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MG MGB GT V8 Factory Originals Technical - Fuel Pressure - Edelbrock/Weber 500 & other stuff
Heh. I'm on holiday, so it's full time playing with the V8. Wooohoo!! <G> Ok, time to stop braggin' <G>
I have a Weber 500 on an Offenhauser manifold. I have an aftermarket fuel pump on my factory V8 but it is one designed to feed SU's so only puts out 2psi or so. I have been to the Edelbrock site and they recommend 6psi for street.. Can someone tell me if I am in trouble here with my SU type pump and if changing the pump for something to output that sort of pressure would be worthwhile? What pumps can I fit in the factory location that put out 6psi? or would I have to relocate a pump to the boot?
Another thing. Has anyone switched from an Offenhauser manifold to a Edelbrock 2198? Comments - was it worth the switch? I hear from Glenn Towery I will need to mill it .2" to clear the bonnet.
Lastly, FWIW I am also going to make up a restrictor plate to drop the 500 down to 400cfm after reading comments on this BBS and advice from Glenn. Apparently 100cfm per litre is a good way to size a carb. Prob explains the bogging(ish) mid range I have and storming top end! Smashes the old setup tho.
|Neil, get a higher pressure pump. No way the SU will give you enough. SU does make a 5.5psi pump that will fit in the stock location. There are many other pumps that to my mind are easier to mount. The Mallory and Holley pumps are good, but they must be mounted vertically (not very hard) and they MUST be soft mounted because the Holley in particular is loud. The Facet Red Top pump is popular with you UK guys but it just doesn't deliver very high fuel volume and I would say is best avoided if you're using a motor bigger than a stock 3.5L - actually most people I know think the Facets are really sub-par. All in, I guess I'd call Burlen over there and see if I could scare up the high-pressure SU. Otherwise throw a Mallory on there and forget about it. Or even go retro and stick a mechanical pump on there ... many V8ers find they work very well indeed and they have the distinct benefit of being silent.|
Thanks for the info. I rang Burlen and they told me they don't have any pumps over 3.8psi - ? Then I called RPI and I bought a Silver top Facet pump. Apparently the red requires a regulator and the silver top puts out 5.5psi. The Weber has a max of 6.5psi so I guess I am a lot closer now. RPI also said they haven't had any problems with the Facets on small capacity engines, the only time they've switched to a Holley is with 4.6+ at over 140mph. The facets just don't flow enough in that situation.
Wonder if I'll notice any difference switching pumps! Doubt it! But better than having a possible lean situation eh.
Cheer & thanks,
This thread was discussed on 28/03/2001
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