Procharged GTA

Fantastic! Your timing sounds pretty close.... i would try to keep it around 30-31* total under boost until you can get it on the dyno where you can make changes and watch closely for detonation, or power to drop off.... Some combinations can be surprising how much timing they like, we once had a street pump gas 383 sbc with Trick Flow twisted wedge heads and 9.6 compression with an NX274 Comp flat tappet cam with a Procharger P600B supercharger pumping 6lb. Boost. It was EFI....On the dyno, we put 34* timing in it and made a pull, it rev'd like a slug. So we bumped it to 38* and it responded well with 426 RWHP....the next pull we bumped it to 40* and it still didn't detonate, but power was no better, so we put it back to 38*. We would have never dreamed it would want that kind of timing under boost on pump gas. This was our Drag Radial car back when it was on the street. Head Chamber and Camshaft design along with compression has EVERYTHING to do with the amount of timing a certain application will want.

As for your vacuum advance, It will be best if it adds an additional 8-10*

If the 750 is shooting gas out of the bowl vents trying to start it, definatley sounds like something hung in the needle and seat. I believe it will see a very good power gain over the 650!! It would probably love somewhere around an 840-850 really....the little blowers love airflow, and big carbs with them doesn't affect driveability like it does with a Naturally Aspirated application.

Dad is running a 3.10 pulley on his truck, but don't currently have a boost gauge installed to see what it's making for boost, but it runs incredibly well....He does have a new 2.8 pulley waiting if he ever decides too... LOL

oh yeah.... hell with the pictures, I want some video!!! Haha!!

skinny z

What vacuum advance arrangement are you using?

1gary

Congrats on a very good build.Been setting here in the cheap seats enjoying it all.Happy for you all the things worked out well.

articwhiteZ

iTrader: (56)

glad ya got it going.
this is pics of the dipstick fix on my block..tap and pluged!


dipstick bung in pan. with oil temp bung and oil return from blower.

and drain plug side.

this pan is 8qt w/filter & made for a 4" stroke.
i also buffed out my freez plugs. then cleared them. will see how long that last.. but its only a weekend driver on sunny days at the track
but i do drive it on the street to the track...

Confuzed1

iTrader: (4)

Brian - I can't thank you enough for all the advice and support throughout this build you've given me.

Just so everyone knows, I've texted this guy at all times of the day with questions and whining throughout my build, and he always replied with good sound advice…a stand-up guy that knows what he's talking about. I plan to keep him on speed dial, and maybe we'll meet up one of these days!

I just got home on Saturday from the Hot Rod Power tour! No - I didn't take the Camaro until the last stretch…honestly, the Challenger SRT is just flat-out a nicer car to travel cross country with….A/C, GPS, CUP HOLDERS (that's BIG), cruise, lumbar etc….everything….plus halfway decent gas mileage (about 22 on the highway) And I took the wife….you know the saying, "Happy wife, happy life".

I can honestly say it was an experience worth doing….not sure if I'd do the whole thing again though. But I have my "Long Hauler" shirt and sign, all is good.

Besides, the Camaro literally only had like 15 minutes of real road time the evening before the tour…and although it ran great, if it were to break in the middle of nowhere…it's not like Autozone or anyone else will have any parts for it.

I did leave early from Bettendorf IA., and drove home to pick up the Z28 and took it 3.5 hours each way to WI. Dells. Ran like a champ and I had no real issues at all (I do have some kind of faint rubbing noise in the rear though) - gotta look into that. Now, to answer the posts:

Brian - I have my total mechanical set up at 36 degrees max, all in by 2200. I still need to tweak my adjustable vacuum advance can to allow a few degrees more I think, since it only seems to be giving me a few degrees when I plug the hose into full manifold vacuum. I have the boost retard dial set to take out 1 degree of advance per pound of boost, so at full boost I'm at 30 degrees advance…it seems like it can take more. Same exhaust as I had on it, but for whatever reason the exhaust note has changed a lot…it sounds real healthy compared to what it was. I got a few compliments at how mean the thing sounds when I was up north with it.

The car seems to be running cool as h*ll for some reason….fan is supposed to kick on at 190, but I think it's running earlier. I've yet to see it run over 180 on my cheap mechanical temp gage. I plan to buy another fan switch and see what happens. The terminal on this one is loose.

