Hi folks. My Huco fuel pump, bought on the pretext that it would deliver precisely the right p.s.i. to my twin Weber 34icts, has been generously supplying 4 p.s.i instead. I learned of this when a crackling and popping began to occur in the noisy cupboard accompanied by a huge loss of power. Having drained the extremely fuel fouled oil out, reset my valves, replaced my needle valves and put in a malpassi fuel regulator nothing has improved. I'm assuming my next stage is to pull the engine and strip down to inspect the damage. My theories are: 1) Best case scenario I replace all the piston rings finding no other damage and build it back up. 2) Worst case scenario I've unwittingly worn the bajeezas out of everything with fuel fouled oil and need to build a new engine. 3) Somewhere in between, please flag up other things I should look for. 4) The fuel fouled oil poured liberally over the van and myself will provide a quick solution to all of the above and bring about a brief moment of light and warmth to these dark wintry days. When I do this will the scoring be obvious on a barrel to suggest it's had it or is there a sliding scale of damage? Is it time to invest in some decent instrumentation to measure tolerances etc and if so what do people recommend? Was really hoping not to pull the engine this year... ah well. Sent from my SM-G950F using Tapatalk
Glitter in oil ? look in the filter. And your 4psi shouldnt have overwhelmed the needle valves in the carburettors, this sounds like the typical Weber needle wear, without a shutoff solenoid to stop the fuel. A full tank of fuel provides enough pressure to fill up the engine without the fuel pump's help at all. Its one of the best bits of advice I was given when I rolled up in 2010 at SGS Aircooled with a Weber progressive, and Scott said "you will need a shutoff solenoid with that, it will leak".. If you lost a lot of power, start before pulling the engine with a compression test before stripping things down. Its probably more than piston rings..
Compression test the cylinders and go from there.. The "massive loss of power" could possibly be running on 3 due to a fouled plug so it's hopefully not over yet ... Oh and thanks for the timely reminder I need to fit the cut off valve I bought last year..... Sent from my SM-G960F using Tapatalk
Weber needle valves are proper poo. You have to be on your guard with them. They don’t like anything over about 2.5psi pressure. Deffo fit a cut off valve & they complain if the carbs get hot. Ive had to fit some fairly thick insulation gaskets to stop percolation & fuel dribbling in after switching off when it’s hot/long run. Gets me that Dell can get them right but Weber can’t.
Purchased some of these before I start my twin carb kit job… https://classiccarbs.co.uk/product/79507v-weber-dmtl-ict-idf-viton-needle-valve I was also warned about faulty huco’s by way out westie Mike… holding back on installation till I can check it…
So only 1 month later I manage to get back to the van. Sigh. I've got a none-return valve to fit (Thank you guys!) Here's where I've got so far. 1) Plugs were fouled. 2) I've got around 100psi on 3 & 4 cylinder on a cold engine. 3) The new needles had the darkened tip coating so I'm hopeful that eurocarb have supplied viton coated. Shall I check 1&2 if only to clean up the plugs? The crackle is defo on the 3/4 carb. The exhaust is filthy black but does that suggest burning off whatever has been sat in there or are the cylinder rings allowing oil to push past and burn. I thought this would more likely be white smoke if the case. Thanks again fellas. Sent from my SM-G950F using Tapatalk
P.S. I've swopped out spark leads and plugs to no avail. Also played with fuel mixtures but same issue. As soon as I increase revs beyond 2000 (guess work here) the popping starts. Any other avenues of exploration of an engine-staying-in variety greatly recieved. Sent from my SM-G950F using Tapatalk
You might not think you're getting anywhere but you probably are. Do you know emulsion tube number and jet sizes?
Could still be a rich mixture. Black smoke is more usually over fuelling especially with popping back up the carbs.. Recheck your assembly - did you forget the copper washer seal under the metering valve body one side ? That would lift the float level a bit or dribble badly if it doesn't seal at all well.. has the main jet vibrated out ?
