I have a 69' 250 in my stang my plan is to run the offy tri power (already have the intake) port the head and make decent power for the street. Just wanted some imput on carbs and cam I see most running webbers but Ive herd there kinda small for a 200 built .......well don't want to under carb so what can I use to step up the cfm? Plan on running it progressive.. would like matching carbs but webber says use a different center... Would this be better? Most tri's I see are 200's anybody got a good running set up on a 250? Also thinking about a 280/280 108* cam... Want it to sound pretty mean and plan on most hp to be in the higher rpm any way. I figure cam specs in ci website are probably based on a 200??? If this cam wont work well for this combo I'm open to sugestions.. Would like to get the most possible power without forced induction or a 2000$ cyl head....
tri power set up help....
- Thread starter 1969coupe
- Start date
.. $.02:
Most tri's I see are 200's anybody got a good running set up on a 250? ... wanted some imput on carbs and cam I see most running webbers ... would like matching carbs but webber says use a different center... .... Also thinking about a 280/280 108* cam... plan on most hp to be in the higher rpm any way. I figure cam specs in ci website are probably based on a 200??? open to sugestions.. Would like to get the most possible power without forced induction or a 2000$ cyl head....
The 250 in my '61 uses the Offy 3X1 successfully. After much experiimentation I run three Holley 1904's as much for performance as personal preference. Most carbs are avilable in a range of CFM so whatever carb you prefer/standardize will typically use a larger CFM (and/or carb throat) on the center. Available 1100's. YF's, Weber's can be used together or mixed. 280 cam will need comparable fuel/ignition/cooling/gearing attention but I'm not versed in cam selection specs or Webers. 250 has more torque than 200 without hi-revs and for fun driving you can widen the powerband.
PS: Cost me @ $1000 machine work/parts prepping head for performance setup. My machinist says "It's simply horsepower per cubic dollar"
Most tri's I see are 200's anybody got a good running set up on a 250? ... wanted some imput on carbs and cam I see most running webbers ... would like matching carbs but webber says use a different center... .... Also thinking about a 280/280 108* cam... plan on most hp to be in the higher rpm any way. I figure cam specs in ci website are probably based on a 200??? open to sugestions.. Would like to get the most possible power without forced induction or a 2000$ cyl head....
The 250 in my '61 uses the Offy 3X1 successfully. After much experiimentation I run three Holley 1904's as much for performance as personal preference. Most carbs are avilable in a range of CFM so whatever carb you prefer/standardize will typically use a larger CFM (and/or carb throat) on the center. Available 1100's. YF's, Weber's can be used together or mixed. 280 cam will need comparable fuel/ignition/cooling/gearing attention but I'm not versed in cam selection specs or Webers. 250 has more torque than 200 without hi-revs and for fun driving you can widen the powerband.
PS: Cost me @ $1000 machine work/parts prepping head for performance setup. My machinist says "It's simply horsepower per cubic dollar"
I use a Autolite 1101 in the center and 1904 Holley's outboard 14 low 14's in my 65 Mustang
What cam are you guys running? Will the 108* cam be too much? Mines going in a 69 mustang so its a bit heavier than the previous years I think... Debating on 3:55 or 3:80 gears with around a 2400 stall speed. Just want it to have respectable power, sound good and be more original with the six. Was the $1000 you spent just on the machine work for the offy? The Intake i got said could be installed at home... Is this not recomended? What set ups are you guys running as far as gears and converter together the six moving? all my experience has been with v8 engines so this is kinda new.
My cam is on 112 .460 .480 lift , you need Way more than a 2400 rated converter, that 2400 is based on a stock 350 cubic inch engine , think 10 inch rated at 3500 , which in your 250 will maybe flash to 2600
Yeah i planned on going with a 3000 stall thinking it would drop about 500rpm. So I need ti figure on a 900rpm drop? I don't doubt that figure just seems steep 2600 sounds pretty good so if i should plan on a 3500 converter that would work.... How's the idle on the 112* cam any love at all or pretty smooth? What is the duration? I have a 274/274 .450 cam just kinda thought i could do better on a 108* cam...
