fireturd350

iTrader: (8)

Does anyone know of a decent shop that will tune my carb?

It's a 750 Speed Demon DP on a healthy 383. I have it close enough to drive, but it's no where near perfect. I set it for most vacuum and even idle corners, but it still has a few flat spots that are noticeable at times at highway speeds. I usually prefer doing stuff myself because I don't trust most shops, but I need help with this.

fireturd350

iTrader: (8)

Don't everyone shout out advice all at once.

I've sent an email to "Illinois Dyno Center" out of Port Byron, IL. Now I'm just waiting to hear back on my questions.

1. Do they adjust jets and etc in the carb to get it running perfect?
2. Do they adjust timing?
3. Am I able to be present for the tuning and dyno pulls?
4. How many estimated hours would something like this require ($125/hour adds up quickly)?
5. Do I need to leave the car there or can I just drop it off and wait?
6. Am I allowed to bring my own parts (jets, gaskets, etc) or do I need to purchase in-house parts?

I'll reply back for answers that way when someone finds this post acouple years down the road I don't have to be going through the email archives for answers.

fireturd350

iTrader: (8)

Here's what I heard back:

"Yes, we can dial in your Formula for you - no problem.

We have a complete assortment of jets for your carb, although if you have any power valves or gaskets for it, it would be good to bring those.

Shop Tuning is $125/hr, and it rarely takes over 1 hour to set the timing, and get the jetting correct in the carb. We encourage you to be here, when we tune it, so you won't have to drop the car off."

t-top havoc

iTrader: (3)

Ok so I'm asking a Q because I can't remember---
Do the Quad Cities areas include Moline???

Yrs ago, probly 10, there was a shop right around the area
of a place called " Rudy's Tacos ", but I can't remember the shop!!
Margaritas were very good!!

Sorry, but I was thinking if you're Moline area & knew of Rudy's,
it might help you or someone else remember the shop name.

They used to ad in Hot Rod, Car Craft, Super Chevy & a couple others.

fireturd350

iTrader: (8)

Yes Moline is QC's.

I know Rev Hard is up there, but I've heard mixed results from them about how they're only there to take money from rich kids looking to make there car "tuned".

I've also heard mix results from Il Dyno Center (IDC), but apparently they did a great job tuning a carb 383 in a vette for one of my friend's family members. I thought I would give them a shot. It only made 350 RWHP which makes me wonder if there dyno is still off as much as people say. The owner seems nice. We'll see I'm getting very tired of shops (especially tire shops) telling me I have transmission issues and they don't want to service my car. Seriously it's an aftermarket stall put your foot down a little bit stop being so girly and trying to idle it around.

I hear very good things from Kurgan Motorsports but there in Byron, IL and that's quiet a bit further (another 1-1.5 hours on my drivetime).

Driving a car that doesn't have working cruise control, AC, blower fan, with 4" exhaust , and etc is alright for short distances but I don't think I want to try to do a 2-3 hour one-way trip in it yet.

whatever84

Wow! I think that would be a great time. I wish we had something like that here.

Mark.

fireturd350

iTrader: (8)

Coming back to this. I got an appointment for next week. I just installed a new power steering pump last week so I think I'm ready for the 70 mile road trip there.

Might swing by Cordova if I get the car tuned up and everything goes well.

Got my fingers crossed hoping to make at least 400 RWHP.

The car is running good currently. It shifts very nice at 6500+ RPMs and lunges forward wanting to go again.

fireturd350

iTrader: (8)

Well it didn't go very well. My street tune was pretty close 13.0 AFR when idling. They tuned that up. The car had a very very lean spot after 2k and up. By lean I mean 14.0 to 18.0. After tuning for about an hour they got it where it was only lean at 2k-3k rpm range. They couldn't figure out why it was still lean there after going to 37 squirters and 96 jets. Turns out I have a leak in the coolant jacket by #1 (intake gasket). I blew antifreeze everywhere on the first run on the dyno shortly after. They also found throttle shaft play and thought that might be a leak too.

