A warning about cams and shims

[22Silver]

A short story, then a note on cams and shims.

There once was a pinhole in a radiator hose, which only leaked under temp/pressure. This leak was spraying onto something hot, so the engine would heat up, start spraying coolant, and boiled it slowly away, leaving no trace of a leak. Naturally I would fill the fluid every week, until one time I think the hole grew and boiled the radiator in a single drive on a 44degree day!

So, she overheated so hard that the rings went soft, supposedly.

After that, my oil burned away pretty quickly (I used to check it once a month) and not a week later I threw a bearing!

Took the car to my uncle, a mechanic with his own garage out in the countryside, and got to work. Replaced all but the head + block + pistons, and reground the cams. Balanced the engine, and did a few little tweaks here and there. Obviously I replaced the shims with thicker ones to accommodate the smaller cam size, but I was getting an issue where the cams were tipping the shims, forcing me to opt away from shim on top of bucket lifters, and get some bucket OVER shim lifters, to prevent the shims from rattling and possibly getting flicked off the lifter.

I found some online, but a guy at the place that did my cams recommended a professional "shim guy". Long story short this guy was an "expert" and could apparently grind the lip off the lifter, harden the new surface, and machine some suitable under bucket shims.

Not only did he take about 3 weeks off, starting 2 days after he received the shims (after telling me it would take 7 days to complete), he then proceeded to send me shims of the wrong diameter as a 'test fit'. We ordered the shims in the correct size, and then waited about a month to receive 15 shims of various (mostly wrong) sizes. Having 16 valves and only 15 shims was a bit of an issue. Once we finally got the correct amount of shims, it turned out that several of them were the wrong width, by quite a few thou. People order shims with measurements accurate to a thousandth of an inch and these had to be machined down AGAIN (by someone closer by and more competent).

Long story short, a job that was supposed to take a week and a bit to finish took from April 15th until June 20th to complete. I wont name and shame, but if anyone is considering a cam regrind, be aware that you MAY need new lifters. If you do KNOW somehow that you will need new lifters, the cost of billet cams may be justifyble once you factor in new shims + regrind vs billet cams and stock lifters.
Also be aware that machining and re-hardening the original lifters can save you time and money (as opposed to ordering from the USA) but be aware that you could also end up with 3 incorrect sets of shims, and 2 and a bit months of wasted time.


On a side note, I've been told not to take the car over 4000RPM for 1000kms, and to change the oil and filter at 1000kms as well. Does that sound about right?
Is there anything else that a fresh engine rebuild should be cared for?

[davekmoore]

4,000 is sensible on a new motor, but don't do a continuous 4,000. Vary it, while avoiding full throttle. 1,000 seems a little soon for an oil change.

I empathise with the learning curve imposed upon you by "experts". Some of them need to either better communicate and believe in the extent of their knowledge, or to learn more, or to accept and pay the consequences of their own mistakes, or burn in hell. Rant over, but if you read some of my posts about my rebuild, you'll know why I feel this way.

[JBT]

There once was a pinhole in a radiator hose, which only leaked under temp/pressure. This leak was spraying onto something hot, so the engine would heat up, start spraying coolant, and boiled it slowly away, leaving no trace of a leak. Naturally I would fill the fluid every week, until one time I think the hole grew and boiled the radiator in a single drive on a 44degree day!

As a caution to others - if you have to keep topping up the coolant in a modern car with expansion tank etc. then get a leak check done to find the problem. It just may prevent things getting to the engine destruction stage.

On a side note, I've been told not to take the car over 4000RPM for 1000kms, and to change the oil and filter at 1000kms as well. Does that sound about right?
Is there anything else that a fresh engine rebuild should be cared for?

Do not use constant revs as per Dave's note and also make sure you do not "labour" the engine.

[Vat]

Vary it, while avoiding full throttle.

Very much this, especially in lower gears.

[22Silver]

Very much appreciated, thanks for the tips!

[sailaholic]

Yes do the 1000km oil change. It's to get rid of any metal particles missed during engine assembly.


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[Lokiel]

4,000 is sensible on a new motor, but don't do a continuous 4,000. Vary it, while avoiding full throttle. 1,000 seems a little soon for an oil change.
:

This is what MX5 Plus advised me when I had my engine rebuilt and they stressed to ensure that I exhausted the 0-4,000rpm rev-range and NOT to drive it like Miss Daisy the whole time to ensure that the rings seated properly.

Note: You should use a heavier oil to run your engine in, typically a mineral oil, so changing your oil after 1,000km is a good idea since the engine will have been run-in by then and you can use your preferred oil.

[lizard]

[quote=

Note: You should use a heavier oil to run your engine in, typically a mineral oil, so changing your oil after 1,000km is a good idea since the engine will have been run-in by then and you can use your preferred oil.

Heavier than what 10 30 ?? and why NOT synthetic ??

[NitroDann]

During the wear in process the engine needs to WEAR in.

There is practically no wear with synthetic which is the point of it.

Dann

[project.r.racing]

This is why when people tell you the option you are looking at is sh*t. You read and listen. I remember you suggesting this avenue for your lifters.

I wonder if you spent the $200 of new solid lifters and $5.50 each on the subs, that you would've told this horror story.

and just to refresh ones memory:-

Change of plan. We're machining the lip off the bucket, hardening it supposedly, and then machining an internal shim for each bucket.

sounds sh*t...

viewtopic.php?f=29&t=63060&p=790910#p790910

The warning should be. Do it once, do it properly.

[22Silver]

I do recall project.r.
However I had already ordered the shims and buckets to be machined, under the advice of an actual mechanic.
After that post I was wary, but the quality of his work was superb. He's just a slowpoke with a void skull and no sense of timeliness.

As for what oil is in the engine, I have absolutely no idea! My mechanic uncle did it all for me. I would assume he knows not to put synth oil in, as long as that is common knowledge and standard procedure. I'm taking it back to him in a few days (after the 1000km) so he can do the oil, possibly oil filter(?) and recheck all the hoses and seals and make sure it sounds fine (there's a little more mechanical tappy noise now, I assume it's because of the aggressive cam grind but I figure I'll get him to have a listen anyway).

I'm going to design, build and install a light that tells me when either oil or coolant is hinting at getting low so I never have to spend this much money on my car again.

[greenMachine]

I'm going to design, build and install a light that tells me when either oil or coolant is hinting at getting low so I never have to spend this much money on my car again.

Makes sense.

Much better option than boring old 'pop the bonnet, check the oil, check the water, shut the bonnet', that is sooo last century.

[Mr Morlock]

you should have left the camshafts alone - apart from the mis diagnosis of why you were adding water ( as JBTaptly pointed out) which apparently did a lot of damage you certainly do not need to dream up systems of checking water and oil -you cannot be serious surely. Engines regularly do 250,000 KM with a need only to make periodical checks. Many owners only make a check service to service. If the uncle is the mechanic and does work on the car why not ask him for advice.