[spinn]

My 305 had a supercharger installed the begining of the month. There have been a few hurdles to deal with. My fuel pump went after changing the pump outlets 90's. The fuel pressure is now stable after replacement. I have been recurving my distributor every few days. There is power, but at higher rpms it seems like power is not ramping up.

build
305 rebulit short 8.9:1
peformer cam
Ls6 beehives little retainers
vortec 906 heads 60cc
E force 122 eaton supercharger
650 cfm AVS
E curve MSD no box
3000 stall
3.73 8.5 rear 28" tire

The manual explains that timing should be reduced 2 degrees for every one lbs of boost. It also recomends a MSD retard boost timing box which I really dont want for 5-6 psi . My curve has been 12 intial 20 more at 3000 rpm for 32 . 8 in the can at 10 " vacuum. After the supercharger locked out at 20 works surprisingly well. The faster the charger spins the more power it makes all the way up. At 10 intial plus 15 at 3000 works good too. Anymore than 25 total after 3000 doesnt work well. The gas is 89 octane.

I do not want to use the MSD box and boost retard. What is the normal acceptable timing curve for a supercharged mild engine? 20 and 25 sound a little short for totals. This also affects normal cruising. Has almost brutal throttle response cruising without the higher timing.

If I go down in plug heat range more will that allow higher total numbers?

Good news, mpg has not changed much.

 

[spinn]

Yes, the cam is small , but for a mild 305 it is good unless you want to start trading off low end. It shifts at 5200 so the build is right in the power curve.

The supercharger is awesome and does what it is advertised to do. It pulls hard. Not to sure more cam would even make a difference in power. Unless you move the power band over 6000rpm.

The MSD E curve distributor cannot be reworked. It has 2 dials to change around the timing. Super easy.

The ratio is, well 7" crank pulley drive, and 3.75" blower snout driven. Bad news is the blower pulley is pressed on. No easy bolt on pulley to make boost. Should be over 5 psi at 5200.

I tried the 800 AVS and it was not any better at 5200 rpm . The 650AVS with .110 high flow needle and seat, set rods 4 % richer .065x.047, orange spring. It is a little under 13:1 a/f on the O2 at power using a tail pipe probe.

The 89 octane fuel works no better than the 93. That probably indicates I am at a limit of some sort. Could be the manual is right and you need to retard for the boost. What did people do before MSD had the boost retard box? Under conditions of light load the timing at 30 feels right over 3000rpm. Under hot, heavy load and up hill it rattles with 93 octane. It is backed off to 20-22 total now and in the summer heat it is safe.

The vortec heads didnt like timing much over 30-32 either before the blower.

 

[painted jester]

Why did you choose a 3000 stall converter with a supercharged engine and small cam? Firbirds got you covered so Ill bow out but I was just curious

Jester:thumbup:

 

[spinn]

The plugs are autolite? 605's which should be 2 stages colder than stock plugs. Before they were 3923's by autolite. I will try those RS9YC champions.

I am 2 stages or 8% richer on the chart at cruise , and 1.5 stages or 6 % richer on power.

Pullies are 7" crank, 3.75" snout.

I have this crazy outlet hose that twists around to clear everything. Could that cause any problems? Temps stay within 180-190 on hot days in traffic.

With 5-6lbs of boost I should be able to run 32 degree total timing at load without detonation? Shifting at a limited 5200.

If so what have I done wrong? Is my compression way more than 9:1 ? The 305 has 9.2:1 pistons with the 58cc heads. Now the heads are 60 cc vortecs? Are my plugs the incorrect heat range?

What are you shifting at in your vortec builds?

 

[spinn]

Those autozone people gave me 605's and they are the same heat range according to a search on google. I need to get cooler plugs.

The stall happened that way because it was built in steps. First a cam, the heads, then a stall, recently a supercharger. It worked well together and figured that a supercharger would work well on an already good running engine package. This is my first time with superchargers. It has been a blast. The power is there.

That 3000 stall is welcome. No negative effect or downsides. Dymanic converters built it and regular driving I cannot even tell it is there. It is not as loose as 10" stalls and not as pointless as most 12".

What does it sound like when you hit the rev limiter? I could be doing that to. If the govenor is reprogrammed to shift at 5200 and the MSD E curve limiter is set below that, could that be confused with detonation?

