328 engine rebuilt

Ditto for an acceleration test keep it at about 3000 rpm then floor it up to 6000 rpm if you get a puff of smoke that clears after initial acceleration then valve guides/ seals probably need attention

 

(1) the reason he had suggested that i should look at the bottom end as well is based on the fact that (a) he is taking the engine out anyway and it would be a waste of opportunity not to do it, and (b) he once replaced the o-ring in the car due to leakage of engine oil into the transmission and he suspect that i had been driving the car for a period with insufficient engine oil which might have caused damage/wear in the bottom-end, and since there's no external leakage since it must be burning oil
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Response
(a) once more, the engine does not have to come out to replace the valve guides, if that is the problem.
(b) What O-ring did he replace? If he suspects it's burning oil,
have a leak down test performed to find out where the problem is.
IMHO, get a second opinion from a shop that HAS worked on Ferraris before.
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(2) while he could measure the liners with only the top-end taken apart he would not be able to examine the rings in detail without taking the bottom end apart as well, and if its apart there's no reason not to put new rings in
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Response
A leak down test will reveal the condition of the rings in each cylinder.
And then with the heads off a visual inspection can be made to check for scoring, and the bore can be checked for compliance.
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(3) he will rebore the liners but only if there's significant damage. honing all cylinder liners would only serve to increase the diametre of the cylinders and that's not a good thing generally speaking and may cause further leakage unless bigger rings are put in
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Response
If the liners are out of compliance, remember...
The 328 engine uses cylinder liners that are nikasil coated.
If they are bored, then they must have the nikasil coating re-applied,
and you will also be purchasing new pistons to fit the new cylinder bore.
The alternative is to purchase new cylinder liners.
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(4) while he hasn't done a rebuild on a 328 engine he's done countless rebuilts on porche engines (used to be a proche mechanic) and the work/skill required is the same, and he needs no special "ferrari tools" to rehone the liners if the bottom end is taken apart
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Response
The nikasil coating on the cylinder liners is very hard,
and proper honing gear must be used.

Please do yourself a very big favor,
Find a shop that HAS worked on Ferraris before!

 

If you look for new cylinder liners and pistons your price for a rebuild will sky rocket!!

I will say it again, measure each liner top/ bottom with heads off in X and Y planes.

If you have a broken ring the liner will be scored more than likely and wear will be visible.

My engine with 73K still had the cross hatching from the original honing in 1979 visible.

There was less than 50% of the accepted tollerence in wear on all cylinders.

Most bottom ends give out between 120K and 150K, you have to ask youself with 40K on the car how many miles a year do you intend to do a year?

Do a PROPER leakdown test,before stripping, by someone who knows how to do one (It is difficult!!,), do it with a hot engine. That will tell you if you have any bottom end ring issues, valve seating issues.

Measure it up and see what the wear is like if there is no scoring and wear is well within tollerance I would leave it alone, unless you have more money than you need.

And definitely get yourself someone who has worked on these engines before

 

If the engine is otherwise running fine, I was just buy a case of oil and check it after each drive. Oil is cheap.

 

Power unlikely to increase significantly unless you have a major leak. Which with those compressions is unlikely.

FYI my car 308 has between 158 and 168 PSI with 73 K miles on it, and having taken the heads off I know that the valve guides were well worn so I probably had one or two sticking valves.

Unless you plan to drive like a deamon and race you won't notice this on day to day driving.

You can see how well seated the valves are by a compression test only - by checking how fast the pressure builds up in each of the cylinders does it take 1,3,5 or 10 turn overs for the cylinder to max on pressure?, the more revolutions of the engine it takes the more likely you have a sticking valve or bottom end wear issue, a good guide for closer inspections, particularly on any cylinder that is slow to build pressure.

 

I agree with the comments above, sounds like you have a good bottom end on the engine and probably the valve seats are good also (but I would still lap them in with grinding paste to get a perfect seating). So you are likely to just need the valve stem seals replaced to cure the oil consumption. I know it is possible to replace these on some cars by pressurising the cylinders to prevent the valves dropping and then pull off the valve spring and seals, that way you don't even need to remove the heads. I don't know if that is possible on this engine ? I suspect not enough room for the front bank. The mechanics comments about damaging the bottom end due to running with low oil makes no sense at all. If the engine is starved of oil, the pressure drops and the oil warning light comes on, the amount of oil in the sump is completely irrelevant so long as you always have oil pressure.

 

IMHO, your next step is to find another shop and have a leak down test performed.

 

I have just about finished my top end rebuild on my 308gt4 76k on the clock. I did a compression test which was showing a health engine. But I was still getting backfire through the carbs (re set all carbs) no oil lost though. So I did a leakdown test which confirmed that all was not well in the valve area. Took the engine out and heads off found that the valve guides had wear in them. Looked at liners and measure them same as Tom still had original engineers marks in bores and no wear also looked at main bearings etc no wear (If it is not broken don't fix it) so rebuilt the heads. Valve guides are tha same as VW and the valve shims are Volvo and used cosworth valve stem oil seals(teflon lined) I would just rebuld the heads if everything else looks Ok. Get the leakdown test done. Do bear in mind that the head gaskets are stupidly expensive. These engines are very tough normally and can take alot of abuse but they need to be used and don't like being stood. I didn't use mine for a year and this is the reason why the valve stem seals were knackered.

 

IMHO, you have put the cart before the horse by ordering a complete gasket set before you know what the problem is.

The leak down test would have pinpointed where your problem was,
and told you where your oil was going.
You are throwing money away by completely rebuilding the top end of your engine without knowing if it is something as simple as valve seals.

A gasket set for the 328 engine does not usually come with valve guides and seals, so If it were me, I would double check what is included in the kit.

Good Luck!