smallfry Posted November 20, 2013 Share Posted November 20, 2013 More hassle, just when its likely to be needed soon...................... As its cold and dark outside, in order to hopefully save some time, I wonder what you guys think. County V8 3.5 litre 8.13 comp ratio. It has been fitted "professionally" with some sort of performance camshaft, and had the top of the inlet manifold cut off, and had a flange fitted which takes a Weber 38 DGMS carburettor. Also a straight through exhaust with no silencers. It has never been really satisfactory, all noise and no action, and I think it was put together by someone who didn't really know what they were doing. The blue hylomar gives it away. You always know when you see that, it was a p*** poor job. It has/had a semi misfire under load.........holding back type thing which is hard to pinpoint. I tried pulling all the HT leads off in turn, and none of them make any appreciable difference...........maybe ALL the cylinders are not working ! Anyhow, when the weather gets better in the spring, I was going to go right through it and find out what has been done and try to set it up something like properly. Unfortunately, it has now decided to be difficult. It suddenly does not idle well, and stalls until it it really warm. The idle rises and falls which it didnt before, by that I mean it seems to rev up a bit, and then drops off until it nearly stalls, then repeats. I was thinking vacuum leak, but cannot find any. What I have also noticed though, it that it puff puff puffs smoke on the overrun, but I cant make out if its all oil or not ( I have had a few oil burners in my time) any wonder if this is connected ? It has always started OK, and still does. It does not overheat, and since I washed a bucketful of mud out of the radiator, the gauge hardly registers, so I suspect no thermostat, but i dont think it is revelent to this problem. I am going to run my leakdown tester on it, but I am waiting for it to come back. I lent it to a mate a couple of years ago and it hasnt come back yet, and he is trying to find it................. Any ideas ? Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 20, 2013 Share Posted November 20, 2013 Sounds carby to me? leaking air, or it's just gone wrong the way carbs do. And a home made manifold could be excellent, but somehow they usually aren't, as anyone who could do it right, would probably avoid that mod Does disconnecting the aux vaccy lines help? I wonder if it's just dirt in the carb? Quote Link to comment Share on other sites More sharing options...
duncmc Posted November 20, 2013 Share Posted November 20, 2013 Blue Hylomar is a Land Rover specified sealant used on the plenum chamber and inlet manifold to seal the surfaces together on the EFI engines. I have nothing against it for such use. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 20, 2013 Share Posted November 20, 2013 Ditto duncmc.... Quote Link to comment Share on other sites More sharing options...
missingsid Posted November 20, 2013 Share Posted November 20, 2013 TBH this sounds exactly the same as my std V8 on SUs. I am guessing too lean possibly air leak as per the previous comment. Plug colour? No thermostat would delay the engine warming up which won't help I would think? Quote Link to comment Share on other sites More sharing options...
Quagmire Posted November 20, 2013 Share Posted November 20, 2013 I use blue hylomar! Quote Link to comment Share on other sites More sharing options...
smallfry Posted November 20, 2013 Author Share Posted November 20, 2013 Blue Hylomar is a Land Rover specified sealant used on the plenum chamber and inlet manifold to seal the surfaces together on the EFI engines. I have nothing against it for such use. I am well aware of that sir, so dont take offence, but what I mean is that you DONT need to use a whole tube or it just to put a rocker cover on, and then if you did, I would hope you would at least clean off most of the excess.......................... Quote Link to comment Share on other sites More sharing options...
smallfry Posted November 21, 2013 Author Share Posted November 21, 2013 Sounds carby to me? leaking air, or it's just gone wrong the way carbs do. And a home made manifold could be excellent, but somehow they usually aren't, as anyone who could do it right, would probably avoid that mod Does disconnecting the aux vaccy lines help? I wonder if it's just dirt in the carb? I thought it might be dirt. Or maybe water in the tank. I know it has done some deepish water/mud by the amount in the radiator and the engine bay generally. Although the carb doesnt actually LOOK very old, I thought I would get a gasket kit for it anyway, and while speaking to the supplier, he didnt think it would be that. I can screw the idle mixture screws right in and out and it doesnt make much, if any, difference. I have tried disconnecting the vacuum advance and retard (cant work out how that works) lines and it just stops dead. The only other thing is the fuel supply..............I get a good flow with the pipe disconnected, but there does not seem to be any actual pressure, and I cant find any value for this in any of the manuals I have (its an in tank pump) also, I know that both the V8 and 2.5 petrols had a restrictor in the return line, which would build some pressure, but there is nothing. So maybe there is not enough fuel delivered to the carb, not that this would induce the particular problem I have now. Unfortunately Weber carbs are something I am not familiar with, and suprisingly there doesnt seem to be very much info available online Quote Link to comment Share on other sites More sharing options...