Its a Crane Grind, not currently in the catalog , but could be special ordered , and it has a great lope , but not radical , I'll find the sheet ok its grind F-228/3067-2-12 , it is 228 238 @.050 advertised duration is 290 Intake 300 Exhaust , that sounds like a lot but its a solid lifter grind , that is all done at 5200 in my combo its advertised at a 2500-6000 range , but that's for the average size take 144 add 250 and divide by 2 = 197 and it would pull to 6000 in a 200
1969coupe":320tqgpt said:
With 272 hyd cam I run 3.80 gears with a T5 OD tranny . ... spent @$1000 to get head ready for Offy mod, suppose it could be installed at home if you're good with a grinder
The Offy progressive setup doesn't just open the secondaries . You can set (fool with) the throttle position and rate of transition to full WOT. At low RPM with cam the intake vac can't handle excessive open throttle, but the short runner Offy tri power can use higher RPM WOT for full kick in-the-pants effect from the torque'y 250 six ....
HAve Fun
I have made a tripower intake manifold adaptor to suit the log head engine.
Main problem with the Offenhauser tri-power and Edlebrock bolt on log triple carb adaptor kits are that they a totally limited in terms of carb area, gasekt face port area, and that the flow rates at wide open thtottle differ. Although not everyone uses them, on the basis of early log heads, you have an approx 1.4" centre hole stock, with two less than 1.25" on the outer sides. Total area is only 1.539 sq in plus two lots of 1.227 sq in, or 2.766 sq in at the gasket face. Any other typical triple carb engine has significantly more port area for a given 200 to 250 cube engine. The later flat top log and hex log versions aren't much better, despite the bigger centre hole.The outer carbs are unable to be expanded mauch due to the limits of the stock iron log trying to fit two outboard 1-bbls. There is always more 90 cubic inches of engine for every sq in of carb throttle, at very best.
A 250 reving to even 4500 rpm has an air speed over three times the ideal figure for maximum power, and that's why our bigger 250 engines really suffer from a lack of power when the three Holley 1904/1908 system is used. Only a a cam swap mitted with a compression ratio bump can make up for it. You can make it work well with the great selection of US grind cams which seem to be made with considerable experience and science having gone into there design, but making good specific power is an effort as the tri power set up constantly restrictive after maximum torque is reached. That's why bigger 250 sixes always flat line at about 4800 rpm. It's been notied by Ford engineers working on performance 250 sixes on dynos since the late sixties. And I've got proof from one of the Ford Australia engineers who did the 2v engine tune. Some of the 250's lack of proportinal increase is due to the simple physics of a longer stroke engine which still has a crapy short rod ratio of 1.5:1. That is the primary reason for a need to match the tri power to the right casm profiles to get a performance response. The other part is the amount of port area and gasket face carburation area. Any log head engine is too small in the log area, but even a 2-bbl direct log mod has 7.20 to 8.35 sq inches of area. The tri powers 2.77 sq in is one third the best 2-bbl log mod. So conclusively, the tripower is too small, and cannot be made large enough due to the size restrictions of having three holes which cannot be exapanded enough to match even the lowliest direct mount 2-bbl.
Compare the above 2.77 sq inches to, say, a Tri power 289 K-code with two just over 200cfms on the end and one 320 in the centre for about 730 cfm rated as a four barrel, or a tri power 389, where there was about 750 cfm there, each had a total open areas at the carb faces of between 10.6 and 13.42 sq inches respectively. The area ratios sit at around 27 to 29 cubic inches per square inch of port. Quite simply, the log head needs three times the area to get the flow rate and the flow efficency needed to make good torque and power. Air speed with any common triple carb log adaptor is too high with any triple1-bbl carb installation you can name. The only way to get past it is to go for a NASCAR style solid lifter cam, bump up the compression and duration, and restrict exhast bleed off as done on 2-bbl oval track racers.
