probably the 300 000 km it's done, probably with minimal maintenance

my brother rebuilt this 4.0 earlier this year. not sure how much this can help ya but check this out

http://www.naxja.org/forum/showthread.php?t=1087751

I'm sure it will, thanks a mil!