A
Anonymous
Guest
i live in perth wa and race street stocks ive got a xf falcon with a 250 xflow we have standard basicly standart motors but i gota say they go hard if you set them up rite
Q1:Could a similar approach be used to built a tuff 250 pre-cross flow using a 2V head?
A1: Yes. The 200 cube Mustang guys are doing this in the States
Q2: Would using 200 (221??) rods give similar benifits when used with the pre-crossflow 250?
A2: Yes to the post 1970 3.3 and 3.2 OHC (6.27"), or maybee 4.0 AU rods (6.06"). The 221 rods are only 5.14" as that engine was basically a 200 with a medium deck height.
Q3: What other bottom end mods would be needed/reccomended
A3: The rope seal needs to be tight, and then the thinghard run to allow the seal to bed in. The other option is fitting the 302 Windsor neoprene seal with modifications to suit. The oil pump and 'macaroni' hex drive are not the same as the X-flow. The US 250 bits don't fit without mods. Cam gears need to be the bigger 530 thou item to suit an XE ignition. Read the posts on cam gears, its easy to stuff up here. There are many differences. The X-flow timing gear is a better bet than the stock stuff.
Q4: should the engine be bored out and by how much
A4: Safest is 30 thou, 40 to 60 possible, but your cash could be burnt money if the cylinder walls have core shift.
Q5: what rod bolts should be used?
A5: Aftermarket 302 Windsor APR numbers.
Q6: Would larger valves be needed if using a 2V head
A6: Yes, go up for intake size. The exhast valve won't take greatly oversized inserts and valves due to the closeness of the water jackets. The Americans don't use our tiny valve guides, their Log head ones are bigger, but also more restrictive. The later post 74 US engines had much bigger valves, almost x-flow size. You can't fit those easily. SI in America have some great stainless steel items.Check Jimbo65's posts
Q7: Are any other valve train mods needed
A7: Not need but there are common swaps. It is critical the stock 250 non-crossflow oiling system has the oil galleries working correctly or the vlave gear will get munted. The roller rockers YT sell are quite a good upgrade, but an expensive one. They are shaft mounted and very strong. A few guys have bailed out on the roller rockers due to some failures from the stock oiling and pushrod librication issues. Check Ricksmols posts. The lifter ratios can go to a higher number if I remeber correctly. The correct kind of seals need to be used to suit the purpose. The
Q8: What would be the best cam spec
A8: Tim and his Tassie mate have 250 Cortinas and Falcons with the last of the aftermarket Crow cams. They are no longer made for the 250 non-cross flow. They are only like 205 degrees at 50 thou, but are kinder to the drive train. If you want wilder, be sure you have soft ramps to perhaps the HX grind used on the 73 XU-1 GTR's, a radical 312 degree cam which will kill most other sixes. Wade make a #392 grind used by Dick Johnston on his Torana and early XD True Blue Falcon, which is similar. (No, its not 392 degress duration, lol).The term to watch for on the Ford sixes is load stress. The ligher valve gear of the non-cross flow will be kinder than the cross-flow items,as they have very heavy valve gear and oil through pushrods which blead off a lot of oil from the oil pump. The X-flows have additional oil pump flow avaliable to make up for the loss in oil. The US 250 had a much more beafed up block and cam gears and crank snout, which made the engine much wider at the sumgasket. The American engine is potentially a much stronger base to work with, but its not worth importing unless you are a fanatic. Cams are affected by valve train harmonics, and all Aussie engines were tremour prone in the 5400 rpm plus zone due to using the 200 cam gears. Don't look at high winding rpms unless you are prepared to do spend big on a Romac balancer.
Q9: and would a small 4 barrel carb be suitable (465 or similar)
A9: Check Mustangaroo and Dbzokale. Thay have been hacking up 2V intakes. The 465 cfm 4-bbl carb is fine, but 600 cfm is easier to tune. Some guys, including my neigbour, have used the double pumper 650 carb on bigger 265 sixes, so don't be shy! The smaller ones may be okay as a start. Follow 253 Commodore Rcer logic! 290 hp hiding in the 465 carb, no worries!
Q10: I know its hard to guess but what sort of power could be produced with a well sorted pre-cross flow 250?
A11: The exhast is the limiter. The 2v intakes are huge, but the exhast ports are Mr Puney-Verse. The options are simply to use a Pacemaker or Clifford header. There are options of using the port divider are only able to be validated on a dynometer. The cross sectional area of the two centre ports is huge, but the four either side are way to small. I'd suggest a full scale weld up of the out side margin, and then high port the exhasts. Then get a custom header made up.