So $220 shop bill to find out I have a vac leak, coolant leak, and I broke the flexplate cover somehow as it filled with coolant.

Dyno pull was very disappointing too only around 340 RWTQ and 291 RWHP, which was probably due to the vac leak (at least I'm hoping).

I was really hoping for around 450 rwtq and 400+ rwhp.

Add in the fact I blew the intake or head gasket out of my other car. I now have 2 broken cars and no way to get to work Monday.

BTW my issues aren't Illinois Dyno Center's fault in any way. The intake gasket blew out cause the front bolts were loose. I previously checked them all last month or so. I guess I'll try to get it all fixed and tune it myself with the GTech Pro to get my jetting closer. I imagine I'll be super rich with 96s after the leaks are fixed.

xpndbl3

iTrader: (5)

96 is ridiculous and there is no reason for them to run the jetting that high at all. They should have known there was vacuum leak or motor issues when playing with jets that large. What's your fuel pressure like? is it keeping up in 3rd gear? For that kind of cash you could have bought a AEM uego wideband and tuned it yourself. I'll be at cordova on november 6th for a track rental we put on if you'll be around. I hope you fix the issues beforehand. Why are they tuning at WOT between 2-3k or was that while they were doing drivability issues at part throttle. I don't bother looking at a/f ratio data below a converters stall speed typically since all it's showing is the pump shot keeping up with the rpm spike. If it was lean during the hit then you would need to play with pump cams and squirters. If the motor needs 37 squirters then you're looking at 50cc pump shot kits added on, but IMO that motor is no where near radical enough to need it.

fireturd350

iTrader: (8)

They were trying to tune a steady state dead spot at part throttle. FP is 7 PSI cold and 6.5 PSI after heat soak. As far as I can tell FP is keeping up with demand it would run alright on the street. Hopefully I can find new Fel Pro 1206s around today. I'd really like to have a car to drive next week. Yeah hopefully I'm back up and running before Nov 6th. It didn't help Tom told me there dyno was broken in the morning and I could never get a call back at all or them to answer the phones to see if they got it fixed. So I basically drove over an hour in hopes there dyno was functioning.

fireturd350

iTrader: (8)

Motor is torn apart now. Gasket didn't really look bad (no rips, tears, etc). Called around no local stores even carry that earliest I can get it around here is Monday or Tuesday, but Winner's Circle has 6 in stock, so time for a 45 minute+ trip. Continuing this discussion about the discolored runners over on my new thread in the tech section. https://www.thirdgen.org/forums/tech...e-runners.html

xpndbl3

iTrader: (5)

Ports that clean are probably from a water/coolant leak which will steam clean the ports up for ya. Your other side seems to have a bit of carbon buildup, what do your plugs look like?

fireturd350

iTrader: (8)

I haven't pulled the plugs yet. I went and got a new 1206 gasket today. It looks slightly different than old 1206s. The new ones have more meat between the water jacket and the intake ports so I'm thinking that should help it seal a lot better since before some of my intake was touching empty space where there was no gasket.

xpndbl3

iTrader: (5)

are you also putting a skim coat of ultra grey around the coolant ports on the heads? I've always done this as added insurance in case the decks aren't 100% straight or warp slightly when heated up. We're talking very thin coats, don't glob it.

fireturd350

iTrader: (8)

I didn't the first time. I put 1/8" of black RTV around all ports this time and used high temp thread sealant on the bolts. I also tq'd them to 25 lbs and did the rotation 5-7 times until they all were tight.

