I have searched and read the the posts regarding the aluminum intakes but I cant tell if they are considered bad becasuse they crack or if they are just generaly bad in any condition.

I recently converted from a 1bbl to a super six and put one of the welded ones on my car. In the process of collecting parts I bought an NOS Carter and an NOS Holley carb. Initially I put on the Carter and it ran well but I have been chasing an off idle flat spot. I decided to try out the Holley since I already had it on the shelf and this carb has the same off idle flat spot.

This car has a 6-1 header and I am using a stock style air cleaner. Im grabbing hot air off of the header tubes and ducting it through hot air mixing door in the air cleaner. I have not tried water heating the base of the intake yet. I flipped the EGR valve around so the gasket blocks the air passage and there are no issues coming from that.

I saw a thread here that talked about hesitation after doing the super six swap and checked all the items that were listed in that thread. I checked the vacuum advance on the distributor and it is not leaking and advances properly. I used the Remflex Gaskets so im pretty sure there are no gasket leaks. The car idles perfectly and and runs smooth.

There are no visible cracks in the aluminum intake. I had no problems before doing the swap 2 bbl swap and I am beginning to think that the aluminum intake itself could be causing pbroblems.

Any thoughts would be appreciated.
Scott

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Scott
1956 Dodge Custom Royal Lancer
1980 Road Runner (Dont call it a Volare!)
2002 Dodge Ram 1500 Quad Cab
1976 Corvette Stingray

Something that I noticed when I had my stock iron 1bbl intake installed with my Clifford headers was that the flange area where the triangular washers (hold downs) on the intake were not as thick as the flange on the header causing the hold downs to be "cocked" when the nuts were tightened down. I constantly had intake leaks because of this, but when I replaced the stock intake with an Offy intake, I noticed that the flange on the Offy intake was much thicker & that it was the same thickness as the header flange. Once this was installed, I had no more intake leaks. So basically, I'm saying that this is something you might want to re-check, maybe squirt the intake flange area with some starting fluid while the engine is running & see if it affects the idle. The factory aluminum intake really is a crudely made piece, and I've seen several with cracks & porosity issues. The iron 2bbl intake although heavier, is a much better piece. Also, if your lucky you may be able to locate the disco'd MP aluminum intake, part # P4529115. I recently saw an n.o.s. one on ebay, so you might luck out.

Thanks. I went on a shopping spree and collected whatever I could find for a while. and have a cast iron 2bbl intake in my garage. The headers have a nut welded to the flange to take up the space that you are talking about.
I will try the starting fluid.
Are the castings actually porous enough to cause a flat spot? I would think that if it was that bad i would have problems just idling also.

Scott

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Scott
1956 Dodge Custom Royal Lancer
1980 Road Runner (Dont call it a Volare!)
2002 Dodge Ram 1500 Quad Cab
1976 Corvette Stingray

Make sure you have a really big pump shot. I had the same off idle bog and cured it by raising my metering rods almost all the way up and giving it as big a pump shot as I could. This was with a 318 BBD and Cilfford headers.

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As I understand it, the weld is porous enough to leak vacuum. How much vacuum or what it causes is determined by the size of the hole(s). Most people clean them to bare metal, butter up the entire weld with epoxy, sand it down and paint it with a good thick coat. It looks like it would be pretty hard to track down one hole and be sure it was the only one.

Aluminum intakes are also notorious for cracking under the carburetor, in the floor of the intake.

Danny

Ive been jacking around with my timing lately and have noticed that flat spot to be less than before but still there. Runs great just like you said but it just falls on its face off the line. I dont have headers yet but I think its the signal strength from a low compression engine. At least thats my reasoning. My car ran like a beast with a 1bbl.

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it's like a vw, sounds like a million miles an hour but goes really slow. (for now)

On the pump shot..... with the Carter ....I took a lot of care to get all the settings measured and set up as per the manual, Then I started adjusting the accelerator pump a bit at a time. I finally set it for a nice big squirt and it seemed to help but there are times in between warm and very hot that it will actually stall while you accelerate after making a 90 degree right turn.

As far as the timing .......I tried the old timer method of advancing it until it pings and then just backing it off a bit. It ran well but there was a hugh drop in RPM going from Neutral to Drive. I went back to the factory specs using a timing light and it seemed to run better overall.

The mixture screws are set using a vaccumm gauage....... Turning them out until I get max vaccuum at idle.

I started looking past the carb when I bolted on the new Holley and got the same flat spot.

This car also ran like a champ with the 1 bbl.

Has anyone else run into this problem?

scott

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Scott
1956 Dodge Custom Royal Lancer
1980 Road Runner (Dont call it a Volare!)
2002 Dodge Ram 1500 Quad Cab
1976 Corvette Stingray