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Boost referance holley TBI regulator?
Posted: Tue Jul 10, 2007 1:01 pm
by BottleFed70
Was wondering if anyone could point me to some info on how to modify the fuel pressure regular in order to have it boost referanced.
The current fuel pressure regular is part of my 900cfm holley TBI unit. I would like to modify it if possible.
Thanks!
Posted: Tue Jul 10, 2007 3:16 pm
by efahl
We converted a Bosch one once by just drilling and tapping the air vent hole and putting a barbed hose fitting in the hole. Measured the pressure across it, while changing the back-side pressure with a hand pump and it worked just as desired.
If you can find the port on the regulator, you're in luck, otherwise you need to somehow enclose the atmosphere-side of the regulator diaphragm to get it to see the inlet pressure.
Eric
Posted: Fri Jul 20, 2007 5:28 am
by long283
If you look closely at your Holley unit you will see a small hole above one of the 4 throttle butterflies close to the regulator press regulator which is the atmosphere reference for your regulator.
If you are going to boost your car by attaching a manifold on top of the Holley unit the fuel pressure regulator will be referenced to the boost pressure at your throttle body. Just make sure your pump can still deliver enough fuel flow at the higher pressure.
Just double check to make sure your unit is the same as the one I'm talking about.
By the way I'm about to start my own project using a Holley 900 cfm pro-jection unit on a 350 chev. Any advice you've got would be much appreciated.
Posted: Fri Jul 20, 2007 10:14 am
by BottleFed70
Thanks long283,
I've heard that from a few sources now, so yes it does appear as tho this holley TBI is already "boost referenced".
The holley TBI's work very well, so I don't have a lot of advice, but can give you some tips:
-consider looking for the smaller 65gph injectors(out of the 700cfm TBI's) if you arn't going with forced induction as the 85ghp's are a little much for a small block.
-buy a weatherpack connector kit. Holley uses weatherpack connectors, so you'll be able to use the existing connectors, and it will come in handy for the rest of your MS wiring.
-Make sure your TBI has 1:1 linkage for the throttle plates. If not, you'll probably want to look into modifying yours so that it is 1:1.
Here's a writeup I did for my MSEFI conversion. It shows a bunch of pics of the TBI, fuel system, etc... it was done with a classic mustang in mind, but I'm sure you'll find some useful information:
http://www.302w.com/Windsor_MegaSquirt_Part1.aspx