I checked the intake for levelness and it looked fine with I put a straight edge against it.

xpndbl3

iTrader: (5)

After a few heat cycles recheck intake torque and you should be all set. Then spray some starting fluid around the intake ports and carb to see if rpms jump up for a split second. Then you'll know about the vacuum leak immediately.

fireturd350

iTrader: (8)

Yeah actually I thought about that already. I have a small propane tank (camping one you use on 2 burner stoves) I was going to use to check for leaks. I checked to see if Winner's Circle knew anything about Speed Demon Bushings and they said Barry Grant doesn't have a kit for them.

xpndbl3

iTrader: (5)

do you have a lot of miles on your carb? Or perhaps the return springs were too tight? Those are the main reasons they would wear down.

fireturd350

iTrader: (8)

Well I bought the carb used off ebay because it was listed as like new condition only used on a strip car. Obviously I got ripped off. I'm only running one of the 2 return springs, which I felt like was enough since I have the 700-r4 kickdown on it also.

Plugs look super rich. I might do some tuning today with the Gtech Pro. I would think 1/4 mile mph would be a good indication for moving jets down.

Well stabbed the distributor again and fired it up. Error'd on the side of caution with timing then I shot it at 10* base w/o vac advance. That's what it was at before when I put 850+ street miles on it. Put a few heat cycles on it today just getting it warm then letting it cool back off. Then I'll check the intake bolts again and look for a leak later. Then I get to pull apart the 3800 series V6 tonight or tomorrow for head gaskets and etc.

xpndbl3

iTrader: (5)

Best bet would be to toss in one brand new $1.79 plug into the motor everytime you make a jet change and drive it around then look at plug color. I'd be looking at primary jetting first since it sounds like you cruise it a lot.

fireturd350

iTrader: (8)

I put 28 squirters back on and I replaced the P jets with #88s. I tested for leaks with starter fluid and found a leak in the throttle shaft around 2000 RPMs (right when it starts to show play). Also looked at the upper primary bowl threads and found the corner one was missing all but 1 or 2 threads. It doesn't leak, but looks like I might have to get a new carb.

Now after I got the motor hot I have an oil leak. Looks like its the back passenger side china wall, so I get to tear that all apart over again....

xpndbl3

iTrader: (5)

squirters were probably fine, 31 is typically the norm for a mild sbc, if you get a lean stumble then you might need to step back up. Primary jets at 88 are huge, think more like 78/86 for front/rear. I hope you're running a power valve still as well and not jetting the carb square.

fireturd350

iTrader: (8)

Amazing I just called Barry Grant to ask about a service kit. Guy was a complete ***.

Convo basically went:

Me: "Hello I have a question about my Speed Demon 750 Double Pumper. I believe I have a vacuum leak at around 2000 RPMs on the Primary throttle shaft."

Him: "Well if you have fuel dripping you have other problems."

Me: "I don't have any fuel leaking. I have a vacuum leak. I noticed it at around 2000 RPMs cause I spray some brake cleaner and saw the RPMs rise."

Him: "Well sir spraying anything next to the throttle shaft won't raise engine RPMS."

Me: "MMMM it would if I had a vacuum leak."

Him: "Well sir since you have all the answers I don't have anything for you."

Me: "Well I was wondering does Barry Grant carry throttle shaft bushing service kits?"

Him: "There are no bushings in our carburetors so NO! Since I can't help you I might as well just go."

Me: "Well since this carb is a trashed can you help me pick a new one?"

Him: "Sure."

Me: Give him the specs [383 SBC, Victor JR, 2" 4-hole spacer (for street tq), 240+ Duration @ 50, AFR 210 2.08 valve heads, 10:1 CR, 2400+ RPM Stall, sees rpms from 2k to 6.5k]

Him: "Well your car isn't setup right you need a lot larger converter for a 240 duration camshaft. If you changed the converter I would recommend a Mighty Demon 750 annular booster double pumper. If you stay with your current converter it's not going to run right with anything you pick out."

Me: "Fine, goodbye."

Do these ppl just enjoy being bitchy? I srsly didn't think 340 RWTQ and 290 RWHP was bad with a coolant leak and vac leak. According to him my car should run like total crap.