I just installed the 750 carb back on it yesterday. The floats needed to be adjusted badly on both sides…they were wayyy off. I had to bend the float tabs quite a lot. As it was, the float would rise to the top and not shut off the fuel at all! And there wasn't enough adjustment to compensate with the top screw/nut adjustment. I doesn't surprise me too much, since I bought this carb off flea bay from a guy that said it was never ran…it just sat on a show truck it's entire life, so I think it never had gas ran throughout it. I still need to road test it with this carb. I have the bowl fuel levels set to the bottom of the sights on the bowls, and it's idling like a champ!

Just yer run-of-the-mill adjustable vacuum can that comes with the Mallory Uni-lite distributor. I plug it into the full manifold vacuum under the blower.

Thanks Gary! You've also helped me a lot on this build!

That's a better setup than I have! My dipstick is working, but it's a PITA to check the oil when the engine is hot (relative term)…it's tucked in between the primary tubes on the headers, and unless I let the car sit for a little bit, I'll burn the crap outta my hands! But at least it doesn't leak….

Guess I'll put this thread to a close. Again, I really do appreciate all the help I've gotten from everyone! If any of you guys have any questions I can't answer, feel free to PM me!

EDIT: Just in case you guys need proof that I was there! The green sticker on the DS windshield is the Long Hauler's parking pass.. :

Procharged GTA

Thanks Confuzed!! I appreciate the kind words...I always love to try and help anyway I can, if I've got the knowledge. Even though I'm only 32, I've been around this stuff my whole life, so I've gained a great deal of knowledge with this stuff,, particularly the forced induction stuff, I love every bit of it. Heck, I have even learned a few things about Top Fuel as I have a good friend that runs a Top Fuel Dragster, but my knowledge is based mostly on pump gas street stuff and Small Tire/Drag Radial heads up drag racing stuff. To me, there is nothing that says BAD *** more than a car with Stock Suspension ,1500hp, that runs a "street drag radial" tire and will run high 4's/low 5's 1/8 mile. Or pulling up to the pump at the local station in your 600 - 800hp street legal driver...

It's great to hear that the power tour went well!! Please keep us updated on how well this runs as tuning progress 's

Brian

Confuzed1

iTrader: (4)

Well, looks like I have an issue with it. I hooked up my boost gage and took it out for a spin around the block. Both times that I opened it up a bit, I didn't read any boost pressure at all.

I still hear the familiar blower whine every time I goose it, but the gage stays at zero. Seems to run great so I thought maybe the gage went bad, so I used about 10 pounds of air and the gage is working. So then I figured maybe I have a leaky vacuum hose, so I disconnected it from under the blower and the power valve port on the carb, and used 10 pounds of air to it....gage worked and no apparent leaks.

I'm stumped! I can only think of a couple reasons thisight be happening:
1. Blower is bad for whatever reason...but it still whines like it's working, and plenty of power. Or-

2. With the new heads and carb, this engine is breathing that much better that it's not building boost?? I dunno....the blower worked fine before I rebuilt this engine, and it was showing 5 pounds of boost....

Any ideas??

Confuzed1

iTrader: (4)

BTW, I'm running a 3.5" pulley on it which used to give me 5 pounds of boost. I have a 2.8" pulley I could try again...that used to give me about 8 psi.

Only differences in this setup is I added AFR 195 Street Eliminator heads, the compression changed from. 0.1:1 to around 8.7:1. I also switched to 1.6 ratio rockers (was 1.5), and I added a bigger Speed Demon DP carb (650 to a 750)... So I don't know what is going on here...

