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EA81 Intake manifold question


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I have a EA1 engine that I obtained. It did not come with an intake manifold. I would like to acquire one and test the motor before opening it for a rebuild.

 

I have been reading about the differences in the EA81 and EA82 manifolds. From what I read I think I should get a EA82 intake manifold due to better air flow and it should fit?

 

Can someone provide feedback whether this is correct? I plan to use this motor on a rail buggy I am beginning to build.

 

Also, I have been using RockAuto for parts list, but is there a good aftermarket performance website?

 

Thanks for the help.

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If your planning to go full custom carburetion any of the manifolds could be made to work via adapters.. Plain old Weber install, stick with the Hitachi manifolds. Just so your aware there are 4 (common) manifold options available. The EA81 carter 1bbl, the EA81 Hitachi 2bbl, EA82 Hitachi 2bbl, and EA82 SPFI with a big round hole and probably the best breather. The EA81 manifolds have the thermostat housing in the rear, the EA82 is in the front. This may be an important factor in making your decision. The EA82 manifolds would likely make little real world difference, unless your building a 120hp monster engine to run at 6500 RPMs all day.

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Thanks for clarification on the different manifolds. I am not trying to go over 100hp. Really a stock build would be fine, but I would like to get a few more HP out of it. So far I am just thinking Webber carb, new cam and since its a buggy high flow exhaust should help get a couple HP's.

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I had a total rebuild recently. 1 mm bigger pistons, spfi manifold ( you need an angled adapter made up) 32/36 carb will soon be rejetted to something like primary main 140, idle 55,air 165....sec main 150,idle 55,air 175. As the spfi is a lot larger. Waiting for jets in the mail. Cam is 15/55 but that for high torque at lower revs good for auto trans.13 d@ btdc. Is already running better than the 38/38 l had on it even dynoed it didn't run as good as the 32/36

Edited by tweety
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Interesting build. Love the trike. I am thinking 32/36 carbs would do me just great.

 

Where did you get most of your parts? I checked out Ram Engines and they have some parts listed, but I am wondering if they have more than listed on the web site.

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They do but they are very expensive as they are geared more toward high output experimental aircraft builds. Get ur rebuild kit off ebay or google "rpm machine ea81 kit". The weber kits are on ebay or here on this site in the usmb store. Take pix and share your build.

Edited by ihscout54
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This is a start. My fingers are crossed for a pit free cam, scoreless round cyls and a sweet crank. I just lost 2 core motors to a flood so wishing you good luck. The hardest part of the tear down is getting the wrist pins out. The plug for the #2 pin will either come right out, or it wont. Youll see what Im talking about when you get there. A long bolt, nut, washers and piece of fuel hose make a great wrist pin puller.

Edited by ihscout54
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Also, I have been using RockAuto for parts list, but is there a good aftermarket performance website?

 

Thanks for the help.

90% of my replacement parts I get from RockAuto. They have always treated me well. Sometimes I go to partsgeek but that is only on occasion.

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This is a start. My fingers are crossed for a pit free cam, scoreless round cyls and a sweet crank. I just lost 2 core motors to a flood so wishing you good luck. The hardest part of the tear down is getting the wrist pins out. The plug for the #2 pin will either come right out, or it wont. Youll see what Im talking about when you get there. A long bolt, nut, washers and piece of fuel hose make a great wrist pin puller.

 

I know what you mean. I am really hoping the inside looks good and just a few  new parts will do the trick.

 

Later, I am going to post a picture of the distributor and see if one of you can identify its brand.

 

 

post-59247-0-02074000-1438189156_thumb.jpg

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Since most EA81 engines left out there have been well used, and they were built a little more dispose-ably (compared to say a Cummins ISB) Ive not had the best luck finding a good/easy core. The liners get out of round from rod issues or what ever, deep scores pits etc. Ive ran into the oil pickup tube being bent from a crushed pan due to mishandling and cams that are often pitted. I wish there was more out there for these engines. Im hoping in time more parts will find their way on to the web for us.

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Well, I got a little further today and a couple questions came up. Overall I am pleased with what I saw today. With the exception of a couple stripped bolts on the exhaust manifolds things look good. The cylinders don't show any pitting which make me positive about the cam condition. I was thinking about taking the heads to the machine shop, but I better make sure the host block is buildable before sink any money into the heads. I have no idea what a ready set of heads are worth should I get stuck wish them. Anyway, can one kind guru help a newbie with these questions?

