V8 inlet manifold refurbishment.

G'day Chris,

Provided the flame trap is just retaining oil, I use the normal spray can of degreaser available from your local autoparts store. Once the build up of hard solids within the wire mesh is underway though, chemical degreasers, Kerosene (Paraffin) and even using a small blow torch are pretty well useless. The writing is on the wall, new ones will soon be needed.

Ron.
 
Good point Graeme. And mine's only done 98K. The heater hoses are definitely on the list I've been compiling tonight, so don't fear. You won't get a phone call from the Rai Saddle one dark and stormy night requesting a supply run of tools and coolant.
 
While on the subject of the V8 inlet manifold, It had been mentioned in other posts about the crud that builds up inside the water gallery around the carby block (where the SU's bolt onto) I have replaced the original small steel bleed pipe (the one that runs to the cool side of the radiator) by drilling the steel pipe out and drilling and tapping a 1/8 BSP hole to enable a better flow of coolant (all this with the manifold off the car), so I have made up a stainless steel tube to screw back in which has a larger inside diameter than the original steel pipe. Seeing as I also had the manifild off from my parts/doner car I investigated this water gallery by removing the welch plugs on the top and the one on the side and this revaled quite a large cavity where the crud can build up over time and as the original small pipe does not generate a volume of flow to keep this cavity clear is probably why it fills up with crud in the first place hence my move to a larger pipe to aid flushing. Also seeing inside the casting allowed me to drill and tap two other holes on this carby block (on my original manifold with welch plugs still in), one on the front side and another below the welch plug at the rear. This enabled me to poke around and flush out a considerable amount of more crud which I otherwise would not have been able to reach from the top. I have noted that the water from this cavity flows back into the main water jacket on the manifold but interestingly the one off my parts car just holds the water and I can't for the life of me find the hole back to the main water jacket (this on the one with the welch plugs removed!!) so either it is well solidified or there has been a casting error which did not properly have this passageway set in. What I aim to do is tap into one of the rear blanked off ports and feed this into the cavity where I have got the extra drilled and tapped hole already to enable a better flow of water. I'll try and post some pics (we have to post them to another website first,don't we???then attach them, not up to speed with this) any thoughts or advice would be most welcome
Regards
 
ghce said:
Renewing flame trap hoses? :oops: I just decided that all those "dirty little fumes" wern't going back into my clean (2 or 3 hundred thousand Kmh)never rebored or reringed engine :? I just elected the two into one pipe and down to the road with all those fumes solution :wink:
As for the heater hoses, it is a false economy not to replace them which I learned to my cost when on the top of the Rai Saddle the rear heater hose decided that it had had enough and all I had was blunt knife as a tool :mrgreen:

Graeme
Click to expand...

Hmmm... The SUs provide a vacuum to take the horrible fumes into the combustion chambers and burn them. The fumes are then replaced with fresh air from the rear of the air filter box.

If you vent them to atomosphere, the horrible fumes stay in the crankcase and sludge up your oil faster.

My car, being a weber fueled thing, doesn't have this system so I will be fitting a PCV valve soon to replace it.

Taking them off will NOT make your engine last longer; quite the opposite.

Richard
 
embarrassing as it is to answer my initial question to my above post on the carby block water flow, I also removed the welch plug on the underside of the manifold (spare one) and on first look there was no feed hole into the upper block to be found, but after giving it a good dose of looking at found a slight dimple which turned out to be the hole I was looking for and indeed it was well choked up with solid crud and once cleared revealed the source of how coolant gets to the carby block, although it is only a 3/16" hole (which is the biggest size drill bit that would fit) so it was well worth drilling and tapping an extra hole to poke around and ensure this small hole is clear on my original manifold, there is sufficient room to make it a 1/4" BSP hole instead of the 1/8" BSP I have made which was still ok to get some wire in to make sure the feed hole was clear. I think I will go the way my thinging is taking me and take a feed off one of the rear blanks and pipe it into the extra hole made in the backside of the block below the welch plug as this should provide a better flow (and heating at this part of the carby intake) to allow coolant out through the top bleed pipe and back through the initial feed hole at the same time and in conjunction with with a good quality coolant mix at regular change intervals should prevent the blocking of these two points. again any advice or suggestions is most welcome
 
thanks ron for your instructions on posting photos, here goes,

IMG_6600.jpg


above: this is where i have replaced the original steel bleed pipe with a larger 3/8" OD stainless tube threaded 1/8" BSP (a 3/8" OD pipe will accept a 1/8 BSP pipe thread) and drilled and tapped likewise in the old hole, to aid the flow and prevent blocking up with sediment (refered to as crud as in previous posts) The extra hole you can see midway down (also drilled and tapped 1/8"BSP was to enable poking in with a piece of tiewire to loosen and flush out more crud and there was a lot of it. This hole will be plugged up.

