Macadoo

So I think I'm sold on this Street Demon carb. But I have an issue, with this carb or any other. In order to get any TV bracket to clear the intake runner, I have to use a carb spacer. Easy enough but I don't really want to give up the low end torque. It's been a while since I measured but I think, at minimum, I have to run a 1/2" spacer. Any suggestions?

Firewalker

Using the non supplied Street Demon TV bracket it comes down about an inch and a half, from the mounting base of an intake. Plenty of metal to grind away if needed and shouldn't affect the strength at all. Grinding a spot on the intake is also a possibility.

shiftbyear

Macadoo, the qjet is used on 9 sec. Stock and Superstock cars, it should be fine for your application. Cliff Ruggles said the TH350 carbs work fine with the 200R4 TV cable. I made a reverse warp plate fixture from pre-cut thick steel I got from a local steel supply store. Pop the carb in the oven @ 350 degrees, re-tighten fasteners every 15-20 min. for approx. 1hr. Let everything cool down together. Works pretty good. Final flattening for the top is on a 12" disc sander. I've had good luck with Q-jets. Good luck on your 455.

Macadoo

I've been researching how thick the intake walls are but not having any luck. I had that bracket on there when I briefly ran the Holley 3310 and it was pretty close to the runner with a 1 inch spacer (IIRC). But yeah, there's some metal there that can be taken away. I'm wondering if the Q-jet TV bracket I'm using will bolt up since I'll be using those anyway. It has a little more clearance. If nothing else, I can make a 1/4 inch spacer from some hard wood. Walnut might look nice

Thanks shiftbyear, I appreciate the info. I'd be interested to see more pics of your jig. I've toyed with the idea of making one myself and using the baking trick. How thick is your steel? On my current Q-jet, I spent hours sanding and filing the float bowl and base plate; it was the air horn I couldn't straighten. Are you removing all the tubes or did you drill holes through the steel for those? Lastly, do you have the shaft drill tool for the new bushings?

Lol, I'm not changing my mind, just back into the Q-jetty headspace.

coppercutlass

They might use qjets in super stocks but those carburetors are far from stock. And probably have more money in a q jet than the cost of a new eliminator carb.

Mac my boss had ruggles redo his q jet ..we where not happy with the q jet the "resto shop" did among a bunch of other questionable work that shop did.

Im a big fan of the Holley but I'm gonna be honest as say you need an 850 imo. I would for a good used 850 cfm Holley and rebuild it. I have only ever bought 1 new carb in 13 years lol. Just fwiw.

Macadoo

Thanks Copper. Surprising that Ruggles didn't do you right but I suppose any shop that gets that big and that busy...well, you know.
I get that an 850 would be better but I'm just not ready for mechanical secondaries and wouldn't the extra 100 cfm only come into play at WOT? I need to quiet that sort of play, I'm going through tires and gas too quickly, lol.

coppercutlass

No the carb ruggles did is great so far. The Resto shop my boss used prior to me digging into his 69 ss impala did the q jet and it was never right. The ruggles carb worked great out the box .

There is plenty of vacuum secondary 850 holleys out there. You can also add a metering block to the rear of that 750 i gave you and upgrade the main body to change air bleeds and what not.

shiftbyear

Macadoo, here's some pictures, the plates are 1/2" thick, the main body plate must be recessed for the venture protrusion (as marked) so it will sit flat, you can use gasket as drill templates. Good luck

shiftbyear

Macadoo, . The chucked stepped drill I had custom made to go all the way through the base plate but isn't really necessary, the bushing/drill kits available should work fine. The stepped reamer I got off E-bay because sometimes the shaft would bind with the new bushings, the reamer trues up all the shaft holes. Chamfering the holes before bushing installation helps. Bushing driver is just a bolt and nut. Good luck.

shiftbyear

Macadoo, yes the airhorn tubes must be removed for the airhorn to sit flat. I use a heat gun first, on stubborn tubes a little penetrating oil helps. I've ruined a few in my day. Stake or loktite when reinstalling, the need to stay in place. I've taken qjets apart and the tubes are laying in the bowl. Don't forget the secondary fuel discharge tubes.

