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Why can I not go any faster?


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Here's my 28/34 carb, that's 56/68. As it came to me used, it has: one of the two power valves frozen up. Both of the power pistons are seized. I converted it to manual choke, but I have the option of electric.

 

It has sight glasses on both fuel bowls, and twin floats. Steel needles. 2 primary and two secondary jets. Adjustable secondaries with a spring and two screws. I'lll go with the screw adjustable tho. The accelerater pump shot is adjustable.

 

picture.php?albumid=162&pictureid=1925

 

Edit: While I'm on the subject. The frozen power valve, I can't remove it without modifying a screwdriver to clear the pin. I would destroy a power valve it I force it with a flat blade. I'll have to do that before I go on. It's just not a priority at the moment. I've sprayed the jets, linkage, anywhere I wanted with CRC penetrant. I can't stand to smell PB Blaster ever again. I have allergies to it now, I think. I'd rather smell liquid wrench. Used it since I was 7 years old.

 

Thees power valves are marked 40. Not exactly sure at this point, what that meant to the Japanese.

 

P.S. I bought this, was described as: very large japanese carb hitachi? He says some guy told him, Mazda 4. He said "hitachi industrial"? I really don't know at this point.

 

It's got glass windows in it. Glass is class.

Edited by Quidam
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Keep in mind brass floats are off the shelf for Hitachi. With a turbo, I'[d braze or solder small copper/brass? tubes in them to reinforce the float, so it doesn't get crushed.

 

Like this:http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=280330473247&viewitem=&sspagename=STRK%3AMEWAX%3AIT

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picture.php?albumid=162&pictureid=1926

 

That is the kit I need for my carb. I don't remember where I got the pic. I do have an email out to a carbologist, so we'll see. The carb does have a symbol on it and numbered in ink, "KCH 348-6". No power valves in the kit. It may be a Nikki carb.

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So Mr. Carbologist says, after I sent him the carb number:

 

"Are you sure on the carb number? That number is not in my book, I've sent a copy of the page on a separate email, Mike."

 

Now, I'm not sure if that's the number. The number I sent him is what the guy I bought it from said it was.

 

I've only got 1.5 power reading glasses, and I need 2.00 power, per my last checkup.

 

I don't have a magnifier in the house. Edit: I do have a 45X magnifying adjustable led microscope thing comming, but here, read this.:" I will send out the item to your eBay address on 29th of Nov. Usually it will takes 18-25 days to arrive your place ,please attention to get it,For I am in backland of China,so the shipping and delivery time will be a little longer, "

 

 

I have allergies that have got my eyes blood shot, Otherwise, I can deal with 1.5 correction.

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Throttle shaft to bore clearance is .005 primary one side, .oo9 the other. Secondary .004 +. All of them could be 4 thousand. Or .002. Or tighter. Air cleaner stud boss busted. I can't screw anything in there. The whole side is missing out of it.

 

4" base, where the air cleaner sits.

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I removed the banjo fuel line fitting. It's 1/4" dia., a small return line goes with it. I'll plug this hole in the back of the carb. The passage that goes from this inlet, goes to each float bowl. On each float bowl there are plugs I can drill out and install fittings. It will be a dual line with no return line. I used to run dual line, double pump Holleys. 30 cc and 50 cc RIO accelerator pumps available for those.

 

The carb top is and fasteners are in the carb dip.

 

 

Well, just to give an idea of what's involved.

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Ok. Now back to the compression gage. Now you have a street car. It's all relative. You might be low, and even on the cranking compression. Car runs good enough. Mabie a little tired, but what the hey...

 

Consider this on a racing engine. As for leaking one down, the way you find out if you have a motor.

 

If every thing is top notch, no more than 2% leakage. 2-4 not so bad. An average leak rate less than 5%. Now this info was givin to me, and I'm more or less quoting someone I admire.

 

5 to 8% is a sub standard seal. If the average is over 8, you don't have an engine, not one that wins in compettitive racing.

 

"This doesn't sound like very much to worry about, but you have to remember that only 1/3 of the heat energy (pressure) developed by each cylinder is actually going to push the piston down. So, if 8% of the cylinder pressure is leaking away, you are theoreticallyy losing 24% of the recoverable flywheel horsepower."

 

If the cranking compression of your engine suits you. Well, who's to argue?

 

Doug

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Bearing this in mind, I am surprised I can turn my engine over by hand at all. I know that my compression is equal and it must be reletively good since I only rebuilt it 2 years ago but with a 10" wrench on the crank shaft I can turn it over with reletive ease.

