Head-ache

[pdsman53]

Hi guys,
After doing a compression test on my trackday, unmodified, naturally aspirated 180,000km BP4W engine, I found that cylinders 2/3 (135/140 cold) are 25% down on cylinders 1/2 (170/180 cold).
There is no obvious white/blue/black(green/yellow/purple) smoke on start-up/idle/running.
No bubbles or oil in the coolant.
No coolant in the oil.

A subsequent Leakdown test indicated some Inlet/Exhaust Valve leakage (and that I need a hearing test)....so I removed the Head over the weekend.
The Head gasket looked in good condition and no obvious burn marks between 2/3.
No obvious issues like broken valves/springs.
No obvious valve/seat damage.
I checked valve clearances on 2/3...only a couple of thou over OEM specified.

Firstly......Can anyone (with a track MX5) recommend a machinist in Brookvale/North side, to do a Head skim and confirm my Valve Train operation/fears??
Secondly...without doing a squish check!!...is it safe to skim 0.020" when using a 0.040" MLS head gasket??
(assuming it's never been skimmed previously. I haven't measured with a dial indicator yet, but the pistons are slightly above the deck at TDC...does anyone know what the OEM specified deck to top of piston distance should be???...or do I have to do the squish??
Thirdly.....does anyone have a spare BP05-12-240 inlet Camshaft, or a suitable EXHIN...that they no longer require??

Thanks,
Jim

[StanTheMan]

there is a machinist in south creek road. will refuse to do anything that's not withing factory tolerance.

I also us a guy in North Gosford for those things that require non factory specs. or go past factory specs.
he did my head , cams , valves & replaced some valve guides on a BP-4W head. its been going hard for about 10k km since just before Christmas.

[pdsman53]

Thanks Stan,
Initially I'm just looking for a Head skim and Valve Train Check.

Was it "CDA" Engine Reconditioning?
Unit 3/169 South Creek Rd Dee Why (Just near Cromer High School)?
Did you get anything done by him?
If so, were you happy with the job?
Did anyone recommend him to you in the first instance?...were they happy with his work?

Or did you decide against him and went to Gosford instead?
Was that "GEM" Engine Reconditioning?

Just on my queries...what are your thoughts?
Cheers,
Jim

[StanTheMan]

Thanks Stan,
Initially I'm just looking for a Head skim and Valve Train Check.

Was it "CDA" Engine Reconditioning?
Unit 3/169 South Creek Rd Dee Why (Just near Cromer High School)?
Did you get anything done by him?
If so, were you happy with the job?
Did anyone recommend him to you in the first instance?...were they happy with his work?

Or did you decide against him and went to Gosford instead?
Was that "GEM" Engine Reconditioning?

Just on my queries...what are your thoughts?
Cheers,
Jim

Yea that was him. I had my head B6 head shaved by him. it was just head shave. I wanted more taken off but he only brought it down to what he thought was max. without talking to me. he just did it. t5old me after that he doesn't do anything below factory specs and took my money.

The job was fine. Just didn't get the compression I wanted.

I decided against him because I wanted a hero head shave and knew the Dee Why guy wasn't going to do.
The guy in Gosford was recommended to me on Facebook. I used to race Mx5's a while back. He took his time but that wasn't an issue with me.

The Gosford Guy has had this particular BP-4W head twice and did the work I wanted. Suggested other stuff but couldn't get the parts during Covid.He will talk to you and communicate. I have absolutely no issues with his work.I alsdo like the way he communicates. He also welded up some damage on the head sustained when some valves got bent. & bits broke off & damaged the combustion chamber

[StanTheMan]

since you have your head out ..... pour some turps down the chambers & see which valves leak. at least you know if they leak.

The Gosford guy will do a standard rebuild of your head which includes re-seating all your valves. Im sure the Dee why Guy has also got a standard price for that.

