I am in the middle of ordering parts for a 455 build. Estimated hp somewhere around 450ish give or take. I am trying to decide on if i want to use a mechanical fuel pump or electric. Can anyone give me any real good reasons to go one way or the other?

Also, can anyone recommend a pump? I have had my eye on the RobbMC 550 mechanical pump but i am undecided right now.

 

I've gone both routes with my 442 but prefer the mechanical. In order to run the electic pump properly you will need to power it with a switched electrical circuit that should be tied into an oil pressure switch. This would shut the pump off in case the engine shuts down or loses oil pressure with the ignition still on. Most electric fuel pumps for street use work best(last longer) with a return line to keep the pump from running at full pressure constantly.
The biggest issue with my electric pump was the noise. It took a few mounting bracket designs before I got the pump quiet enough for my liking.
One thing to watch out for with the bigger mechanical pumps is size. The current mechanical pump I am running required trimming my alternator bracket to allow the top exit fuel line.

 

Somewhere around that HP, the stock size mechanical pump becomes insufficient. Either a bigger RobbMc mechaical or an electric pump will be needed if you plan more than a quick stab of the pedal.

 

Thanks guys. I'm leaning towards the robbmc mechanical pump. My carb is a qjet tuned specifically to my car. Knowing that and the power ill have, will my stock sending unit and lined from the tank need upgraded as well? I have heard the stories about qjets having a problem running dry. These stories were probably from ppl who didn't know how to set them up either though. Just want to make sure with all the performance mode I don't starve the motor while still appearing stock

 

Is this a street car?

 

I just looked this pump up online and it is the same pump I am running on my car. I am very happy with the pump. But I did have to rework the alternator bracket. The bracket I am using is off of a 74 455 with air.

 

It is a street car. It will be hot dogged around town mostly but could occasionally see the track

 

excellent. My car doesn't have air but I don't have a problem modifying the bracket if need be. What size lines are you running from the tank to pump and pump to carb?

 

I was told my engine set up would make between 400-425HP, never dynoed just the builders claim. I am running 3/8 fuel line from the sending unit to the pump and -6 lines from the pump to the carb, which is a 750 DP.
Another thing to keep in mind when running a larger pump is the flow rate of the fuel filters. Make sure they will allow the proper flow as well.

 

3/8" is ok