Horsepower stats anywhere?

[rbastedo]

I've been digging in the Wiki a bit and found the stock HP numbers.

Is there any way to find out roughly (without actually testing) the HP generated by my current configuration.

H72 head on a A15 with dual 1.5 inch side draft carbs.

 

I know from the seat of the pants perspective that there's more power now - but how much?

[zerow]

Well, IIRC, the SUs were a 10 HP upgrade, out of the box. I have the info for an L18 so the numbers shouldn't be too unreasonable for the A15.

[rbastedo]

What about switching from the economy cylinder head with small round intake ports to the oval port head?

Or is the 10 HP you mention with the whole package, cylinder head, SU's and manifold?

 

 

Well, IIRC, the SUs were a 10 HP upgrade, out of the box. I have the info for an L18 so the numbers shouldn't be too unreasonable for the A15.

[hang_510]

if you have the weight and 1/4mi times... http://www.angelfire.com/fl/procrastination/quarter.html

[zerow]

What about switching from the economy cylinder head with small round intake ports to the oval port head?

Or is the 10 HP you mention with the whole package, cylinder head, SU's and manifold?

Whole package. Cylinder head, SUs, removed smog equipment (SSS didn't have no stinking smog...). It feels like its pulling harder because it is pulling harder. Dual 1.5s open differently than the progressive (puny) stock carb. You are effectively force feeding the combustion chamber with synchonous carbs.

[rbastedo]

Ok, so a slightly different question:

 

What's considered redline on these motors?

It's never been an issue until now, the old puny carb wouldn't allow much over 5k rpm anyway.

[zerow]

Ok, so a slightly different question:

 

What's considered redline on these motors?

It's never been an issue until now, the old puny carb wouldn't allow much over 5k rpm anyway.

6000 RPM...

(citing my source): http://datsun1200.com/modules/mediawiki/index.php?title=Tachometer

[metalmonkey47]

Ahhh the good ol' A-series!

 

These are pretty good motors to build, because if you do it right, you can build a pretty torquey motor out of them. From what I've been told on Datsun1200.com, they can handle revs in stock form up to and not 1RPM over 6500, but I would never take mine higher then 6000. I've heard of gains through that kind of setup ranging from 10-15HP, but thats depending on a lot of variables.

 

If you want to rev higher, then you want to look for stronger valve springs like the GX springs. Also, if you haven't already you need to upgrade from the stock coil. Now that you're putting more air and fuel in the engine, you want to put more spark through to make sure you burn off every little bit of gas. More spark=more efficiency and more power. With that said, you also want to open the spark gap to take full advantage of the increased spark.

A good coil for the A15's is the MSD Blaster series. I'm running a Blaster 3 coil with the 8OHM ballast resistor (REQUIRED!!!) and I can tell the difference in the way it revs, idles, and how much cleaner the new plugs seem to be.

 

You might try jumping on the Datsun1200.com forums for this question, because those guys are A-series gurus.

[rbastedo]

With my current transmission and rear end 6k rpm in 4th would give me 102 mph.

At the moment I really don't need more than that... :)

 

Yes, I'm a member over at datsun1200 forum but haven't spent much time there lately.

I'll go back and dig around.

 

On my way home today the front carb started over flowing, gas coming out the vent tube.

Probably gunked up float valve. Crud!!

[zerow]

On my way home today the front carb started over flowing, gas coming out the vent tube.

Probably gunked up float valve. Crud!!

Or a brass float full of gas...

Plastic floats for the SUs: 16061-K1407

[rbastedo]

Or a brass float full of gas...

Plastic floats for the SUs: 16061-K1407

 

 

Thanks!

[DRIVEN]

Ok, so a slightly different question:

 

What's considered redline on these motors?

It's never been an issue until now, the old puny carb wouldn't allow much over 5k rpm anyway.

Mine runs out of cam way before 6500. Also, the pushrods are fairly heavy for as small as they are so valve float will come into play. I rarely take it past 6K because there's no more power up there. If you have oil and water in it -- you'll have to work pretty hard to hurt it.

 

As for rough HP estimate...85 maybe?

[zerow]

Thanks!

;) No Problem

[rbastedo]

Or a brass float full of gas...

Plastic floats for the SUs: 16061-K1407

 

I pulled it and flipped it over and took it apart.

It already has a plastic float.

The float valve seats and shuts off, I put it back together and the thing is still pouting gas out the overflow pipe.

Either the float has a hole in it or it is sticking.

I'll have to take it apart again tomorrow.

[zerow]

I pulled it and flipped it over and took it apart.

It already has a plastic float.

The float valve seats and shuts off, I put it back together and the thing is still pouting gas out the overflow pipe.

Either the float has a hole in it or it is sticking.

I'll have to take it apart again tomorrow.

Unless you hear gas swishing around in the float, The float is fine...

