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Old 11-29-2003, 03:36 PM
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Need some intake manifold help

Hi, I've got a question about my intake concerning clearance and power.

Here's what I'm building: 388 stroker with a 282 cam (planning on using a two piece timing cover so that I can swap to a roller later). Dart 180cc intake 72cc heads. Slight dome on the pistons so about 11.5:1 compression. I want my RPM band to be between 1500-2200 low end and 5500 or no higher than 6000 high end.

Here's the question: I'm having trouble choosing an intake and carb. I have an old 305 with a performer manifold and an edelbrock 600 carb with one of those triangular rounded cross-hatched air cleaners. This setup just barely clears the hood as is. On my new smallblock (the aforementioned stroker) I'd like to use a performer RPM because I've heard really good things about them. I was going to go with a stealth, but I found out the difference in height btw the two was only .4 inches. The RPM is .7 inches taller than my setup now, and I'd really like to use it. How can I free up some space, what are the tricks? One thing I did notice is that a while ago I traded my 600 holley to a friend and put the edlebrock on. I think I noted a tighter fit with the edelbrock... is that true or was I just imagining it? If that's true should I go holley for the carb to free up some space? Is it true that some four barrels are shorter than others?

One other option was that I could go Single plane on the intake. The x cellerator intake divided plenum is taller than the RPM so its out, but the same model marked as "low rise" is only 3.5 inches, .5 inches shorter than my current setup! Does anybody know how this intake would perform?

Thank you all in advance for your help-

K
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Old 11-29-2003, 03:41 PM
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Throw that Edelbrock air cleaner away immediately. They are by far the worst air cleaners made. They don't flow nearly enough air to feed your engine properly. I don't think they are even enough for a stock 350. get a dropped base instead. You can prop the back of the hood like I have stated in other posts. That way there will be no irreversible damage to the hood. I have a '73 Camaro and my RPM Air Gap has plenty of clearance with my dropped base aircleaner and new found hood clearance.
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Old 11-29-2003, 03:44 PM
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I'm unfamiliar with the term "dropped base" aircleaner. Could you explain what that is and give me an example of one?

Also, I haven't read your previous posts, could you either direct me to one that talks about propping the hood or explain how to do it?

Thanks-

K
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Old 11-29-2003, 03:53 PM
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A dropped base is just that. The base of the air cleaner sits lower than the carb's mounting surface. Edelbrock Pro Flows are an example of a dropped base. I would get one with a high flow reusable filter like a K&N or a Holley.

What I did to shim the back of my hood was I got some longer bolts for the hood hinges. The ones that bolt the hinges to the hood, not the hinges to the body. Then I use I think 6 3/8 flat washers in the front of the hinge and 12 in the back. You want to kick the hood at an angle slightly, and raise it all together at the rear. My hood closes just as it did before and it pulls in cold air just like a cowl induction hood. NO cutting or damaging any original parts.
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Old 11-29-2003, 04:24 PM
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I see. Does anybody know if some carburators are shorter than others?
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Old 11-29-2003, 04:31 PM
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I would have to recommend the Performer RPM Air Gap. That is a really good intake, and it matches your motor very well. I would go with a 750 carb, and if it is too much fuel, jet it down.

Adam
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Old 11-29-2003, 04:40 PM
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? The air gap is like 70 dollars more than the standard RPM. Is it really worth it?
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Old 11-29-2003, 04:48 PM
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The Air gap is worth the money in my opinion, It will make more power and torque, I have seen several tests done with the Air Gap, compared to other manifolds and from what I have seen, it is the best dual plane intake made today.

Adam
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Old 11-29-2003, 07:30 PM
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You feel a big difference in temperature at the intake runners on the Air Gap as opposed to the standard RPM.
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Old 11-29-2003, 08:42 PM
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well first off like said take out that air cleaner.. i had one of these on my 86 iroc.. one back fire thro the carb and u got a fire and no air cleaner.. a friend of mine just did a 2 barrel 4 barrel swap and used the drop base air cleaner as stated.. but be careful cuz its a tight fit.. well on a Q jet it was.. the throttle linkage was hitting the dropped part of the air cleaner.. also if u havent already taken out the insulation on the bottom of the hood u could do that.. or cut it out.. wutever works.. hope this helps
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Old 11-29-2003, 08:46 PM
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is it safe to remove the insulation from the inside of the hood?
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Old 11-29-2003, 09:15 PM
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I know it's expensive, but aside from shimming the hood, you could always just get a cowl induction hood. These 2nd gen f-bodies have little, if any extra clearance and the cowl hood would clear that rite up and look better, IMO. I plan to install one when I get the cash as my air cleaner is hitting the hood right now. As for the intake, the RPM Air Gap is supposedly an awesome product. I saw a test once where it was a stock 454 crate engine and they swapped the stock intake for an air gap and it gained at least 50 hp, I wanna say even more.

One question if you have time, why go with bigger chambers and domes instead of smaller chambers (like 58cc or a lil smaller if you want super high comp.) and flattops? is it just that you already have the heads? Cause I have always heard to avoid domes if you can as a dome can cause spark problems, just what I heard though and I was wondering. Take it easy man...
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Old 11-29-2003, 09:32 PM
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Quote:
Originally posted by killerformula
is it safe to remove the insulation from the inside of the hood?
That was on of the first things I did. My insulation was deteriorating and falling down onto the engine.

One question if you have time, why go with bigger chambers and domes instead of smaller chambers (like 58cc or a lil smaller if you want super high comp.) and flattops? is it just that you already have the heads? Cause I have always heard to avoid domes if you can as a dome can cause spark problems, just what I heard though and I was wondering. Take it easy man... [/B][/QUOTE]

A dome piston is an airflow obstruction. Dome pistons loose power compared to a flat top. Smaller chambers are more efficient. The flame front has less area to travel.
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Old 11-29-2003, 09:53 PM
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I bought the shortblock from somebody pre-built for a good price. Open chambers typically flow better than closed anyway. But yeah, it would be better if I could just use flattops.

Wont the removed insulation damage my paint with heat?

K
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Old 11-29-2003, 10:07 PM
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yeah, thats what I figured man, still a sweet set of heads and a nice engine
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