4180C info for a 4160

[854vragtop]

I had almost the exact same setup that you have on my '85 GT. I was never able to completely get rid of the slight stumble when shifting when the engine was completely up to temp. Here were the specs that I had at the time. Timing 14* BTDC, stock '85 5.0L with stock '87 H-pipe, freshly rebuilt 4180C with holley rebuild kit, 64 jets, orange and green and black accelerator pump cams in positions #1 and #2. With the choke set correctly and working carb heat, it stumbled very badly when cold. After warm up, it would have a slight stumble when starting out and getting on the gas while shifting through the gears.

I had a nearly similar experience with my Holley 4160, except the cold driveablilty was much, much better and the stumble while shifting was nearly completely eliminated....nearly.

I've since installed the Summit 600 CFM vacuum secondary carb and have NO hesitation issues at all. My theory is that the Summit carb uses the older style orange umbrella accelerator pump check valve at the bottom of the primary bowl instead of the newer ball bearing check valve in both the 4180c and the 4160. I think the ball bearing takes slightly longer to seat, therefore delaying the pump shot.

That being said, the only other thing that I can think you can verify is that your accelerator pump arm/bolt/spring assembly is adjusted so that there is absolutely no play. Make sure the choke is completely disengaged and the engine up to operating temp when you do this. If the choke is on a fast idle detent when you take all the slop out of the pump arm, there will be a lot of slop when the choke does come off the detent.

Good luck.

[CJK440]

If you actuate your throttle by hand (engine off) you will see with fast open, the acc pump linkage spring compresses so the pump shot lasts longer than the actual throttle open as the spring catches up. Pump cams won't show that much of a change especially with a realtively quick throttle opening.

I agree with 854, verify there is no slop in the linkage.

[8ballEinstein]

If you actuate your throttle by hand (engine off) you will see with fast open, the acc pump linkage spring compresses so the pump shot lasts longer than the actual throttle open as the spring catches up. Pump cams won't show that much of a change especially with a realtively quick throttle opening.

This is true but the main reason for a pump cam change is to adjust the volume of fuel sent to the squirters.

Mgino, those plugs look awfully rough. The one from cylinder #7 looks like it's bridged. This would explain the problems you're having.

[JACook]

A bit late to the party here, but you cannot use the 4180C primary jetting as a guide for much
of anything. The 4180C has annular primary boosters, which will present a very different venturi
signal profile than what you'll find on any 4150/4160.

And yes, contrary to what you may have read (even on Holley's site) a 2-stage power valve
is not incompatible with performance applications, and can be of benefit on the street because
it adds the enrichment more progressively than a single-stage power valve.

The power valve channel restrictions in a gasoline 4150 or 4160 are smaller than whatever
restriction the power valve may present. This whole nonsense about "window" power valves
is just that, unless you're running alcohol, or a Dominator.

Make sure your stumble is not being caused by something external to the carburetor, such as
vacuum advance. A properly tuned carburetor is -supposed- to stumble if the vacuum advance
isn't working right. Otherwise you're just covering up the problem with extra fuel.

[Mgino757]

Accelerator pump linkage has no slop. It squirts fuel as soon as the throttle moves. It runs great right now. The one spark plugs from cylinder 7 was not bridged, it's just the angle I took the pic at. Like I've said, all of the vacuum advance stuff has been replaced, it's fresh and working properly. My timing was actually at 12* BTDC, I put it there to make diagnosis easier. Since last night, I've bumped the base timing up to 15* BTDC, no pinging so far. Either way, the single stage 6.5 inHg power valve wasn't doing it any favors.

Now, I'm a little rusty on reading spark plugs, but what do those 3 random plugs tell y'all?

[IDMooseMan]

Did a quick search on, "How to read spark plugs" and came up with these results:

Spark plug reading charts and images

[Mgino757]

Okay, since I've just installed a new set of plugs the other night, how long should it take for me to be able to see what's going on with the new plugs?

[IDMooseMan]

Depends on engine condition and how hard you drive the car. For "normal" driving, I'd say drive it for the day. Pull the plugs from the cylinders you found issues with to check their condition. Do that daily (or after each day of driving) to see the changes in plug condition.

[Puter]

What kind of octane booster are you running?

[Mgino757]

What kind of octane booster are you running?

I'm not. That stuff is a waste of money. I have it running on 87 mixed with some 93. I'll back the base timing off when it starts pinging.

