MPFI Manifolds?

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Xplitive
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MPFI Manifolds?

Post by Xplitive »

Are there any readily available MPFI AMC 360 manifolds on the market?

I have numerous chevy parts including an entire engine with an edelbrock pro flo MPFI system on it. Pretty sure I can adapt almost everything with the exception of the manifold. I'm going to contact the manufacturer and see if they will sell a manifold alone but want to know what my options were.... doesn't seem like many after a search...
Erik
1989 GW, 31s on rancho front and general spring rear
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Re: MPFI Manifolds?

Post by shimniok »

Edelbrock is the only game in town that I know of.
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tgreese
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Re: MPFI Manifolds?

Post by tgreese »

My understanding is that designing a correct 'dry' manifold for MPFI is no trivial matter. You can install the bungs in a 'wet' manifold previously used for carburetion, but it won't work as well as it might. Some claim that, without the correct manifold, there is no advantage to MPFI over TBI.

JMO - I'd look to sell the Chevy parts and go with TBI. You can go mass flow or speed density with the GM ECU. Somebody here or on IFSJA has used the GM mass flow sensor on an AMC V8 with good results ...
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JeepsAndGuns
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Re: MPFI Manifolds?

Post by JeepsAndGuns »

Edelbrock is the only one I know of. And it is made for their pro-flow system. You can order just the bare intake, but the throttle body is specific to their intake, and no other throttle bodies will bolt to it. So you will be left with making a adapter plate to bolt on some other TB. I used the edelbrock intake and made a plate to bolt on a 75mm single blade chevy throttle body. It was a tight fit but works good. I also made some brackets to raise their fuel rails high enough to use regular bosch style injectors instead of the short pico style their kit uses.
http://www.ifsja.org/forums/vb/showthread.php?t=148346
http://www.ifsja.org/forums/vb/showthread.php?t=154287
79 Cherokee Cheif. MPFI 401, T18/D20, hydroboost, otherwise stock.
93 YJ. 4.0, 5 Speed, SYE, hydroboost, WJ knuckles/brakes, 8.8 rear, OME 2.5in lift, warn M10000 winch. 31x10.50's
99 WJ limited. 4.0, auto, 2wd, stock.

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Xplitive
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Re: MPFI Manifolds?

Post by Xplitive »

Thanks, can you explain more on the brackets to raise the fuel rail for the bosch injectors?

I already have the throttle body and injectors but just evaluating better ideas. The manifold is around $430, trying to see if I can get it cheaper from another company.
Erik
1989 GW, 31s on rancho front and general spring rear
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JeepsAndGuns
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Re: MPFI Manifolds?

Post by JeepsAndGuns »

The brackets are really simple. I made them from 1x1 angle iron I got at lowes. Just trim to fit, mark and drill the holes. I had to drill and tap holes in the bottom of the fuel rails for them to bolt to.

Image


What throttle body do you have? The size and shape of the opening does not leave any room for a two barrel throttle body. You are stuck either using edelbrocks TB or using a large single blade one like I did. The one I used was from a vortec chevy 350 (late 90's). It tapered in slightly under the throttle blade which I machined out to make it 75mm straight through. I then replaced the throttle blade (which has a air deflector on it) with one from a late model cadillac northstar TB that is flat.

The clearance between the TB and the fuel rail is tight after you raise the rails.

Image
79 Cherokee Cheif. MPFI 401, T18/D20, hydroboost, otherwise stock.
93 YJ. 4.0, 5 Speed, SYE, hydroboost, WJ knuckles/brakes, 8.8 rear, OME 2.5in lift, warn M10000 winch. 31x10.50's
99 WJ limited. 4.0, auto, 2wd, stock.

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Xplitive
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Re: MPFI Manifolds?

Post by Xplitive »

thanks, I see now the injectors you used must be taller. the TB I have is the edelbrock one that came with my SBC kit. After calling, getting part numbers, and then pricing, the cost to convert from the SBC to AMC manifold would be $430 and each rail would be $62. Then add the adjustable fuel pressure regulator, depending on brand, $100-$180. I also converted my system to FAST EZ EFI so its fuel only and mechanical advance. The price was adding up to way more than I was willing to spend.

About when EFI started looking no bueno, a TBI system with a painless harness fell in my lap for a great price from another car forum I'm on. I've yet to receive it so not much to say at this point.
Erik
1989 GW, 31s on rancho front and general spring rear
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JeepsAndGuns
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Re: MPFI Manifolds?

Post by JeepsAndGuns »

Yes, the injectors I used are regular bosch style injectors. The injectors edelbrock use are some type of short pico style. I wanted to use a oem app injector. That way if a replacement is needed down the road, I could get one without much trouble. I am using bosch 0280155931 injectors that were used in a corvette LS1. Using the same intake setup on a 360 would probably want a injector with a slightly lower flow rate.
The edelbrock fuel rail uses a chevy LT1 fuel pressure regulator. Most stock ones are set to 43.5 psi. I bought a adjustable one and I am running 45 psi.
79 Cherokee Cheif. MPFI 401, T18/D20, hydroboost, otherwise stock.
93 YJ. 4.0, 5 Speed, SYE, hydroboost, WJ knuckles/brakes, 8.8 rear, OME 2.5in lift, warn M10000 winch. 31x10.50's
99 WJ limited. 4.0, auto, 2wd, stock.
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husker77
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Re: MPFI Manifolds?

Post by husker77 »

JeepsAndGuns wrote: used the edelbrock intake and made a plate to bolt on a 75mm single blade chevy throttle body.
What did you do with your throttle cable? I have a torker intake I am going to install bungs on for injectors but I did the same thing with getting a gm throttle body to install on it. Figure I get tps and iac built right in and should be easy to upgrade if I need more powa.
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JeepsAndGuns
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Re: MPFI Manifolds?

Post by JeepsAndGuns »

That's my big problem, cause I hope it never breaks! I pulled it from some random GM car in the junkyard and did not pay attention to what it was!
I think I slightly modded the original cable bracket for the TB I used, then found a cable in a random GM car that used almost the exact same setup on the TB side, and the other end was almost exactly the same hookup at the firewall as the stock cable. It seems like I remember slightly modding the cable where it hooks up to the pedal.
79 Cherokee Cheif. MPFI 401, T18/D20, hydroboost, otherwise stock.
93 YJ. 4.0, 5 Speed, SYE, hydroboost, WJ knuckles/brakes, 8.8 rear, OME 2.5in lift, warn M10000 winch. 31x10.50's
99 WJ limited. 4.0, auto, 2wd, stock.
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