Is this just sitting, or have you tried taking it for a quick spin? I've found after heavy over fueling it can take a good 'Italian tune up' to get things right again?! Defo do 1&2 as well.
Hi Guys. Maybe should start a new thread but as it's in search for a solution to the same problem -popping in both carbs and no power resulting in 30mph max- I thought I'd post my findings here. After much jiggery pockery and no positive results I pulled the engine. 1) There's evidence of exhaust leaks on both heat exchanges to cylinder heads; black fouling around the seals between them. Would this affect performance to the extent I've described? 2) Despite getting decent compression readings theres evidence of oil pushing past inti the ignition chamber on Pistons 3 & 4 with potentially same on 1 & 2. Would this burn off account for popping and loss of power at high revs? 3) Is the Cam worn excessively? I realise that measuring up the wear properly is the best route to knowing this but before I split the case (never done before!) I hoped one of you learned genes might have a good eye for how much was too much. I'm hoping the pictures below might result in everyone clamouring to say, "replace all your piston rings, get your head to exhaust seals sorted and put it back together!" This is my best case scenario but I'm braced for a more involved worst case. Either way, thanks for all the help! Sent from my SM-G950F using Tapatalk
Do you know the history of the engine? Cam type, CR etc. Piston crowns and cylinder walls look low mileage but while you have it apart you might as well fit new rings – make sure the rings have the correct end gaps. The pic of the cam is grainy or does the cam have a rough surface? What do the followers look like? Did you check the valve lift before you took the heads off? If not, measure the cam lift on each lobe. One exhaust valve has probably run hot but the rest look okay and there is nothing obvious to cause a lack of power – unless the cam is flat.
Yes @Soggz too many times apart! It was a recon bottom end CJ with standard cam fitted. I built it up 4 years ago with new B&Ps, heads and Weber 34ict's from previous. I was assuming I get cam lift measurement when I tune up and gap the valves which I did very recently but please elaborate further if this isn't the case. What would I be looking for in the state of the followers? Cheers @77 Westy. Zedders I did not check vacuum advance.. as I am a fool...I have another Van I part own with a friend using the same engine setup. Could I swop out the dizzy's on the running one to see whether this is the culprit or is there another way? I can't get any more/better pictures of cam or followers (also fitted new) to you until Tuesday as I am applying a new mechanical technique of fixing the engine by being away from it. I'll keep you posted on my success rate but I think I'm onto something.. Sent from my SM-G950F using Tapatalk
Followers - good surfaces are slightly domed so they rock if placed face to face. Loss of a cam lobe will show because its worn smaller than the same cam lobe at the other end of the engine. So you actually have to measure how far the valve stem moves when it's supposed to be open and closed. And two opposing cylinders will share the symptoms of loss of power or backfiring up the intake if it's an exhaust valve that is staying closed. If its struggling to run fast it could also be fighting against destroyed bearings - as you were starting off with petrol in the oil there may be some severe bearing damage that is holding the engine back. Small leaks from the cylinder head aren't helpful but mostly make a noise that's obvious when you stop it I the end.. A bit of oil in the cylinder likewise is smoky but not the end of the world. But if you are used to your engines sounds - then you might not notice the odd exhaust leak. E.g. there was one engine at TE that was basically idling on one cylinder and yanking the alternator drive belt so hard it was yelping. The owner took a bit of persuasion it wasn't right. Some time with adjusting the linkage and balancing the idle air flow on all four carburettor barrels and it sounded totally different at idle. It worked OK at speed just it was trying to tear off the alternator pulley at idle.
Valve lift is how far the valves open, when you gap the valves all you are doing is measuring how far the followers are from the cam base circle. If the cam is worn flat there is less valve lift but the valve gap doesn't change because the followers don't touch the base circle (unless they are hydraulic). The cam and followers take a hammering when you run the engine with a fuel/oil mix, bearing suffer too, pistons not so much.
That's unimportant, I meant the mechanical advance, but from the rest of your post you've decided, without checking the distributor is working properly, that the cause of your abysmal performance lies inside the engine? Or did I miss something?
