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Discussion Starter · #1 ·
I was looking through the Summit Catalog today and came across carb spacers.

From my understanding:

improved fuel atomization resulting in more HP, more TQ and better fuel economy

Is this correct? Any downsides? Should I get one? My truck is a daily driver. I drive to work and back and to school and back (600 mile trip about 6 times a year)

The part numbers I'm looking at is TRD-2084 (1" spacer $19.95), TRD-2103 (1" spacer with PCV fitting $21.95) and TRD-2081 (2" spacer $29.95).
 

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Carb spacers effect engines differently.  But generally 4 hole spacers give more low end power and open spacers give more top end power.  There is a good chance that a 4 hole spacer will give more fuel mileage and torque. 

I don't know what year of vehicle your working with is or what carb or manifold.  I wouldn't' recommend a carb spacer if your using  an Edelbrock on a spreadbore intake that has to have an adapter plate.
 

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Discussion Starter · #3 ·
Sorry for my lack of information.

I have a '87 RC 318 2bbl Holley carb. Everything is stock on this.
 
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On that setup, I wouldn't bother. Speaking strictly on oem manifolds, the spacers , in general, seem to do the most good on short squat manifolds that force a sharp turn immediately after airflow passes through the carb. The 318 units, and Mopar in general, don't suffer so much from this, unlike some of the GM and Ford units. Spacers for those models will improve performance by effectively smoothing out airflow, sorta like a low buck high rise manifold. Now, would you see a change in output on your setup? Sure, minor. In your case, a 318 responds dramatically to real changes. A better cam, matching intake and exhaust mods, would achieve much better results.
 

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I doubt you would find a spacer that would fit the small 318 carb.  It is different then the larger more common 2 bbl bolt pattern.  Something you can do if your bored is stack gaskets up on the 318.  It will require longer studs.  The gaskets are 1/4" each and if you put 4 in there, then you would basically have an inch spacer.  Then you risk the chance of a vacuum leak and choke linkage not reaching.
 
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You'd probably see more, not that it'd be much, by just double stacking air filters or substituting one of those big ones they use in 454-powered trucks. First choke point is that tiny carb.
 

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Discussion Starter · #7 ·
So (not to get off subject of the post), should I get a larger 2bbl or a small 4bbl. Would I see any improvement in fuel efficiency. I'm bound and determined to eventually get into the mid to high teens on this truck.

Would a better cam due me any good other than performance? I'd love to put a nice cam in the truck but not sure I'm ready to do engine mods like that just yet for lack of 1. experience and 2. time before I absolutely need the truck running to get me back to school.

What do you mean?
gen1dak said:
matching intake and exhaust mods
Are you talking about the ports on the heads? I've only seen this done on Horsepower TV. Do you think I could do this given a fairly simple garage and a good weekend? Again I'm just gettin into wrenchin. I know enough to get myself in trouble.

Any good tutorials or videos you would suggest?
 
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A bigger 2 barrel won't fit the stock 318 intake. Even if you hogged out the carb base for a larger carb, you'd have nowhere to bolt it down. The easiest way is to get a 4 barrel intake. The old Edelbrock SP2-P is dynamite for stock or modestly upgraded 318's. The current edelbrock Performer is the de facto upgrade. Where the sp2-p peaks around 4500 rpm, the Performer is good through 5500 rpm. I ran an sp2-p with 750cfm carb, 318, CompCams 260 High Energy cam, headers. In a 3800lb '69 Charger it ran very well, had great low rpm power, and regularly pegged 19mpg while getting the snot run out of it. It routinely was run to 5800 rpm shift points. The sp2-p can have it's rpm range boosted with, ironically, a carb spacer.  I wasn't talking about cylinder head work. The original small port 318 heads work well with mild cam upgrades. The 318 responds dramatically to the basics, meaning better cam, better intake/carb, better exhaust. While hp and torque will really improve, this translates to improved efficiency, and that means better mileage. I learned about engine rebuilds old school. They were called books. There are better cam grinds now, and with the Performer you can't go wrong.
 

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Discussion Starter · #9 ·
So if I were to go with a new camshaft what would you suggest.

How about this?
http://www.summitracing.com/parts/SUM-K6900/

and my plan is to fuel inject my truck. I would really like to do MPFI but I have a good feeling it's most likely going to be a TBI system running a MegaSquirt ECM. So if I were to change intakes, I think I would just save longer and due that upgrade or just look into a 95 or so EBD1 engine (I believe that's what I want if I remember reading that how-to about swapping a magnum into a 89).
 
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Well now you're going in two different directions. You could rebuild the engine and add Magnum heads and intake. That's a good old cam you linked to. Thirty years ago it would have been in the top 3 choices I'd make for an RC 318 with a carb. Now, not so much. Hughes engines has a special Performer RPM AirGsp intake for Magnum MPI. You'd need the Magnum heads to match the ports of the intake. Your 318 has small ports. All the Magnums (318 and 360) have large ports like the LA 360. This becomes an issue when considering available matching intakes.
 
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