IMG_6602.jpg


above: looking at the rear of the carby block I again drilled (and tapped 1/8"BSP) a hole to help loosen and clear to flush out more crud, and through this hole poke in some wire to locate the feed hole and make sure it was clear into the main water jacket (for info I drill a small pilot hole then the 17/32" tapping drill for 1/8"BSP thread) and as you can see I will fit a larger tube and feed this from a point at the rear blanked off port. The theory being is that water into here will flow out the bleed pipe and the small (3/16") feed hole as well keeping it clear of crud, and probably helping to heat up better this part of the carby block.

IMG_6593.jpg


above: this is looking into the cavity after I removed the welch plug on my spare manifold and down in the dark part is where the feed hole is which would be impossible to reach from the bleed hole itself without drilling the extra one as in the previous pic, as there would be no other way of clearing/checking this hole unless you removed the welch plug underneath the manifold.

IMG_6615.jpg


above: as you can see after removing the welch plug underneath you can find the 3/16" hole which feeds up into the carby block and on this my spare was comletely blocked solid and was not noticable at first glance until I noticed a slight dimple then poked it clear with a small screwdriver.

IMG_6591.jpg


above: this is the blanked off part at the rear of the manifold which I have drilled and tapped 1/4"BSP to take a 1/4-1/8 BSP reducer then fit a 3/8 (threaded 1/8BSP) pipe from here to the back of the carby block to improve the flow, better heat this part of the manifold and help keep this cavity from filling up with sediment, any thoughts and comments are most welcome.

Image008.jpg


above: oh and this is my rover before I started work on it. the original green was Arden and last owner gave it a respray in what looks like British Racing Green, which I must say looks very nice as you can see the original darker Arden green inside the door opening
 
Hello Scott,

Glad you got the PM,...great pics and a very nice Rover you have too... :D British Racing Green ones are few and far between indeed, and yours is only the second one that I have seen. A friend has had one since 1977, but years of being parked out in the sun have taken their toll, so it currently awaits restoration.

The 1/4"BSP thread that you have tapped to take a pipe from the blanked off section at the rear of the manifold to the newly installed pipe on the rear of the tower,...how will the coolant circulate in this instance, given that the pipe to be installed in the 1/4"BSP is not tapped into a coolant gallery within the manifold?

Ron.
 
Hi Ron, the rear port that is blanked off is actually part of the coolant gallery that flows up from the block at the rear up into the cylinder head and flows to the front and then out at the front port into the inlet manifold then out through the thermostat housing, the fact it is blanked off by the inlet manifold does not mean there is no flow here, there is, so this is why I thought to tap in here and direct some into the carby block rather than rely on the 3/16" feed hole into the cavity. I could take coolant from either side at the blanked off part of the manifold as they both have coolant flowing past them, which is why the initial post had a bit of a crud build up at his blanked off ports, hope this explains it well.

Regards,
 
Hello Scott,

Yes the penny has dropped,...I can see what you are doing now.

The cylinder heads are all non sided, so there is an exit point for coolant at each end. However, the inlet manifolds whether they be the Rover designed twin SU manifold or a Bosch designed Thor manifold for the 4.0 and 4.6 all have one point in common. Coolant can only enter the inlet manifold after having travelled right through the cylinder heads. Their design precludes entry of coolant into the inlet manifold at any other point.

Your modification will allow coolant to exit one cylinder head at the rear, travelling directly up and into the tower, a far easier path than travelling through the head. I am now thinking that this may reduce or slow down the flow of coolant through the effected cylinder head, with possible unpleasant and expensive side effects.

You could always tap into one of the coolant channels at the front of the inlet manifold and run a hose back to your newly installed entry pipe on the rear of the tower... :?

It is just a thought Scott.

Ron.
 
I do have the choke warning light sender blanked off and I could use this point (as the previous owners attemt to remove it resulted in all three bolts shearing off, so there was enough meat there to tap it 3/8"BSP and plug it up) youre right in that it would draw coolant out of the tower but would still rely on it entering though the small feed hole initially whereas my thinking is that if a supply was fed into the tower from the blanked part I have opeded it would still be in the direction of flow from the back to the thermostat front end through the small hole and also through the bleed pipe to the cooler side of the rad creating a flow path. I would say once the thermostat opens and a flow starts with normal convection from hot to cold added with that the water pump pushing things along it shouldn't be much of a problem with this small pipe branching off to the tower, I'll progress and plumb it up and post photos before installing the manifold to elicit more comments and suggestions. It may be a while as I'm on hols and will need to get into work to make up the other fittings I need, so it (the rover) is getting a good dose of looking at in the meantime with probably the carbys fitted back on the manifold and air cleaner (temporarily) to see what room I have for pipework/hoses etc.
Thanks for you comments Ron, they do make me think about it a bit more, but it's good to try and improve on some of the inherrent problems with the P6 (such as this small hole becoming blocked) thats just one of my traits being a mechanical fitter, always looking to improve on the original.

Thanks again, Regards,
 
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