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Engine is "even" but not "smooth" ?? 

 

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 Post subject: Engine is "even" but not "smooth" ??
Posted: Sat Apr 30, 2011 9:54 am 
Getting Side Ways
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Location: FNQ
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I recently did the head gasket on my EF. It hadn't actually blown or overheated or anything nasty - my reason for doing the gasket was that the coolant had gone black, temp was going a bit higher than it normally does and coolant level was gradually dropping with no signs of external leakage. Oil was clean etc. so I figured maybe a cylinder was blowing thru to the coolant but it hadn't started coming back the other way. Mechanix had looked it over and reckoned they couldn't find evidence of a head leak in spite of the coolant being black and full of shi t.

When I pulled the head, it was hard to spot anything for sure but the head surface between no. 6 bore and the coolant passages didn't look real healthy.

Anyhow, with my chinese Dremel tool knock off I took the opportunity to tidy up the ports - ie. smooth the curves where there were edges from factory milling and take out bad dags etc. In the inlet ports I removed the absolute minimum of material and apart from rounding and smoothing shapes plus removing any big bad blobs inside the runners, I did no "polishing" in the intake ports. In the exhaust ports I found quite a bad mismatch between the lower part of the six ports from casting alignment so did a lot of work to make all six match as well as possible to the best one. What I mean is that two of the exhaust throats had nice low small radius but the others were very much higher - so I made all six as close to the shape of the best of the good two as I could (hopefully left enough meat between the ports and coolant passages! ). The "roofs" didn't seem to have the same dislocation problem. I also smoothed the exhaust ports right thru as well as I could - tho I didn't get it to a polished finish. The exhaust guide bosses looked like they could benefit from being tapered but I didn't have the gear for heavy material removal and had used up my patience spending about 10 hours straight doing the throats so just satisfied myself with rounding the ends of them so they weren't flat shelves around the guides - and I put small channels where they met the port walls.

The cylinders were all holding good compression and she was running sweet before so I didn't get the valves and seats done by the workshop (they asked $380 to do it! ) - I just got the head surface milled the bare minimum for serviceable fit. I did beadblast the whole head when I cleaned it - including the seats - so I gave the valves a light hand grind / lap with paste and a stick - they all came up with good contact bands in the right places and stictioned nicely when completely clean and lighty wiped with WD40. After dry assembly all the valves held their seal against metho no worries but of course I didn't actually vacuum check them.

I fitted Crow performance springs (130lb I think they are) with new collets - and the cam I've had in the engine is a regrind and been working ok with 2.9mm of extra shimming, but clicking a bit on cold start - so I've put it all back together with 3.4mm shims (ie. in addition to the single original factory "shim"). The cam I think must have something like 500 thou or so of lift. I measured all the spring seat to retainer heights to ensure they were all ok before fitting the springs - they were all spot on - and of course I fitted new guide seals.

The headgasket I used is a MLS style one from Shiftkits (Durapro) - so there's been the theoretical comression increase.

Back together and it fired up no worries. On the road it's going great - no lifter or chain noises or anything else untoward - power is terrific - with off idle response very noticeably improved - gotta be real careful cornering - and it revs out to 5500 fine (keep in mind the exhaust is stock as a rock 2.25 press bent factory from manifolds to tailpipe!! ). Haven't tried it yet but I suspect it would lite up no sweat going straight off the line with a tiny bit of stalling - damned close to just doing it straight up. It doesn't pull as hard above 3000 as I'd really like, but I put that down to the std exhaust. Temperature is lower than it used to run before unless it's made to work at higher revs for a while - again restricted exhaust probably partly to blame.

The thing that has me puzzled is that the engine runs "evenly" - especially considering the cam - but it's not "smooth".

Hard to describe what I mean - but initially I thought it was a vibration - which I've steered away from as I've realised it matches the exhaust note. As I said, it runs very "evenly" with just the occasional "bobble" - very decent for the size of the cam - the exhaust note tho isn't the normal "burble" - but is rather a DEEP and sharp edged "growl" - almost like very thick fabric tearing. Blipping the throttle in neutral causes instantaneous and fast revving - it's sort of like one of those top fuel dragcars - and as I say, on the road it's very lively. This growl is there right thru the rev range on the road and you can "feel" it thru the whole car - tho it's not worse at higher revs - if anything it goes from most to least as the revs go up and in general decreases with load. It sort of sounds and feels ALL the time like some jap engines do when you get them spinning above 4000rpm or so and they start to really growl and feel tough and you feel that growl thru the car - if that makes sense?

What I'm wondering is whether this is just normal for an engine with hard springs, big cam and good compression (it's theoretically higher than std but shouldn't be what could be called "high" ) - or whether there might be some underlying problem?? Guys with "heavily worked" engines might be able to shed some light maybe? Is it in fact a sign of cra p valve sealing or something like that??

Next up I'm going to do the exhaust - ie. put a Berklee or Redback cat back system on - but not doing the cat or extractors just yet - and I might replace the factory hydraulic engine mounts with EL ones. That won't all be for maybe a couple of months tho.