 

What do you suppose the percentage of leak would be for a factory stock EA71? Or any standard road going car for that matter.

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Hey,

 

This piston is from a 1.2L EMPI Subaru. I got it as an ex mail car with a bad tranny. I didn't drive it at all, but I tuned it up and ran it for a bit. It ran and sounded fine.

 

The compression ring clearance-to- ring land is .0045. Factory spec is .0014 to .0030. Subaru says max .0030, believe it. This piston will be recycled as scrap.

 

The extra clearance allowed oil to seep past and cause pre detonation. See the rough area up there to the left? That's damage. If I stuck a new set of pistons and rings in it, it would run great. That's without even correcting the bore wear that it has. It would still be rebuilt. Remanufactured requires boring, piston, and ring. IMO.

 

picture.php?albumid=162&pictureid=1927

 

And here's what happens. A turbo is installed, boost it up...and they do. Next thing you know, where you see that damage, the piston is blown up, caved in, it's done.

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Hitachi 4 Bore, that's all I can call it for now. This is a sophisticated carb. I copied and pasted that word, now look what happened. 26 pieces of screw in brass. I've got 16 out, need a different screwdriver for those.

 

picture.php?albumid=162&pictureid=1938

 

17 mm accelerator pump. I've never seen another like it. But it's only got one. Mechanical secondary is not hard to do. I just wouldn't have the 2nd pump for it. The brass plugs you see is where I'll tap on each end for the dual feed lines. One for each float bowll. Externally adjustable needle and seats would be nice to have.

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My fuel inlet is filtered by the big screen. Each needle/seat is filtered by a small screen. If a carb car sits around, it will build varnish and such in the float bowl. From here unfiltered, it goes to that tiny hole in the power valve.

 

I'm leaving all three out and drilling a bigger hole in the power valves.

 

 

picture.php?albumid=162&pictureid=1939

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Externally adjustable floats are doable with off the shelf parts. The needle seat is made up of six pieces on these. I haven't been able to source the brass floats i need.

 

Doug

 

PS-I'm getting old and I'd like to install a white led in each float bowl, with a switch. So I can see the fuel level, without reading glasses and a light, any time of the day.

 

Damn, someone might think I'm really out there on that one.

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Yea. I stripped it with only a Subaru screwdriver and one other after dunking it in chem dip, and multiple hits with penetrant. I need to get a jet driver. Webber jets have the same thread. It's going through the last dip and such.

 

Well, the throttle body FI is a good and viable option. Take my choice at any given time.

 

I'm amazed at the current technology technology with carbs tho too.

 

It's not one or the other for me.

 

How about this carb with stand-alone full MSD ignition. I was making good power with carbs before FI even came along.

 

On the other hand, for the same power. Price complete FI system. Price carburetion. I can do it cheaper with a carb.

 

Without a wideband.

 

Doug

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Which comes back to, why he can't go faster. I'm positive his car doesn't have the vacume signal it had when it was new. Re rebuilt it. The carb can only be it's best with the best vacuum signal.

 

If he converts it to FI, it will run better. FI is an effective crutch that covers this up.

 

He will go faster, probably.

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I just realized that, say if you have a clogged power valve with your Hitachi. If you stick a bigger jet in the primary, you can totally compensate for the clogged valve. There is a factory power valve plug out there too.

 

So that's a tuning option for me. I could plug both those valves.

 

Holley jet driver looks good. I can use jet extensions to move them out of that hole and easier to change. Of course, I can see in the float bowl so it will be easier to fish one out if I loose it in there.

 

Edit: Fuel pressure regulator. This will work. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=260403874645&category=33555&_trksid=p4012.m8&_trkparms=algo%3DMW%26its%3DC%26itu%3DUCC%26otn%3D20%26ps%3D63

Edited by Quidam
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Ah Ha! So now we get to the dirty details.

 

Doug, did you read my threads named 'knock or preigition' and 'my suspect wrist pin'?

 

Your post about the worn piston got me thinking about my strange noises. As did the post about my bores. What did those people have to say about them?

 

Is it possible to rebuild this block for the third time or should I be throwing it away? I do have access to oversize pistons and bearings etc.

 

Great new avatar by the way!

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Ha:) Do you have a point type distributor? Theres vacuum advance, mechanical advance, total advance, so on and so forth.

 

You want the major thrust on the power stroke about ten degrees after top dead center.

 

You have to find out what the motor wants with timing. I had one that wanted thirty eight degrees total, not more or less.

 

Over size and rebuild when/if you get around to it.

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