So far things are going well on the top end re-work. However, I've come up against another little teaser, this time on the intake manifold. When it came to cleaning it and remove the carb and other items, I noticed two things that didn't quite add up, bare in mind I've never stripped a V8 before. Where the manifold meets the cylinder head on either side, I saw ports/openings other than the ones delivering fuel/air mix, Hmm I thought, what's this about. Looking at the manifold (carb uppermost with the Thermostat housing nearest you) there appears to be two cast tubes that run front to back at the outer edges of the manifold, the one on the right has a small flanged outlet on the top face (blocked off on mine) The 4 holes on the joining face appear to go nowhere ? As they are blocked off by the valley plate/gasket. The one on the left is flangeless. At the rear of them (near the firewall/bulkhead, the two small core plugs are almost corroded away. Where did the flange, presumably connected to a pipe of some sort, go to ? I want to replace the core plugs but it seems this 'tube' does nothing. Second item that has baffled me, although I think I've hit on it in a roundabout way, is the large L shaped ports that open up inwards and under the carb area, then they flow backwards and open up at dual openings at the rear of the manifold on it's top face right near the No`8 mark in the casting. This too had been blocked off with a flat plate bolted to it. Is this system there to warm the casting beneath the carb with low pressure exhaust gases, to stop the fuel/air mix condensing on the cold metal on start up ? If it is, then mine being blanked off, has got nowhere for the gases to go.and surely isn't doing what the designers intended. Did the original pipe or pipes get fed into the exhaust pipes (my system has been replaced by a dual stainless item, many years ago. or out into the open via a filter system or what? I'm going mad here trying to fatham it out. I need to rebuild the manifold and re-install it, but not without rectifying some previous owners handy work, if you know what I mean. I don't posses a manual and need to know the torque settings for the head bolts etc. Any help any one may be able to offer to clear my aching head, will be very gratefully received. Are there manuals available on the internet or via any of you dudes ? Thanks for listening, take care out there. Dave.
Dave, The tubes on the edges of the intake manifold are part of the A.I.R emissions system. It consists of an engine driven air pump that injects air into the exhaust ports resulting in continued combustion to reduce emissions. The other opening at the back of the manifold is for the E.G.R. valve, another emissions device that introduces exhaust gases into the intake manifold to reduce peak combustion temperatures, to control formation of oxides of nitrogen. Your manifold should look like this.
Dave, You really need to get a chassis manual for your car. If you can't find them in print(I think Poston sells repros), get them on CD ROM. The torque specs for intake manifold to head bolts are 55 ft. lbs. for the 350, and 65 ft. lbs. for the 455. The sequence is pictured below.
MANY THANX GUYS, SO I GUESS I DON'T NEED THESE A.I.R OR E.G.R SYSTEMS THEN? THE CAR SEEMS TO RUN FINE WITHOUT EM !I'LL LET YOU KNOW HOW THINGS GO OVER THE NEXT COPLE OF DAYS, ALL BEING WELL. HAVE A GOOD ONE. DAVE.