 

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96 EF Auto GLi - Bilstein Shocks - Adjustable Front sway bar - JMM Cam - TI Perf J3 - TCI 2500/3000 stall converter. 2015 Jeep Cherokee Trailhawk.

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 Post subject: Re: Engine is "even" but not "smooth" ??
Posted: Sat Apr 30, 2011 10:24 am 
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Ride: ford falcon au3 xr8

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the only thing that catches my attention is the thicknes of the shims your using??

depending on who the cam is from? but most regrinds usually have an extra 1.9mm shim only.
your hla,s may be at the point of maximum preload causing a minor sealing problem at rpm, which could also explane a slight lack of top end power and the odd exhaust sound???
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 Post subject: Re: Engine is "even" but not "smooth" ??
Posted: Sat Apr 30, 2011 1:40 pm 
Getting Side Ways
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Good point...

This is the cam I've had in my ED for something like 10 years with one 1.9mm factory shim PLUS one 1mm washer in each rocker in addition to the original factory shim (factory + 2.9mm total). I'd found that the extra factory shim alone definitely wasn't enough and extra 0.5 didn't quite do it - but 1.0mm worked (I had been told by JMM it would need 1mm washer as well as an extra factory shim already but tried just the extra factory shim and then 0.5mm washer just for chuckles).

That was in a new factory EF XR6 head in the ED.

I pulled the cam and entire rocker gear out of the ED and dropped it all into the EF about a year ago and it's all been running fine except for some rattling almost always on cold start and very occasionally on hot start - so I figured going to an extra 0.5mm worth a try (ie. factory + 3.4mm total).

But indeed I didn't take measurements as such - just made sure I had some clearance on no. 1 inlet rocker roller at TDC with flat lifter - which it did - I'd guesstimate it was in the order of at least 1mm (originally was thinking 35 thou but it was way more than that - there was plenty of movement at the lifter end). It all rattled it's a*** off for the first 30 seconds or so and took a few minutes until they were all quiet.

If the valves were riding slightly would it cause what I've described?? - I hadn't even considered something so basic and major because I assumed it would run really badly from get go...

Has anyone had experience with slightly overadjusting solid lifter engines? - ie. what the result is.

 

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96 EF Auto GLi - Bilstein Shocks - Adjustable Front sway bar - JMM Cam - TI Perf J3 - TCI 2500/3000 stall converter. 2015 Jeep Cherokee Trailhawk.

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 Post subject: Re: Engine is "even" but not "smooth" ??
Posted: Tue May 03, 2011 8:50 am 
Getting Side Ways
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Age: 50

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Location: FNQ
QLD, Australia

To be honest I had a little play with the chambers so am really actually trying to eliminate whether this "growling" is normal for an engine with big cam + slightly pumped compression or whether it's down to what I did to the chambers (which is uniformly the same for all six) or simply something like a bad valve job - but it would mean they're ALL bad I think - but surely it'd be making worse power? - and be idling bad? Same for tight lifters?. . Really wishing I'd got the valves done by the workshop now. Other concern is that the valve job IS crap but being masked by good effects from my chamber work.

Overall it runs better and more powerfully than it did before - when I say it could be better above 3000 - I mean that it's still very decent but not spinning up as QUICKLY in HIGHER revs as say an AU XR6 (power/torque is huge - pulls as hard up a hill as straight - and KILLS the XR6 below 4000 even for acceleration rate) - but again that's with stock factory exhaust - the press bends look to go down to about 1.5 inches! What I'm concerned about is the oddness of this "growl" that's right thru it now.

The "growl" is there right from idle thru to 5500 - slighly less at higher revs than lower in the range - and indeed feels almost exactly like many Jap engines do when you get up them and they develop that snarl/growl as they pull power at revs - I'm feeling it with heavy throttle above 3500rpm in the Terios I'm driving at work at the moment - it's EXACTLY the same thing. It's not a BAD sound or sensation by any means - in fact it's quite reminiscent of an "english sports car" - but it's very DIFFERENT from how the engine felt and sounded before I did the head.

I'm away from home for work until late in the month - meantime my wife has been driving it (it's normally my work car) and reckons it's going good - she refuses to use Power mode as she says it's dangerous because the car "gets away from her". Keep in mind it's running an EF XR6 ECU so power mode probably actually does something (as in the shift strategy is probably more aggressive than std power mode) - tho the difference between power and Economy has never been so noticeable before. During the time from when I got it all back together and had to fly out (a week) I wasn't game to really give it a hard time - but by the time I get back it should have all settled in etc. so I can really give it a good try out - ie. rev it to limit cut in each gear etc. Also I'll do comp checks, fit a 2.5 exhaust + maybe a fresh set of AU injectors - and possibly EL engine mounts - maybe try putting the lifter shims back to how they were as well just for elimination - and take it from there. I'm shy of putting it on a dyno but might even try that.

In the final analysis as long as it's performing good I guess there's no need to be panicking.

 

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96 EF Auto GLi - Bilstein Shocks - Adjustable Front sway bar - JMM Cam - TI Perf J3 - TCI 2500/3000 stall converter. 2015 Jeep Cherokee Trailhawk.

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