20 replies to this topic

[73TORANA!]

Hi all, I am seeking some constructive thoughts to an issue I have with my red 202. In brief here is the engine specs.

Bore +60, ACL race series pistons rings and bearings. 1.5 thou big ends and 2 thou mains, starfire rods, XU1 cam (485 speco), top secret head hehe and a blue crank thats been knife edged ( mistake I know ), oh and cam bearing clearance 1.5 thou. Tripple stromberg carbs. Oil HPR30.

The problem I have was originally I had a red 202 crank when first rebuilt and ran with out issue for 500 km or so then its first real blast the engine vibrated badly between 5-6k rpm, second blast it went flat. Long story short cam bearing 2 and 3 picked up and turned. 

Take 2, same thing happened and again only after a boot full. Oil pressure when hot 20psi @idle, 40@ 1500 and 60 @ 4k rpm.

Take 3, Knife edge blue motor crank ( see pix, green paint is primer) and made sure this time the cam bearing were broached? Previuosly requested as it seems maybe block twist with vibration at hi rpm may be the cause?????? vibration at 5-6k abot 70% better than red crank but still shook, hence mistake with knife edgeing ? miss guided info :( But this time it did not go flat and felt strong so I put up with the vib as I was happy with the rest of the engine and assumed the cam bearing issue was fixed.

About 10,000 odd km of spirited driving a slight knock only when hot could be heard @ idle ( 900rpm ) from about #1-2 area, oil pressure still the same as above. Slowly over time the erratic knock had become worse, just off idle it disappeared and no other sign to indicate a bearing issue. Engine perfect when cold and for about the first half hour. Knock is erratic like once every 3 to 4 revolutions or so. Suspected cam gear; changed and checked everything I could with engine in car but still the same. It did not have the typical symptoms of worn bearings. 

I had enough. Pulled the engine out; all crank bearings checked with plasti gauge and were that close to the above figures and bearings look sweet so the knock still a mystery.

#2 cam bearing had picked up only very slightly but did not turn, who knows when that happened but it still span freely with no restriction and oil hole not blocked. Crank spins very freely in block, minimal friction. 

So my main question here; is block twist an issue here with the cam bearings ? or just not enough cam bearing clearance for a hotty. Any one else had this problem ?

Is vibration the cause? as the motor had same clearances with the red crack that shook the rear vision mirror but it only lasted 2 boot fulls of right foot.

Getting rid of the knife edge crank and getting a race prep crank from Aus crank to get rid of the vibe

Any thoughts Ideas appreciated as I dont want to have this happen with the next build. $$$$$

Cheers.

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[warrenm]

What harmonic balancer?

What weight flywheel?

[73TORANA!]

Hi Warrenm,

Fly wheel is a steel Yella terra and the balancer is a B&M 4.1 kgs. I did forget to mention #5 cylinder has had a re sleeve and JP/crow cams helical timing gears.

thx.

[LC-GTR-1969]

Hi Warrenm,

Fly wheel is a steel Yella terra and the balancer is a B&M 4.1 kgs. I did forget to mention #5 cylinder has had a re sleeve and JP/crow cams helical timing gears.

thx.

 

Funny you say B&M balancer... I had a very similar knock to the one you described... turned out the B&M 4.1kg balancer flogged out the keyway so it had a bees dick of play over the crank snout, which was causing the knock at idle.

 

As you say you pulled the engine down and the bearings were all good (the last time), perhaps inspect for movement of the balancer- this has nothing to do with your previous issue of picking up bearings but it may give some answer as to your last 'mystery' knock.

[73TORANA!]

Funny you say B&M balancer... I had a very similar knock to the one you described... turned out the B&M 4.1kg balancer flogged out the keyway so it had a bees dick of play over the crank snout, which was causing the knock at idle.

 

As you say you pulled the engine down and the bearings were all good (the last time), perhaps inspect for movement of the balancer- this has nothing to do with your previous issue of picking up bearings but it may give some answer as to your last 'mystery' knock.