[StanTheMan]

why would you backwards on the cams? get your current BP4W cams reground to something aggressive if your class you race in allows. Your ECU will probably cope with the certain amount of change if its the OEM ECU. Cost of regrinding cams is less than new billet cams and you will need to re space your cam followers regardless. especially if your valves will need re seating

I ran 272 Duration cams on Factory ECU for a little while , yes it looses urgency with the OEM ECU but its very drivable.
the 272 were around 229@0.50 & about 9mm lift. If you go higher with the lift you need to clear the lifter guides for the cam lobes. you need clearance 0.2mm for the oil not to be stripped off the lobes when you're at high rpm.,


Your Min Cylinder head Height (factory Spec)is between 133.8-134.0 mm. again if the class you're race in allows modification. Ive gone way past that myself. Cant recall how far. (mine is a street car)
With the thin head gasket, check you piston protrusion over the deck .a lot of B6 motors have that. not so much the BP's I had issues on my B6 with that. When the engine warmed up the pistons hit the head over 3000 rpm. I think you need at least 0.2 mm clearance. I don't recall exactly factory spec ,. I suggest you ask you machinist.


so my specs are
lighten flywheel
some clutch which was ,meant for turbo
crane cams: lobe 108 232@0.50 10.4mm lift
Volvo Valve valve springs
BP-ZE block with BP-4W head with approx 11.0: 1 compression (maybe even close to 11.5:1)
port matched square top intake
2.25 inch dual exsaust
Mania intake
Ms2PnP


and if your going to do any of that. don't skimp out on cheap cam sprockets. LOL

Camgear is toast.jpg

[pdsman53]

Hi Stan,
Have you Dynoed your current version?

Thanks...the deck height dims should help confirm if mine is stock.
I was just going to...eyes closed and get a skim 0.020"....assuming stock.

I haven't measured yet, but the crown on my pistons protrude above the block...I assume, no more than the OEM 0.040" gasket thickness.
Maybe I need to do a 'squish' test to confirm clearances.

ooops...I meant BP5A (not BP05, as I wrote).

I'm aiming to stick with the simplest low level budget mod (but a useful one)....that's why I'm thinking about the BP5A Intake valve "drop-in swap".
https://supermiata.com/mazdaspeed-miata-intake-cam.aspx

I haven't been able to source a BP5A-12-240 in OZ.
I could get one from Supermiata (for $497AUD incl. shipping from the US)....not really low budget and the shipping time factor.

That's why I started thinking about the EXHIN mod....using the BP4W-12-440.
but it's a little more fiddly than the BP5A.

So if you know anyone on the Forum, or in OZ, that can point me in the direction to either...it would be appreciated.

Cheers,
Jim

[StanTheMan]

It got Dynoed yesterday at Mania.

115kw at wheel.... which is nothing to write home about when you read the American get around 130rw KWso I'm thinking my tune might be able to get more since Ive tuned it myself at home.
torque curve is 154NM at 5600 and stays there until 7300 when it drops just slightly

My afr's are quite out as well. running at around 11:1 from around 3500-6000 rpm but are on 12 from about 6500-7500


having said all that, the car still give me an incredible grin from ear to ear driving it. LOL I get so much joy.
so in a lot of ways its totally irrelevant

[PaulF]

It seems pretty widely agreed that American dynos produce bigger numbers than Aussie ones for the same real world power, so you're probably not as far off the mark as you think.

[StanTheMan]

so our horses are actually stronger than theirs? LOL

[pdsman53]

Thanks guys,

So...does anyone know where/who might be able to direct me to either:-

1...an 'SE' inlet camshaft (BP5A-12-240).

2...a BP4W Exhaust camshaft (BP4W-12-440).

Thanks,
Jim

[pdsman53]

Hi guys,
For those looking for an Engine Reco machinist on the Northern Beaches of Sydney....I went to "Peninsula Engine Reconditioners", in Sydenham Rd Brookvale....Phil and Daniel run the place...they usually reco performance engines, but were happy look over mine and provided me with their opinion on what needed to be done.
My self diagnosis Leak-down indicated probable Valves Train issues....but was never convinced, due to limited air compressor pressure.
'Peninsular' found that the Valve Spring Rates were down around 25-30 psi (Spec is 60), and the Valves/Seats were badly worn....so he sorted those and skimmed the Head. While he was waiting for the Springs, I did some basic Inlet/Exhaust Porting....my tools didn't reach down the Runners, so I got 'Peninsula' to finish it.
While he was working on the Head, I decided to pull the Block/Gearbox to confirm a probable Rear Main Seal/Sump Joint leak.
Since I had the Block out, I decided to check the bottom end pistons/bearings/rings...end play/ring gaps etc. Mostly were just 'outside' Mazda Spec., but well within Maximum allowances...some slight scuffing on Pistons, minimal wear on Bearings etc...but decided to get 'Peninsular' to confirm.
The Cylinder Bores were Tapered, again just outside Specs, but well within the maximum allowable....'Peninsular' managed to Hone the taper out and minimise the skim. Whilst the Bearings were in acceptable condition, but borderline on clearances...he suggested that I renew anyway.
I picked up some ACL 'H' series bearings on Friday and over the weekend, started the long journey back.
So hopefully it should be pushing out the high 190's compression, once again.
I am fitting a Skidnation coolant reroute as well....just for insurance.

