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N/A A15 build tech questions


gdat210

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What is the best head/carb/intake combo to wake up an A15 motor with an emissions head? I am about to have an extra A15 laying around that I want to build and put into a 210 Wagon. Any advice  or ideas are welcome. I had an account here long ago but forgot all the details associated with it, so hello again! Hope all is well in the neighborhood. I am currently in the planning phase of this build and I have 2 Dell'Orto's side drafts I would like to either use or sell to recoup money for other ideas. Pics of the wagon will come Saturday for anyone interested! I am going to pick it up this weekend and drive it 5 hours back to Jackson, MS from Huntsville, AL, so it should be a fun trip. I plan to snag a bunch of parts off of my donor car (a running and driving 81 210 hatch but has been wrecked in the front) and take them with me in case anything goes wrong.

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I would definitely say some kind of multi carb, but side draft, and SU type or slide carbs from a motorcycle. I'm convinced that slide type or constant velocity are the best all round from putting R-1 motorcycle carbs on a home made manifold for my L20B. Idle and off idle is incredible smooth and strong, almost impossible to stall. It now pulls all the way to 6K where before it had run out of steam above 4K and it was a long wait to get to 5. Being constant velocity the throttle basically self adjusts and opens as needed so absolutely no bog and no shortage of gas and air and with a 1.5" opening for all cylinders there is no restriction. I can look in the open end and see the intake valve so no 900 elbows or bends..  

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2 hours ago, gdat210 said:

What is the best head/carb/intake combo to wake up an A15 motor with an emissions head? I am about to have an extra A15 laying around that I want to build and put into a 210 Wagon. Any advice  or ideas are welcome. I had an account here long ago but forgot all the details associated with it, so hello again! Hope all is well in the neighborhood. I am currently in the planning phase of this build and I have 2 Dell'Orto's side drafts I would like to either use or sell to recoup money for other ideas. Pics of the wagon will come Saturday for anyone interested! I am going to pick it up this weekend and drive it 5 hours back to Jackson, MS from Huntsville, AL, so it should be a fun trip. I plan to snag a bunch of parts off of my donor car (a running and driving 81 210 hatch but has been wrecked in the front) and take them with me in case anything goes wrong.

 

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19 minutes ago, datzenmike said:

I would definitely say some kind of multi carb, but side draft, and SU type or slide carbs from a motorcycle. I'm convinced that slide type or constant velocity are the best all round from putting R-1 motorcycle carbs on a home made manifold for my L20B. Idle and off idle is incredible smooth and strong, almost impossible to stall. It now pulls all the way to 6K where before it had run out of steam above 4K and it was a long wait to get to 5. Being constant velocity the throttle basically self adjusts and opens as needed so absolutely no bog and no shortage of gas and air and with a 1.5" opening for all cylinders there is no restriction. I can look in the open end and see the intake valve so no 900 elbows or bends..  

never attempted to fabricate my own manifold at this point, but I'd like to give some fab work a shot. I've done very little and looking to gain experience. any pointers on the design aspect of making an intake manifold?

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Make sure the carbs clear the strut tower and brake master by adjusting the runner lengths to suit. I made a two flanges each with two intake pipes that bolt to the head out of 1/2" steel and 1/5" muffler pipe so I could just weld it. If I had a TIG I would have used aluminum. The 1/2" is the same as the exhaust manifold flange thickness. This is because the L series use bolts with a cone washer and nut that bridge across both. One bolt clamps the intake and the exhaust manifolds. if one flange is thinner the cone washer might not clamp properly. I don't know off hand how the A series are, probably the same. 

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2 minutes ago, datzenmike said:

Make sure the carbs clear the strut tower and brake master but adjusting the runner lengths to suit. I made a two flanges each with two intake pipes that bolt to the head out of 1/2" steel and 1/5" muffler pipe so I could just weld it. If I had a TIG I would have used aluminum. 

what type of welder did you use? I don't suppose its something my little harbor freight flux-core special could knock out is it?

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I have a 180 Lincoln. The trick is to not blow holes in the thin muffler pipe yet get good penetration into the 1/2" plate. 

 

I'll post some pictures after work. I used a 1/5" hole saw on a cheap $80 drill press. Took about 45 minutes a hole through the 1/2" steel by using a water bottle with a hole in the cap. Just keep it swimming in water to keep the teeth cool and easy on the down force. Got the 1/2" plate as scrap and bought the muffler pipe but just a easily could be scrounged from a muffler shop dumpster. You only need four 6" lengths.