Rather than follow this approach, I devised a fairly cost effective kit early this year which allows 7.9 sq inches at the gasket face, enough to support a 250 at a pinch, but certainly a 200 cube six. It was designed in response to kevinl1058's 180 hp plus Falcon with triple 1-bbl Webers, a car very well tuned and matched, but unable to instantly generate the peak hp numbers he was expecting due to a lack of head and carb port area.
My kit deals with those issues, so that port velocities of 165 ft/sec for maximum torque and 260ft/sec for maximum power are preserved. Total port area at gasket face for a 200 and 250 making power and reving to 5500 rpm are 8.44 and 13.20 sq inches respectively to make that 260 feet per second ideal. The tri power manifolds as simply no where near that, and as a consequence, peak power suffers a heck of a lot compared to both a good single 2-bbl and an independent runner Weber system. Figures for 3-bbl Offys and Edelbrocks always suffer disproportionally, and especially when compared to 9 port GM engines in the 200 to 250 range. Engine Analyser programs bare this out too.
If you are interested in buying one or more details, register your interest by emailing XECLtd@yahoo.co.nz for non cross flows (log head only at present, 2v, Classic Inlines to follow) and quote NCHO-6V.
For Aussie 3.3/4.1 Cross flows, email Morning.Star@xtra.co.nz, quote XFHO-6V
The kit is designed around 2-bbl Holley Weber or 32/36 Weber carbs, and is not staged, but each carb runs constantly on a primary barrel, opening up to a secondary barrel depending on throttle postion. My kit is best described as a triple Zenith/ Stromberg CD175 or SU HIF44/HIF6/HS6/1.75" SU emulator. The carbs are mechanical secondary, with a total rated 4-bbl flow at 1.5"Hg of 615 cfm to 725 cfm depending on venturi size, but the emulsion tubes, venturi size, fuel and air corrector jetting are designed around a certain 280 degree hydraulic cam used with a mushy stock stall C3 or C4 torque converter with 2.73 to 3:1 diff ratios and supports high mount air conditioning, power steering, EGR, AIR pump, carb heat stove, stock exhast header and an 8.8:1 compression ratio for use with stock 87 octane unleaded pump gas. Exhast past the header or catalytic converters must be dual out 1966 289 Mustang GT or 1983 5.0 Fox V8 Mustang GT spec to reduce back pressure to an acceptable level. Thats 1.875 to 2.0" internal diameter. The kit is designed around a certain back pressure level based on stock iron headers and the later post 1975 head flow rates with my chosen 280 degree cam. I run one on my Mustang, and that's how I know the stock tripower carb system is too small.
Main problem with the Offenhauser tri-power and Edlebrock bolt on log triple carb adaptor kits are that they a totally limited in terms of carb area, gasekt face port area, and that the flow rates at wide open thtottle differ. Although not everyone uses them, on the basis of early log heads, you have an approx 1.4" centre hole stock, with two less than 1.25" on the outer sides. Total area is only 1.539 sq in plus two lots of 1.227 sq in, or 2.766 sq in at the gasket face. Any other typical triple carb engine has significantly more port area for a given 200 to 250 cube engine. The later flat top log and hex log versions aren't much better, despite the bigger centre hole.The outer carbs are unable to be expanded mauch due to the limits of the stock iron log trying to fit two outboard 1-bbls. There is always more 90 cubic inches of engine for every sq in of carb throttle, at very best.