smallfry Posted November 21, 2013 Author Share Posted November 21, 2013 TBH this sounds exactly the same as my std V8 on SUs. I am guessing too lean possibly air leak as per the previous comment. Plug colour? No thermostat would delay the engine warming up which won't help I would think? Plugs are fairly white which would suggest a vacuum leak, but I am bu**ered if I can find one ! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 21, 2013 Share Posted November 21, 2013 Fuel pump pressure is likely to be around 4-7psi, so hardly noticeable to the thumb test. Any if you use the later rubber rocker gaskets no need for any sealant at all... Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted November 21, 2013 Share Posted November 21, 2013 It does sound a lot like an air leak. Hunting, mixture screw not having any effect and lumpy idle. Apologies if I'm teaching granny to suck eggs, but wd40 sprayed liberally around joints which meant to be airtight has always worked for me. If it revs up when you spray, your a winner! Josh Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 21, 2013 Share Posted November 21, 2013 I was thinking blank the vacuum brake line rather than pull it, as that would weaken it a lot, but pulling the vacuum advance shouldn't finish it off? I mean slow it down, or lumpy, but not kill it. I bought a fuel pressure gauge. It tells why we stopped, or to look else where. It's handy like a dash mounted volt meter. If it were low fuel pressure I don't think it would move around at all. (ours doesn't) So I'm sticking with 'air leak' or dirt in a slow-running jet. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 21, 2013 Share Posted November 21, 2013 What dizzy is it running? Quote Link to comment Share on other sites More sharing options...
Tanuki Posted November 21, 2013 Share Posted November 21, 2013 I'd suggest first doing a compression-test. If the engine's been put together by an amateur you could have cracked rings. Also, check the valve-clearances - a 'tight' one or two (or three or four...) can cause all sorts of evil. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted November 21, 2013 Share Posted November 21, 2013 8.13 is always going to be a slow V8. Is this one of the pulsair V8s ?Nige Quote Link to comment Share on other sites More sharing options...
duncmc Posted November 21, 2013 Share Posted November 21, 2013 I am well aware of that sir, so dont take offence, but what I mean is that you DONT need to use a whole tube or it just to put a rocker cover on, and then if you did, I would hope you would at least clean off most of the excess.......................... No offence taken. I see what you mean now, if a whole tube has been used or a huge gob of it. Quote Link to comment Share on other sites More sharing options...
Landowner Posted November 21, 2013 Share Posted November 21, 2013 If it stops when the vac advance tube is taken off then its running retarded ignition timing. Try advancing it till it starts without the vac advance then putting it back on should see the idle pick up a couple of hundred revs approx. You can adjust it down to normal then on the throttle stops. You can advance it till it pinks under load then back it off a little. Give it some more fuel, if tickover speeds up then you are going the right way, if not lean it off until revs are at highest. Quote Link to comment Share on other sites More sharing options...
smallfry Posted November 22, 2013 Author Share Posted November 22, 2013 Thanks for all the replies gents.....................gives me something to think about, and the onset of failing memory isnt helping I have not had a petrol engined vehicle for a few years now, even longer for one with a carburettor...................... It has the 35 DM8 setup, the one with the amplifier under the coil on the inner wing. All the components are original except for the leads, cap and rotor, and appears to be working OK. Regular sparking from the king lead which jumps a 20mmish gap, and which does not short through the rotor arm. Not checked the actual ignition timing yet, but groping around in the dark this evening, it seems that the TDC pointer is missing. No matter though, as I have a couple somewhere.................. Didnt think of the brake vacuum hose or the servo, as we like to overlook the obvious. Have tried the WD 40 test with no result, but of course the underside of the manifold cannot be checked, but I think I will take it off anyway to examine the welded on flange more closely, and also have a visual check of the camshaft lobes. I did do a compression test, but it was dark and started to rain, and when I went indoors with my woefully low results, ranging from 90 to 105 psi, I realised that i had not opened the throttle butterflies...................so will have to do that again, and will also do a leakdown test when I get the tester back. I also found a rather curious arrangement for the engine breathers..............it appears that the hoses from the rocker covers vent into a tee piece, one for each side, with one branch feeding into the air filter box, and the other to a pipe which joins to the carburettor flange on the manifold, which must surely not help as it would cause a vacuum leak ??? However, before the advent of the problem it has now, it has been run like this for a long time. It WAS a pulsair engine, but all that was removed before I bought it, except for the pipes on the heads which had been pinched off. Again why this was not done properly when the carb was installed, I have no idea. Anyway, I have removed all that and plugged the outlets now, as it did chuff a bit. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted November 22, 2013 Share Posted November 22, 2013 Ah ha Pulsair engines are odd Remove the pipes along the head an blank off The carbs have restrictor plste in - remove - or better still shove a pair of su carbs on The dizxy and advance retard and bob weights etc are hopeless replace with a non Pulsair dizxy Set timing for normal 3.5 v8 That will make a vast difference but at 8.13 it will alwsys be poor on performance Nige Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 22, 2013 Share Posted November 22, 2013 Got a different carb on it Nige Quote Link to comment Share on other sites More sharing options...
Team Idris Posted November 22, 2013 Share Posted November 22, 2013 "I also found a rather curious arrangement for the engine breathers..............it appears that the hoses from the rocker covers vent into a tee piece, one for each side, with one branch feeding into the air filter box, and the other to a pipe which joins to the carburettor flange on the manifold, which must surely not help as it would cause a vacuum leak ??? However, before the advent of the problem it has now, it has been run like this for a long time." That sounds wrong from first principals. You could have one rocker connected to the clean/filtered side of the air filter and the other rocker connected to the carb? Then it sucks filtered air into the engine which purges damp gas and feeds it into the inlet manifold. Normally something has to break to change the engines running, but machines run on statistics. Once all the faults add up to a fictitious value it fricks around. Change that value by fixing one part and it runs So any 'problems' being fixed will help get it closer to it's 'happy' place. Quote Link to comment Share on other sites More sharing options...
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