gryphonclan":31fak8ij said:
I bought a 250, and C4 to drop into my Falcon based on getting the intake and head off the CI site. I had not even looked at the forums before doing so. I'm not super invested in it, but would probably have just gone the 289 route instead since parts are cheap and plentiful.
I'm sure there are a lot of people that are bummed out about what's happened to the CI site, and the owner. Not being one to give up though, I'm considering still going with the 250. I can go the 3 single carb route and have some groovy eye candy, maybe even full on turbo.
What are other folks doing with their heavy cast heads? Beyond a port and polish, what are my options for squeezing ponies out of this head? 1970 power plant that was donated from a Mustang.
A few things to form a baseline between 250 and 289/302 engines. The Classic Inlines head Mike devised is simply the M code 2v head 170 hp gross cylinder head, in aluminum, with the best porting and development money can buy.
Stock 1970 Mustang L code 250 engine had 155 hp gross, but only perhaps 98 hp net.
http://mustangattitude.com/cgi-bin/pics ... mm=&page=1
The Australian L code 1-bbl 250 version had an extra 4 hp net (102 hp installed) due to better combustion chamber and less emissions gear, and was also rated at 155 hp gross for five years, no change, no emissions equipment. Same as the US 250 L code, but different in detail.
The M code is the Australian performance I6. It existed because it was cheaper to hop up an I6 than to import a US made V8. The 170 hp gross rating was interesting. Actual installed figures were about 149 HP SAE net was the M codes rating with the tubing headers (which were an 18 hp gain to 120 hp net over the 1-bbl stock exhaust). The extra 19 hp on top of that came via the better breathing head.
The stock iron log exhaust really is that restrictive. Ak Miller confirmed an unlocking of 13%, or 10 rear wheel hp in 1967 on the 200. , and nothing much changed untill the advent of headers on the M code in Australia in 1971, and the 4-1/4" exhaust on the C code 250's and B code 200's in 1980. The gains go up in the 13 to 18% mark, depending on instillation and variances.
Same cam remained 155 hp 1v verses 170 hp 2v. So a Classic Inlines head and header system will better the stock 47 hp increase at the flywheel.
The Australian 2-bbl carb was the Bendix Stromberg WW, last used on US GM and Mopar vehicles in 1966. It flowed between 220 & 240 CFM at 3"Hg, and was the same carb used on the 230 and 240 hp 302 Cleveland 2-bbl. That carb was an Autoilite 1.14 300 cfm replacement. Both carbs, the M code 170 Hp and the 230/240 Hp 302C 2V, used the same carb and jetting. So in every way except torque, the M code was the
equal of the Australian market, American designed Y code 302C. That engine was a destroked 250 to 265 hp 351C 2V engine
The 60 to 70 hp less 250 2V
outperformed the same spec 159 pound heavier 302C, which means the V8 had about 168 hp SAE net in 230 hp single exhaust form. I a heavy intermediate Falcon station wagon with auto transmission, 17.8 second 1/4 mile at 81 mph.
That little 302 Cleveland 2-bbl engine later on became the Australian P code 4.9 4bbl and 188 hp net 4-bbl. Compared to the US C-code 289 2-bbl (200 hp gross came in at 131 hp net according to the 1/4 mile figures, or 173 hp net according to the Germans), the F code 157 hp 5.0 from 1982 with a 369 cfm 1.21 2150m Motorcraft 4bbl, the 2V 250 with headers makes a brilliantly good 289 2V stand in.
(All figures from post #40
http://vb.foureyedpride.com/showthread. ... er-2/page2
And posts #13 and # 21
/viewtopic.php?f=1&t=74460 )
Any US 250 in good condition with just a header and a Classic Inlines head will do even better for increases.
Direct mount 2-bbls often crack..but not always. We've seen well over 205 hp net from just a little 200 with a direct mount 500 cfm 4412 Holley and a 274 Clay Smith cam. Now, you can do the same without the "one carb has to service six ports" issues. Past that normally aspirated power level, you need to look at two carbs to by pass the log heads restrictions.Three carb instillations have further merrit, but you won't package three 2-bbls very easily.
You can just package two 270 to 350 cfm Holley, Holley Weber, or Weber carbs. There are other choices. 2CG Rochesters and 2100 Autolites (190 to 424 cfm) or 2150 Motorcrafts (287 to 369 cfm)
One, two or three steel or iron plates over where the 1 bbl was. Secure it to the head, and put the two 2-bbl carbs on.
Examples are
Peugeot Bill's
http://i608.photobucket.com/albums/tt16 ... ecar02.jpg
and
ducktang
63comet's
viewtopic.php?f=1&t=55426
On 350 cfm Holleys, you'll have to reduce the power valve channel restrictions to 19 thou. Use two 4.5 power valves, and keep your jetting back to about 62 to 65. That allows an easy 200 hp plus net flywheel horsepower potential.
325 cc/min or 62 thou nominal, 63 call size jet; On Autolites and Motocrafts, a 58F jet flows approx 325 cc/min.
For jet interchanges, see
http://vb.foureyedpride.com/showthread. ... -Carb-Jets
Two of these jets and a small power valve in each carb of about 19 thou will flow 650 cc/minute not including the enrichment of the power valves. One horspower requires 3.24 cc per minute in each cylinder.
My bacground has been smaller 4 cylinder engines like 1098/1275 A series and Pinto 1594 and 1993 cc OHC's.
Powervalves are just to cope with one carbs need to wet about 21 inches of flow path. When you go to two or three carbs, you drastically downgrade the Power Valve Channle restrictions. On my Pinto 2000 engined conversion to a 2-bbl Holley 350 cfm carb from a 302 V8, the 59 thou PVCR's were too large, so we had to bring them down to 16 thou. A 250 Six with two carbs is like having two bored out Pinto 2 liter engines, so use two of the same 2-bbl Holley's that works so well on them.