A 250 reving to even 4500 rpm has an air speed over three times the ideal figure for maximum power, and that's why our bigger 250 engines really suffer from a lack of power when the three Holley 1904/1908 system is used. Only a a cam swap mitted with a compression ratio bump can make up for it. You can make it work well with the great selection of US grind cams which seem to be made with considerable experience and science having gone into there design, but making good specific power is an effort as the tri power set up constantly restrictive after maximum torque is reached. That's why bigger 250 sixes always flat line at about 4800 rpm. It's been notied by Ford engineers working on performance 250 sixes on dynos since the late sixties. And I've got proof from one of the Ford Australia engineers who did the 2v engine tune. Some of the 250's lack of proportinal increase is due to the simple physics of a longer stroke engine which still has a crapy short rod ratio of 1.5:1. That is the primary reason for a need to match the tri power to the right casm profiles to get a performance response. The other part is the amount of port area and gasket face carburation area. Any log head engine is too small in the log area, but even a 2-bbl direct log mod has 7.20 to 8.35 sq inches of area. The tri powers 2.77 sq in is one third the best 2-bbl log mod. So conclusively, the tripower is too small, and cannot be made large enough due to the size restrictions of having three holes which cannot be exapanded enough to match even the lowliest direct mount 2-bbl.
Compare the above 2.77 sq inches to, say, a Tri power 289 K-code with two just over 200cfms on the end and one 320 in the centre for about 730 cfm rated as a four barrel, or a tri power 389, where there was about 750 cfm there, each had a total open areas at the carb faces of between 10.6 and 13.42 sq inches respectively. The area ratios sit at around 27 to 29 cubic inches per square inch of port. Quite simply, the log head needs three times the area to get the flow rate and the flow efficency needed to make good torque and power. Air speed with any common triple carb log adaptor is too high with any triple1-bbl carb installation you can name. The only way to get past it is to go for a NASCAR style solid lifter cam, bump up the compression and duration, and restrict exhast bleed off as done on 2-bbl oval track racers.
Rather than follow this approach, I devised a fairly cost effective kit early this year which allows 7.9 sq inches at the gasket face, enough to support a 250 at a pinch, but certainly a 200 cube six. It was designed in response to kevinl1058's 180 hp plus Falcon with triple 1-bbl Webers, a car very well tuned and matched, but unable to instantly generate the peak hp numbers he was expecting due to a lack of head and carb port area.
My kit deals with those issues, so that port velocities of 165 ft/sec for maximum torque and 260ft/sec for maximum power are preserved. Total port area at gasket face for a 200 and 250 making power and reving to 5500 rpm are 8.44 and 13.20 sq inches respectively to make that 260 feet per second ideal. The tri power manifolds as simply no where near that, and as a consequence, peak power suffers a heck of a lot compared to both a good single 2-bbl and an independent runner Weber system. Figures for 3-bbl Offys and Edelbrocks always suffer disproportionally, and especially when compared to 9 port GM engines in the 200 to 250 range. Engine Analyser programs bare this out too.
If you are interested in buying one or more details, register your interest by emailing XECLtd@yahoo.co.nz for non cross flows (log head only at present, 2v, Classic Inlines to follow) and quote NCHO-6V.
For Aussie 3.3/4.1 Cross flows, email Morning.Star@xtra.co.nz, quote XFHO-6V
The kit is designed around 2-bbl Holley Weber or 32/36 Weber carbs, and is not staged, but each carb runs constantly on a primary barrel, opening up to a secondary barrel depending on throttle postion. My kit is best described as a triple Zenith/ Stromberg CD175 or SU HIF44/HIF6/HS6/1.75" SU emulator. The carbs are mechanical secondary, with a total rated 4-bbl flow at 1.5"Hg of 615 cfm to 725 cfm depending on venturi size, but the emulsion tubes, venturi size, fuel and air corrector jetting are designed around a certain 280 degree hydraulic cam used with a mushy stock stall C3 or C4 torque converter with 2.73 to 3:1 diff ratios and supports high mount air conditioning, power steering, EGR, AIR pump, carb heat stove, stock exhast header and an 8.8:1 compression ratio for use with stock 87 octane unleaded pump gas. Exhast past the header or catalytic converters must be dual out 1966 289 Mustang GT or 1983 5.0 Fox V8 Mustang GT spec to reduce back pressure to an acceptable level. Thats 1.875 to 2.0" internal diameter. The kit is designed around a certain back pressure level based on stock iron headers and the later post 1975 head flow rates with my chosen 280 degree cam. I run one on my Mustang, and that's how I know the stock tripower carb system is too small.
