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-   -   Modifying a stock 454/502 mpi intake (https://www.offshoreonly.com/forums/general-q/103922-modifying-stock-454-502-mpi-intake.html)

articfriends 09-26-2011 07:17 PM

I recently had a few guys ask me about modifying the mpi intake so I dragged up this old thread. I have since also bored out the throttle body and had the intake full ported. Last time on dyno we made 1115 with the blower and 657 NA, Smitty

offthefront 10-21-2011 10:35 AM

4 Attachment(s)
progress on my intake's ..... I guess this is first stab at it ...fuel rails are going to need some more work ...port side ended up too close to the Distributor .... I'm thinking now feed them from the front and put a return about midway inder each rail ....or ...open to suggestions ....:)

Smitty ... those are your Deka 80lb injectors .... No 1 long block should be ready in the next cpl of weeks and hopefully can start rigging the motor ...m

snapmorgan 10-21-2011 01:50 PM

I modified my stock fuel rail by taking a long 1/2" drill bit and drilling all the way through the rail and then opening each injector passage to 3/8". I then tapped each end to 3/8 pipe thread. I also tapped the side hole to 3/8 pipe to use as a return. I will have to feed it from the front as there is not enough clearance between the rail and distributor in the rear. Wasn't difficult at all, took about 2 hrs to complete.

articfriends 10-21-2011 05:15 PM


Originally Posted by snapmorgan (Post 3533250)
I modified my stock fuel rail by taking a long 1/2" drill bit and drilling all the way through the rail and then opening each injector passage to 3/8". I then tapped each end to 3/8 pipe thread. I also tapped the side hole to 3/8 pipe to use as a return. I will have to feed it from the front as there is not enough clearance between the rail and distributor in the rear. Wasn't difficult at all, took about 2 hrs to complete.

I did almost the same exact thing when I was still running the stock rail. When I went to bigger injectors at the time I ended up with real tall ones so new rails were mandatory. These days you can get big injectors in short versions too, Smitty

articfriends 10-21-2011 05:19 PM


Originally Posted by offthefront (Post 3533105)
progress on my intake's ..... I guess this is first stab at it ...fuel rails are going to need some more work ...port side ended up too close to the Distributor .... I'm thinking now feed them from the front and put a return about midway inder each rail ....or ...open to suggestions ....:)

Smitty ... those are your Deka 80lb injectors .... No 1 long block should be ready in the next cpl of weeks and hopefully can start rigging the motor ...m

Looking good, cut the fuel rail off a little shorter that is too close to the distributer cap, re-tap it and put a plug in. Install a straight thru regulator at fuel rail inlets, bleed the extra off thru the regulator and it will work just fine, not ideal but it's how I did mine because of the same issue. I did install a small oil cooler as a fuel cooler though after the pump/before the rails, Smitty

ezstriper 10-22-2011 08:47 AM

Smitty, my hats off to you on this....great work !!! would really love to see what the H/P diff would be with this vs a properly done blow thru carb....Rob

Gh700xx 02-12-2014 03:15 PM

so how did these setups end up running? I know its an old thread but im curious as im about to start working on mine and plan on the same modifications. any input would be awesome.

GPM 02-12-2014 06:57 PM

Is it really worth it when you can buy something like this, http://www.ebay.com/itm/FAST-INTAKE-...55b421&vxp=mtr

Gh700xx 02-12-2014 07:23 PM

I would definitely say yes it is considering you have to buy another 500-1000 worth of crap to make it work. So yes a few hours of grinding is way cheaper and worth it to me I'm cheap deal with it.

GPM 02-12-2014 07:28 PM

Good luck


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