heminate

I just changed my small block 360 from a 2 barrel to a 4 barrel holley 4160 carb with a dual plane manifold (weiand). I started it up, and it is only running on one side of the cylinders. What did I do wrong? It is running on the even, or passenger side cylinders. I can unplug all the odd plugs and it runs the same. I figure perhaps something is wrong with one side of the carb circuit, but I don't know for sure. Anyone have any ideas? The carb was used, I rebuilt it.

Thanks

Sgt. Veteran

Just a shot and I will take it as you had spark on all wires, you said you rebuilt the carb, its not hard to put metering block gasket on backwards, or a passage that should be open is not because when they made the gasket the little cut out for a port stayed it place, I have gotten the wrong kit more then once and if your not doing them everyday its not hard to miss something - plus dont forget the smallest peice of crap can plug them small passages ... don't know what else to tell you without seeing it happen, Jake

heminate

I've been troubleshooting this since I posted the first post. I took the carb off, and looked at the plenums on the Weiand manifold. Each side of the carb feeds both sides of the engine. So that rules out the carb. I took out all the spark plugs, they all looked fine. The engine ran fine, on all 8 cylinders before I did all this. (So why did I do this you might ask.) I did a compression test on all 8 cylinders. Range was 118-130. The two highest compressions were on the dead side of the engine. So that pretty much narrows it down to the ignition system. But for the life of me I don't understand why it ran perfectly just before I performed this operation, and now it only runs on the even cylinders. I can't imagine that by coincidence 2 plugs or 4 wires have gone bad just by sitting there. There has got to be a better explanation. I will keep digging, but if anyone has a revelation for me, I'd appreciate it.

Sgt. Veteran

Very weird indeed, I will confess about 15 years ago I put a Weiand intake on this kids rustang and gods honest truth it did the same thing, put a diffrent manifold on ran great, put the Weiand back on ran like crap. Ended up putting some factory manifold on in the end, still don't know what or why but yours sounds the same, you have checked everything so once again scratching my head.

sweeperking

Ok I dont know whole lot about this but could there be some kind of blockage with in the manifold itself?

Sgt. Veteran

First thing I thought, but so weird its a weiand and so was the one I had doing the same thing .... I wrote it off as a furd thing

Archer

H -

1. Flood the engine. Make sure that the exit ports on both sides are wet, or that there's raw gas in the cylinders on both sides. If they are wet, that rules out the carb and intake.

2. What kind of ignition do you have? Points or a std electronic box, won't do that, but a "computerized one" might. Naturally, you can check for spark at one or more of the non-firing wires to confirm.

Archer

heminate

No blockage. Manifold was brand new. Wide open passages.

heminate

I have ordinary mopar electronic ignition, no computers. This is a 1971 vehicle. Someone must have put the electronic ignition on since I think 71 was the last year of points? Not sure on that but in any case, I had strong ignition before doing this swap.

I am tempted to buy new spark plugs because I don't have a spark plug tester, but I really don't want to if I don't need to.

Archer

H -

You know the drill on testing plugs. You can just turn the engine over with the plug or plugs out and look for spark, or CAREFULLY place a screw driver in the wire boot and hold it near a ground. You'll see a spark if there is one.

If you have a timing light, it's even easier, with the motor running, just clip the pick up on one of the wires and see if you get a flash.

The real question is WHY only on one side???

Archer

heminate

I think I found the problem. I am 99% sure this is what it is, and it's not good news. I either have a miscast manifold, or I set it down on the engine wrong.
I sprayed some water between the intake manifold and the head on the "dead" cylinders, and it sucked the water in instantly. Huge vacuum leak.
I guess now I have to take everything off, and take a closer look.
I just don't see how I could have put the manifold down wrong. I put the gaskets down on the heads, and carefully set the manifold on top the gaskets, lining everything up! How can you go wrong setting a manifold down and bolting it up?
How likely is it that it is a bad manifold? I don't want to go through the work of putting it back on only to find out it still doesn't fit. This is very frustrating!