[Puter]

I'm not.

I was asking because of the pink color on the plugs. The only time I had seen that with mine is when I used octane booster (it was actually closer to orange).

[Mgino757]

I was asking because of the pink color on the plugs. The only time I had seen that with mine is when I used octane booster (it was actually closer to orange).

Yeah. I did put some Stabil in the fuel. This car sits sometimes and I don't want this craptastic fuel making my carb run like junk. lol

[cb84capri]

i used fuel stabilizer once. that was also the last time i used it.

cale

[Mgino757]

Well, tonight I decided to modify my 4180C that I had shelved when I put the 80475S on. I've come to realize the advantage of annular boosters. I have no idea what I was thinking when I swapped carbs in the first place, but the stocker is there to stay now. Only thing is, my carb seems to be missing the spring for the fuel filter. Would anyone have an idea as to where I can find another one?

[8ballEinstein]

Well, tonight I decided to modify my 4180C that I had shelved when I put the 80475S on. I've come to realize the advantage of annular boosters. I have no idea what I was thinking when I swapped carbs in the first place, but the stocker is there to stay now. Only thing is, my carb seems to be missing the spring for the fuel filter. Would anyone have an idea as to where I can find another one?

Somehow, I figured you'd see higher truth in how well the 4180c works with our cars.

[Mgino757]

It came to me when I realized what boosters the other carb has, same boosters that are in the secondaries. The main problem I had with my 4180C was it idled high, even with the idle screw turned all the way out. Turns out, that by some way, the secondaries were open too far. I adjusted the secondary throttle stop to where I had the 4160 set at. Whaddya know, it idles like it should! I gave the 4180 a freshening up and made the mods that JA Cook had posted about his carb. I cannibalized the good stuff from the 4160, so the mods were basically free. lol


Maybe for the fuel filter, I can use a hose fitting where the hardline would go? Anyone recall what size that would be? I'm talking about the fitting for the fuel inlet. I'm pretty sure that my fuel filter isn't doing much filtering without that spring that's supposed to be in there.

[JACook]

It's the same spring that is in GM carbs that use the sintered bronze style fuel filter. Dorman #15544
or Napa 7321078.

If you've already cut your fuel line, you could also use the Ford-style screw-on filter that was used on
earlier versions of the 4180C. Motorcraft FG19C, or Wix 33019. But I wouldn't cut up an original fuel
line to do that.

[Mgino757]

Well, I had cut the fuel line by the temp sensor and used rubber hose to connect to a generic fuel filter to use it with the 4160. I now have that hose joining the two sections of the fuel line where I had originally cut it. I think Ill just get the spring.

Would those screw in filters do a better job?

[JACook]

I don't know that the paper element filters do a functionally better job than the bronze style, but
they probably can hold a bit more garbage. And while they do trap smaller sediment that can pass
through the bronze filters, I'm just not convinced it matters.

[854vragtop]

Well, tonight I decided to modify my 4180C that I had shelved when I put the 80475S on. I've come to realize the advantage of annular boosters.

If you like two annular boosters, you'll like the four that are on the Summit 600 cfm carbs. So far, this has been a great carburetor!

[Mgino757]

I've noticed my choke takes a while to come off fully. I tested voltage at the lead and it check out at 7 volts, which is normal. It appears that the factory choke isn't adjustable. Would I be able to swap over the adjustable choke from my 4160 to my 4180?

[burntorange84]

I've noticed my choke takes a while to come off fully. I tested voltage at the lead and it check out at 7 volts, which is normal. It appears that the factory choke isn't adjustable. Would I be able to swap over the adjustable choke from my 4160 to my 4180?

It is adjustable if you modify it; if you remove the protrusion sticking out, IIRC on the red plate so the choke can rotate. You could use the 4160 one, but it uses 12 volts intead of the 7 from the alternator. I like having the adjustment. I usually adjust mine for winter weather, and then for Texas summer weather. I adjust for the time it takes to pull off fully compared to the engine warm-up required.

-j

[Mgino757]

Are you talking about the plastic disk that goes between the choke heating element and the choke mounting piece? If so, I'd rather do that. In the garage, it doesn't take long for the choke to open, just when it's outside in the cold, then it takes a while. It'll be 5-7 mins until it is finally off of the last step. It still accelerates very smoothly though, even when cold!