ADHA to DFEV carb/manifold swap on '79

[wetminkey]

I started with a full rebuild of my '79 Spider 2000's ADHA, and as I learned more, I realized how limited that carb and associated dual plane manifold are, and how many possible points of failure the ADHA has, due to multiple emissions modules that the other Weber's do not have.
A little peer pressure, and I found it to be time for a change,...
A single plane manifold and larger carburetor swap is the answer.
I have opted for the DFEV because of it's smaller primary of 32mm (for mpg) and the 36mm secondary (for "GO"). Same overall air flow as the 34mm,...
No fuel return on the DFEV, so I'll block that off clean, and I should get a pressure regulator for my supply.
I'll have to plumb my crankcase ventilation and charcoal vapor canister into the new air cleaner (and block off the old ADHA's float bowl vapor inlet on the top of the canister).
I found a used single plane that has an accommodation for the 2000cc engine head's rear coolant outlet (for the dual plane's emissions junk and the ADHA's water choke). The manifold has got to either block the outlet, or have it's own coolant outlet for water choke.
I had to strip the manifold of a vacuum fitting on top (18 x 1.5mm) and two electrical emissions fittings underneath (a 16 x 1.5mm and a 22 x 1.5mm). This particular manifold had an external Exhaust Gas Recirculation pipe that attached to the driver's side, that leaves a 16 x 1.5mm hole when removed. Pics in the next post,...
The 2000cc has an EGR hole that crosses the block at the front of the head, allowing exhaust gases to flow from the exhaust EGR pipe, through the head, to the intake manifold's EGR pipe. I have seen it blocked at the exhaust EGR pipe's entrance to the head, but I'd like to try to close the EGR hole on the driver's side of the block. We'll see,...
Right now I'm seeking the small parts, such as plugs for the holes in the manifold, gaskets/carb spacer, throttle linkage necessities, and an air cleaner. I'll have specifics on sources when I'm sure of them. Pics and more, soon.
Todd.

[wetminkey]

Pics.
First order of business is to get all of the emissions garbage off of the 'new to me' single plane manifold,...



And then cleaning it, wiping out the inside and wire-brushing the outside.
I found a great selection of steel Allen plugs at JC Winco,...had to register to order, but the hardware is cheap. Sizes in the post above,...

The manifold needed a small bit of 'porting' to the edge of it's carb flange. Now it conforms to the carb gasket better:

Todd.

[wetminkey]

Today, I struggled a bunch and pulled this great big fish out!

I was able to do it 'easily' from above, by loosening the alternator and pivoting it off to the driver's side. Once the gulp valve and associated hardware was removed from the driver's inner fender (above the vapor canister), I had no trouble reaching under the manifold to access it's bolts/nuts.


Drained my cooling system and had to remove my timing belt cover to be able to remove my driver's side upper, rear timing cover,...necessary to remove the old manifold from it's mounting studs. The thermocouple module, at the rear, also needs to be loosened. The big manifold is a shoehorn fit in there, and will take a little jiggling to find the right angle for removal.
When you're done, it leaves this GIANT hole:

Good time to replace the crankcase vent hoses! They needed it,...
Manifold gasket, spacer, and 8mm throttle ball-stud coming. And waiting for plugs.
More soon.
Todd.

[geospider]

looks great. What a cleaner look you will have, besides the much better driving experience.
All of that stuff is what I get to put back on in a month or so to get smogged here in Ca. then taking it all off again.
Hopefully AB 210 will pass.

Also, a good time to wire in a starter relay if you don't already have one.
I need to double check, but I believe I used a fuel filter that has 2 in and 1 out (to carb). the smaller line being the return.
like I said. need to double check that.

can't wait to see progress.

Geo

[wetminkey]

I have not seen a fuel filter like that. perhaps a pressure regulator? I'll look into it.
Long ago, I bought a small, electric fuel pump for my car (from Midwest-Bayless,...meant for the Spider). The engine starts so quickly that I've never had a concern about adding a relay to the circuit. Once the key is turned to ON, the engine will turn less than a full revolution and start.
I have a couple of vehicles that I've swapped to electric fuel pumps,...finding quiet ones is the key! And the Spider does not require a volume pump - just a small, dependable one,...Weber specifically states that the carb should have NO MORE than 3psi, and if regulated, should be set to 2psi,...surprised me.
The fact that this car will probably not pass emissions again has concerned me a bit,...cities along the front range of the mountains require emissions, but the rest of the state does not. It's got a new cat, and I always tune as lean as possible, but I think definitions require that the car "could been optioned with the equipment in that model year",...
A little sore today,...

[geospider]

Todd,

The relay idea is primarily to save the ignition switch as stated by so many here.
$10 relay and a few bucks in wires.

