Nice work.
Carb size for sixes with 250 cubic inches can be compared to carb sizes for 302 V8 engines.
In the USA, 630 CFM 4--BBL vacum secondary for 175 to 210 hp net (1983-1985 5.0 4V HO),
and in Australia, 800 cfm mechancial secondary 4-bbls for 188 to 207 hp net (1977 TO 1982 4.9 4-BBL ).
On a 20% capacity reduction, 670 cfm is perefect for a performance 250. In fact, a mechanical secondary is evern better, but a vac sec is just fine.
From the 5.0 orientated forum I frequent, we've got some
really good guys who run wide bands on their 1984-1985 4bbl HO 5 speed 5.0's.
For full size, click the link below, and select the magnification glass icon
http://i1215.photobucket.com/albums/cc5 ... v2_afr.jpg
http://i1215.photobucket.com/albums/cc5 ... Nv_afr.jpg
The factory rating Ford quoted for this 4-bbl 4180c carb SATURN V uses was under reported in press material at a ludicris 570 cfm at 2"Hg, but it is actually 630 cfm at 1.5 "Hg carb. And its actually a little too small for even a 175 to 210 hp V8, the Aussie 302 had the Mopar 318/360/400 Carter TQ 9800 800 to 850 cfm carbs, and it was ideal for economy and power.
4.1 liter Inline sixes like about as much carburation as 5.0's, since they make better low end torque in the off idle to 2800 rpm range, and in the first 150 feet, they always eclispe a naturally aspirated 5.0. Over sizeing on the cfm basis doesn't created a soggy response on an intake with 2300 cc's of intake runner like the Classic Inines intake has.
The follwing three posts describe how people retune the stock 4-bbl vac sec Holley for a 210 to 355 net hp (SATURN V's 5.0 is upgraded with the 1986 exhaust, BaconB8's smog legal 85 Saleen is 280 rwhp with alloy AFR 165 heads and a host of other hot parts)
http://vb.foureyedpride.com/showthread. ... AFR-tuning
Saturn V":197jqivd said:
........
My carb only has mixture screws for the primaries, not the secondaries as some have. Maybe it’s because my carb is a service replacement? I used a 3/32” Allen wrench about 3 inches long. Next time I’ll get a second wrench so that I can leave one in each idle mixture screw. Swapping the wrench from side to side and trying to get the wrench into the screw socket each time with a hot, running engine wasn’t easy. Anyway, the best I could get manifold vacuum at 800 RPM was 19.5 inHG with AFR around 13.0. This seems rich to me for idle. Below is a table of the results. All are with a bare carb at about 800 RPM, except for the last line when I installed the air cleaner, which leaned out the mixture a little . I measured the number of turns on the idle mixture screw as precisely as I could, but these may not be exact.
http://youtu.be/U3adrHH7ENc
http://youtu.be/9gz8UX3eFXo
http://vb.foureyedpride.com/showthread. ... ne-jetting
Ethyl Cat":197jqivd said:
.......
If I were jetting that car to run w/o a PV I would have started at 70 square, giving all four corners equal fuel (approx 430cc/min@WOT 6000rpm)
Since we have a PV, take away 8 jet sizes and install 62's in the primary.
If that gives an idle that is the correct ratio @ 1.5 turns out and cruises lean enough w/o hesitation that's great, if not I would change the primary jets. BUT...if cruise is good and WOT is too lean then adding fuel to the rear ONLY will offset the balance fuel.
Depending on the amount (%) needed, it could mean only drilling the PVRC or drilling and adding jet to the rear(not too common).
This process has not once let me down and always improves overall performance.
Hope this helps
Glad to hear it is running well
Steve
[/quote]
http://vb.foureyedpride.com/showthread. ... -catalysts
The propane method for leaks
wsa111 and SATURN V and BaconB8 do full data plots. Do what I do when tunning my or customers cars.
Mount the camera in the sunvisor, and video the LM-1 Innovate screen as you down load.
In my case, I have a cell phone app that does my AFR linkup, runs off the OBD I port Ford used from 1981 to 1995 Fords, that allows me to make user specified TPS (% throttle), MAP (Abs baro, manifold from Bosch 4.1 Falcon 1986-1992 XF sensor) and AFR ( in my case, narrow band) on one graph.
http://i1215.photobucket.com/albums/cc5 ... 14_957.jpg
http://i1215.photobucket.com/albums/cc5 ... 15_016.jpg
Once you plot everything, you'll find base idle, and curb idle makes a difference, but lets not get ahead of oursleves.
My best advice ever has come from Ethyl Cat, and that is the three points.
First