So next question is do I try to fix the SP750DP (holley bushing/helicoil that upper bowl thread) or just buy a mighty demon?

xpndbl3

iTrader: (5)

I would never buy a demon anything but that's just me Too many carbs I've taken apart brand new out of the box with aluminum shavings inside them, it's not worth my time to blow them out and clean up a brand new carb. I'm a huge fan of quick fuel carbs, their tech line is great and they have parts in stock for servicing them. Also with that cam I would have thought a 3500 stall minimum and a 4000 wouldn't be out of line at all for that much duration. If you street drive it a ton I'd go with the Q series 750, but at the track I did pick up swapping to the 950 and didn't notice any driveability issues that couldn't be tuned out with the larger carb. I also know of 3 other cars that picked up ET from swapping to a 950 over a 750.

fireturd350

iTrader: (8)

Well I think my stall is flashing around 3k now. Hard to tell for sure when the carb is acting up at times tho.

The stall was originally made for 2400 RPM flash behind my old stock 350. I'm pretty sure the new 383 is making a lot more tq.

I would just like to get it running and get some decent numbers. Really sucked to see my friend throw down 553 RWHP, then 12+ dyno pulls later throw down 690 RWHP in his Mustang then I get a 290 RWHP pull and blow the intake gasket followed by an hour+ drive home in the car.

xpndbl3

iTrader: (5)

had an old combo that put down 350rwhp and ran 10.80s at the track. Dyno numbers are a tuning aid only, nothing else matters.

fireturd350

iTrader: (8)

Back together and running again. I went ahead and put 37 squirters back on the large #90 jets again since the throttleshaft is leaking vacuum (even through BG says it's impossible for a throttleshaft to leak vacuum). I managed to strip another upper bowl thread, at least it isn't leaking so must be holding enough to drive around for now. Time for a new carb I guess.

xpndbl3

iTrader: (5)

how are you stripping all these bowl threads? you do know it's basically hand tight right? I think you should buy a screwdriver type nut driver so you don't overtorque them. Back in the day when carb float bowl screws had a slot in the middle, I'd use a quarter to tighten them up with no leaks. Also 90s in the primaries are far too large, I can't believe it's not burning your eyes with the gas smell and fouling out the plugs.

fireturd350

iTrader: (8)

All I did was snug them down. Apparently I don't know my own strength. I ended up pulling 1/2 threads out on the bolt. Carb looks like it was abused before. The linkage bracket was cut in half when I bought it off ebay.

I think the reason why I'm not fouling plugs is the throttle shaft leak. From what I can tell it leaks anytime around 2k rpms or higher. According to there AFR I was still pulling 17:1 in some of the rpm range.

I'm just going to suck it up and order a new Mighty Demon 750 Annular carb today. I'll probably box the Speed Demon until I get bored and decide to bushing and helicoil it someday.

I looked at the EZ-EFI but I don't feel like spending $1600 on something I can't eventually run a nitrous shot on.

Switched to some 78s front that cleaned up the response a lot. I didn't have time to switch the rears or check them yet.

I just put a new Mighty Demon 750 DP Annular on order. After reviewing dyno results and testing between annular and downleg (dog leg) styles looks like annular produces a little more torque and some hp. Probably just drop my Speed Demon off at a machine shop sometime and have them fix the helicoils and put a bushing on the shaft. I looked at service kits for Holley Bushings but there $80 or so. I imagine I can get a shop to do it cheaper than that.

xpndbl3

iTrader: (5)

i guess all my advice on NOT buying another demon is going unnoticed. Get a quick fuel, you'll be much happier in the end.

fireturd350

iTrader: (8)

I did take it into consideration. I did research around. I agree a Quick Fuel does look nice. I don't know if it's worth the extra cash for it though since I plan on mostly street miles. I even looked into the Pro Systems custom tuned carbs too.

