Quote: port size just under standard felpro
Just make sure that the port and runner sizes match the hurricane runner sizes... if they get too wide too quickly the velocity in the runners will bottom out and you may end up with fuel issues, or the build will want more rpm to stay happy (at idle it may want to be at 1200 instead of 800 rpm...)
Quote: Basic performance rebuild on a standard 904, shift kit, 23-2500 stall
2.76 7.25 with 24" tires
Unknown weight on car, we'll just say heavy. 24-2500lbs?
Also, due to the lighter end valve springs and me not trusting the machinist I used much farther than I can toss him, I wont be spinning this thing above 5k for a while. When I planned the build I was hoping to see
6k
You will definitely want to upgrade the A904 and may need a convertor change. Also unless you replaced the bumpers and front clip to fiberglass... a 1976 Dart Sport is going to be closer to 3400lbs with you in it and a full tank of gas. You won't be able to spin the engine up to 6000 rpm in gear without a manual shift body to allow it...(most race guys that let the A904 do the shifting get up to about 4000 rpm before the upshift if the 904 is prepped right)
This build can see the upper end of 190HP and a lot more torque.... also the cam will want a slightly higher rpm band for best power: 2.76 7.25 with 24" tires ... this rear end and gears are not going to get you to the power band for best cruise/mpg, and the 7.25" is not going to take this kind of abuse for long, be on the active hunt for an 8 1/4" with 3.21's or a 3.27 Ford rear (or deeper if you get bigger tires). Your distributor will need to be recurved to have the mechanical all in at 2700 rpm, and a 17 degree vacc. advance would make things safe at highway use at cruise (assume A904 with 2.76 and 195/70R14)
Quote: Alright, I've been lookin for a carb to perch atop my Hurricane, and I've narrowed it down to 2 (I think)
Quick Fuel Slayer series, 450cfm, vacuum secondaries
Downleg booster
Electric choke
Changeable idle air and high speed air bleeds
Three stage emulsion circuit
Changeable primary idle feed and power valve restrictions
Vacuum secondary adjustment screw
https://www.summitracing.com/parts/qft- ... /overview/
Quote: Summit Racing M2008 series, 500cfm, vacuum sec
Annular booster
Electric Choke
Changeable air bleeds
I believe all the rest of the adjustable doohickies are the same as the above, the main difference I am seeing here is the annular boosters. Supposedly butterflies are smaller than the 600 with the same boosters.
https://www.summitracing.com/parts/sum- ... /overview/
Quote: Would the annular boosters make the larger carb not seem, for lack of a better term, doggy?
Annular boosters give you 2 advantages for a carburator:
1) It restricts the venturi a bit more so you get better 'signal' when in the mains (for a holley 4150 adding them to all 4 corners on a 600 cfm makes it closer to a 575-580 cfm...) once tuned this mean better accelerator response in the mains...
2) It also spreads the fuel over a greater area in the venturi allows for better atomization in the air stream.
That being said... I ran a Holley 0-1848 model 4150 with downleg boosters and the combination offered no advantage
in mileage over the 390 cfm holley 8007 (worse by 3 mpg overall city/highway)... and lacked the power that a 600 annular got.... (slightly more than the 390...about .2 seconds worth in the 1/4) FYI.
Quote: I don't plan on (at the moment) rotating the carb east-west and dividing the plenum (sorry D.I.), and I don't plan on making use of all the adjustabilities (an actual word?) just yet, if I cant get something ironed out with conventional tuning then I will turn to it, but I could see this extra stuff making it possible to get it perfect. I'm also not hunting for every last mpg, although if it got better than 15 on the highway that would be fine Rolling Eyes...
If it's all dialed in, it should do better than 15 mpg highway... but you can always make one change at a time and see if it does better for you (the 600 cfm Holley 4010 with the secondaries locked out might be slightly worse at 13 mpg highway and all the airbleeds restricted to get it to work right on a little engine with the long manifold).
Quote: Also, I'm having some trouble deciding where to set the intake centerline. It's ground on a 109 LSA, and a 4* advance built in. I'm seeing a lot of recommendations for 99-101*, but how much of a difference is there in those 2 degrees on the powerband? What about when it comes to DCR? Since I'm not really planning on spinning it, I don't have the best gears or stall at the moment, and my car is a bit on the fat side, would shooting for the 99* be my best bet? Or am I way off here? I'm willing to run 89 or 91 octane if it need be.
Since you have no accurate math on what your machinist will do let's make a WAG that to get 10.01:1 we assu/me you are having the following done:
3.445 bore for 2.2L piston
Head was cut .066 to make the chamber 44cc from the stock 54cc
Deck height at .090 (on a late 70's-80's block that's about a 0.075-0.085 cut)
OCG 346 ground at approx adv durations of 284/278/109 CL105
Running the DCR calculator... If you install the OCG 346 at the 105 centerline as ground... your DCR is 7.86... setting it to 102 will put you at the 8.01:1 DCR sweet spot ...101 = 8.05 so no issue there,
99 = 8.22:1... so all will work on pump gas with no problem depending on the distributor timing...
If your SCR goes up then the numbers will shift...
That being said... the peak of the torqueband at original centerline of 105 will be between 4000-4500 rpm... if advanced to 99-102...peaks at 3500-4000 rpm regardless of 99 or 102, and goes no lower (horsepower number will just be lower...but if this is a street car, torqueband matters, HP is just top end...and you aren't driving in the Trans American...but the HP peak will be at the 4-5000 rpm range if curious)...
It's a lot of information, and since we don't have all the real world numbers it's a hand grenade estimate... but it will give you an idea of what to expect subjectively...
|
lets hear those opinions!