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Rb26 Compression With Poncams Type-B

andre_gtr

By andre_gtr,
in Engines & Forced Induction

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andre_gtr Contributor

andre_gtr

Posted
Posted

Hi Guys

testing compression on my rebuilt motor returns about 100psi across all 6, so my question is is this normal with these cams and have others experienced the same numbers

I have checked some guys having the same results but didnt find too many

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SiR_RB
SiR_RB

Idling for 30mins? I was told start up check for leaks then go for a drive with varying loads Minimize idling during run in

GTSBoy
GTSBoy

It's actually funny how the old and sensible instruction to avoid idling a newly built engine coupled with the old and sensible advice to run the engine through a variety of loads and speeds (but not

Sinista32 Grand Master

Sinista32

Posted
Posted (edited)

did you drop the oil and see excess of fuel in oil ? (fuel running down the side of the cylinders)

A loose build i.e. large clearances. or even rings. Who did the build and how was it fired up / run in

100psi is far to low for a fresh rebuild.

Edit:

Not to cause concern, more to make you even more wary and check it out thoroughly.

I run Type B's not that that has much to do with it.

After my first build it was around 85 because the builder had made a mistake which caused a catastrophic failure.

one of the symptoms before the failure was fuel in the oil.

2nd build by CRD and is around 170 across the lot.

Have you tried 2 different gauges when measuring

Edited by Sinista32
andre_gtr Contributor

andre_gtr

Posted
  • Author
Posted

I did the rebuild evrything was in spec initial startup was with normal mineral oil idling for about 30 min

I then drained the oil and started driving but the conditions was a bit rich and battled with tuning then after another 200km i drained the oil that was also smelling of fuel

some new oil now and smelling of fuel again after 150k

its still stock bore with stock pistons and new rings bores was honed before assembly for bedding

Sinista32 Grand Master

Sinista32

Posted
Posted

I wouldn't call fooked just yet. The boys on here are pretty good.

It maybe a case of pulling it out if your in doubt of any of the work.

You rebuilt with all stock internals.

Were the rings put on factory spec / positioning and double checked ?

Piggaz Grand Master

Piggaz

Posted
Posted

Sitting there idling doesn't do anything for ring seal. Got to get the gases in behind the rings to push them against the bore otherwise they're just "going for the ride".

http://www.mototuneusa.com/break_in_secrets.htm

Give that a read.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

^^^ What he said. It may be too late but give it a shot anyway. Drop the synthetic oil if that's what you've got and put mineral oil in. Do not labour the engine but give it plenty of welly - up to 6000 and button off and repeat. Watch for overheating and leaks and if ok continue for half an hour - then retest.

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