 

1. How do I get the oil pick up tube out? I tried everything I could think of.

2. Can anyone tell me what distributor this is?

 

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Edited by 11zip
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Personally Ide leave the pickup tube in. I realize the o-ring is tempting to replace but its almost impossible to get the tube out without damaging the mating surface. If you must u need a soft metal chisel. Unbolt it from the block (do not loosen the clamp its needed for proper alignment). Hit it HARD on the o-ring flange right where it sits slightly above the oil pan mating surface. Keep ur chisel as true with this surface as possible, or you will crush the tube. You will have to file the nicked edges down, as I said it will get damaged. Reinstall requires some time in the freezer....

That distributor is a Nippondenso which appears to be incomplete. Cant say what year it is, early ones had external modules, later had internal. My opinion; find another disty Hitachi (reman only with internal modual 1981 +) or Nippondenso (used or new with internal module 1982 +) there are other options we can discuss when the time comes. Either will fit, the only difference with install between the 2 is one tooth. I have always dumped the Hitachi for F.I. Or a Nipp, due to the well known play issue with them.

Edited by ihscout54
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Just a few comments.

 

If you try tofit the SPFI manifold you'll need to file down the block halves immediately under the manifold by about 2mm. The manifold will rock otherwise. Be careful only to file just enough so the manifold can bolt down.Once filed own ther e isn't a lot of met left on the block.

 

If you get the heads shaved or the block faces shaved then you'll find the holes at each end of the SPFI manifold wont line up. You'll need to ream all 6 holes. see pic.

 

Finally read my post "ea81 weber 38/38 to 32/36" - you'll get a lot out o that thread. Chees

 

Tony

 

IMG_0035.jpg

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Just a quick late night update. As suggested I soaked the wrist pin plugs for a couple of days wth sea foam penetrating fluid and was able to get 3 of the 4 pin out. I split the case and I am in the process of getting the 4th pin out. Letting it soak overnight. I will clean up and post pics tomorrow.

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  • 1 year later...

Just a few comments.

 

If you try tofit the SPFI manifold you'll need to file down the block halves immediately under the manifold by about 2mm. The manifold will rock otherwise. Be careful only to file just enough so the manifold can bolt down.Once filed own ther e isn't a lot of met left on the block.

 

If you get the heads shaved or the block faces shaved then you'll find the holes at each end of the SPFI manifold wont line up. You'll need to ream all 6 holes. see pic.

 

Finally read my post "ea81 weber 38/38 to 32/36" - you'll get a lot out o that thread. Chees

 

 

 

TWEETY!

 

I have been cautioned more than once about using dual carbs, the inherent difficulties involved, but please tell me what you think about this, as you have the most direct experience with supercharging these engines and what must/can be done with the intake manifold accordingly...

 

Check out what this guy did:

 

 

 

http://bb.bbboy.net/...rum=8&thread=82

 

http://i148.photobuc...baruSwap005.jpg

 

He wanted to mount dual carbs, obviously, but one thing that appeals to me is your concept of using super-chargers after the carbs to draw air in through the carbs, instead of compressing it into the carbs, which presents its own problems, and I agree with your concept.

In my situation, with a Brat, almost impossible to do much without things coming up through the hood, lol.

However, if I used a custom fabricated intake manifold setup like this guy did, I could also use the separate 'stack' tubes concept to allow for adaptability in how the carbs and supercharger(s) are mounted. Even though less efficient, I could also possibly mount the super-chargers at some right angle or something. In fact, if I am doing anything similar, the possibilities are enticing at the very least, I could still use one carb and supercharger if needed.

I might also (fantasy thinking here) Have two carbs mounted closely side-by-side, maybe facing opposite directions, to make direct, physical linkage to dispense with one or more problems concerning the two carbs remaining equally  matched or tuned, as one throttle cable could easily control both carbs in such a set-up, as well as other linkages.

 

In any case, I am thinking that I could possibly use the spare tire area for things, running the two manifolds at near right angle towards the back, and having more room for the carbs and super-charger(s) just to the rear of the engine, in that ample space, and have more choice in how I might have to cut the hood, and how things stick up through the hood.

 

Your thoughts???

 

 

Edited by RAD
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