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Guest Message by DevFuse

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need info on using spfi intake for a carb

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14 replies to this topic

#1 Guest_4wheeln2_*

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Posted 21 April 2002 - 09:12 AM

Hey folks, I finally scored an spfi intake, and plan to modify it to have a carburetor base like the weber/holley 5200. I know a couple people out there have done this, or fooled with it some. I would like to know a little more about the connections on this intake what and where they are. I know this sounds like a dumb question, but I am trying to get some info beforehand, so I don't overlook anything. Also, would like to know what others have done about egr(blocked or not) and using the forward facing thermostat. I got the radiator hose that came with the intake, and it looks like it may be close to fitting on the ea81 I have. Any help would be appreciated, I will share what I learn. Thanks, Pat

#2 Guest_PaganQWA_*

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Posted 21 April 2002 - 09:37 AM

I'm very interested in this mod as well. I own an EA82 SPFI so if you need any help on specific plugs, wires, or tubes let me know and I can trace them down. It would take some time to list them ALL :lol: I swear the intake manifold is like the central nervous system of the EA82 SPFI. It can be a challenging mess at times but I just hooked mine all back up so its pretty fresh in my mind.

Good luck, keep us posted, and were here to help! :)

#3 Guest_Mike W_*

Guest_Mike W_*
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Posted 21 April 2002 - 10:02 AM

Well I've finally got mine installed in a way that I'm happy with, so here's what I've learned.

1.) I used the thermostat housing from my EA81 (the part the hose connects to.) It will bolt right on and face either forward or to the rear. You can also rotate the SPFI 'stat housing, it's your choice.
2.) There's a small coolant hose fitting coming off the bottom of the thermostat housing. Bummer, the distributer advance mechanism will run into it when you rotate the disty. I bent mine but nearly snapped it off in the process. You'll want to drill out the hole and tap it for pipe threads then install a 90' elbow fitting.
3.) Use your old temp. sender unit that screws into the thermostat housing.
4.) The coolant pipe for the heater core needs a bit of bending to clear the oil filler neck.
5.) There's a coolant line coming off the above mentioned pipe, it used to go to the throttle body. I plugged up this hose since I'm not heating the carb base.
6.) The other electrical sender units don't get used. I bundled up the wires incase I ever wanted them.
7.) I used the big vacuum fitting on the drivers side for the brake master cylinder.
8.) I used the small vacuum fitting the passenger side for the EGR.
9.) I used the vac fitting on the carb for the distributer advance.
10.) All the other vac fittings can be removed or plugged. Lot's of spare plugs available on the Hitachi.
11.) On my engine there was a bit of the engine case material that interfered with the bottom of the SPFI intake. It was just excess material of no importance so I ground it down. If left there the intake wouldn't mate properly with the heads.
12.) PCV system stays the same. I routed my passenger side valve cover hose to the carb. The drivers side valve cover hose goes to the funky "T" fitting, so does the hose from the PCV valve, and the smaller hose from the "T" goes to a small air filter I made (same idea as the stock system where it took fresh air from the air cleaner.)

I kept my EGR system working since I haven't heard of any real power gains by killing it. I did kill my air injection system, but there's no reason you couldn't keep it working...the wiring and vacuume valves are easy to transfer over to the SPFI intake and Weber system.

Hmmm, what else? I'll go out and look things over and see what other fun lessons I learned doing the swap.

#4 Guest_PaganQWA_*

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Posted 21 April 2002 - 10:10 AM

Mike your a genius :D

Afer a litte revising this could almost be a complete set of instructions for the swap! I could see everything as I was reading it :)

#5 Guest_4wheeln2_*

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Posted 21 April 2002 - 01:13 PM

Hey, thanks that was exactly the kind of info that I was looking for. Once I get my intake all fabbed up, and find a cheap carb to go on it, I will try to take some pics of it and figure out how to post them. Thanks again, Pat

#6 Guest_beauregaardhooligan_*

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Posted 21 April 2002 - 02:01 PM

How much better is the SPFI over the original manifold?

#7 Guest_PBDLoyale_*

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Posted 21 April 2002 - 02:16 PM

If anyone needs extra parts I have two extra complete spfi intake manifolds and one ea82 spfi engine.

#8 Guest_Mike W_*

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Posted 21 April 2002 - 11:08 PM

Really the only thing better about the SPFI intake is that there is more material that can be cut away to enlarge the opening where the carb mounts up. It looks like it should flow much better but weather it really does or not will have to be determined by someone with a flow bench. My car does have a lot more pep now with the 38/38 carb on there.

#9 Guest_PaganQWA_*

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Posted 23 April 2002 - 03:34 PM

Find any more minor details to add to your analysis above Mike?

This is a great thread!

#10 Guest_SubaruJunkie_*

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Posted 23 April 2002 - 04:24 PM

PBDLoyale... email me. Im interested in one of your manifolds. I would have emailed you, but you dont have a email address listed.

Mine is listed below in my signature.


#11 Guest_Mike W_*

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Posted 23 April 2002 - 10:23 PM

Well I stood there looking under the hood for a couple minutes and didn't see anything else funky so I guess my above description pretty much covers it. Maybe I should point out that my carb adapter plate is angled to compensate for the forward lean of the intake manifold. If you just bolted a carb right onto the intake where the throttle body used to be, the carb would be tilted forward at a fairly severe angle. So weather you are bolting or welding your carb adapter on, take that tilt into account.

#12 Guest_SubaruJunkie_*

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Posted 24 April 2002 - 12:11 AM

what will the angle do to the carb? Will it effect performance?


#13 Guest_cameron_*

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Posted 24 April 2002 - 02:47 AM

it will affect float hight and the way the jets work.

#14 Guest_4wheeln2_*

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Posted 24 April 2002 - 03:48 PM

Mike, do you have any idea what angle the difference is between the manifold and the adaptor? I guess what I mean is if I welded a piece of aluminum on to the manifold, would it need to be thinner or thicker at the front and by how much. This sounds like a question from someone who is in over their head, but I just dont have an extra block/heads to mock this intake up on. My spfi manifold doesn't appear to have an extreme rake to it, but its still in the back of my brat. Thanks again, Pat

#15 Guest_Mike W_*

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Posted 25 April 2002 - 10:14 PM

I'll try to get out there tomorrow or the next day and get some dimensions and angles for you. Just going off memory, I'd say the front of the adapter is about 3/4" taller than the rear.

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