1991sleeper

iTrader: (-3)

I'd say try the 2.8 and c what happens .. 5psi ain't a lot so it could possibly b the fact of improving airflow so much that the blower is just barely keeping up with the airflow requirements of the engine in N/A form ? Idk

91' bird 305 TBI T-5, trick flow 175 cc heads, 4.10 gears, lots of suspension upgrades. 24mpg @ 2500rpm hwy. 8.63@ 85mph 1/8th on street tires... 8.000's soon

Procharged GTA

I would go with number 2 on your list....that thing is breathing much better with the AFR heads and 1.6 rocker, that's the reason for the change in exhaust note also.... I would definitely change the 3.5" pulley for a smaller pulley....and see what happens. If it starts showing boost with the smaller pulley, it is just breathing alot better. I agree boost looks good on the gauge, but in the end, it's nothing more than a indicator of airflow restriction the engine simply cannot eat. You can take a race engine that pumps 25# boost and change the Heads and Camshaft to alot better flowing parts, and the result may be the new combo only pumps 20# spinning the supercharger the same speed as before, but the engine may make a couple hundred more horsepower with 5# less boost because the engine is acually eating it. Same thing happens when increasing cubic inches...it will lose boost spinning the supercharger the same RPM as before, but it will make MORE power .

I don't think there is anything wrong with the supercharger, I believe your new combination is happily using the airflow that the supercharger is producing with the 3.5" pulley. I would drop down to atleast a 3.10" on your combination. Maybe even the 2.8" if belt slip could be controlled.... another PLUS is that a better breathing engine will tend to reduce belt slippage issues some, because the supercharger is easier to drive do to less restriction to have to pump against....

Brian

Confuzed1

iTrader: (4)

Thanks a lot for the replies! I was doing a bit of web searching, and indeed the combination of changing heads, the bigger carb and introducing higher lifts with the 1.6 ratio arms will tend to lower boost pressures - not to mention the compression drop with these new heads with slightly larger chambers (72cc to 75cc)...I used a thinner compressed head gasket, but still lost a little compression.

The 2.8" pulley I believe is the next step down from the 3.5"....I didn't see anything in between available when I bought it. It's also the smallest pulley for the blower. So I'm done after this - assuming this works.

I realize boost pressure is just boost stacked up in the intake that the engine is essentially not using, but I'd be happy if I can maintain a few psi so I know I'm not "under-feeding" it.

The only other possibility is that the internal bypass valve is not shutting, but I kinda doubt it since I still hear the blower whine as if it's feeding it when I get on it. I could check its operation with a hand held vacuum pump I guess, but I'd have to buy one. I'll try the pulley change first!

Procharged GTA

We ordered ours staight from Magnuson... the 3.10" and the 2.80"... they are standard .400" offset keyed pulleys.

Confuzed1

iTrader: (4)

Brian - Yeah, I believe I got mine from Magnuson too....

I had to go look to verify what I currently have on the car vs. what I have on the shelf. Turns out I have a 3" currently on the car, and a 2.8" on the shelf.

I'm wondering how big a difference that'll make....I'm thinking very little...

1991sleeper

iTrader: (-3)

Possibly try a different size crank pulley to get it spinning a little faster ... That's about the only thing I can think of if u can't get smaller than 2.8 ... Or try to sell ur blower n get a bigger one

Edit : or c if a nearby machine shop can custom make u a 2" - 2.5" out of billet aluminum

91' bird 305 TBI T-5, trick flow 175 cc heads, 4.10 gears, lots of suspension upgrades. 24mpg @ 2500rpm hwy. 8.63@ 85mph 1/8th on street tires... 8.000's soon

1991sleeper

iTrader: (-3)

http://www.innovatorswest.com/Blower-Pulleys.html

Custom pulleys ^^^

91' bird 305 TBI T-5, trick flow 175 cc heads, 4.10 gears, lots of suspension upgrades. 24mpg @ 2500rpm hwy. 8.63@ 85mph 1/8th on street tires... 8.000's soon

Confuzed1

iTrader: (4)

Thanks for the quick reply '91! I see your search skills are way advanced compared to mine!

Working 12 hour night shifts at the moment, but I plan to just go ahead and try the 2.8 pulley after I'm of my last shift here. Can't hurt....even if I get a measly 2 pounds of actual boost with it. At least I know the car is actually using the boost and I'll feel better rolling with that for a while.

I seem to recall talking to another Brian at Magnuson when I ordered the 2.8 pulley, and he told me it was the smallest recommended one for this blower...if I drive it any faster, the charge will be too hot to be worth it....and no intercooler.

I'm afraid if I want more, I'll need to step up to a bigger blower as you mentioned. After the huge costs associated with this current build, I just can't swing that right now. I need to pour $$ into my house (new roof, floors etc.)

