Bull Bar Cowboy Posted September 19, 2006 Share Posted September 19, 2006 that isn't quite true. the valve timing can be designed even on normally aspirate engines to get over 100 % but it is related to the engine rpm so will not be the same value across the rev range (variable valve timing is the futrue).bact to compression test; I am not sure the absolute value is that important providing it is not stupidly low, more important is that the readings match across the cylinders. If you can get over 100% then you had better patent it ……….. in fact you wont get 100% ………. Laws of physics and engine design deny this ………. Its just like the fact that you cant use copper tubes as anti crush spacers…. Ian Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 19, 2006 Author Share Posted September 19, 2006 Well, I've done a cold and dry compression test, I didn't try it wet (oo err) as the values didn't look too bad to me - noticable difference between left bank and right bank but between cyls it seemed at least within the realms of health. 1 - 135 2 - 160 3 - 130 4 - 150 5 - 132 6 - 162 7 - 147 8 - 140 Split into left/right head you have: 1 - 135 3 - 130 5 - 132 7 - 147 and 2 - 160 4 - 150 6 - 162 8 - 140 It then proceeded to start with only a tiny bit of smoke and drive OK although still not going to win any races it seems to have cheered up a bit (now it has it's new tyres on). The plugs were all way too pale (&*^%ing open-loop EFi) so I wound the AFM correction screw back in a bit and have stuck a cap & arm in it just cos they haven't been done since I've had it. There is a small amount of oil coming from the small mushroom filter thing on the back of the left rocker cover, I will get a new flame trap & install although the one that's in there does flow air OK. Current plan is to see how it behaves over the next week or so and go from there, I have a MegaSquirt that's sat round begging to go into it Quote Link to comment Share on other sites More sharing options...
02GF74 Posted September 19, 2006 Share Posted September 19, 2006 If you can get over 100% then you had better patent it ……….. in fact you wont get 100% ………. Laws of physics and engine design deny this ………. Its just like the fact that you cant use copper tubes as anti crush spacers…. Ian I'm afraid I can't since it has already been done. As I said originally, it can be done by design of valve tming but will only occur for a limited rpm. Read about it here: search for "pulse tuning" Now come here, remove your glasses and allow me to slap you with this small length of 1/2 inch copper tube [smug] B) Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted September 19, 2006 Share Posted September 19, 2006 Pulse tuning has been around for years…… primarily with miniature 2 strokes…….in terms of BHP per litre phenomenal figures can be produced………. but it all relative to the smaller scale. However, for those of us using what could be described as old fashioned diagnostics, then its better to understand the fundamentals applicable to the average engine we are likely to see. When was the last time you worked on a pulse tuned engine ? Now put yer copper pipe back in as anti crush tubes and read my f’kin post again, Compression ration is usually defined as………. the piston displacement plus clearance volume, divided by the clearance volume. This is the nominal compression ratio of the perfect engine determined by the cylinder geometry alone. In practice, the actual compression ratio is appreciably less than the ‘perfect’ value because the volumetric efficiency of engine is less than 100%. This is mostly affected because of late intake valve closing and valve overlap. The above assumes a naturally aspirated engine. Ian Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted September 19, 2006 Share Posted September 19, 2006 Split into left/right head you have:1 - 135 3 - 130 5 - 132 7 - 147 and 2 - 160 4 - 150 6 - 162 8 - 140 Looking at those figures I would suspect that the head gasket on the left hand bank is slightly leaking in the valley ……….. the classic RV8 fault. However, the numbers are OK and not too much to worry about. IIRC the standard setting for the AFM is fully in and then 2 ½ turns back. Ian Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 20, 2006 Author Share Posted September 20, 2006 Well today it started with only a very slight haze of smoke, clearly mocking me now I thought I'd take the opportunity to set the TPS and idle air bypass as well as the AFM screw. AFM screw was well out from where it should be, now exactly 2.5 turns out and it did make a difference to the idle. TPS was correct, which surprised me The idle adjustment is still annoying me, the thing just won't idle reliably - never has. I got it set lovely, it idled great for 30 secs then spluttered and stopped I think I need to check the timing, which means sticking an old HT lead on #1 as the Magnecors are too well insulated to trigger my inductive timing light Quote Link to comment Share on other sites More sharing options...
