Stock Engine Swap-in. Having Issues

[Sid_RallyX_82]

Is this the manifold I'm looking for?
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[Sid_RallyX_82]

I posted a wtb add in the For Sale section for a B6 exhaust manifold, if anyone in this section has any info

[FestYboy]

Well, I say use the T gauge for the mere fact that the bearings may be over sized, creating a stacked tolerance and throwing your measurements off.

Remember: just because it's new doesn't make it good.

[Sid_RallyX_82]

Sorry, I should have said nominal diameter... That where a dial caliper and T gauge come into play. Just another way to verify plastigauge.

I can check my book for Nominal thickness. Prob not gonna bother using a T gauge on the bearings. If the gap is too big, it doesn't change anything to measure it another way. If anything, if I did something wrong, the gap would most like read too small, right?

[ryanprins13]

That's some BS. What if the dyno is feeling particularly generous that day and throws all the cars that run at the limit over? They just DQ the whole lot and say tough luck???

How else would you do it?

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[FestYboy]

Sorry, I should have said nominal diameter... That where a dial caliper and T gauge come into play. Just another way to verify plastigauge.

[Sid_RallyX_82]

My other book says Main Journal bearing clearance should be "0.0007- 0.0014 (0.018- 0.036mm)"
Also says Service Limit is "0.0039 (0.100mm)"
I'm using plastigauge, not T gauge. It reads between 0.002- 0.003in (0.051- 0.076mm)
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[FestYboy]

I have a sneaking suspicion that my machine shop polished 0.002" out of the main journals and then ordered stock bearings...

If they polished that much out, they should have gone further to step into the next size bearing. What's the journal nominal clearance vs. actual? What's the T gauge read with the bearings torqued in?

[FestYboy]

BINGO!
Therein lies the rub! It's not uncomon in an SCCA Majors race for the top20 Spec Miata finishers to come off track and be lined up at a portable dyno to be tested, over 130hp all three of three pulls and you are DQ.
It took some experimentation to enter values in the presets of the Mustang dyno to get equivalent results. Obviously there are no guarantees, too many variables! This was SCCA's solution to rampant cheating in that class. Pretty sad for an "Ivy League Club"

That's some BS. What if the dyno is feeling particularly generous that day and throws all the cars that run at the limit over? They just DQ the whole lot and say tough luck???

[Sid_RallyX_82]

I have a sneaking suspicion that my machine shop polished 0.002" out of the main journals and then ordered stock bearings...

[Sid_RallyX_82]

Main bearing gaps are wider than the spec in my book. Says they should be "0.024-0.042mm (0.0009- 0.00017 in)" [must be a type-o, because 0.042mm = ~0.0017in]. My plastigauge reads consistently between 0.051- 0.076mm (0.002- 0.003in). I applied assembly lube, spun the crank, wiped off lube, applied plastigauge, and torqued to spec. Is this usable? Or should I go back and get tighter bearings?

[Dragonhealer]

Wait, you have a HP limit!?! Unless all engines are run on the same dyno, and with the same operator, how can they regulate the output?

BINGO!
Therein lies the rub! It's not uncomon in an SCCA Majors race for the top20 Spec Miata finishers to come off track and be lined up at a portable dyno to be tested, over 130hp all three of three pulls and you are DQ.
It took some experimentation to enter values in the presets of the Mustang dyno to get equivalent results. Obviously there are no guarantees, too many variables! This was SCCA's solution to rampant cheating in that class. Pretty sad for an "Ivy League Club"

[FestYboy]

Wait, you have a HP limit!?! Unless all engines are run on the same dyno, and with the same operator, how can they regulate the output?

[Dragonhealer]

Best break-in for these engines in my experience is moderate throttling, stop and go city driving, don't lug it, and don't rev over 5000 for the first 2K miles.
Our spec class engine builds (totally stock) go in the DD cars of certain wives to run errands for 6 months before they go in a race car and off to the dyno for final tune/adjust. These tend to make 4 more horse power than class allows, so we detune slightly.

[Dragonhealer]

I see no reason to spend money on fancy oils for regular engines, walfart cheap supertec 10W30, a quality oil filter is key, buy the Mazda, Motorcraft or Wix (someone mentioned the NAPA Gold is a Wix).
change every 3K miles or 4 months, whichever comes first.
I don't recomend Synthetic oil untill rings are seated and bearings are heat cycled enough to be fully hardened, could be 5k to 35K, depends on what parts are used.