Deep breathing...or how to put IDFs on your X

carl

carl

True Classic
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Got a manifold from Classic Performance and had the IDFs laying around. Basically same set up I have on Fatrat. Need to get some shorter mounting studs (probably pull them from my 124 manifold) and then bolt them on.

Comments about you can't put IDFs on a transverse motor won't deter me.
 
Just let us know how many Gs it can pull before fuel starvation sets in. Actually, I was more concerned about whether or not the height would be a problem but then I figured you would probably put a big scoop on it.
 
carl said:
Need to get some shorter mounting studs (probably pull them from my 124 manifold) and then bolt them on.
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You need to get some IDF phenolic spacers for under the carbs, then the studs will be the right length.

SteveC
 
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fiatfactory said:
You need to get some IDF phenolic spacers for under the carbs, then the studs will be the right length.

SteveC
Click to expand...
I agree! You're going to want rubber or phenolic spacers between the manifold and carbs. Any height you add can be negated with stub stacks at the top. Those stock Weber air horns are very poor flowing anyway, you want a full radius edge for proper airflow...💨🤓
 
This was just a quick lash up to get the interlink correct. The manifold sets the carbs about 1/2" further apart than on a 124 manifold so I had to weld on an extended tab on the interlink. They will get the usual insulators. I have this same setup on Fatrat for years and no problem with air cleaner clearance. Will those stacks fit, who knows, certainly more clearance than under a spider hood. Yes, the supplied studs are way too long. For now I'll swap out the short studs on the 124 manifold. This is a street car so big Gs are just not a big deal. As I always say, build your motor for your actual driving style. Then you can put flares, snorkel and 8" wide wheels on.

The real G test is not when the motor will stumble with these carbs but when your phone slides off it's magnetic mount.
 
In case you're interested, I modeled and 3d printed a stubby bellmouth stack for the IDF.
 

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That link is not working for me.

I do have a few sets of bellmouths, not sure why those are on the carb.
 
I'd prefer metal over plastic myself.

For anyone interested, I tried to model the "best" curvature from the velocity stacks chart posted to this forum a few times by SteveC.
 
fiatfactory said:
You need to get some IDF phenolic spacers for under the carbs, then the studs will be the right length.
Click to expand...
and the carbs will be even taller, completely blocking your rear view, but who needs to see all those car you're passing with that massive powerplant? hehehe I seriously thought about this because the carbs are so cheaply available brand new
 
I drove my IDFed spider once with the hood off, it was a hoot....twin cam pulley wheels spinning around, engine rocking on the motor mounts, carbs barking.

If I kept this X in the garage when not driving it I would consider a large opening in the engine cover with four tall velocity stacks sticking up six inches! Sadly, I'm trying to keep this one stock looking, the Fatrat is for external silliness.
 
Progress after the arctic blast left town. carbs mounted and fired right up. quality time balancing (helps to get the dirt out of one idle jet).

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then scrounged up an air filter assembly base and velocity stacks short enough to fit under the filter top correctly (not the ones on the initial install)

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Finally put the filter element and top on. I used a 1x2 on top of the stacks with some crinkled aluminum foil on the 1X2 and closed the engine cover. The aluminum foil will squish down and give you the correct clearance under the engine cover.

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Drove it around the neighborhood and seems OK. Will hook up the O2 sensor tomorrow and check the jetting.
 
Looking good. I like those filters. Any idea if they're available somewhere these days?

I have the lunchbox type on my spiders. Now and again one of the 4 clips goes missing. Sometimes I find one stuck to the starter but most go really missing.
 
Dude you did it! so does it fit under the cover...or are you gonna get a faza hood scoop, lol...So I know nothing of IDF's, but they just looked really tall to me...Is the bowl orientation wrong for our cars?
 
They are nice looking filters and I have no idea where I got them. I think someone here or on MIRA gifted them to me. They were meant for a VW as they had a linkage mounting appendage on each one that I cut off. They are too long to fit on a 124 as they would overlap each other. But they fit perfectly on an X manifold (about 2mm apart) which sets the IDFs about 1/2" farter apart than on a 124 manifold.

Kevin, there is a lot more room under an X (1500) engine cover than under a 124 hood so I was never worried about clearance. This is the third X I have put IDFs on (the first was the nonflared X that was massacred in front of my house, the second is the Fatrat which sits out front waiting to be hit)

The filter base and the velocity stacks are actually too big for the 40 IDF as the venturi holes are bigger in diameter than the top opening of the carb venturis. Probably flow issue at high rpm but it's all I had and this is a street motor.

On one of my spiders I had four Uni foam pod filters clamped to the stock IDF 3/15 stacks. That was a nice setup as they were flexible and you could see where the 124 hood has pushed down a tad on the filter tops.

If my investment portfolios hadn't been bleeding all over the place in the last few years I would have thought of doing an hour or so at a dyno just playing with different velocity stack configurations to see their impact on power....if any at street rpm.
 
so I edited my comment...last question was about bowl orientation...don't know anything about IDF's...are the float bowls orientated wrong for our engines? I was really looking into these as brand new IDF's are (were) a hellava lot cheaper than DCNF's...I have a 77 cover tho, and what I got now barely fits...
 
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