Hey there ..... me again.

Got the remanufactured Holley 4180c installed and running nicely. Now I am wondering if there are any tricks/upgrades/etc... that I can do to this carb to get more performance out of it? I have read a lot online about different methods for getting more out of this carb on a 460 setup including messing with the base timing also .... setting it at 10-12deg rather than the stock 8deg. However I am more interested in things that can be done to the carb to improve its performance over stock. Also been doing a lot of research on carb spacers and still not too sure.
Any ideas would be greatly appreciated

 

I'm not a Holley guru (some out there are lol'ing), but mainly what you can do with a carb is to get it dialed in for the engine, temp, etc. That includes the idle/air mix, the accelerator pump settings, the cruise and WOT air/fuel ratios, and secondary opening point. However, if your engine is stock and your carb was put back to spec, it is probably pretty close to "right".

Having said that, in my experience there are two areas where the OEM's were conservative - cruise AFR and secondary opening point. So you might get a bit more part-throttle performance by going one or two jet-sizes larger, but you will hurt the economy. And, you might get a bit more power by having the secondaries open earlier, but that only helps for a second or two, and it may actually cause the engine to bog.

So, IMHO, you are better off leaving the carb alone and advancing the timing. Much easier to do as well as to put back, and bigger gains to boot.

 

The 4180c is a emissions carb. Good for putting on a original engine with all the original hoses so you can pass the sniffer and visual inspections. If I wanted more power I would have started with a aftermarket holley rather than a 4180c.

 

Unfortunately I am subject to the biannual smog check crap here in CA so I had to go with the 4180c. It is a remanufactured unit but it is a 4 year older version than the one I had originally. D9TE-9510-AEA ... and the original was E3TE-TC ... not too much different from what I can tell visually ... biggest difference is that the primary air/idle screws are not hidden behind plugs ... they're flathead screwdriver plugs that are in plain sight ... still in the baseplate but much easier to deal with. I guess 1979 was the last year they did this before they were switched to allen screws and hidden behind lead plugs. Now since its a '79 carb I am wondering if there are any other differences that I can't see.....and I was wondering what basic mods can be made to improve things a bit over stock. From the sound of it the jetting and accelerator pump upgrades may help throttle response at the expense of MPG ... does anyone want to chime in on a 1-2" carb spacer? Do they really improve things? This truck had a 1" universal spacer on it when I bought it but I found out that was the cause of the carb baseplate breaking .... the mounting holes didn't line up perfectly putting more stress on the baseplate than it could take. So that was removed. Just curious. IF and When I am no longer required to smog this beast I will ditch the 4180 for a more appropriate carb.

 

I am thinking of getting the secondary spring quick change setup that Holley sells. Then I can mess around with different secondary springs to find that sweet spot .... and not destroy countless diaphragms in the process.

 

When the carb is rebuilt, the plugs are taken out. You cut them out with a hacksaw. Since you have a rebuilt carb, that's why you can see the adjuster screws.

I would not mess with it. It's not going to pass your emissions tests if you do. You could possibly mess around with the secondary adjustments, but make it easy to put back. I don't know what type of testing they do, but if the secondaries fly open or open too early while they are doing their test you will certainly fail.

They have got you coming and going. You only choice is to get a older truck that is not subject to emissions testing, if there is such a thing in California.

 

In my limited experience a spacer plate is always a question mark - you won't know until you try it. Sometimes it works, sometimes it doesn't, and most times you really don't know for sure.

As for changes, you can always try changing the jetting as it is cheap and easily done. Go up one or two sizes and see what you think. However, unless you have a bog on hard acceleration I don't think a change on the accelerator pump will help - although again it is cheap and easily done.

 

I know about the plugs being taken out ... this is not the case with this one. If you look at the base you can see it is molded differently and there never were any plus to be removed. The idle screws are not in a molded housing within the base plate ... they stick out completely free of the base plate. I have seen hundreds of the rebuilt ones that had the plugs removed and this is different. If you can find a photo of the 1979 model of this carb you can see what I am seeing. I looked just to be sure myself and found several other '79 models that had the same setup as mine. Its so much easier to adjust since you can actually see the idle screw when looking down at the carb mounted on the manifold.

 

And in the county I live in here in CA there are some more rural zip codes that do not require smog except when the vehicle is sold. There is a slight chance that I will be moving to one of these zip codes within the next 2 years .... so if and when that happens I will make some serious changes to this old beast

 

This is not a pic of my carb but it is a picture of the same year model. As you can see, the idle mixture screws are different than on the 1980 and up 4180 models. They are still in the baseplate but they're much more easily accessible and you can actually see them without contorting yourself like a circus freak .... plus a flathead screwdriver is all it takes. I am liking this part of my rebuilt carb a lot

 

Here is another angle .... see how easy it is to see the screw on the left? The one on the right is also fairly easy to see if you are facing it just off angle to the right ... it isn't as hidden by the accelerator pump housing as it is on the other models.