dollythelw Posted September 20, 2006 Share Posted September 20, 2006 diese.......... oh never mind Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted September 20, 2006 Share Posted September 20, 2006 BTW The eales doesn't have any valve stem seals ! It Puffs on cold start up, once warm fine, Nige Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted September 20, 2006 Share Posted September 20, 2006 If you have set up the base idle OK ……… then I doubt whether the timing is to blame. Three problem areas come to mind ……… is it the originals fuel reg ? if so it could be shagged tired out and is showing its age as it attemps to drop the pressure by 7 psi at tickover (Its probably going well down and falling the longer its on tickover) ……….. or the fuel pump may be playing up. Don’t ask me why, but it always seems to show up on tickover rather than gunning it down the m’way. Lastly, did you reset the butterfly in the plenum ………. As it wears it becomes uncentral and often the 2 thou air gap is variable……….. slacken the screws, open and close it a few times and then tighten the screws ………. I usually give them a dab of nail varnish to make sure they stay there (no Jez ……calm down……… steady on………. its got nothing to do with gimps and rubber suits ). If you need a fuel reg ……………. I’ve got one you can have. Ian Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 20, 2006 Author Share Posted September 20, 2006 diese..........oh never mind Fuc...... oh, never mind Ian - I hadn't considered the FPR, it's possible although when I bought the vehicle the FPR was changed a few times in the search for what turned out to be a HR fuel pump wire cheers for the offer but I have several EFi setups kicking round, I seem to collect them! Also haven't tried the butterfly, which two screws are you talking about - the ones in the middle of the butterfuly itself? Nail varnish I'll ask the lodger, he's a goth Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted September 20, 2006 Share Posted September 20, 2006 Yes, the two screws that hold the butterfly into the split spindle …….. make sure they cant come loose though, but be careful as they are brass threads ………….. does Andy have a good line in red nail varnish ? Ian Quote Link to comment Share on other sites More sharing options...
02GF74 Posted September 21, 2006 Share Posted September 21, 2006 Looking at those figures I would suspect that the head gasket on the left hand bank is slightly leaking in the valley ……….. the classic RV8 fault. how is that possible? Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted September 21, 2006 Share Posted September 21, 2006 how is that possible? Gasket failure on the inside edge of the cylinders causes venting of exhuast gasses into the valley, usually given away by oil getting forced out of various joints on the engine. More common on older engines with the third row of head bolts which tend to twist the heads. Seems to be one of the most common failures on older V8s. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 21, 2006 Author Share Posted September 21, 2006 Wonder if slackening off the outer bolts would provide a temporary respite? It died totally on the motorway earlier for about 5 secs, I suspect the coil may be on its way out... dropped a spare Bosch one in and it seems to be happier although loads of smoke on startup today Quote Link to comment Share on other sites More sharing options...
Nigel H Posted September 21, 2006 Share Posted September 21, 2006 ... loads of smoke on startup today Yeah, mine smoked a lot on start up today - as it does every day, but then again... Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 25, 2006 Author Share Posted September 25, 2006 Well, this weekend saw some progress... It was really suffering towing Petal to 7S, very down on power and not sounding good didn't enjoy the BIG hill up to the site at all. At 7S I tried changing the ignition amp to the later type but that didn't really work, so instead I stuck the original back on with a brand new coil. It started & ran a bit better with this on, and whilst looking at the engine I noticed what looked like a loose plug lead... um... Seems someone hadn't tightened the plug up enough after the compression test and two of them were rather loose in their holes Went considerably better after that, the power hasn't dropped off and once I got Petal off the trailer it's been back to its old self. The smoking seems to have stopped for the minute too, not sure why/how but as long as it's running I'm happy It took some abuse from Andy on the way home, but he had Moglite on a 7.5 ton flatbed and we had Petal on a tilting flatbed trailer, plus four people and all our gear - reckon we were pushing 6ton GVW and it managed 70 given a decent run on a level bit of road, that'll do me just fine. Also got 16mpg which was bloomin' amazing for the amount it was pulling Quote Link to comment Share on other sites More sharing options...
MogLite Posted September 25, 2006 Share Posted September 25, 2006 It took some abuse from Andy on the way home, but he had Moglite on a 7.5 ton flatbed and we had Petal on a tilting flatbed trailer, plus four people and all our gear - reckon we were pushing 6ton GVW and it managed 70 given a decent run on a level bit of road, that'll do me just fine. Also got 16mpg which was bloomin' amazing for the amount it was pulling It was quite a train rate for sure. Especially impressive as it drove there and back, and around site too. Alas I must have been dozing when you hit 70 - I didn't spot it. Maybe your speedo chi needs more alignment with my tachograph or a GPS. It lives to fight another day which is the most important thing. 16mpg is good too. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted September 25, 2006 Share Posted September 25, 2006 John, can you tell Al to text, Alex to email "him" that I think it was when we were being chased by the world kickboxing champion on the M4.. Thanks for the haul by the way! B) Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 25, 2006 Author Share Posted September 25, 2006 I think it was after you went off, I only hit 70 very briefly as I really didn't want to be carrying that much momentum anywhere Have you noticed when you're towing MogLite (as with Petal) that people take longer than you'd expect to overtake? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 25, 2006 Author Share Posted September 25, 2006 John, can you tell Al to text, Alex to email "him" that I think it was when we were being chased by the world kickboxing champion on the M4.. I'm so glad we got away, I was scared... that I might wet myself laughing. He did look like a bit of a champion but not of kickboxing Quote Link to comment Share on other sites More sharing options...
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