 

[painted jester]

I was curious because a supercharged engine torque curve is right from Idle to upper rpm range! your not having to brake torque the engine to 3000 rpm to hit the engines torque curve like a naturally aspirated engine with a big cam and your small cam should work very well with the forced induction!! The 3000 stall will have slippage even if you don't notice it and youll lose bottom end power! And with the torque a supercharger produces at bottom end your 3000 stall converter could even be stalling at a higher RPM like 3500 or 4000! Stall converters are sold with average stall calculations and the higher the torque applied and the faster it comes in the higher the converter will stall ! I was just curious I ran superchargers for many years and you'll enjoy it:thumbup: it just takes a little tuning in and firbirds got you on track

Jester

 

[painted jester]

When I mentioned stall characteristics of a torque converter! I wasn't meaning that your specific engine torque would stall the convertor at 3500 or 4000. It was just an example to get a point across. :mwink:

Jester

 

[painted jester]

I have this crazy outlet hose that twists around to clear everything no idea what you are saying...

F-BIRD I'm interested in the thread but don't understand this sentence? I read it over and over:drunk::smash:LOL.

Can you still get blower cams from B.D.S.? ( Blower Drive Service) They had many grinds available from street to full race plus #1 through#4 stage

Chris

 

[spinn]

I got new plugs. Not sure if that is the problem.

Twisting the MSD limiter to 5k , I felt what that is like. It is not like detonation. Scratch that one off.

The carb is a 650 edelbrock AVS. Jets are primary .098 secondary .105 , The rod is .065x.047 , orange spring, the air door has been loosened, an has .110 high flow seats.

This morning I droppped in a .065x.037 rod to add more fuel , and returned to 30 total timing at 3000. The sound has been affected. Strange that i set the carb with a gas probe, and it is lean. So that was not a suspect. Your calibration suggested is off the map, but I get where you are coming from. With a plug change to the recommended plugs rs9yc , a richer power mixture it should work out. My belief is the combination of heat range and lean mixture is the cause.

The air is from the engine compartment. So it is hotter air.

It only makes the noise right before it shifts, when the blower is making the most boost.

That water outlet hose does not have anything to do with it. Pretty sure .

The fuel is 89 octane . Both side R n L are full. I will fill one side with 93 when it is time.

 

[spinn]

Plugs made real no difference. The primary jet was changed to .101 the secondary was and is .104 there was a error in my post.

Contacted edelbrock, and they say that the timing should be retarded about 10 degrees. That would place me around 24-26 total at 3000 if the MSD boost retard was installed to auto correct the timing. Setting the mechanical total to that number does not give the stellar performance it is capable of.

This engine wants the advance, but cannot handle what it wants. The sound is detonation. I can twist the distributor and get it rattling like rocks in a can.

Poor fuel is a concern I never had to deal with. My method of building 9:1 engines that spin to 5500rpm make 89 octane pretty safe. Nothing is wrong really, I need to tune it using what is avalible.

My options seem clear, buy the boost retard or run race gas. I will get back to you when I figure out more. Thanks to all. Your experience Fbird is appreciated. I am not going to blow up anything. These engines are tough, and Im not beating it up. Only playing with a new peice of technology.

 

[bentwings]

l press to cause you to have to retard the timing

Congrats on your build. I often think a small motor supercharged would be a good combo. I had a T-bird SC with a 3.8 supercharged for over 200k miles. I even ran it on 87 for a while.

I think your cam is just a little too light. It probably builds just enough cylinder pressure to cause you to have to retard the timing. I run 34 deg total at 2100 and let the initial fall where it may....just so it doesn't kick back on the starter. I use an RPM cam which has a bit more timing so cyl press is a bit lower. I also run vac adv however the cam causes the idle vac to be a bit low so I only get about 4 deg additional at idle. Cruising I have enough vac for the full 10 deg extra. This allows me to lean the cruise mix to 14.8-15.2. I've been all up and down the scale. I have over $100 in main jets alone. I can go leaner however I reached a very slight lean surge and a loss of mpg so I backed off just a little and mpg came backup and surge went away. I get 12.0 12.4 wot and 6-8 psi boost but I have throttle stopped the carbs to about 1/4 of secondary opening and have all the power I can use on the street.
I up to 16-17 mpg now and getting better all the time....I've been running 87 for 2 years now and approaching 20k miles.

I do use Holley 750 dp's however. They are far more adjustable in the idle and just off idle in my opinion. I would guess that better than 90% of my driving is on the idle and transition circuits.

I would suggest moving your AFR sensor up the pipe to about 24 in from the heads. Way back at the tail pipe leaves you open to air leaks which will quickly destroy accuracy. When you are playing with fire you need all the help you can get.

Cool air to the carb is a very good idea. I've measured my blower temp as high as 200 deg F even though it has lots of air going over it. I've also measured polished blowers at over 50 deg hotter than my sandcast blower...which is why I chose to go this route years ago.

I also would suggest you investigate water /alcohol injection. This will help a lot to safeguard your motor. It's pretty easy with a single carb.

 

[spinn]

II think the 650 is set pretty rich. It is the timing. The vacuum advance connects to the back of the e force unit at a corrected manifold source.

Cold air system is on.