If the exhast is just cleaned, the head gas-flowed, the 465 used, then 260 hp should be possible with a screamer cam if you were able to make it rev to 5500 rpm. The exhast clean up will allow the engine to flow more air, run less lift to get more torque. The limiter is then the crank.
The 250 2v will never be a like an E49 265, able to take 6500rpm all day.It is a long stroke engine, and long rods, the better 2v head can't make up for a the small piston area and long stroke crank.
A1: Yes. The 200 cube Mustang guys are doing this in the States
Q2: Would using 200 (221??) rods give similar benifits when used with the pre-crossflow 250?
A2: Yes to the post 1970 3.3 and 3.2 OHC (6.27"), or maybee 4.0 AU rods (6.06"). The 221 rods are only 5.14" as that engine was basically a 200 with a medium deck height.
Q3: What other bottom end mods would be needed/reccomended
A3: The rope seal needs to be tight, and then the thinghard run to allow the seal to bed in. The other option is fitting the 302 Windsor neoprene seal with modifications to suit. The oil pump and 'macaroni' hex drive are not the same as the X-flow. The US 250 bits don't fit without mods. Cam gears need to be the bigger 530 thou item to suit an XE ignition. Read the posts on cam gears, its easy to stuff up here. There are many differences. The X-flow timing gear is a better bet than the stock stuff.
Q4: should the engine be bored out and by how much
A4: Safest is 30 thou, 40 to 60 possible, but your cash could be burnt money if the cylinder walls have core shift.
Q5: what rod bolts should be used?
A5: Aftermarket 302 Windsor APR numbers.
Q6: Would larger valves be needed if using a 2V head
A6: Yes, go up for intake size. The exhast valve won't take greatly oversized inserts and valves due to the closeness of the water jackets. The Americans don't use our tiny valve guides, their Log head ones are bigger, but also more restrictive. The later post 74 US engines had much bigger valves, almost x-flow size. You can't fit those easily. SI in America have some great stainless steel items.Check Jimbo65's posts
Q7: Are any other valve train mods needed
A7: Not need but there are common swaps. It is critical the stock 250 non-crossflow oiling system has the oil galleries working correctly or the vlave gear will get munted. The roller rockers YT sell are quite a good upgrade, but an expensive one. They are shaft mounted and very strong. A few guys have bailed out on the roller rockers due to some failures from the stock oiling and pushrod librication issues. Check Ricksmols posts. The lifter ratios can go to a higher number if I remeber correctly. The correct kind of seals need to be used to suit the purpose. The
Q8: What would be the best cam spec
A8: Tim and his Tassie mate have 250 Cortinas and Falcons with the last of the aftermarket Crow cams. They are no longer made for the 250 non-cross flow. They are only like 205 degrees at 50 thou, but are kinder to the drive train. If you want wilder, be sure you have soft ramps to perhaps the HX grind used on the 73 XU-1 GTR's, a radical 312 degree cam which will kill most other sixes. Wade make a #392 grind used by Dick Johnston on his Torana and early XD True Blue Falcon, which is similar. (No, its not 392 degress duration, lol).The term to watch for on the Ford sixes is load stress. The ligher valve gear of the non-cross flow will be kinder than the cross-flow items,as they have very heavy valve gear and oil through pushrods which blead off a lot of oil from the oil pump. The X-flows have additional oil pump flow avaliable to make up for the loss in oil. The US 250 had a much more beafed up block and cam gears and crank snout, which made the engine much wider at the sumgasket. The American engine is potentially a much stronger base to work with, but its not worth importing unless you are a fanatic. Cams are affected by valve train harmonics, and all Aussie engines were tremour prone in the 5400 rpm plus zone due to using the 200 cam gears. Don't look at high winding rpms unless you are prepared to do spend big on a Romac balancer.
Q9: and would a small 4 barrel carb be suitable (465 or similar)
A9: Check Mustangaroo and Dbzokale. Thay have been hacking up 2V intakes. The 465 cfm 4-bbl carb is fine, but 600 cfm is easier to tune. Some guys, including my neigbour, have used the double pumper 650 carb on bigger 265 sixes, so don't be shy! The smaller ones may be okay as a start. Follow 253 Commodore Rcer logic! 290 hp hiding in the 465 carb, no worries!
Q10: I know its hard to guess but what sort of power could be produced with a well sorted pre-cross flow 250?
A11: The exhast is the limiter. The 2v intakes are huge, but the exhast ports are Mr Puney-Verse. The options are simply to use a Pacemaker or Clifford header. There are options of using the port divider are only able to be validated on a dynometer. The cross sectional area of the two centre ports is huge, but the four either side are way to small. I'd suggest a full scale weld up of the out side margin, and then high port the exhasts. Then get a custom header made up.
