Wraparound vs. flat sidedraft thoughts
 

I'm at the point where I am deciding on what intake manifold to get for my car.

Engine is a stock port S4 6-port. Carburetor is a 48 DHLA. These two are givens and aren't going to change.

The upper I have is for a GSL-SE lower, which obviously ain't going to work.

Attachment 602933

So I have three options: The $162 sidedraft to S4 lower adaptor upper, which is the cheap/easy button. But it looks scrody as all heck flow-wise.

Option #2 is a one piece wraparound I found on eBay for $250. It looks better design-wise but scrody manufacturing-wise.

Option #3, that I'd prefer, is the Atkins flat manifold also for $250. The sticking point against getting this is I am not sure it will fit the FB chassis, and I have heard that you need to massively alter the carb's jetting when using it.

So I guess the point of the post is, does anyone have experience using the Atkins (Lake Cities) manifold on a FB with a Dell'Orto, and what had to be done jetting-wise to the carb to make it run well? Did an air cleaner fit? I'm wondering if the "needs a lot less jet" is because there isn't much room for a proper air filter and the lid was choking flow to the trumpets.

FM had a lake cities on his for a bit. it works great, which we know.

space is tight, there was room for an air filter, but not a huge one. might be better to run a carb hat and a filter up front.

its also very low in the car, practically knee height.

can't comment too much on jetting. it was a 34 or 36 DCOE (or 42? who remembers), so really small, and i thought the air corrector was really big, but it ran well.

I'm running a Lake Cities manifold with a Weber DCOE and there's no room to put the original trumpets on.
They fit if you put them and an air filter on the carb before installing it (and if studs aren't used on the manifold), but then you'd have to remove the carb to change venturis.

Can't comment on jetting changes as I haven't run the other set up on the current 12A. I had a wrap around manifold with a 48DCO on a 6 port 13B, I remember the jets I needed were quite leaner than Racing Beat's recommendation page.

The wrap around will give you better low rpm torque and smoother response across the rpm range, but
(theres always a butt) it will not rev as high as an IDA or other carb setups.

The straight short intake will give you IDA like performance but its really close on the side by the passenger inner fender and it suffers from sitting right over the headers. Would need good heat shielding.

In either case I would think you would be better off with a box and remote air filter to make it easier
to maintain.

I also am running a Lake Cities (flat) manifold, albiet on a 12a. As noted, the carb is low and space is tight. Instead of trumpets I am running a small foam "dome" filter. As noted, it is superb at higher rpm, although with my stockport, I don't notice much loss at low RPM vs. the Holley I was running before.

As far as jetting, I'm running the jets that came with the carb, which appear to be the Racing Beat recommended jets/tubes/etc. I am running an AFR guage, and cruising aroung it gets a little lean (I don't have the added progression hole) but when I am accelerating it stays in the low 13's for A/F, which is fine by me.

One thing to note, if you do choose this manifold you will need to do something for your throttle/throttle cable. Your factory cable won't be long enough. Luckily, the guy I bought my setup from made a nifty (but odd) throttle linkage setup that allowed me to retain the stock cable.

ETA: As far as heat shielding, I am running DEI Titanium header wrap on my header, and no heat shield. I've had it this way for 2 years now and have not had problems with it getting too hot, even on a hot day or spirited driving.

Interesting. I heard that the 12A throttle cable was sufficient.

Very hmm. I just may get the Atkins then.

I'm probably going to go with a box manifold. Don't want the noise of a header.

the FC manifold works really well. it flows enough for a stock engine, and its a small "exhaust box" so its going to be less picky about mufflers/cats

Nope, decided, getting Atkins.

I never did like the way any other intake manifold required to bend along a tall cross section, anyway...

drivefast7 has a lake cities manifold with 48 dellorto on his race car. he maybe able to share some insights

It would be damn near ideal with a proper air box and 4" intake tube.

Ive thought about doing the exact same thing, because although I dont like the idea of the carb being a tight fit, every car I saw running one was extremely well suited to the track.

and as for loss of low end, the only one I ever drove was a large street port R5 engine, (12a) and it lacked nothing of the sort. It was just as effective down low as a comparable down draft. Only cars Ive ever been around with wrap around manifolds didnt seem nearly as crisp, and kinda always put me in mind of an engine slightly out of tune.