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26 minutes ago, datzenmike said:

I have a 180 Lincoln. The trick is to not blow holes in the thin muffler pipe yet get good penetration into the 1/2" plate. 

 

I'll post some pictures after work. I used a 1/5" hole saw on a cheap $80 drill press. Took about 45 minutes a hole through the 1/2" steel by using a water bottle with a hole in the cap. Just keep it swimming in water to keep the teeth cool and easy on the down force. Got the 1/2" plate as scrap and bought the muffler pipe but just a easily could be scrounged from a muffler shop dumpster. You only need four 6" lengths.

thanks, that sounds doable. I'll be waiting on pictures! Is there a reason you used water instead of cutting oil? Or just what you had on hand?

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I had a spare intake so I cut the flange off. Probably could just stand it up and trace around it.

 

Frm05Vt.jpg

 

The teeth tend to bight into the steel so you have to be ready to pull it back quickly to prevent it stalling. I used lots of water to keep them cool. I guess 45 minutes was for each flange so 200 minutes a hole. It chatters a lot but worked well.

 

nOJEK2i.jpg

 

I remember now... I put the pipe in and welded the inside then welded the outside just for support and show. It doesn't have top seal as the inside weld does this.

 

DJgz2uK.jpg

 

I couldn't bend the pipe for the two inside ones so I mitered them and welded them up with two bends.

 

LCka2fz.jpg

 

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Lots of test fits on a spare head.

 

mpe9Nxe.jpg

 

Silver rust paint. Remember these outer welds don't have to be air tight or perfect and they sure ain't perfect to look at.

 

YNvfspL.jpg

 

Five minutes each with a ball peen hammer and some scrap exhaust pipe and ... velocity stacks!!!!

 

MPtNYN6.jpg

 

Two pieces of scrap, one with holes...

 

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280zx air filter...

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$2 serving tray as a heat shield.

4Ln1Nz9.jpg

 

YwDun0Y.jpg

 

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12 hours ago, datzenmike said:

I had a spare intake so I cut the flange off. Probably could just stand it up and trace around it.

 

 

 

The teeth tend to bight into the steel so you have to be ready to pull it back quickly to prevent it stalling. I used lots of water to keep them cool. I guess 45 minutes was for each flange so 200 minutes a hole. It chatters a lot but worked well.

 

 

 

I remember now... I put the pipe in and welded the inside then welded the outside just for support and show. It doesn't have top seal as the inside weld does this.

 

 

 

I couldn't bend the pipe for the two inside ones so I mitered them and welded them up with two bends.

 

 

 

 

 

Lots of test fits on a spare head.

 

 

 

Silver rust paint. Remember these outer welds don't have to be air tight or perfect and they sure ain't perfect to look at.

 

 

 

Five minutes each with a ball peen hammer and some scrap exhaust pipe and ... velocity stacks!!!!

 

 

 

Two pieces of scrap, one with holes...

 

 

 

280zx air filter...

 

 

$2 serving tray as a heat shield.

 

 

 

 

Great write up, thanks for sharing!

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The ports in the head and the manifolds rarely line up perfectly as things shift around during the molding process. Get a new manifold gasket and position on the head. Use a nail to scratch the outline in the aluminum or just spray paint it. Remove the gasket and anything inside the line or any paint showing can be ground away with a dremel. Blend into the ports and smooth as far as you can. Now do the same with the intake and the exhaust manifold. When done intake and exhaust have a smooth unobstructed path into and out of the cylinder.

 

The dremel can also be used to remove material around the valves closest the cylinder walls to un-shroud them and improve flow. Roundness is the name of the game. No sharp edges. NOTE removing material will lower your compression ratio depending how much you remove.

 

If the valves are out you can dremel and smooth the aluminum just below the valve seats. Often these are machined out and burs left, or there is casting flashing on the port walls. DON'T touch the valve seats!! You can also chuck the valves into an electric drill and hold against sandpaper to round and remove the sharp edges off the inlet and  outlet side... again DON'T touch the actual valve face that contacts the valve seat! Great care is needed doing this. The combustion chambers can be sanded smooth and polished to a shine. This resists carbon build ip and the resultant hot spots that can become ignition points. The mirror surface also reflects heat and reduces heat transfer into the head reducing the quench effect keeping the heat in the combustion chamber where it does work. Install the plugs you intend to run and torque down. If any threads show above the surface of the combustion chamber surface grind them away carefully. At this time you may want to experiment with different thicknesses of washers so that when torqued the plug ground strap is facing away from the intake valve. It's supposed to add .0002 hp per cylinder of something. Won't hurt I guess.