Can't wait to try the smallest pulley and see if I can read some boost again!!

EDIT: If it works out, I'll get the car back on the chassis dyno again just to get a feel of how much more power I'm laying down compared to my previous setup....any guesses??

Confuzed1

iTrader: (4)

Welp - I installed the smallest pulley…. the 2.8"….and still not showing any boost.

I'm perplexed. It's running strong, I clearly hearing the blower whining when I open it up like it's doing something….but no pressure reading on the gage.

Only things I think I can check is that the internal bypass valve seems to be shutting…I'll need to go out and buy one of those bellows-type vacuum pumps to see if it seems to operate.

-Another thought I had was to also check the vacuum advance can on the distributor. I basically have a vacuum hose tapped off at the base of the blower, and it tees off to the vacuum advance, the MSD boost retard box, the boost gage and the power valve port on the carb.

I know normally the vacuum advance can on a normal NA car never sees pressure, but in my application it does. Just wondering if I ruptured the rubber diaprahm in the can…I dunno, reaching for straws here….

skinny z

Sounds like something basic has failed. The gauge itself perhaps? If the vacuum diaphragm is toast, that would keep any boost pressure from reaching the gauge you would think. Eliminate one item at a time from the network like any troubleshooting operation. How likely is it that the blower isn't producing any boost? Not very.
(Your house sounds like mine)

Confuzed1

iTrader: (4)

First off - Thanks for replying Skinny ….

This really has me stumped. I put the smallest drive pulley I have on the thing, and I'm still not showing any boost pressure on the gage. On the previous setup, this same pulley gave me anywhere from 6-8 pounds of boost.

I've checked the boost gage to make sure it wasn't broke….I used compressed air and turned on my compressor and let it pump up to 10 PSI, and used an air nozzle in the hose to the gage - it jumped right up to 10 PSI. So the gage works.

Today, I went out and bought one of those "Mighty Vacuum" hand pumps at the local Harbor Freight. I put about 10-15" of vacuum on the bellows for the internal bypass valve on the blower. Vacuum at idle (around 10-15") is supposed to hold the valve wide open. So I put 15" of vacuum on it with the hand pump and the valve opened up fully like it should. So I let it sit there like that for 15 minutes, and it didnt leak at all.

Next thing I did was slowly release the vacuum, and the linkage began moving to the closed position. By the time the vacuum dropped to 5", the linkage was in it's closed position against the stop screw- exactly like it's supposed to work. I checked the hose from the intake to the gage and boost retard, and it held vacuum just fine.

The only thing I can't really check is the internal bypass valve itself - since it's internal….I don't know of a way to check it to ensure it's not leaking past it's seat.

I know it's pumping air….soon as I go WOT, I get the familiar blower whine and it hauls *ss….

I think I'm down to only 3 possibilities …

The blower is not pumping air (I seriously doubt that though)

-Or-

The internal bypass valve is leaking through badly (how could I confirm?)

-Or-

This new setup is actually using ALL the boost?? But if it is, I never imagined the addition of the AFR heads (was old 200cc Dart Iron Eagles), changing the intake/exhaust rocker ratio to 1.6 (was 1.52 roller tips), and the bigger 750cfm carb (was 650) would make the engine out breathe the blower?? Oh - also my compression ratio dropped from 9.1:1 to 8.7:1 with these AFR heads….but still….

Open to any ideas here…..or should I even be concerned?….

EDIT: And I didn't bother checking the vacuum advance can on the distributor since I have it connected to a fitting on the carb base plate, so it's out of the picture as far as this issue is concerned.

Confuzed1

iTrader: (4)

Just for an update - All the boost is back. Seems when I had the blower off the car and gave it a good wash, I got water in the bypass valve's diaphragm. So it wouldn't shut due to the water in the chamber.

It has a tiny hole in it to allow air in/out, but apparently it was full of water so it wasn't allowing the bypass valve to shut when I went WOT. After about two weeks I guess it almost dried out and I was getting more and more boost readings in my gage. I discovered this after looking over the thing and seeing a drop of water dripping off that vacuum chamber. So no- it wasn't out breathing the blower…the blower bypass was just not closing.

Chad85T/A

iTrader: (1)

👍
I was just wondering about what became of this the other day.