1966sportfury

is it a used intake? maybe it was milled? or have you milled your heads and block quite a bit?

heminate

I bought the manifold on ebay from "perfomance overstock", I think it was new, but I guess you never really know when you buy stuff on ebay. I can't imagine it was milled.
I think my engine has been rebuilt before I bought it, but I highly doubt the head to manifold surface was milled, but I suppose it could have been.
I have since pulled the manifold, and applied RTV all over. I really don't like RTV, but if it will help in this situation, I guess I could learn to like it.
I read in my rebuilding small block mopar book that a "composition" gasket should be used with aluminum intake manifolds. The gasket I am using is metal, I think it's aluminum. I don't know why I should use a composition gasket, it never said in the book.
I am going to give the additional RTV a try and hope it fills any gaps. I'll make sure I torque following the sequence, several times, including after the engine has warmed up. I'll report tomorrow if it works.
While installing the manifold a second time, I did not notice anything wrong with the first install. Everything seemed straightforward and simple. I don't see how the manifold could be installed crooked.

1966sportfury

also what heads do you have. i assume they are 360. but... the reason im asking is some ppl will put 273 heads on to gain compression. but 67 and earlier heads will create a vacuum leak at the manifold where you are having problems with 68 and later intakes. since the angle of the intake side of the head differ.

heminate

I'm pretty sure they are 360 heads. They have bigger ports. When I bought the Fel Pro gaskets, I made sure I got the taller, bigger gaskets. However, at the very top of the port, the metal gasket covers about 1/16" of the inside of the very top of the port. I thought this was strange since my heads seem like stock 360 heads, I wondered why the gaskets didn't fit perfectly.

sweeperking

Did you properly torque the manifold using the correct sequence?

heminate

Thinking back to the first install, I didn't torque it by the book. Part of the reason why is that some of the bolts are inaccessible by a torque wrench. I did my best to do it evenly, but thinking back, I could have done better.

This time around, I am torquing by sequence in the book, at least three times in a row, but again, some of the bolts cannot be torqued by a torque wrench, so I must do them by feel.

I appreciate the input. I'm going out this morning to finish putting it together. If this time around doesn't work, I'll go back and try some "the right stuff" as I've heard/read good things about this sealant.

heminate

It turns out the problem was the gasket. Since I did not receive the instructions with this manifold, I didn't know how important the gaskets where. See this:
http://www.holley.com/data/Products/Technical/W521.pdf

I went and bought some new gaskets as recommended by Holley/Weiand. These new gaskets were a composition style gasket. They have a blue ring of silicone around each port to help seal the ports.

When I put the intake manifold on with these new composition gaskets, I noticed I could see the entire blue line of silicone on the gasket at the top of the port, even though the manifold was installed. It seemed like the manifold was not big enough to cover the entire port. So I took the manifold off, and measured the port. The port on the manifold is 2" tall, the port on the head was 2-1/8" or so tall. This baffled me because this manifold is suppose to be good for 340's and 360's and mine is a completely stock 360, which I was removing a 2 bbl from, but the ports on the heads where taller than the "performance" manifold I was putting on.

Since I could see the blue seal ring, if thought it wasn't going to seal, but apparently there was barely enough gasket to cover the top of the port, and the engine will idle good enough.

I can't figure out why the new manifold doesn't fit perfectly, so I suspected the manifold had been machined. I bought another completely new identical manifold. It fit exactly the same as the one I have now. So that rules out that the manifold was machined.

I wonder if my heads have been machined down. But I can't imagine this being the case because they don't make intake manifolds that are wider than stock. They just make stock width, and people will mill the manifold if they need it milled. Also, my stock iron 2bbl manifold fit perfectly, and the bolt holes on my new Weiand Action Plus 8007 lined up perfectly too, it just seemed that the manifold was built more for a 318 with smaller ports than my 360, even though they specify that the 8007 is for the 318-340-360.

So my vehicle runs good enough, but I'm not too sure about the 8007 manifold on a 360.

Thanks