Yeah, its not like I can't pull the 4bbl intake and carb off again if I decide I don't like it.

Now, to come up with a manifold....
The Carquest that I deal with has a 351/400 edelbrock performer thats been sitting on the shelf for about 10 years...

 

well, you can't really compare 4bbl and 2 bbls that way. Apparently 4 bbls use different testing to figure cfm than does 2bbl and 1bbl. But after ready alot yesterday, what most do for better mpg and decent power, they tune primaries a little lean, then tune secondaried a little rich. I haven't tried any of this since I don't have a 4 bbl yet. But since there seems to be no real straight comparison, I might do a little write up when I do get one. All things being the same comparison. I know I will have better power, but not positive on the mpg's.

 

Agreed
It would be neat to have some real world comparison.
Maybe 46 can do that.

 

I'll definitely post my results, I have an old autolite 4300a laying around as well. Maybe I'll throw that into the mix too, for comparison's sake.
Provided I don't find a bent pushrod or something when I pull the intake this should go rather quickly..

 

Ok, after a long day of chasing air leaks and tuning carbs, I have finally gotten this thing going with the 4bbl carb.
I drove it around that morning with the old 2bbl setup, parked it, let it cool, and then went to work.
After closer inspection of my 4100 I found it to be missing a few minor pieces, so for the time being I have decided to use the 4300A I had pulled from my old 429. The performance increase is very significant, even staying out of the secondaries. I'll report back with fuel economy figures once I have them.

Now, while I was in there I checked the pushrods, and as I expected I had a few bent ones. None were seriously bent, but they wouldn't roll true.
I replaced them with some brand new ones, nothing was close to binding so I called it good. I imagine those have been bent for a long time....
Once I got the engine running again the old familiar tick that comes from under the passenger side valve cover returned quite a bit worse. Depending on the rpm it almost can sound like a knock. Once the engine is warm the volume of the noise lessens. The whole valve train used to clatter some, but the fresh pushrods seemed to have taken care of that with the exception of this one. Could I have a rocker assembly that is shot? I didn't really inspect them all that thoroughly when I had it apart earlier. The noise comes from up high, it comes from the valve cover. I've been under the engine while it was running and it doesn't seem to come from the pan like a rod would, besides it wouldn't get worse just from messing with the valve train.
I have to go to pick n pull today to get a part for a customer, and I'm tempted to snag a set of rockers if there are any decent ones to be had.

Ideas anyone?

 

Could be a worn shaft, could be a sticky guide, but without being there it's hard to say.
I'd put her together and run 'er.
She's old old and has a few aches and pains but she's tough.
Maybe a little Marvel mystery oil in the oil to try and clean'er up a bit.

 

I had the heads rebuilt 20k ago, and it has always made this noise.
Motor is still squeaky clean inside. That was nice to see.
The truck has been in the family since it was new and has made this noise for decades, somehow persisting through two rebuilds and 335,000 miles. I guess I should stop worrying myself about it....

I had to drive a 200 mile or so round trip yesterday, gas mileage appears to be around 10 or so. It has seemed a little rich, as it starts with very little choke and wants to flood if the choke plate closes very much at all. It runs too well in general I guess. I'm assuming since the carb was last on a 429 that it is jetted to feed a larger motor. It has #62 jets in it, just like my 2150 did though....
I'll go down to #59s and see what happens unless anyone has any better ideas.

 

while I think the numbers you are talking about are ball-park jet sizes, my better idea would be to get an actual wideband 02 meter, install it in your truck, and adjust accordingly.

 

Now that would make things just too easy. Where is the fun in that?
And yes, I am referring to motorcraft jets. I've accumulated a pretty good handful of them.

 

Hah, a true hot rodder.
Would be neat though eh?

 

I'll admit that I have looked into those. I'm open to recommendations as to a good brand.

Now, I put the leaner jets in and got my gas mileage back at the expense of a good part of the performance I gained. When the secondaries open it hardly makes a difference other than some noise, which tells me that I should run them a great deal richer so I have power back when they open. Is there anything I can do on a 4300 to do that? I have read that the secondary jetting is fixed.
Maybe I should just get the 4100 I have straightened out the rest of the way any put it on. I'm not sold on the 4300, the accelerator pump is nearly worthless which gives it a real nice off idle bog.

 

Gave up on the 4300, it started bleeding over real bad and I couldn't make it stop.
Between the poor fuel economy and it being a pain to work on, I just got tired of fooling with it.
I was able to straighten out my autolite 4100 to the point of functionality and tossed it on.

Wow, what a difference, after only minor adjustment the engine runs and idles better than some fuel injected ones. It doesn't seem to have as much power as it did with the 4300, but that thing was dumping tons of fuel, so that doesn't surprise me.
Now to get the choke and transmission kickdown sorted out...