As for your elec fuel pump. I assume you have one now, and I would guess the ADHA required the same pressure, so you are prob fine.
The Facet (the same you get at AR) pump I have is rated for these. There are a ton of these out there. I did get a pressure regulator, but haven't set it up since everything worked great. I did have to adjust the float; that is important. First was way too high: flooding the motor with fuel. the I adjusted to low and it would run itself (the bowl) out of gas. Now I have it right.

fuel filter:
one like this
https://www.amazon.com/WIX-Filters-Comp ... ive&sr=1-2

My carb guy recommended this for this application

Geo

[wetminkey]

As an ex-Navy sonar tech/electronics tech, I know the benefits of the relay (can't believe that Fiat didn't put one in!),...it will just have to be a project for another time. Luckily, there will be plenty of room to get to everything under the single plane manifold (including the starter), now! Amazing!
Yeah, the small electric pumps don't put out too much pressure, so if I can provide a return line, fuel pressure will be just fine. Thanks for the link! I'll get a couple of those filters with the return line. If I had to plug the return line, I would want to regulate pressure (just in case).
I'll open the new DFEV and be sure it's clean inside, and check the float adjustment, before I install.
Thanks, again. Todd.

[wetminkey]

What comes out, and what goes back in,...28/32 Weber/dual plane to 32/36 Weber/single plane:


Impressive.

[geospider]

What great side-by-side view.
Simplicity. You are so close.
had a great time driving around today. The sound from under the hood will excite you as well.

[manoa matt]

Stack washers, shorter studs, or thicker spacer?

[wetminkey]

Yeah, those LONG carb studs,...I bought AR's recommended 14mm spacer (with gaskets) and I'll still need to add one extra washer to each carb bolt. I can live with that,...
AR's intake manifold gasket also came today,...very nice, heavy gasket. Quite pleased with this!
AR's 8mm throttle-ball stud fitted perfectly, with a couple of larger washers, and a 'double-nut' lock,...accelerator linkage should work as original,...
Plugs for sealing this manifold should be here soon. JCWinco has sent,...
Next, I need to engineer a way to hold the oil dipstick, and a way to block the driver's side EGR hole.
BTW, geospider, this will sound all that much better with the new exhaust that I had installed a little while back,...new cat, larger pipe (from the 4-2-1 to the rear), and just a resonator! Scotty (Ken's Muffler's/Fort Collins) had owned Spiders, and done Spider's exhaust before,...
Flange clean-up and test fit manifold tomorrow. I want to get the dipstick and EGR hole projects completed before installing the manifold.
Spring chores slowing the process slightly,...
All have a great weekend!
Todd.

[geospider]

Todd,

this is how I secured the oil dipstick: some flat aluminum strip, bent and drilled at engine to fit into the last bolt hole from the old manifold, then twisted and secured as shown. I imagine you can also attach to same place with however you decide to block the EGR at driver side.



geo

[wetminkey]

Looks great, geo!
That hole had no bolt through my old, dual plane manifold,...is it the same diameter and thread as the other manifold bolts? I haven't it checked yet.
I'd like to place a small plate (to cover the EGR hole and the separate casting hollow just behind it) in that area, using that hole to secure both it, and a dipstick 'strut', like your's,...
Spent the day mostly with other chores, but got the head's intake flange nice and clean. Ready for test-fitting the manifold!
I hope to investigate further tomorrow, and search for plate/strut material ASAP.
All have a good weekend!
Todd.

[wetminkey]

I had a chance to check this morning. The hole is threaded the same, and probably was intended to have a bolt,...none was there.
I found a nut that fits one of my intake manifold bolts (in my Bucket O Nuts),...so it's time to head to the hardware store for plate material, material for a dipstick strut, and a bolt to hold it all in place! I think I'll rotate the dipstick tube toward the engine centerline and position it nearer the timing belt cover,...'tuck' things up a bit. Also leave better access to the area under the new intake manifold.
Enjoy your weekend!
Todd.

[wetminkey]

Got my tapered, threaded, steel Allen plugs from JW Winco today,...they're perfect.
I used some Permatex thread sealant on each one, and set them into the manifold with my big metric Allen wrench.
A 16x1.5mm and a 22x1.5mm below, a 16x1.5mm for the EGR pipe inlet on the side, and an 18x1.5mm above are required for this particular manifold,...some manifolds will not have the external EGR pipe.
PaulC states that the smaller side port on this manifold is 10x1.5mm, but I won't block mine, since I can use it for my auto tranny,...
I think I'm ready to put this thing together now!
Todd.

Edit: The tranny vacuum fits nicely to one of the vacuum ports from my intake's "triple port" vacuum fitting,...I'll go there and eliminate the small intake manifold vacuum fitting with a shortened 10x1.5 bolt since Allen plugs of that size are not available locally,...