GJ wrote:Sup guys
I build a 598 bbc for myself .
The cam is 288/298 dur , 825/7xx lift , 114 lobe sep .Heads were borowed dart 345 pro 1 heads . Compression is 15.1:1 . I don't have vac pump . The only thing we did was putting the timing at 36 degrees (crank trigger) and put a out of the box demon 1190 cfm.
We went to the track yesterday and the car ran first pass 8.70@153 mph ,60 feet was 1.21 . Not bad for first try . The only problem is we didn't dyno it so we don't know where it makes peak power . We put the shift point at 7000 rpm . The converter is a nealchance and it stalls at 5000 rpm . We set the 2 step at 4000 just for now . I was thinking on on to a chassis dyno (dyno dynamics) and check were it makes peak power and torque . What I was wondering was the timing . I hear people running 38-40 degrees which sounds like alot .The dome is 39cc . We were in a hurry that we didn't even drop the fuel presure which was about 12psi . I think it was rich , we didn't check the plugs yet . We only had a few runs for testing . But I will doubl;e check these on the dyno . Any sugestions on timing and a good starting point for demon carb jetting . I know every engine is diferent but i just want to see if the jetting is even close to what I need . Thanx
GJ
GJ ... this is a Single(1)-4 Barrell Carb 598cid similar to yours .
but it has the 26deg Edelbrock Victor Race Heads on it,
and highly modified Sniper with Welded/Extended Runners
1026 Peak HP
this particular Combo only wanted
32 deg BTDC...but this greatly
depends upon Motor Octane, actual static and effective CompRatio
and Ve% as well as other factors involved to the point your Engine
is a unique Combination of Parts and may require much different
BTDC Timing .
Just try different BTDC Timing on the Dyno or DragStrip
and let the Engine tell you what it wants or likes.
i don't think anyone can tell you exact number, but just a starting point
i'd start off around 32 BTDC
and try 2 deg increments or even 1 deg increments
and watchout the 1st Torque/HP Numbers at the begining RPMs
on the Dyno and if you tryout 2 more deg BTDC and HP would happen
to be better...but TQ down low is worse..be careful..back down 2 deg
to keep it safe
choose the most BTDC timing that shows no TQ losses down at the
starting RPM point on the Dyno and that gives you the most
Average TQ and HP Numbers over your desired RPM Range
at 2460 Lbs it went
60FT= 1.108 at 12:38PM Run time
330= 3.208
660= 4.967 - 141.79
1000= 6.483
1320= 7.770 - 174.26
Friday Oct 20, 2006
4.600x4.500 = 598.4 CID BBC Chevy Engine
with
26degree Edelbrock Heads 2.350"Int/1.860"Exh
413 CFM to 418 CFM @ 28" w/.900" Lift
on 4.500" Bore Flow Fixture SF-600
Jesel 1.90/1.90 shaft rockers
Jesel fronr-drive distributor
MSD Crank Trigger
Royal Purple 5W/30 10 qts.
Moroso 3-Stage Oil Pump
Billet Fab alum pan 10.5" deep
CM solid roller standard core size 113 Centers
Moroso 4-vane vac pump
14.5:1 CR 227 cranking psi
2.375 Primaries x 35" inches 4.500 Collectors x 11
ProSystems Carb
32 deg BTDC .025" lash across
SF-901 Dyno 600 RPM/SEC
with Sniper's welded/extended Runner Divider Walls
Edelbrock Super Victor___ProFiler Sniper (Welded/Extended)
w/1" spacer______________w/1" spacer---(Profiler)
RPM--Torque--HP__________Torque--HP----(HPGain/Loss)
5500--821.1--859.9_______838.3--877.9--( + 18.0 HP )
5600--816.4--870.5_______852.6--909.1--( + 38.6 )
5700--830.3--901.1_______843.1--915.1--( + 14.0 )
5800--821.9--907.7_______836.7--924.0--( + 16.3 )
5900--824.9--926.7_______840.8--944.5--( + 17.8 )
6000--813.2--929.0_______827.8--945.7--( + 16.7 )
6100--808.3--938.8_______831.4--965.6--( + 26.8 )
6200--805.0--950.3_______825.8--974.8--( + 24.5 )
6300--804.5--965.0_______822.1--986.1--( + 21.1 )
6400--803.9--979.6_______816.2--994.7--( + 15.1 )
6500--797.6--987.1_______814.4--1000.8-( + 13.7 )
6600--792.2--995.5_______808.8--1016.4-( + 20.9 )
6700--788.1-1005.4_______804.4--1026.4-( + 21.0 )
6800--780.2-1010.1_______793.0--1026.7-( + 16.6 )
6900--764.6-1004.1_______776.2--1019.7-( + 15.6 )
7000--751.3-1001.3_______764.4--1018.8-( + 17.5 )
7100--742.7-1004.1_______745.9--1008.4-( + 4.3 )
7200--731.6-1002.9_______739.8--1014.2-( + 11.3 )
7300--723.9-1006.2_______720.5--1001.5-( - 4.7 )
7400--712.0-1003.2_______710.1--1000.5-( - 2.7 )
_________________
the 598 CID 1026 HP engine is in Leon Mark's 1979 Camaro @ 2460 Lbs.
that ran this weekend ...First time out with RaceCar
No Problem Raceway - Oct 28, 2006 Saturday noon at 12:38 PM
Incrementals were=>
60FT= 1.108 at 12:38PM Run time
330= 3.208
660= 4.967 - 141.79
1000= 6.483
1320= 7.770 - 174.26
their Weather Station reported=>
30.03 Baro, 67.0 F , 51.0 % Rh , 12 Ft Track Elev
with a Crosswind of 7 MPH
Weather undergrounds weather data for Bell Rose, La or Patterson
at 12:35pm was
30.14 Baro, 64.4F, 52.0% Rh, 6.9 cross wind NNW, clear, 20 Ft Elev
according to ET_Analyst ETAVBWIN simulation
its running the incrementals almost on the money for 1026 HP
..actually its running a little faster at the 1/8th mile than it should
for 1026 HP => 141.76 MPH
Converter Lockup approx. = 93.0 to 93.5
Tire Growth Rate = approx 80%
2.465 GForce Launch
90.0% Drivetrain eff in both gears
Powerglide with 1.80 1st gear
4.10 rear gears
2460 Lbs weight with Driver
7300 Shift point
7600 approx Cross RPM
A1-Converter approx 2:1 Multiplication 6000 Stall (a little too high)
17.3" wide Tire x 33" on 16" wide 15" dia Rims
Chris and Mark report .... extremely responsive and very crisp
throttle response with ProFiler Sniper Intake
they said they could probably Leave on the Footbrake
the Car's got so much bottom-end Torque and responsiveness