 

Thanks LC, I had a real close look this arvo and cant really see any witness marks on the snout to suggest any movement although the balancer has been off numerous times on this and my old engine over the years; the key way is tighter if I put it on backwards by hand so you may be onto something. Just hard to confirm.

Did you only get the knock when hot? as mentioned its erratic like knock knock...........knock....knock knock........knock.

Was your balancer hard to pull off or did it come off the crank easy.? Mine is requires a bit of effort to remove. 

I also had a good look at the multi key way crank gear. Any one had any issues with these walking around or JP gears in general

Any recommendations on a good balancer.

Cheers.

[73TORANA!]

Thanks Grant,

When I fitted the Cut back/knife edge crank( pix above ) a few years back and had crank, flywheel and balancer done together and had the rod weights matched.

You say knife edge, do you mean counter weight leading edge machined while leaving most of the counter weight or cut back knife edge like mine? Ive heard both styles called the same.

I did drop the timing back while playing around but to no avail.

The cam is a std XU1 grind with 428 lift, 308 valves with about 220 lbs spring pressure at full cam lift.

Shes no Bathurst winner but on the dyno; 286ft lbs tq and 185rwhp.

 

Cam bearings with the red crank only failed after a heap of right foot which is why I though of twist but as its not a big hi po motor it seems maybe bearings too tight or off center as you say.

Time for a different block ???

[73TORANA!]

Yep was kinda thinking the same as its no big HP donk and thousands of reds have been built and raced without these issues..... massive sigh....... start again with a different machinist im thinking

[S pack]

Cam bearings with the red crank only failed after a heap of right foot which is why I though of twist but as its not a big hi po motor it seems maybe bearings too tight or off center as you say.

Time for a different block ???

Makes you wonder if they even bothered to line ream the new cam bearings.

[73TORANA!]

G'day S pack,

Yeah I was suspicious of that so when the knife crank was fitted I made sure it was done and when the motor was pulled to investigate the clunk an inspection of the cam bearings showed #2 had ever so slightly picked up some time during the 10-15000km so maybe not enough broaching. Incidentally I could only get a 1.5 thou feeler between cam and bearing, not the right way to measure but did not have correct tool will get machinist to check.

 

Might have an answer to clunk. will post shortly.

Edited by 73TORANA!, 26 September 2017 - 07:54 PM.

[73TORANA!]

Thx to the suggestion by LC-GTR re the balancer I revisited the snout area; I had an old std balancer that had sloppy key way, pushing on a little by hand and rotating back and forth I could simulate a similar type clunk and funly enough the clunk appeared to be coming from #2-3 area. 

I had a more thorough inspection where the multi key way gear sits and it appeared to be only contacting about 10% of its potential seating area by the witness marks on the gear and snout. Next I checked my trusty old 186 and its gear showed a footprint of about 90% on gear and snout. Same JP gear set all be it 20 years older.

The key on the knife crank looks good but the gear maybe moving on the crank; see pix, I cant measure anything but taking a pix through a magnify glass then zooming in it does look like some movement is evident ?? Gears have 9 thou backlash, may be the hi rpm vibe along with the back lash has worked the gear. Am I dreaming ? Both crank snouts measured up the same.

 

Any thoughts ? Has anyone had any or know of any issues with multi key crank gears

 

First pic is the old 186; 2nd and 3 rd are the 202 crank and gear

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[warrenm]

You are using a 4kg balancer, correct? Does the crank have a retaining bolt in the balancer end? If not, the balancer may have moved slightly allowing the gear & balancer to flog on the crank snout, I have seen heavy balancers move because it wasn't tight enough fit on the snout, but the snout or the balancer usually is galled. The marks on the gear look about normal, it is an interference fit. 

[LC-GTR-1969]

Thanks LC, I had a real close look this arvo and cant really see any witness marks on the snout to suggest any movement although the balancer has been off numerous times on this and my old engine over the years; the key way is tighter if I put it on backwards by hand so you may be onto something. Just hard to confirm.
Did you only get the knock when hot? as mentioned its erratic like knock knock...........knock....knock knock........knock.
Was your balancer hard to pull off or did it come off the crank easy.? Mine is requires a bit of effort to remove.
I also had a good look at the multi key way crank gear. Any one had any issues with these walking around or JP gears in general
Any recommendations on a good balancer.
Cheers.

