360 Intake on a 318 - What To Expect?

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YoungBlood

YoungBlood

Jolt the Squares
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I realize there is a port size difference, but will putting an iron 73' 360 dual-plane intake on my 318 hinder my mileage?

I'm not expecting a performance gain, but will it make performance worse?

The deal is, my 318 (although tired) is a good runner. The previous owner put a Holley Street Dominator and 4 barrel on a stock motor with tall gears and manifolds. Needless to say, 13mpg on the highway was a good day...

It would save me about $3200 (for the motor I want to build) and 2 months down-time if I just got going with the current tired 318 and got some much needed seat-time.

A big issue to me is this Street Dominator; I'm not going to drive another inch with it on my stock 318. The next motor is getting 360 heads and, with that being the plan, I had picked up a really nice 73-dated 360 intake for $35.

What I dont want to do is spend $100(ebay-used) to $200+(new) on a dual plane intake that may only be on for 6 months and have more pieces of useless engine parts laying around thereafter.

Is there a MAJOR reason why this 360 dual-plane intake on my stock-ish 318 would NOT be advised for a temporary band-aid?

Thanks all,
Tyson

P.S. It is my understanding that this year iron 360 intake is a pretty decent piece. Would it be considered a 'High-Flow' or 'Standard-Flow' intake? I don't have a pic unfortunately, but it doesn't appear to be a 'Low-Rise' by any means...
 
ok, so your wanting to take the street dominator off, the tired 318 that your wanting to use for a driver motor, and swap it with a iron 360 inatke till you get another motor built? correct? well if you are, obviously there's a port mis match that you already know about, then your gonna be adding a good 30 or 40 lbs (they're heavier than one would think). i really don't see it doin much,if anything. i would almost bet that it would hamper performance, with out even knowing any of your other info
(vehicle,weight,gears,etc.)

I have heard the cast iron 360's are "ok" intakes if thats all ya have or you wanna go with a strict sleeper build.. i also heard they make power too around 5,000 or so.
I have 2 holley street dominators PN 300-7, i've found em to be good little intakes for a stock, mild 318. I also have a stock Iron 360 4bbl intake too, if it wasn't goin on my old 318 dodge farm truck in the near future (tired of messin with the old wore out carters i have) i would have probably scrapped it by now. if you already have it on there, i wouldn't change it, but it's only my oppinion. maybe someone else can chime in later, and tell ya more than i can..
 
I think the best idea would be to score a Performer 318 off the web of ebay or a local swap. The intakes are ok. The bigger problem to me is the port mismatch which in this case is the worst you can get in terms of performance. But a 318 intake should be easy and cheap to locate. I''ve got one but it would be cheaper to find one closer than 3K miles...lol.
 
intake port must be smaller or the same size as the port in the head. never bigger. This should never be a question asked if you know of the difference. You can do this when though water flows up hill . I have seen this asked on here many times . You would be in the same boat if you were to get a 4bbl to a 2bbl. adapter and keep your 2bbl intake. Unless you find a intake with the same port size as a 318 head. your decreasing milage and performance. A good choice if you could find em 1. edelbrock LD4B. and 2. 273 hipo. all the rest are multi purpose but they do look look nice?
 
The OE iron intake sould be considered a standard flow manifold and a low rise.

The Street Dominator is a low rise and standard flow as well but should actually provide better mileage at Hwy. speed because it is a single plane intake and a small runner and plenum design for easy quick unobstucted flow.

The port mismatch isn't a big problem and mileage shouldn't be adversely effected badly.

At 13 mpg's, I'd look to the overall tune of the engine starting with the air cleaner on down and distributor.
 
Well in my experience the port mismatch on a basically stock engine is not a big deal, hell the factory did it on some of the mid 80's 318 four barrel packages. However it is not going to make your mileage any better. If you want mileage go to a boneyard and get a 318 two barrel intake and carb. The older Carter BBD style carbs with the metering rods can be adjusted to get better mileage and as Rumble said, look at the tune of your engine to increase your mileage, not the intake manifold.
 
Thanks for everyone's input. With some thought put in to it now, I'm probably gonna buy a Performer (new or used) or just stick it out with the Street Dominator.

As far as the tuning goes: I've timed the car, plugs, wires, cap, rotor, dialed the carb... Perhaps it's something in the Eddy (float issue?) or the massive amount of blow-by and Motor Honey is in order.

I appreciate the help. Case-closed.
 
An add after the case is closed....

Don't waste your money on the performer, what you have now is the best manifold for your street 318.
 
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