Antone: Interesting idea. The cams were okay when I originally had that head on the car, though (it's the head that the car had when I originally bought it). Although saying that, I would have no idea what the ignition timing setting was set at. I think I posted some images of the cam lobes earlier - must go back and have a look. The thing is, retarded ignition timing greatly reduces the noise... so you'd think that this rules out any mechanical wear related cause. Keith: Yeah, retarding the dizzy to a certain point reduces the noise quite a lot, but you can still just hear it when booting it up a motorway or something at high revs. Disconnecting the vacuum pipe then eliminates it completely because it's no longer advancing at the high revs.
Right, after about seven or eight months I'm just getting round to putting a nice ABF into this car. I can't believe it has been so long. The car has actually done about 8,000 miles with the engine like this without getting any better or worse, but with the ignition retarded so that the noise doesn't occur (and, of course, the car drives like a 1.3). Because the head on the engine is a newly rebuilt head, I need to determine whether the rattle is a fault with that, or the block. When I visited Stealth, vince said that an engine stripdown is in order because it's definitely a mechanical rattle, not pinking. He could not determine where it was coming from though. Before I remove the engine, can anyone suggest any more tests I can do to try and determine the source of the rattle? Now, remembering that retarding the ignition lessens the rattle, I hoped that I could isolate the fault to a single cylinder by running the engine with one HT lead unplugged. I set the timing to a more normal setting (so that the engine would definitely rattle) and disconnected / reconnected each HT lead in sequence. When blipping the throttle hard (ensuring 3000ish RPM), the rattle still occurred briefly (just after releasing the throttle) no matter which HT lead was disabled. If the problem was a dead bearing on one of the cylinders, and given that the rattle seems to be timing / load related, then I would have thought that disconnecting one of the leads would have eliminated the rattle. Given this finding, could the problem be down to a common component, e.g. camshaft...? I don't think the head has done enough miles to have worn cam lobes, but maybe oil starvation has knackered a cam bearing and this results in a rattle under load and normal ignition timings...? Maybe I can use Plastigauge to determine this. Let's say I really wanted to be sure that it's the rebuilt head... reckon I could get away with re-using the head bolts and gasket just for the purpose of briefly trying a different old head on the engine...?
Just because you arent getting a compression stroke on one cylinder, doesnt mean the parts arent moving though Trev. Anything related to the parts in question moving, compression or not, id have thought would yield the same results?? (ie the rattle) With reference to re-using the head bolts, as they are stretch, does this in anyway cause the thread to change when they are removed? Might damage the block when doing them up?
I've reused head bolts plenty of times (and head gaskets too! ) on cheapo fixes - no problems. Not ideal obviously, but it won't explode or anything.......
Dislclaimer: Parz takes no responsibility if it does explode and mortally wound you. If you are mortally wounded, Parz would like a testicle, remember to carry your donor card!
the easiest way to rule out the head is to refit the flowed head?????? I've used the head bolts again on my old valver. well I said I did it was the guy working on my engine that reused them I wasn't really too happy, but they didn't snap or anythng.
Hi Trev, As you are retarding the ignition to compensate for the pinking it could be that it isn't fueling properley with the engine under load. Have you had the air / fuel ratio tested with engine under load? Do you have the right inlet manifold gasket that splits the upper and lower of the manifold. On pic number 4 it looks like it might be for a smaller manifold and might not be seating properley, thus allowing un-metered air into the engine. Other possibility is a leak in the inlet tumbing, are the injectors seating correctly, test these by spraying with carb cleaner when running and look for changes in revs. Cheers, Chris
Hi Chris, I think that both a normal garage and also Stealth came to the conclusion that the fuel and air intake system is fine. I have also tried replacing every single injection and intake component, because I had a donor 16V nearby and I swapped over the metering unit, air intake, manifold with injectors, etc. The rattle is a rock solid problem that will just not go away
Id really like to know what this problem is, ive recently fitted a 6a to my valver, and had it set up at stealth no problem, then about a week leter started getting a slapping kinda noise coming from the head area, comes in under acceleration at about 3000-3200 and stays till i change gear, then does the same thing again in every gear, then again when you lift off, is very worrying, seems to be getting louder. took it to my mates garage and he immidiately said cam bearing caps, I havent had the chance to take the cover off and investigate it yet, but he thinks there will be obvious signs of wear (like glazed or scored) sound rite? im just hopeing its not the bottom end, am going to Le Mans in 2 weeks, need the car running properly for the 1000 mile round trip
If the cam caps were that bad to make a noiselike you describe, I'd think you would be seeing the oil pressure light too.......
You can have them bored out and bearing shells put in - but it'd probably be cheaper just to get a secondhand head!
Rite boys and girls, I finally got round to taking the cam cover off my valver last night, and the cam chain is VERY loose, and i do mean loose, you can deflect it at the top about 3/4 of an inch and there loads of sideways movement......... Could this be the couse of the noise im getting (nothing below 3K, then it starts) and is worse when i lift off the gas???
Yep, that's a lot of play! But is it due to the chain stretching (never seen one THAT bad), or the bearing surfaces being nuked and the cam moving sideways?
riite, i changed the cam chain, its quietend it down a little, but there was quiet a lot of slack in the other one, but its still rattley... can anyone tell me what the differences are beteen the different sets of cams i have, 027 ext cam, 027H ext cam and 027M whats the difference?