I did find an old article in Super Chevy online about a 750 Mighty being put on a 383 and tuned for the street with good results. Also another used on the "Danger Mouse" build with a very similar solid roller camshaft. For now I've decided to just stay with a demon. I probably should have never picked the Speed Demon line since my camshaft was over 240* duration especially since it was used and unknown condition. The Mighty Demon comes with slightly larger jets out of the box and doesn't have the choke tower (didn't worry about running a choke before anyways).

xpndbl3

iTrader: (5)

well when you have problems with your new carb too, I get to say I told you so. If it's a money thing even the proform is nicer, but you won't get the same quality as a more expensive one.

fireturd350

iTrader: (8)

Probably. Also upon further thinking if I truly only have 10* initial that's no where close too enough. The distributor is set to 19* bushing so that only gives me 29* at WOT and 39* when cruising (vac advance). Hopefully the new carb and bumping up timing to 16* initial (35* total at WOT) improves my power numbers and driveability. I wonder why the shop didn't stop to bump up the timing. You would think when I told them 19* bushing in the distributor they would have thought that 29* wasn't enough. Might also explain why peak HP was in low 5000s RPM range on a 0.600+ lift solid roller.

xpndbl3

iTrader: (5)

also can explain why the motor wanted so much jetting.

fireturd350

iTrader: (8)

Checked rear jets. They were 80s. Why they did Secondaries smaller than primaries is beyond me.

I also checked the balancer and it is correctly marked at 0*. I shot the base timing with my snap-on dial light and got 10*. I then shot it with the cheap AutoZone Actron light and confirmed it lite up past the mark around the 10* advance area. Set the dial to 16* set the initial there. I then set dial to 35* and rev'd it, which I'm sure neighbors loved at 9 PM at night. Looks right around 34*-35* total. Hooked vac advance back up and rev'd it again looks like 44*-45* total on it. So that's set.

I took it for a short drive. I didn't hear any pinging. It still wants to die if I tip it in from dead stop and snap the butterflies shut quickly. I'm hoping that's due to throttle shaft leak. Maybe I'll play with Gtech tomorrow and see if mph improves last time I ran it was 13.7 @ 112 mph.

fireturd350

iTrader: (8)

Also should add I changed those rear jets out to 86s like you recommended.

We'll see how the car runs tomorrow. Hopefully this gets me back going so I can pull my Bonneville in and start on head gaskets for it.

fireturd350

iTrader: (8)

Feel free to say I told you so...

Carb came today I corrected settings out of the box. There trans slot looked like a rectangle. I threw carb on there. Motor fired up I turned up set screw to let it warm up. Once at 160* I turned set screw back to normal, which made it go into rough idle of 500-700 rpm. I turned idle mixtures in until it stopped smoking and corrected out at a nice 1000 rpm for now. Hooked up my vac lines and put my vac gauge on the full manifold port (next to the timed port that my distributor, tcc solenoid, etc use). No vacuum what so ever on that full port. I then turned the car off. I pulled the hose out made sure I could make the gauge bounce and put the hose back on the carb. I tried to blow air into that port and nothing. It's like it's totally sealed. I pulled the carb back off and made sure nothing is in it. It's still not working without it on the manifold so the gasket isn't blocking it. I shined a light in there... nothing totally sealed. It's like they didn't drill it correctly or when they put the tube in there sealant blocked it off. Tech line is closed now so no help there. Am I seriously this bad at carbs?

fireturd350

iTrader: (8)

Dropped a finishing nail in there just to see. It goes completely in the timed but the manifold vac stikcs out an inch or so. From what I can tell they didn't even drill the baseplate.... $550 for a carb I shouldn't have to deal with crap like this.

I called Jegs and told them to mark it as return/exchange and I'll make up my mind. I'm seriously thinking about returning this POS and going to a Quick Fuel now. Recommendations on exact models?

xpndbl3

iTrader: (5)

did you pull off the hoses on the ported vacuum source to make sure you don't have them flipped? One of those two fittings should have vacuum going to them, if not box the thing back up after draining the fluid and buy something quality Take the metering block off the carb and try to shoot some carb cleaner down that port, wear safety glasses so you don't get any in your eyes.

http://www.summitracing.com/parts/QFT-Q-750/

http://www.summitracing.com/parts/QFT-Q-850/

depends if you think the combo will grow in the future if you want to step up carb size. I run the 950cfm one and sold the 750 cfm and it was worth .08 at the track just with that swap alone, back to back passes same day.

fireturd350

iTrader: (8)

Car ran much better with the new carb. Feels like it hits and tips in much harder/faster.

