lowering fuel pressure

[Grim304]

Hi, can I use just a regulator to drop the fuel pressure to 4psi from the standard pump?
The reason I ask is that I am going to carburettor to try so I can work on a modified intake manifold.

My worry is that trying to reduce a pump that can push 50-70psi it will be too much for a regulator?
I will run a regulator anyway but I gather I will need to buy a low pressure fuel pump instead of using the stock unit.

So far I have a 4-barrel intake manifold with 1" spacer and 650dp, I also have spare bonnet to cut a hole for it as well.
I may actually stay with carb as the sound of a carby V8 is pretty awesome at WOT.

[hot308vb]

Just make sure you get a good quality fuel pressure reg and it will do it no problem, my mate is using a Aeromotive one(i think) on his Carbied 6/71 charged ls 6 litre using two Bosch 044s with great results.

[Grim304]

Thanks for the advice

[Grim304]

I have picked up a Holley with single in, and has a return line so i can plug it into my existing setup.

The carby will likely be a temporary setup as I need to open up the injection manifold and I plan to put a top plenum on it and eventually run an 80mm TB.

I may need some help with the ECU though as not sure what exactly will happen or if it will run correct timing and what will happen to the Auto Trans settings.

[antus]

It might throw some fueling DTCs if the tune isnt as good as it expects and of course when it trys to apply fuel trims they'll have no effect, but it'll handle spark and the trans OK. If you want to clean that up you can mask those DTCs and turn them back on when you go fuel injection again.

[VL400]

There are a few spark only delco setups on here. Mounting a TPS is worth doing or you work from the idle spark table.

http://pcmhacking.net/forums/viewtopic. ... 36&p=18433

[Grim304]

cheers team, at this stage the plan is temporary, i am running some pretty nice flowing heads that actually match the full available gasket holes whereas the injection has mm's to spare, at least the gaskets give me a size to work with

[Jayme]

ive run an 808 with spark only before. if I left the tps off, it would run off the idle spark table only. but if I left it plugged in but not acutally connected to the throttle shaft, the ecm would set an error code and then it would run off the main spark table like I wanted .
I just disconnected the injectors, IAC and MAT, bolted on the holley and plugged in a tps and shoved it under the manifold to hide with the carby tuned up and widebanded it ran ok, but after I ran the EFI style spark map, it drove like an injected one. you could swear it was stiil an injected 304

[Holden202T]

we run a similar setup to Jayme, carby 202 with delco for spark and TPS connected to the loom only.... its a pig when cold because its methanol and has no choke, but once its warmed up it runs so nice!

[Grim304]

That sounds too simple....
Thank millions, you have made me feel much more confident. TPS it is then.

I had to grind a little off the manifold as the heads have a small lip and it was stopping it sitting flush. I am still waiting on the Holley regulator to turn up but that should be be pretty straight forward.
I have a few alterations to do to the hoses and vacuum to make it tidy, then I have roller rockers once all the other stuff is sorted.