If I would have know about your manifold when I bought the offy I would have bought it since I'm looking for performance. But I already have close to $400 in the offy set up soi think im kinda stuck too deepto change now..... I looked at kevins 200 tri build thread.... Don't remember if the 180hp was flywheel or at the wheels but I would be pretty happy with 180 at the wheels.. wouldn't this be easier to achieve using the 250? Seems like the "there's no replacement for displacement" would still factor in even woth a poor rod ratio... I know the early 4.6 mustang didn't even produce 180 to the wheels In stock form.. not wanting a drag car just want to be able to have a good acceleration spotlight to stoplight kind of car
Falconsedan: any idea of the hp your producing? 14 is a pretty quick 1/4, i saw where your pretty hight on compression and yours is race fuel only so im sure i wont have quite as much power as you....
Falconsedan: any idea of the hp your producing? 14 is a pretty quick 1/4, i saw where your pretty hight on compression and yours is race fuel only so im sure i wont have quite as much power as you....
Hey 69 , not sure what your end goal is but 200-225 is do able on the 250, I know because mine makes that . I suggest setting a goal , find out if its reachable with the big 3 , Time Money , and Talent , if your lacking on any of those the others need to make up for it
1969coupe":26gv7s13 said:
That's all good. In good old American English, the tri-power may not be perfect for performance, but it'll get darn close...
Look at the above avatar
Those figures are state of the tri power art, and a Falcon or Mustang so equiped will never be a turkey. 220 hp via Tri Power sounds just fine to me!!!
In difference to the above, my kit is designed around a study of 30 years of experience with similarly spec'd Austin Healy 3000, Triumph GT6 and TR 5 and 6, Jaguar XK, Aston Martin DB, AC Ace (Mays Zephyr engine), Reliant Sabre (Mays Zephyr engine), Vauxhall P and V series 2.6 and 3.3 sixes, and of course, Ford, Chrysler and GM six in line engines being oval track raced in street sedan and circuit racing in England, Australia, New Zealand, and I said nothing about it before Sunday July 3, 2011
As I've said, the cam and compression make the tri power system work. On its own, with lower lift and lower duration cams, it's lacking in specific power, but with the right stuff, the limits of its comparitively restricted port area are a minor issue which is not insurmountable. American cam design allows just enough duration to get performance, and a tri power the ability to avoid detonation with a higher compression ratio. Three carbs help stop detonation via better fuel distribution, and running, say 9.7:1 with a tri power and a bigger cam with an iron head results in a low effective compression ratio. A 250 six like this will be less detonation prone on 87 octane than, say, my alloy headed SOHC 4 liter Explorer is with a 185 at 50 thou cam.
The 250 when blue printed is highly responsive to the right gear, and if the 103 thou piston shortfall is removed, it's not detonation prone even with an iron head. The lesson with aftermarket cams on 250 tripowers is like the legacy of Super Cobra jet cam profiles bleeding of combustion pressure, yet still allowing a 6/71 supercharger to make boost without detonation on 390, 427's and 428's.
Porting is critical. Without big improvements to airflow thur the intake and exhaust ports, a big cam and carbs will not produce big power, just big driveability issues.
MustangSix":50r6ppkq said:
X2.I run 3 webber ICHs which add up to 450 cfms.theoreticly that sould feed 250 cubes up to 6,000 rpm. I would call Mike at Classic inlines for a recommendation on the cam.
Similar threads
All Small Six
Autolite 1101 Power Valve Adjustment
All Small Six
I have a few questions about the 250ci
