Tuning Street Demon carb

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Test drive went well, AFR at WOT is more where I want it in the mid-12s but up in the higher RPMs it's leaning out a tad, just about hitting 13.0:1 around 5500 RPM. I remember talking to a guy at a track day/car show combo event a couple years ago and he said specifically the Street Demon carb wants more fuel flow at higher RPMs for it to not lean out. He had moved to CO from TX and had a lot of experience working in engine and hot rod shops tuning muscle cars and had a customer with a Street Demon where the final solution was to do a return-style fuel system with an electric pump (iirc) and rising-rate regulator. I'm not interested in going through all that and it doesn't lean out to the point of being dangerous to the engine so for now I'm just going to live with it and probably get a DP carb on it at some point like I've wanted to do for a while. I guess a return-style fuel system wouldn't be a bad idea overall but I don't feel like running a return line to the tank anytime soon lol. Other mods/upgrades are higher priority on the list right now.
 
What you need is the proper TQ, not the SD joke. Holley omitted the air valve dashpot. Saving money?
 
Bewy said:
What you need is the proper TQ, not the SD joke. Holley omitted the air valve dashpot. Saving money?
Click to expand...

I've messed with TQs in the past, they're a pain unless you can get one in perfect shape and the ones worth running were made over 45 years ago at this point. I agree it's a better design overall but they are pretty friggin complicated compared to a SD. Look at the name of this carb anyway, Street Demon. The target market is owners of old cars and trucks with near-stock engines that only see WOT once in a while who want something that will bolt on and work OOTB and get good gas mileage. My setup is on the edge of being fit for its intended application, 222/226* @.050" on a 110 LSA cam with only 9:1 static compression, open-chamber heads and a cheap shitty loose 2600 RPM-stall converter. All things considered it works pretty awesome tbh and I have no complaints other than the fuel curve at WOT which isn't that big of a deal. I don't see how the air valve dashpot would be worth the trouble on this carb anyway the reaction time when opening the secondaries is at least on par with AFB-style carbs I've run if not better.
 
MopaR&D.

The TQs work fine, but you have to adjust them properly, using the factory specs as a starting point. One of the TQ benefits can also become a headache: the large number of adjustments.
- the mech linkage that raises the met rods out of the jets. No other carb that I am aware of had this feature from day one. It means better throttle response because enrichment fuel starts flowing BEFORE the vac drop effect has time to act.
- sec adjustments. You have the air valve spring adjustment; AV dashpot rod adjustment; WOT position of the AV. If these are not adjusted properly, you can get bogging. That is not the carb's fault, that is the tuner's fault. However, these adjustments can be tweaked to improve performance. That is one of the great things about the TQ, the number of things that can be changed. Another one is the WOT position of the sec throttle blades. Because they are so large, they can have a noticeable affect on distribution & WOT power.

If you want to get a TQ & put a kit in it, you can PM me & I will give you some tips on further tuning. best to get a 6000 series. They might be 45 yrs old, but rarely are they unusable & unless badly corroded.
 
I had a realization yesterday... The SD comes with anti-pullover acc. pump squirters. I have one or two regular ones I'm going to try swapping in, see if that helps richen it a hair on the top end.
 
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