If the exhast is just cleaned, the head gas-flowed, the 465 used, then 260 hp should be possible with a screamer cam if you were able to make it rev to 5500 rpm. The exhast clean up will allow the engine to flow more air, run less lift to get more torque. The limiter is then the crank.
The 250 2v will never be a like an E49 265, able to take 6500rpm all day.It is a long stroke engine, and long rods, the better 2v head can't make up for a the small piston area and long stroke crank.
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Anonymous
Guest
I'm not trying to alienate people here, but as this is my first, I'm sure I will... Despite popular belief, it is possible to boost a high compression motor. Yes, I'm sure you all hate Hondas, but with a properly worked combustion chamber, a 14:1 compression, with 15 lbs of boost, on 92 octane, daily driven is more than possible, and very safe for 50,000 miles. Has anyone tried high compression with high boost on these motors? and did they have good luck with accelerating the engine? again, I"m serious, if you disagree, technology has come a long way, and I can provide you some insight as to how if you have a slightly open mind... I"m just curious if anyone involved here has tried any softhead technology on a ford six...
I've been very interested in Larrry Widmer's work since the late seventies. He could probably do some very interesting stuff to a head, but the cost would probably be astronomical!
But at any rate, his work is interesting reading and I highly recommnd a visit to his site at Energy Dynamics.
But at any rate, his work is interesting reading and I highly recommnd a visit to his site at Energy Dynamics.
A
Anonymous
Guest
Thanks for all that info xtaxi I will start looking for all the extra bits I need, but i just have a few more questions. Do I need a special piston to run 200 rods in a 250 pre-crossflow (i think i read that ACL make pistons to suit the 250 crossflow with 200 rods) or will any oversized replacement pistons suit? If the car was to run on optimax what compression ratio should I be aiming to achieve? Are the larger stainless steel intake valves you mentioned avialable in Australia, if not what else could be used for a similar result? And finally you mentioned using XE cam and timing gear, can I also use an elctronic distributor from an XE in a pre-crossflow 250 or will it need to be modified to suit? This engine will be going into an XP falcon sedan with a four speed so I difinately think a brake and diff upgrade may also be needed as its running all the standard tiny four stud parts at the moment.
I've not done a full pre x-flow rebuild yet, but I have to work through the same cam and valve issues myself soon. I'm using every post here as a good foundation. The specifics have to be worked out with the engine builder. There is so much to deal with!
Q1
o I need a special piston to run 200 rods in a 250 pre-crossflow (i think i read that ACL make pistons to suit the 250 crossflow with 200 rods) or will any oversized replacement pistons suit?
A1: No, but I've heard tell from others that the 200 rods need clearance with the pistons to gudgeon pin and skirts. Normal linishing should help. I've not seen any confirmed cleance problems, although Overdose has some evil pictures of side skirt breakage, which we thought was cam related.
Q2: If the car was to run on optimax what compression ratio should I be aiming to achieve?
A2: That's Shells 95, or is it 98 octane? The deal is that if the engine has a bigger cam, and runs the normal Aussie engines close piston to deck register, it should be able to hack high 9's. All engine builders tend to err on the cutious side by never going over 9:1, and maybe 9.5:1 on an cast alloy head. Its your call. If you go for those low load stress, long duration cams, it should be able to take a large amount of compression. I'd follow the best mean advance method for seting advance, and check the psi while being cranked. If its over 180 psi, then alter the cam timing to reduce the pressure to 160 psi. Then it won't knock. Last option is water injection. Yeah, poo-hoo it if you want but its got its place!
MustangGeezer's 200 with a single 500 Holley is on 11.2:1 with the Log head, are you game? He runs water injection, and a wilder 272 cam, from memory.
Q3:Are the larger stainless steel intake valves you mentioned avaliable in Australia, if not what else could be used for a similar result?
A3:The best option is to check out Chevy ones from the Ferras range, or do some local Yella Terra Bat 1200 Red/Blue L6 and XT5 V8 checks. You have to look at a more exotic material than the later valves, Nimonic, Iconnel are rare, but some early intake (21N material) valves can be used as exhast valves. The key is allowing the heat to be conducted without scuffing to take place, and a stainelss steel is the best option. The tuliped, Rimflo types are best, but it all gets very expensive quickly with valves.
The key is finding the critical height dimensions, and then doing the leg work. Sorry, can't help past that. In New Zealand, we find Sedgins has most of the details, and you can do custom valves if you know what you need. When Addo gets back, PM him, and tell him I sent you.
Q4:And finally you mentioned using XE cam and timing gear, can I also use an elctronic distributor from an XE in a pre-crossflow 250 or will it need to be modified to suit?