Inline

I was the one compairing old genuine Carters ( last "real" Carters before FM took over) to new Edelbrocks. Old Carter is contoured nicely, and has no casting flaws on it.
New ones, sharp edges, theyve even removed some contouring from the main body just before venturis, and casting flaws everywhere. Plus shafts had pretty noticeable sideplay, which old, worn originals didnt have. The quality is indeed lackluster, takes few hours to contour and remove Flash just to get it match original Carters, plus shimming the shafts end-play.
And for the one asking about Weber-logos on new Edelbrocks, well, Weber casts them, thats why they have em.
Otherwise i like the working principle of Edelbrock/ Carter better than Holley-style carbs. Excluding the Street Demon.

cutlassefi

Inline

Most of that even by reading belongs to AFB's, and from unmentioned models id dare to quess 95%. Bogging. Due to weighted airdoor on secondaries. Yes, its opening rate may be altered, but what a work for hit'n'miss type approach. AVS aint any different anymore from secondary working principle than SD. Curious to see how the new AVS2's will work.

olds 307 and 403

Look how many complained on here about crappy running cars, almost all Edelbrock carbs, some with hours of tuning. There is still the hot start issues and had it since they first came out, just another reason to go with something else. I think the poor castings show why some can never be made right without extensive work.

Firewalker

I don't see much of this as anything other than mostly normal, for several reasons. The carbs are aluminum and great heat transfers heating up faster and this causes more problems in hotter environments. Next is the gasoline today is not like the gasoline when they were developed and used in the 1950s, when gasoline's evaporation rates was much much much lower. The third thing is for those who are new to carburetors they are more like black boxes they don't understand, or know how to deal with/tune them.

A bog may be to much gas at the wrong time rather than to little. Also the float levels change the tune or characteristics of carbs, and they maybe specked wrong from the factory, for the best running results.

coppercutlass

Every edelbrock i have had my hands on. Needed more pump shot. Once that was out of the way it ran great. I have my loaner 1405 .There hasn't been one engine thats been on that it didnt work on once we set the timing. My 750 HP. Needed way more initial shot. Flipped the pump cam but i can still add a bit more fuel off idle to WOT. I finally added an AFR gauge and at idle my carb is pretty good im yet to drive it. Mac that should be your next addition.

Macadoo

You mean a gauge like this one from Summit?
https://www.summitracing.com/parts/inn-3891
Add that to the price of Mark's QF carb suggestion and I'm inches from efi, lol. I'm glad I'm not in a hurry. Lots to consider.
I'm definitely having fuel boiling issues in the hot weather; I can hear it. And that's on a 1 inch phenolic spacer. That makes that Demon composite bowl look pretty good.

olds 307 and 403

The AFB/AVS had the hot start issues when Dodge used them in the 60's on new cars. The Thermoquad's design was done for a few reasons, hot starts is one. I agree once you get over $500 for a carb, a Sniper makes much more sense. The plug in Holley fuel pump module for our stock tanks also makes the switch easier.

Firewalker

I bought new wideband AEM O2 sensor gauge, for well under a 100 a few year back. Now they seem to be 150 and up new.

For the boiling issue, sometimes a piece of 1/8" plywood quite a bit larger than than the base of the carb helps. I had a younger friend that worked at a small gasket company that said he used a grey teflon like material under his carb, to stop that on his Chevy350 in his Datsun Z. He gave me a large piece of it he had left over. It was about an 1/8 thick and slick and shiny. Another person put a 12v computer fan next to his carb withed into his run power. Those fans are cheap LOL

Something like this with 3 speeds and even LEDs LOL

https://www.ebay.com/itm/Antec-TriCo...ZIsB:rk:8:pf:0

coppercutlass

The sniper EFI is about 1k. Installed depnding on your taste can run closer to 1600. Im in at about 1350 with mine installed. I ran an inline pump and filter but going intank will cost alot more. Look around for a good used carb and soend half the money even with a rebuild.

olds 307 and 403

https://www.summitracing.com/parts/hly-12-303/
Yah probably $1500 all in but the above fuel pump is just over $300 US. So basically $1000 more than the Street Demon. Of course the tuning kit and TV cable bracket adds to the cost.

Firewalker

For a tuning kit I would suggest something this, for part of one.

https://www.ebay.com/itm/CARTER-EDEL...Wfp:rk:34:pf:0

olds 307 and 403

The springs are available separate, also from Demon and 9 metering rods are available separate from the big kit from Demon. Of course Edelbrock primary rods can be used correct? There are 7 size available separate. The secondary jets are Holley, the primary jets are unique as far as I understand.

Macadoo

I've got like 10 of those computer fans laying around. I'll just hang them from the air cleaner. The blue LEDs would match the engine!
Thanks for all the input fellas. And thanks for the spring kit link, Firewalker.

Firewalker

All AFB type carbs floats, needle and seats, and metering springs and rods should be the same on interchangeability. This may include the acceleration pump and the Thermoquad parts. The front jets are not holley, but may interchange as well with other carbs. The back jets are holley. To me, what Holley offers in their kits is limited, and over priced to me.