Yep, I made sure I didn't have ports mixed up. I also rev'd the crap out of the motor 5k+ RPM and still nothing on the gauge. According the directions outside most is ported/timed inside is direct manifold vac. The Direct manifold vacuum is the one with the issue. I even tapped on the nail it didn't move. Nails in the picture are the same length. Outside one goes in just into the baseplate area. The valve parts are drilled further towards the center in that channel so that shouldn't be an issue. I also double checked on my Speed Demon I can get air movement through both with the carb off.



ARG 7/8-20 compared to the 9/16-24 I'll need new fuel inlet AN connectors too.

fireturd350

iTrader: (8)

Don't Annular boosters make a little more power and allow for a better mixture for street use?

http://www.summitracing.com/parts/QFT-Q-750-AN/

xpndbl3

iTrader: (5)

Annular boosters really shine if there is a weaker carb signal or less velocity running through it, I'm sure if you google the answer it'll be some sort of description like that. I've never run one or put one on a car so I can't say, I thought I saw years ago an flow chart vs. the different boosters, but I can't recall it at the moment. After adding in the price of new fuel line fittings you're basically at the price of the quick fuel anyways and can save yourself the hassle of an inferior product.

fireturd350

iTrader: (8)

http://www.carcraft.com/techarticles...own/index.html

Interesting writeup and dyno results showing annular made 90+ more tq at low rpms. Looks like annular for street use for me.

Found JEGs has there generic 7/8-20 to -8 AN fittings for $25. Now if I can just get them to match the price of CarShop's Q-750-AN at $633 I'd switch.

fireturd350

iTrader: (8)

New Pro-Systems Carb arrived yesterday. After talking with Patrick he told me I didn't need or should want annular boosters. He said on my motor there just a bandaid for poorly sized carb, which made me feel good since he could have just sold them to me anyways and made more of a profit.

It's a 4150 Holley 950HP Main Body with downlegs, red baseplate, and all the other fancy features everywhere including float level sights. I haven't got it on the car yet because I need to run up to QC's for new bowl fittings. Hoping I can throw it on and play with timing and pick up some throttle response and power. 290 RWHP isn't anywhere close to what I should be making.

xpndbl3

iTrader: (5)

congrats, hope to see it running well soon. If not november 6th is coming up for my cordova track rental

Deimos140

I've heard very bad things about barry grant carbs. I have talked to carb manufacturers and speced out my engine, apparenty annular boosters is good if you have a heavier car like an impala. X2 with the quick fuel ebing awesome cabrs,

fireturd350

iTrader: (8)

Back from the dead... I'm cursed put new carb on everything going great good throttle response etc. No more dead spots under 3000 rpms actually perks right up with throttle now. Was noticing hard starts after it gets warm. I figured it was just heatsoak so I checked my connections and wrapped the starter to cool it down. I went and bought $20 gas today. After that i went to start the car barely cranked over and then eventually heard POP followed by smoke and now starter is not working. I hate my life... I have voltage and connections are good so I had to have the car tow'd since the gas station basically told me I had to push it on the street then told me I could leave it for acouple hours. So I had to have it tow'd even tho it was in a parking spot. Anyway $130 later car is home again and probably replace the starter next week.

fireturd350

iTrader: (8)

Back from the dead again. I had rear end issues (broken cross shafts) when I tore it apart to check on wear. 9 bolt is now swapped out for a 10 bolt. Now that is taken care of I'm starting to think about tuning the Pro Systems Carb again.

I could either buy a wideband and hope I can figure it out myself or make another trip to the dyno center again. I wouldn't mind going to the dyno with a bunch of spacers to dial that in.

I'm kinda split a wideband would be nice to have and from that last trip I could have paid for one right there, but on the other hand I'm leery of trying to figure out all the tuning on my own.

Ideas?