Yes my damaged HB was hard like normal to get off.. i tested the flogged out balancer by puting it on to home position than cranking over the HB forward and backward and you could feel some slight movement (without moving the crank). Because the HB has a long keyway it was only damaged on keyway in home position.. hence it feels tight in all other positions other than home.

When diagnosing the knock it sounded like a bottom end knock.. with my stethoscope it deadset sounded like number 3 main. The knock was resonating along the crank like a bell. Sometimes all is not what it seams!

Nonetheless this may not be the source of your mystery noise but it might be worth looking into, especially if your bearings look ok.

[73TORANA!]

Yes my damaged HB was hard like normal to get off.. i tested the flogged out balancer by puting it on to home position than cranking over the HB forward and backward and you could feel some slight movement (without moving the crank). Because the HB has a long keyway it was only damaged on keyway in home position.. hence it feels tight in all other positions other than home.

When diagnosing the knock it sounded like a bottom end knock.. with my stethoscope it deadset sounded like number 3 main. The knock was resonating along the crank like a bell. Sometimes all is not what it seams!

Nonetheless this may not be the source of your mystery noise but it might be worth looking into, especially if your bearings look ok.

Mate thats exactly what it sound like; everyone that heard it said main bearing and yeh #3, but it had no other bearing symptoms and they look brand new with 1.5 thou clearance across all 6. Thanks you so much LC for your input, most helpfull ,  Visually the key and key way look fine but I will replace the key and sus the key slot in the balancer and try to measure it up. Will refit to crank and investigate, might be hard as engine now on a stand. Oh and will tap a thread in the snout. I am toying with the idea of getting rid of the knife edge crank in favour of a normal blue black crank from crankshaft re builders ( Aus crank ) only reason in an attempt to stop the vib at 6k rpm.... any thoughts. 

 

Cheers and thx again 

[LC-GTR-1969]

Dont thank me yet mate I could be barking up the wrong tree.. to be honest, as Warren said, you would typically see some galling on the crank snout if the balancer has been moving.. plus you shoukd be abke to feel the play when the HB is in the home position...

Good luck mate

[73TORANA!]

Hey LC,

I put the HB and timing gear back on the crank and locked the crank up as its in the engine stand but no sign of movement so fitted 2 bolts to the HB ( for turn / leverage purposes) and heated the HB, block and crank. Now I could get a very slight movement if I used a crow bar between the 2 bolts applying fwd , backward rotations. every thing was hot too touch. Thinking back when I could here the knock, if I turned engine off and re started only 3 mins or so later the knock was gone and would slowly come back, heat soak? But I recon I have the same issue as you had and it was more noticeable after I changed the cam gears and put it all back together.

[73TORANA!]

Gave the bottom end a freshen up, new crank and  bearings etc new cam gears, same cam with refaced lifters, cam bearing measured all good. Had block line bored to bring cam gear  tooth clearance back into spec and a new romac HB bolted on, new slugs, the lot. Engine has never been this smooth and feels and sounds really nice until it gets hot then the dreaded knock came back. WTF. Oil press 25 -30 @ 900rpm hot   50 @2500 hot and 60+ @ 6k rpm

Cam end float was 4 thou, too much, not enough ? within spec. Only things didnt change was Fuel pump, Dizzy and oil pump oh and the cam it self but all these were in really good nick. Over it. The valve spring are quite heavy and maybe causing cam end float chatter ???? 

 

Time for a 2JZ GTE hehehe 

Edited by 73TORANA!, 10 April 2018 - 02:12 PM.

[warrenm]

.004" is ok for cam end float.

[hip6]

If they're hyd lifters,they could be bleeding down once they're properly warm making the noise you're describing...for reals.

[Torana 202]

Have experienced what Hip6 described with hydraulic lifters and heavy valve springs.

 

Not my car :