I purchased:-
1....a "Felpro" full gasket (street) set...which came with an 'MLS' Head Gasket.
2....a set of 'Permaseal' (torque-to-yield) Headbolts.

Note: Reality Check.
It's just a refreshed naturally aspirated, 'stock' BP4W engine...road registered for getting to 6-8 Dual Entry Trackdays/year (50%/50%).

My Query:
Will the basic 'Felpro' (street) MLS Head gasket, (that arrived in the VRS kit from US) suffice??? (considering the limited number of 7-800 laps/year and the Block and Head have been skimmed and a new Coolant Reroute upgrade fitted).
....or do I:-
A....bite another circa $200 bullet in favour of a 'Cometic' H.G.?
then....if I do that, should I then:-
B....bite another circa $280 bullet and fit 'APR' Headbolts??....but I'm hoping not to remove the head again, unless absolutely necessary.
C....your advice on the use of "hylomar" spray on the Head Gasket, to minimise the water ingress on initial cold start up/first heat cycle??
D....I am leaning toward using Demin water only for the initial start-up Heat cycles (and then introduce Redline's 'Water Wetter' and eventually some anti-freeze for those few days in the country, that see overnight below zero temps.
E....for the run-in, I've heard that Mineral Oil is preferred...II was thinking Gulf Western 10w-30 with Redline's break-in additive, for say 500kms?? then filter/oil change to Penrite racing 10/10ths 10w-40??

One more thing...after fitting the new rings and bearings, including Thrust bearings...I checked the crankshaft endplay and it was 0.011" (nearly the upper limit on specs)...I should have ordered +0.005" to tighten it up, but was hoping that the new ones would bring me back to mid-spec (around 0.007-8").
I'm reluctant to break it back down again, wait for new thrusts to arrive and re-do what has already been done...considering that it is within spec and I haven't had any previous crank noise issues.

Your experienced thoughts would be appreciated.
Thanks in advance,
Jim

[pdsman53]

Hi guys,
I had a hiccup in my assembly, after the Rings and Bearings install.
I bought Permaseal Headbolts through Repco's online vehicle specific search engine.
The search engine gave me one option for my vehicle, so I purchased them.
During my assembly of the skimmed Head/new Felpro Gasket.

Bolts were torqued 30/40/50 ft lb, to Mazda's sequence...a loud bang...like a gunshot.

"I must have broken a headbolt"...surely not, I didn't even get to the Spec Torque 56-60 ft lb.

I backed the bolts back out, in sequence...the offending bolt was still whole, but it had stripped the thread out of the block.

Back to the Repco website, for a check....the same Permaseal bolts were nominated.

I rummaged around and found my old headbolts....122mm long.
The Permaseal Bolt was 107mm long.

I sent a claim in to Repco...they checked their system, then Permaseal and to their credit accepted liability...paid for the Bolts and the Thread repair.

Since then, I've assembled everything and am ready for the restart...just awaiting break-in oil.

My Query is:-
1...when I assembled the Oil Pump, I smeared it with some Vaseline...but I'm not sure if I used enough for it to Prime the Oil Pump.
I've read that you can remove the Oil Sensor beside the Filter and pump oil through the system...that's OK if you have the gear.

What method have you used for Oil Priming on your engine rebuild....'prestart' procedure, to confirm the Pump is primed and ready for the 1st Crank???

Thanks,
Jim

[greenMachine]

Geeze Jim, in my books 'bang' =/= stripped thread, that is a newie for me. Glad to hear that it is fixed though.

On your question, I smear the bearings with oil on assembly, and then spin the motor over with the starter motor plugs out. I would also prime it through the relief valve hole, that would be more accessible and is directly feeding the OP. Once the oil pressure shows it is pretty well good to go.

Never heard of using vaseline before, but it is petroleum based so should be ok. Just don't use it on your condoms though.

[PaulF]

Good lesson to be learned for all of us in that head bolt story. Normally the parts catalogues are pretty good for MX5s (unlike my RS Clio for which almost every "OEM replacement" part is wrong) but always good to check.

Did you end up getting a correct set of Permaseal bolts or did you have to get a different brand?