Firewalker

Or take the extras, and line them up across the dash.... I only have 2 of those. One is working full time inside my huge CPU heatsink, and the other is a spare. I love them...

Inline

This a bit of hi-Jack, but information to Macadoo nonetheless.. Have any of you ( Firewalker?) been dynoing these. Locally there i know 2 Street Demons, which they couldnt get tuned, especially the transition from mains secondary, no matter what they tried. Googling behind all the magazine/ set-it up and forget praise, you found similiar issues. One guy i remember had to custom fabricate his own rods, which had really weird step on main rod, really huge. Got it working "ok" but not perfect still. Also i remember from some more indepth talk that Street Demon would be missing one circuit on secondaries that Q-Jet and TQ had to pull fuel during that transition. Design is sound ( since they copycatted from the best, took Holley only some 110 years to develop carb that dont leak fuel ), but on tuning-parts they lack it. Edelbrock parts working for these is new to me.

Firewalker

I know one racer, in a magazine article said the 625 dynoed at 500, or a little more on an LS engine.

On the secondaries the flapper valve on the Thermoquad had a dampening pot. It prevented them opening until the choke came off, and slowed the rate of opening down some. I think if there is a problem for some on the secondary its the fuel not starting fast enough, but there is a simple fix for that, if true.

https://mooregoodink.com/evil-twins-...hotrod-engine/

Macadoo

The quadrajets I've worked on also lock out the secondary air door until the choke is open. It's a nice feature.

Macadoo

I pulled the trigger on the Street Demon 750 with a larger pump squirter, spring kit, TV bracket, and a long -6 AN inlet fitting. I know some will think this is a mistake and others will not. I did a lot of reading and thinking and I'm choosing crisp response and peppy over WOT performance. My only concern at this point is the idle circuit. I may need to drill holes in the primary butterflies to feed this beast.
I'll report back with performance, or lack there of, but it will be a while. We still have about 6 inches of snow on the ground and negative 20* temps outside (NOT windchill, actual temps, lol). The house isn't getting good gas mileage right now!

Firewalker

I may be wrong, but I doubt the holes will be needed in the primary blades. There is also the option of opening the secondaries slightly, if a tad more air is needed. The metering rods will probably need a spring change. Taking all the bolts out of the bottom holding it together leaves two more in the top. Forgetting the one in the choke horn was a common fail, for those trying to open up the thermoquads, as they tried to pry the plastic body from the top and cracked it. The plastic is different now, but the bolt in the choke horn remains.

You should be getting a new fun toy, with possibilities.

Macadoo

I'll definitely look into those other options, if needed. I remember your post about bolting it on with just the top bolts holding it together while tuning but good call on the choke horn bolt. That might have been me! (although I tend to shy away from prying things).
Not being familiar with this design, how does one go about cracking the secondaries for a little more air? Is it bending the linkage?
Now, if I could just get the shop above 30 degrees.

Macadoo

I should mention; I'm actually pulling pretty good vacuum with this cam. 14 inches at 850 rpm. Most of those springs are rated for well under that, iirc.

Firewalker

14 inches is not bad. The secondary lever on the linkage has a small slot and that slot size might be fiddle with to open it a tad, at close. But just about any controlled air leak will do if needed. I am out spraying weeds today, as its mid 60s here. I want them dead
by spring.

Macadoo

Just rubbing it in?!

Firewalker

It got down to the lower double digits this winter, but not cold enough or long enough to kill the weeds off. And they seem to thrive like the yard was a fricken garden. Rubbing it in was my next door neighbor yelling good luck when she saw me spraying...again LOL One thing I did this winter was put a hole in my 2 gallon plastic pump sprayer, and I put a tire valve in it.

https://www.ebay.com/itm/4-CHROME-METAL-BOLT-IN-TIRE-VALVE-STEMS-VH-8-TR416-453-625-HOLES-1-LONG/254057810041?ssPageName=STRK%3AMEBIDX%3AIT&_trksid =p2057872.m2749.l2649

Now I can pressure it up with my compressor.

Macadoo

Now THAT'S a good idea. How much pressure do you put in there?

Firewalker

So far only 15-20 psi today, but I imagine it will hold at 50-100 quite easily. Plastic soda bottles will hold a lot more pressure before going boom then most might think, and this is heavy thick plastic.

Another change to the cheap sprayer I made was installing a brass nozzle like is found on expensive sprayers and lengthened the plastic spray wand past the trigger.

ragz442

Good luck with the Street Demon. Why don't people post their location so I have a clue where the sane people live in the winter......lol

Macadoo

Well sir, I know a few CO fellows live in Chi-beria (Chicago) Illinoiz and they had it just as bad. You folks in MI doing okay?