Holley or Weber carburator

I am trying to decide what carburetor I want to go with for my new intake manifold on my 300 inline six cylinder. I am looking at running either a dual carb intake or a single carb manifold. Clifford Performance suggest two 38Dgas Webers or I can buy the single carb intake and run a Holley. My next question would be if I could run two Holley 2brl carbs in replace of the dual webers would there be a performance or running advantage?

Here is a picture of the single carb intake kit and a picture of the dual carb setup. For a visual ref. You can run a 4150 on the single carb intake with a adapter.


I have noticed I can get a turbo bonnet for the weber carbuators. That might be another route to go since I do have a turbocharger sitting here for the engine.

Whether you use two Webers, or two Holley's , I'd definitely use the dual carb intake as it is much more favorable for fuel/air distribution than the single carb setup.
And if you're going to turbo it, that's all the better!!

Better than that just cut one cyl. off a set of Boss 302 heads and put them together & put on your 300.
a guy in MD. did that back in 69 or 70, that was one bad ass 6cyl.

The fast 6 cylinders that I have seen always had two Holleys, have not seen many though.

If you plan to turbocharge it dealing with one carb will be much easier than two.

Jess

I'd save my money and waste it on the big truck......,

The little red is my daily driver now. im going to swap the intake and exhaust manifold I just have to decide what would work best.

I thought about driving the big truck but since the wife found out how much the engine cost she says I'm not about to wear it out just driving to work and back. "I thought that was a race motor" (I guess we should have went high compression and larger camshaft!)

You probably would have regretted doing that in the long run, I know I likely would have if I did it on my Big Block and am still going to skip it now while it is apart. Almost went with a smaller cam then I had before, and it's not a daily driver but, still could be.
Had this nice little 212-218 490something Comp Cam in my hand with matched lifter for about 50 and thought quite a bit about getting it over the Lunati 275.

jones wrote:The little red is my daily driver now. im going to swap the intake and exhaust manifold I just have to decide what would work best.

I thought about driving the big truck but since the wife found out how much the engine cost she says I'm not about to wear it out just driving to work and back. "I thought that was a race motor" (I guess we should have went high compression and larger camshaft!)

Stock stuff is awesome and cheap.... On a daily 6 cylinder.

Now if you come across some cool stuff at the junkyard or second hand for nothing for it.... That's a different story....,

I think I am going to go with what Mr Randy said. The Webers might give the most HP but I don't feel like they will provide the "setup and forget" like a 4150.
I'm currently getting 12-16 mpg depending on grade of gas and which way the wind is blowing! ( seriously the wind plays a large part in how fast the truck runs and mpg!)
The intake manifold has leaks from the Egr parts that I just can't seem to fix. The exhaust manifold has a huge exhaust leak when cold but after 45 min of driving its running as smooth as a sewing machine. (No I'm not exaggerating)

jones wrote:I think I am going to go with what Mr Randy said. The Webers might give the most HP but I don't feel like they will provide the "setup and forget" like a 4150.
I'm currently getting 12-16 mpg depending on grade of gas and which way the wind is blowing! ( seriously the wind plays a large part in how fast the truck runs and mpg!)
The intake manifold has leaks from the Egr parts that I just can't seem to fix. The exhaust manifold has a huge exhaust leak when cold but after 45 min of driving its running as smooth as a sewing machine. (No I'm not exaggerating)

I patched up a small exhaust leak on an exhaust manifold by the doughnut gasket and a couple of small ones after the cat, made a night and day difference how the truck ran, granted it was still learning the timing fuel curve from an Ecm reset.

I now officially hate the 300 inline 6 intake and exhaust system. Does anyone have any helpful hints for lining the gasket and starting the bolts?

The exhaust manifold lines up pretty good but the old intake manifold is banana shaped! I have it back together but I think I'm going to order a intake that will bolt to this new exhaust manifold.

Instead of using bolts, put studs in the head.... slip the manifolds on, follow with washers & nuts.

It runs but it sounds like it is missing two cylinders. I'm sure it has some leaks, it will do until I get a aluminum intake.

I got the engine up to temperature and checked exhaust port temps with my thermal gun. Two of the exhaust ports are almost 100 degrees less than the other four. (400vs300)

Once I really get some temp in the engine the two cylinders come alive and it runs much smoother. What could be wrong with those cylinders? It was running like this before I swapped exhaust manifolds but it's real noticeable now.

I'm wonder it's something a rebuild cylinder head will fix or if I should plan on a cylinder bore and rings at a minimum.

Plugs? wires? Ignition maintence? First place to look.

Easiest engine on earth to do a compression check, too.

I have checked all the electronics.
Compression check is a good idea.

I can tell the engine has been rebuilt at one point in its life. The oil pan is gray, block is blue and gray and head is bare. I know it's a crap shoot at what's inside. If I had to guess, it has a burnt valve or two and some bad rings from the amount of crankcase pressure.

Did a compression test, WOT coil disconnected and spun over till maxed out.
1.)145
2.)145
3.)125
4.)135
5.)140
6.)140

I think I figured out a lot of my problem with a can of starter fluid. It seems that each intake port has a slight vacuum leak. Looks like I will have to try it all over again. I will have to use the two piece gasket or come up with another plan.

Surface the intake?

I thought those engines had a heat shield between the exhaust/intake ports I do not remember how/where they mounted if it is under the intake it could make a difference.

Ok, I ordered:
Edelbrock Thunder Series AVS® 500 cfm(#1801)
Offy dual port intake manifold
Headman Headers
Edelbrock tuning kit
Gaskets

I'm actually very happy that the engine had such good compression numbers and the cause of the poor tune is the intake gaskets.

I decided to pull the engine to replace the clutch. I'm going to replace the oil pump, water pump, gaskets, timing gears, camshaft, lifters, check the valve springs if not replace and lap the valves.

Should I replace the freeze plugs, I see that they are crusty and rusty?