It wasn’t idling hardly at all when I took it for a run into work, so I had another slight tweak of the timing but haven’t had the chance to fire it up from cold since. I guess if the timing s now done, there’s a chance the carb needs a little adjustment too, and I’ve not ever had a go at that. There’s still an oily residue appearing around where I initially panicked about a crack in the manifold, but as a crack has been ruled out, I’m just ignoring it for the moment
I don’t know. Everyone says there can’t be a crack, so I am thinking perhaps there is oil just around and in the join between the steel pipes and the alloy jacket, and that it is just ‘collecting’ there? A little oil goes a long way. I’m cleaning it off every time, so hopefully I’ll eventually have cleaned it all. Perhaps!
Its probably a hairline crack where the steel pipe goes into the casting. You could give it a blast of carb cleaner, then JB weld over it to stop it being visible any more. It is probably seeping the oily stuff that runs down the inside of the manifold from the oil bath - my progressive always has a little oil collecting in the seal under the air box on top of the carb, some oil spray from the air cleaner. Not idling well could be the choke 12 volt feed being loose - it would start OK then idle worse later on when the engine warms up when the mixture is too rich by miles unless the choke flap pops out of the way as the cam drops down - the cam that holds the throttle open for cold starting is on the same shaft as the choke flap. My old carb used to stick and hold the choke on and the throttle end stop step in the wrong place. Sometimes idled at 2000 rpm or more.
Sorry but I'm getting very confused here. Oily residue from the oil bath air cleaner, coming down through the carb into the inside of the inlet manifold. Yep, I get that. If it's then visible on the outside of the inlet manifold, that implies a crack in the steel, and we're now back to where we were at the start of my thread, ie a cracked inlet manifold which obviously isn't going to help with the running of the engine, as air will be leaking in where it shouldn't. Is this what we're saying, because others were saying this wasn't possible, and it was just oil collected in the space between the steel and the alloy jacket, ie no actual crack in the steel and therefore no air leak? I'm sorry if this all sounds like I have no idea, but it's true - I don't! Cracks in anything are not good, and I'm beginning to think that getting the old manifold put back on (hoping mechanic Alex didn't bin it) is the best idea and chalking it up to a £200 very bad idea. This all started because I was getting exhaust fumes into the cab via the air vents: logical assumption was that there was a small hole in the inlet manifold between the exhaust gases and the heat risers - backed up by the fact there was some discolouration on the outside, indicating gas escape. Answer: get a 'new' manifold. Not working out so good as it turns out. Humph. (I'll check the spade connection on the choke, but I think it's okay. Idling is bad when cold, but better when hot. Other points raised in this thread appear to indicate that my oil bath may not be functioning correctly anyway as although there is vacuum pressure from the top down to the actuator, there is no vacuum from the manifold into the top of the oil bath, and apparently there should be.)
It could be a pin hole and smaller than the typical gap round the throttle spindle for example. If the crack is full of oil then air will not be going in there. As I said JB weld will make 100% sure. Dont bother changing it back . The problem will be something disturbed in the switchover from manifold to manifold. More likely your troubles are down to the vacuum hose going to the air cleaner not holding vacuum .. you have both a bigger air leak there and an absence of hot air feed. Sometimes touching a hose is enough for it to crack.
Hi Mike, is this the type of thing you mean? J-B High Heat Epoxy Putty … https://www.amazon.co.uk/dp/B007PP26RI/ref=cm_sw_r_cp_api_piB7zbNC532DM There seemed to be quite a few JB Weld compounds, but I assume the High Heat one would be the best for a manifold. Cheers.
Even ordinary JB weld works on/in the engine block. The high temperature stuff will work but the ordinary stuff works on my EMPI manifold when I managed to make one of the side tubes fall out of the casting.. here it is... hiding behind the alternator stand in the circle
Thanks Mike. I did buy some in the end, although after driving, cleaning, driving, cleaning, the oily residue didn’t reappear on the manifold this last time so I’m hopeful that it was just oily engine bay detritus collecting in a corner, so-to-speak. I did use it to mend the metal cutlery drainer that lives in my kitchen sink though, so Win / Win really
I’m not sure to be honest. Like you said at the beginning of the thread, the pipes run through a jacket/ so what looks like a join actually isn’t. I think it was just oily residue that was collecting and making me think something was leaking. There no sign of it now. As for the slightly rough running, all is good once the engine warms up and it’s smooth as a really smooth thing. Starting and idling when cold is still a big issue, I don’t seem to have an idle speed at all for the first 5 minutes of driving . Choke not working maybe? Distributor timing when set for revs is 30 degrees but this gives a zero advance at idle which probably isn’t helping. @davidoft is kindly furnishing me with another dizzy to see if this helps. Also my single solex might be a bit worn but as they are a bit like hens teeth these days (I haven’t got £350 burning a hole in my pocket right now for a proper refurbished Machine 7 one) I’ll try other things first. Whatever it is, I don’t think it’s the manifold