 

Having the head re-surfaced is an easy way to raise the compression after grinding and polishing the combustion chamber. It's a good idea the cc the combustion chambers to see what your compression ratio is and how much to mill to get it back or raise it..

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  • 2 weeks later...

Ok late to the party but as one of the few guys on here racing an A-serIes powered car I will chime in.

 

First, I too am a fan of bike carbs. I was lucky enough to score a set of flat slide carbs and custom manifolds about 10 years ago. Mine are non CV which do not have the restriction of the throttle plate like CV carbs do. CV carbs are still perfectly fine they just flow less. The bike carbs like R1 or Keihin flat slides like I use are essentially downdraft (45 degree angle) and so they clear the brake master cylinders. The classics dual DCOE style require the master cylinders to be moved.

 

As as for cylinder heads; the A15 motor commonly used shrouded ports. Datsun1200.com has pictures that show the obstruction. No one has tried hogging out the port for fear of hitting a water jacket. The heads you want are either the H89 or the GX head. GX heads are pricey. A race ported one one will set you back as much as $2000, I paid $600 for an umodified GX head several months ago and then put about 20 hours in the head.

 

As for porting the biggest gain is in the valve seat valve bowl area; the seats are narrow then the port and protrude into the port by near 2mm. Cutting back this step with a dremel and then taking material from around the valve guid to open up the port will net the most gains. Then of course match the manifold gasket to the head and manifold.

 

You can go few ways here: 

 

A. Install a weber DGEV 32/36, port whatever head you have, use a Delta 278 cam (moderate street cam), Isky valve springs, header and 2" exhaust. This will net you around 12-15 horsepower.

 

B. Get an H89 or GX head port it and fabricate a manifold for bike carbs, use SI tapered stem valves , Delta 278 cam and 2" exhaust. This will net you 25-30 horsepower. 

 

C. Add a set of flat top pistons to B. and you get 99hp at th wheels (this is the set up in my car)

 

D. Use .30 over Mazda Miata pistons which will take the motor out to 1600cc. You will have mill 2mm of the top of the Miata pistons and have the small end of the connecting rods from 19mm to 20mm. This will necessitate the use of premium as well as being consecutive on the timing becuase the motor will now be at 12-1 compression.  This will get the car up to 112-115hp at the weeks but you'll now have ventured into the less street friendly zone.

 

E. Order 77mm pistons from SW Motorsports in Australia ($170 US including rings) these have an 8cc dish and keep the compression to 9.5-1 with a standard head gasket and 10-1 with the .6 race gasket. 

 

With all that said cost wise I'd go with A. as for the cost of building up an A-series you could swap over to a L20 or KA24.

 

 

 

 

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  • 1 month later...

I'm going the option A route with my A14. I'm doing a 4 speed swap and planning on pulling the engine to clean it up and re- seal it. While it's out I'm going to Port and polish the head and do the valve springs. Do you have the isky valve springs part number and the spec on the delta cam. Did you replace your lifters when you replaced your cam? Thanks.

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I've got a H89 head for sale btw.

 

The 79 A15 is supposed to have less dished pistons for a little bit higher comprsssion than later pistons.

 

The dellorto carbs will be awesome, be sure to get a wideband o2 sensor and tune them in right.

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18 hours ago, head trauma johnny said:

I'm going the option A route with my A14. I'm doing a 4 speed swap and planning on pulling the engine to clean it up and re- seal it. While it's out I'm going to Port and polish the head and do the valve springs. Do you have the isky valve springs part number and the spec on the delta cam. Did you replace your lifters when you replaced your cam? Thanks.

 

Install an intake/exhaust gasket on the studs and scratch the port outlines into the soft aluminum. Use a Dremel and carbide burr to open up the ports to match the gasket. Blend and smooth into the ports at least an inch with sand paper rolls. Carefully do the intake and now there will be zero mismatch or step up or down when air passes through. The stock exhaust is iron or the header steel but try to match as best you can. The goal is free flowing air without sharp edges that cause turbulence.

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