It is much better.

The cam is possibly too small, and not bleeding off enough compression. Hard to believe but true.

Recalibrating the govenor shifts to 4,500 rpm with timing at 32 it is fine.

This E curve is a trip. You set the total then dial it back with 2 dials. The manual/instructions contradict themself. Telling me to set it at 2 and 9 and it is supposed to idle at 12 and total at 32. It does not. Even the chart in the back differs. I set it with the dial back light and it seems better. You cannot trust anything new anymore. Should have stuck with the old springs and weights.

 

[BogiesAnnex1]

My 305 had a supercharger installed the begining of the month. There have been a few hurdles to deal with. My fuel pump went after changing the pump outlets 90's. The fuel pressure is now stable after replacement. I have been recurving my distributor every few days. There is power, but at higher rpms it seems like power is not ramping up.

build
305 rebulit short 8.9:1
peformer cam
Ls6 beehives little retainers
vortec 906 heads 60cc
E force 122 eaton supercharger
650 cfm AVS
E curve MSD no box
3000 stall
3.73 8.5 rear 28" tire

The manual explains that timing should be reduced 2 degrees for every one lbs of boost. It also recomends a MSD retard boost timing box which I really dont want for 5-6 psi . My curve has been 12 intial 20 more at 3000 rpm for 32 . 8 in the can at 10 " vacuum. After the supercharger locked out at 20 works surprisingly well. The faster the charger spins the more power it makes all the way up. At 10 intial plus 15 at 3000 works good too. Anymore than 25 total after 3000 doesnt work well. The gas is 89 octane.

I do not want to use the MSD box and boost retard. What is the normal acceptable timing curve for a supercharged mild engine? 20 and 25 sound a little short for totals. This also affects normal cruising. Has almost brutal throttle response cruising without the higher timing.

If I go down in plug heat range more will that allow higher total numbers?

Good news, mpg has not changed much.

As the charge density (molecules of fuel and air) inside the cylinder goes up so does the speed of the burn. This also has a dependency upon turbulence of the mixture inside the cylinder.

An unsupercharged engine with a moderate cam from idle to legal cruise speeds has low charge density and turbulence. Therefore, in order to get the burn to occur so as to place the maximum cylinder pressure at the optimum piston position in its bore travel to extract the best power in moderate conditions it takes quite a bit of advance. However, as engine speed picks up and the throttle is opened the density and turbulence within the cylinder substantially increase which speeds the burn rate such that the optimum advance is achieved around 3000 RPM where no further advance is needed in spite of the significant reduction in burn time. For a normally aspirated engine running at atmospheric pressure the needed advance is about 32 to 38 degrees this depends a lot on cam timing, compression ratio, combustion chamber shape, spark plug location and heat range.

When supercharging is introduced the mixture density and turbulence inside the cylinder is increased which reduces burn time thus reducing the need for as much advance as an unboosted engine. The super charger manufacturer in your case recommends removing 2 degrees per pound of boost. Detonation is the limiting factor as to how much boost and how much advance the engine will accept before blowing some expensive part to pieces (usually a piston often taking other things with it). The boundary can be pushed around with changing mixtures rich tend to cool the cylinder by the energy it takes to phase change the extra fuel from liquid to vapor and physically interferes with the flame travel forcing the fire around large molecules adding distance and time. Adding alcohol and or water injection does a similar thing where the phase change absorbs energy (heat) and adds burn time by physically adding distance to the flame front as it tries to get around the globules of liquid. This should not be confused with burning alcohol as a fuel which brings what appears to greater octane resistance, this is a function of the previous descriptions of interference with the cylinder temps and flame front speeds but goes much further into the heat energy difference lesser of alcohol against equal weights of gasoline. So pure alcohol takes a lot more compression to extract its heat energy in the burn.

All of this is to say that while you have instructions from the manufacturer, you do have a unique combination and will have to tease out what set up will work with the engine configuration you've built and the fuel you wish to use. Frankly I much prefer the MSD retard device as electronic control of the advance/retard system is a lot more discrete and reliable than the old vacuum and centrifugal systems.

Bogie
As the charge density (molecules of fuel and air) inside the cylinder goes up so does the speed of the burn. This also has a dependency upon turbulance of the mixture inside the cylinder.

An unsupercharged engine with a moderate cam from idle to legal cruise speeds has low charge density and turbulance. Therefore, in order to get the burn to occur so as to place the maximium cylinder pressure at the optimium piston position in its bore travel to extract the best power in moderate conditions it takes quite a bit of advance. However, as engine speed picks up and the throttle is opened the density and turbulance within the cylinder substantially increase which speeds the burn rate such that the optimium advance is achieved around 3000 RPM where no further advance is needed inspite of the significant reduction in burn time. For a normally aispirated engine running at atmospheric pressure the needed advance is about 32 to 38 degrees this depends a lot on cam timing, compression ratio, combustion chamber shape and spark plug location.