A4o a search on the cam gear failures on this Aussie forum. The best option is getting a brand new Crow gear, and check that the dissy diameter is the same, that the distrubutor is well oiled with both lituim grease and half weekly doses of 10 mls on 20/40 when running in. The XE dissy needs a specail M8 or 5/16 bolt placed on the dissy flange to hold it tight, as per the stock XE item.
The end float must be within spec, and a new brass bush, 10 bucks from Ford, needs to be fitted. There are some details I can share some time on the rebuild. I haven't run a 200 or pre-log with an XD/XE electronic, yet!
Q5:This engine will be going into an XP falcon sedan with a four speed so I difinately think a brake and diff upgrade may also be needed as its running all the standard tiny four stud parts at the moment.
A5: Yep, you'll need it.
Sorry bud, out of my depth. The valves are the key to sucess. Don't go too big on the exhast, and don't settle for short valves, as the rocker geometry with small base circle cams is often not as good.
Best wishes,
Deano
Q1
o I need a special piston to run 200 rods in a 250 pre-crossflow (i think i read that ACL make pistons to suit the 250 crossflow with 200 rods) or will any oversized replacement pistons suit? A1: No, but I've heard tell from others that the 200 rods need clearance with the pistons to gudgeon pin and skirts. Normal linishing should help. I've not seen any confirmed cleance problems, although Overdose has some evil pictures of side skirt breakage, which we thought was cam related.
Q2: If the car was to run on optimax what compression ratio should I be aiming to achieve?
A2: That's Shells 95, or is it 98 octane? The deal is that if the engine has a bigger cam, and runs the normal Aussie engines close piston to deck register, it should be able to hack high 9's. All engine builders tend to err on the cutious side by never going over 9:1, and maybe 9.5:1 on an cast alloy head. Its your call. If you go for those low load stress, long duration cams, it should be able to take a large amount of compression. I'd follow the best mean advance method for seting advance, and check the psi while being cranked. If its over 180 psi, then alter the cam timing to reduce the pressure to 160 psi. Then it won't knock. Last option is water injection. Yeah, poo-hoo it if you want but its got its place!
MustangGeezer's 200 with a single 500 Holley is on 11.2:1 with the Log head, are you game? He runs water injection, and a wilder 272 cam, from memory.
Q3:Are the larger stainless steel intake valves you mentioned avaliable in Australia, if not what else could be used for a similar result?
A3:The best option is to check out Chevy ones from the Ferras range, or do some local Yella Terra Bat 1200 Red/Blue L6 and XT5 V8 checks. You have to look at a more exotic material than the later valves, Nimonic, Iconnel are rare, but some early intake (21N material) valves can be used as exhast valves. The key is allowing the heat to be conducted without scuffing to take place, and a stainelss steel is the best option. The tuliped, Rimflo types are best, but it all gets very expensive quickly with valves.
The key is finding the critical height dimensions, and then doing the leg work. Sorry, can't help past that. In New Zealand, we find Sedgins has most of the details, and you can do custom valves if you know what you need. When Addo gets back, PM him, and tell him I sent you.
Q4:And finally you mentioned using XE cam and timing gear, can I also use an elctronic distributor from an XE in a pre-crossflow 250 or will it need to be modified to suit?
A4
o a search on the cam gear failures on this Aussie forum. The best option is getting a brand new Crow gear, and check that the dissy diameter is the same, that the distrubutor is well oiled with both lituim grease and half weekly doses of 10 mls on 20/40 when running in. The XE dissy needs a specail M8 or 5/16 bolt placed on the dissy flange to hold it tight, as per the stock XE item.The end float must be within spec, and a new brass bush, 10 bucks from Ford, needs to be fitted. There are some details I can share some time on the rebuild. I haven't run a 200 or pre-log with an XD/XE electronic, yet!
Q5:This engine will be going into an XP falcon sedan with a four speed so I difinately think a brake and diff upgrade may also be needed as its running all the standard tiny four stud parts at the moment.
A5: Yep, you'll need it.
Sorry bud, out of my depth. The valves are the key to sucess. Don't go too big on the exhast, and don't settle for short valves, as the rocker geometry with small base circle cams is often not as good.
Best wishes,
Deano
A
Anonymous
Guest
hi guys i thought that i would drop my veiw on the ultimate crossflow engine . if your looking for the ultimate power for a 250 xflow , it has to be fuel injected and turbo charged. fuel injection is more efficient and is very easy to set up . rods and pistons have to be changed. i have a crossflow thats been highly modified , its producing 600hp and my friend has a similar setup producing 660hp. so if your looking for the ultimate power out of a 250 crossflow, a turbo charger and fuel injection is a must.
mts
mts
A
Anonymous
Guest
Amen ^^^^^
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