I'm about to reinstate the stock pre heat set-up on a weber prog manifold....the intake side is more or less sorted (on paper) but I'm wondering what'd be the best bet with the heat risers: I'm taking exhaust gas from cyl 2 up into the manifold and back out to the collector box (Bluebird stainless system)...there are several ways I can do this: have a single continuous tube made up with the same OD/ID as the riser tube, which pushes into the manifold (as per) and bolts to the collector via a proper flange fitting... have a two piece pipe that connects somewhere accessible, using the aftermarket riser tube plus a bespoke piece connected by flange fittings use stainless flexi pipe from the manifold to the collector using spigot connections. All three options involve having a suitable connector welded to the collector. I prefer the idea of one continuous pipe, but just know it will probably be an arse to fit. The second option will make fitting easier but will involve more work, and another potential source for leaks. The last option would be a breeze, and wouldn't require much effort, but I'm not 100% what sort of fitting would be appropriate. If anyone has any experience, or can offer some ideas, I'd be grateful. I'm hoping some of the known welders and metal wranglers (@zed @Paul Weeding et al) might offer some pearls of wisdom..... Vielen Dank
Just what I was thinking, or a pair of ICT's, nothing wrong with them and they come up cheap as people don't know how to jet them.
So this is a modification to add the pre-heat connections to the header? Which bluebird system do you have? This one?
A 4 into 1....it has the heat riser flanges on the headers, as above, but this just has the effect of pulsing gas from 2 and 4 cylinders. Basically, I'm trying to find out if a 5/8 OD tube (same as the heat riser tubes) can be welded into either end of some stainless flexi....one end pushes into the inlet manifold, the other would have a flange fitting on it so I can mate it to the collector....simples....
Wouldn't this be easier....? http://www.vwheritage.com/vw_spares...D_62235.htm?crumbStartPage=4&crumbStartRow=46
Also how vw originally made them (I can't remember which way round it goes) cylinder 2 exhaust preheat feeds through the manifold, and there is an internal tube within the exhaust to make it vacuum draw the exhaust gasses through the pre-heat pipe!!
Don't think it matters which way round it flows, provided opposing cylinders are used....I have the riser tubes in the link....i want to replace one with a flexi to the collector where the headers merge....
Another option would be to tap the manifold riser inlets and plumb my oil through it...keep the carb warm and cool the oil at the same time
On the other hand if you have it full flowed and could wind in suitable fittings... But it wouldn't give enough heat, remember it's continually sucking in cold air in a vacuum.
Agreed, but the engine oil still gets hot....It's full flow, so it's definitely doable...just not sure if it will provide enough heat from start up compared to exhaust gas... I had an IMDU of sorts when I was running a Pict...@Dicky blagged some heater wire from a guy at British Aerospace....think they were used to pre-heat fuel venturis on jet engines...or something similar....worked at treat....didn't bother to check the amp draw though. He may have some more knocking around...