When supercharging is introduced the mixture density and turbulance inside the cylinder is increased which reduces burn time thus reducing the need for as much advance as an unboosted engine. The super charger manufacturer in your case recommends removing 2 degrees per pound of boost. Detonation is the limiting factor as to how much boost and how much advance the engine will accept before blowing some expensive part to pieces (usually a piston often taking other things with it). The boundry can be pushed around with changing mixtures rich tend to cool the cylinder by the energy it takes to phase change the extra fuel from liquid to vapor and physially interfers with the flame travel forcing the fire around large molecules adding distance and time. Adding alcohol and or water injection does a similar thing where the phase change absorbes energy (heat) and adds burn time by physiaclly adding distance to the flame front as it tries to get around the globules of liquid. This should not be confused with burning alcohol as a fuel which brings what appears to greater octane resistance, this is a function of the previous descritons of interferance with the cylinder temps and flame front speeds but goes much further into the heat energy difference lessor of alcohol against equal weights of gasoline. So pure alcohol takes a lot more compression to extract it's heat energy in the burn.

All of this is to say that while you have instructions from the manufacturer, you do have a unique combination and will have to tease out what set up will work with the engine configuation you've built and the fuel you wish to use. Frankly I much prefer the MSD retard device as electronic control of the advance/retard system is a lot more descrete and reliable than the old vacuum and centrifugal systems.

Bogie

 

[spinn]

If the cruise control vacuum accumulator is connected in the same Tee as the vacuum advance, will it provide vacuum to the distributor once vacuum lowers at wide open throttle? There is no vacuum leaks in the advance lines, and no one way valve there, but they connect to multiple places. If so, this could be why locked out timing and no vacuum advance worked without problems.

They need to make a timing display device that shows what the exact timing is at operation. I am too old to ride the fenders.

It is a competitve build. It will challenge any NA $2000 combo. It is no space shuttle, but a monster of a 305.

I heard about the statin finish blower housing too. They disipate the heat via the grainy surface. For a cooler charge, low temp.

Thanks bogie, makes perfect sense. At least the second time.

My cam could be alright, but the springs are not really well. The beehives were grabbed from a GM series II v6. At .420 sqeeze they had around 260 lbs of open and 300 at .500. For seat they were in the 90's at installed height. This could be valve float and the blower is increasing the stress on the seat causing preignition.

The cam could be small and out of power range after 4500 , and go lean based on duration and lift for the ammount of power it is making.

I am not in my element, and beyond my knowledge a little bit.

 

[spinn]

F bird - I will try the .107 sec jet and recalibrate to 5200 shifts again. Also get some boost and vacuum numbers for you.

Another thing those timing numbers were not correct. The e curve has a inital then you add that to your inital. The manual does not go into detail about this. If it curves 10+ 25 and you set it with 10 inital of your own , you have 45 mechanical. That is detonation territory. I even contacted MSD and they suggested buying the retard and MSD wires, also they explainrd to start out with timing locked and just setting the total. That worked.

 

[spinn]

A quick run through on the e curve. It has solid state circuitry, no springs and weights. 2 dials to select the curve one for the rev limit. All curves A-T start advancing at 1200rpm and finish at 2000 - 3500 , that way you are not adding over timing as rpm climbs after. What you have to watch is were the iniatial from the e curve starts. If you lock it out with "T" at 25 and give 10 with the dial back light , yes it is a total of 35. The other curves have 25 total but come in at different initals. If you set up a curve that starts at 0 with zero inital, then dial a curve that starts at 10 or 15 defrees at zero, you have to add that to the total. Because if it starts at zero and you place 15 mechanically twisting you are going to start 0 rpm with 20+ degrees and end over 40+ total . Depending how it is set. Makes no sense trying to explain. Ill include a link. If it works the figure 3 diagram shows the curves.

The cruise control accumulator can supply vacuum to the vacuum advance then?



http://www.msdignition.com/WorkArea/DownloadAsset.aspx?id=15032386286

 

[spinn]

Will disconnect my other vacuum accesories and dedicate the vacuum advance line.

The curve selected is F . I have 5 degrees twisted in with the light. Plus the 10 from the F curve is 15 inital. Then starting at 1200 by 3000 rpm adds 20 , totals out at 35 and stops. Vacuum advance is curve 1. Dials set at 0 and 6. limiter is at 5500. Govenor at 5200 shifts. That is how it sits , unless you have some other suggestion.

When it was locked and verified at 35 no vac advance , that felt good. Have not jetted secondaries to .107 yet.

The choke door has also been wired open in case it was sucking closed.

Will return with more results.