 

I would remove the float bowl tops again (I know, I know...)

 

CAREFULLY disassemble the needle assembly. Don't lose any of the small parts, especially the little keeper spring.

Use carb cleaner and a Q-Tip and clean the seating surface first. You will want to do this a couple of times until its squaeky clean.

Take the needle and use something simple and non-abrasive. Kleenex or straight up 'John Wayne' tissue paper (A paper restaurant napkin will do, too) and polish up the needle. Make sure its good and clean, too.

 

Reassemble. Repeat for effect on the other float bowl.

[rbastedo]

Unless you hear gas swishing around in the float, The float is fine...

 

I would remove the float bowl tops again (I know, I know...)

 

CAREFULLY disassemble the needle assembly. Don't lose any of the small parts, especially the little keeper spring.

Use carb cleaner and a Q-Tip and clean the seating surface first. You will want to do this a couple of times until its squaeky clean.

Take the needle and use something simple and non-abrasive. Kleenex or straight up 'John Wayne' tissue paper (A paper restaurant napkin will do, too) and polish up the needle. Make sure its good and clean, too.

 

Reassemble. Repeat for effect on the other float bowl.

 

Ok, will do today after work.

 

Does anyone know if there's a local place (Seattle area) where I can buy new floats and float valves?

[zerow]

Ok, will do today after work.

 

Does anyone know if there's a local place (Seattle area) where I can buy new floats and float valves?

You will know if the floats are bad. Trust me. The gas will be trapped in them and they will be found at the bottom of the float bowl full of gas. Don't discount them...yet...

 

Needle valves are best bought from Z-Therapy. ZT31-608...

[rbastedo]

NAPA part number: CRB 21284A

 

About $18 per kit.

 

http://www.napaonline.com/Search/Detail.aspx?R=CRB21284A_0185975786

 

I called my local NAPA store and the nice lady ordered two kits that will be there tomorrow morning.

 

I specified a 1974 MGB - which came with these carbs - if you know of another car that came from the factory with them that would likely work as well.

[zerow]

NAPA part number: CRB 21284A

 

About $18 per kit.

 

http://www.napaonline.com/Search/Detail.aspx?R=CRB21284A_0185975786

 

I called my local NAPA store and the nice lady ordered two kits that will be there tomorrow morning.

 

I specified a 1974 MGB - which came with these carbs - if you know of another car that came from the factory with them that would likely work as well.

You are running MGB carbs on your Datsun?? That would be why my part numbers aren't going to work for you...

[rbastedo]

You are running MGB carbs on your Datsun?? That would be why my part numbers aren't going to work for you...

 

Datsun motor & trans in an MG Midget.

 

So I run with the MG crowd and someone had a pair of HIF4 carbs so we got together last weekend and made the swap of my old econo head & hitachi downdraft to the H72 and HIF4's.

 

Now if you happen to know what needle/jet works best with the Datsun A15 & H72 & HIF4?

[zerow]

Datsun motor & trans in an MG Midget.

 

So I run with the MG crowd and someone had a pair of HIF4 carbs so we got together last weekend and made the swap of my old econo head & hitachi downdraft to the H72 and HIF4's.

 

Now if you happen to know what needle/jet works best with the Datsun A15 & H72 & HIF4?

:lol: Look at me thinking you had a full Datsun setup (engine to carbs) My mistake...

 

I do not, but, I do know of a company that may be able to help you. Contact these guys:

 

APT Performance http://www.aptfast.com/APT_Parts/SU_Parts/a_SU_components.htm

These are the guys who I bought my CNC machined stub stacks from. They (IMHO) are the local authority in this knowledge. If David Anton doesn't have it or know it, he will direct you to someone who does. Plain and simple

[rbastedo]

:lol: Look at me thinking you had a full Datsun setup (engine to carbs) My mistake...

 

I do not, but, I do know of a company that may be able to help you. Contact these guys:

 

APT Performance http://www.aptfast.com/APT_Parts/SU_Parts/a_SU_components.htm

These are the guys who I bought my CNC machined stub stacks from. They (IMHO) are the local authority in this knowledge. If David Anton doesn't have it or know it, he will direct you to someone who does. Plain and simple

 

Thanks, I will look over what they have to offer.

So far the grand experiment is working out pretty well.

Once I get the fuel overflow thing fixed I know I'm going to be pretty happy with this setup.

The Midget is a light little car, and the A15 with this head & carbs provide plenty of power to the wheels!

[hogboy52]

Fuel overflow comes from the float sticking, usually from too much float drop or a groove worn in the brass float lever or both, which will jam the needle. Polish out any groove you can see in the float lever. You can check the needle for wear or pitting with a magnifying glass.

[rbastedo]

all that is fixed, new float valves and adjusted the floats

runs way better now, except that I am having trouble getting s nice low rpm idle