New to group 250 owner need some advise
- Thread starter Econoline
- Start date
Actually you can degree a 250 by using an offset crank key. And if you are concerned about this throwing the balancer off you can do what my machinest did. He cut down on the length of the offset keyway to be the same width as the timing chain gear and installed this short keyway first and then cut the stock keyway to the proper length and installed that. This way the balancer is still in the proper position relative to the crank.[/quote]
I would hope that is the way HE did it as any other way would be wrong , Just Saying :nono:
I would hope that is the way HE did it as any other way would be wrong , Just Saying :nono:
Econoline:
Another very interesting thread.
I'm guessing at some of your stuff for the Gonkulator, maybe you can fill these in?
Weight: 3100lb curb (full tank and spare) plus driver (guessing cuz I dont believe published weights)
3.50 gears
Stock exhaust manifold and a single 2-1/4 smooth glasspack or magnaflow or superturbo etc
Deck is .001 so your deck height is now about 9.418" after milling?
I did some comparisons taking the Gonkulator down the quarter mile with these different cams/advances, they are all pretty close.
Most significant is the 214-214-112 cam likes a 4 degree advance in your combo, a .16 sec (about a carlength) edge in the 1/8 mile, which actually is significant and you can even begin to feel that difference from one day to the next.
As far as I can tell from my Gasolator, which is semi-empirical, based on numbers and experience:
9.30cr for the 214-214-112 at 0a
9.18cr for the 214-214-112 at 4a
9.05cr for the 208-208-110 at 4a
All these three setups have the same "octane requirement" which is right around 87 octane, or what they call regular out here in Cali.
The other thing as best I can estimate it is that decking the block, while it raises the CR, actually doesnt change the octane requirement, the higher CR is just about offset by better quench and swirl so as usual, zero decking is a win.
Of course, octane requirement depends on a lot of other stuff like piston material, intake air temp, engine temp, chamber shape, etc but I'd say if your chambers are all 65cc youre pretty much "there".
Another very interesting thread.
I'm guessing at some of your stuff for the Gonkulator, maybe you can fill these in?
Weight: 3100lb curb (full tank and spare) plus driver (guessing cuz I dont believe published weights)
3.50 gears
Stock exhaust manifold and a single 2-1/4 smooth glasspack or magnaflow or superturbo etc
Deck is .001 so your deck height is now about 9.418" after milling?
I did some comparisons taking the Gonkulator down the quarter mile with these different cams/advances, they are all pretty close.
Most significant is the 214-214-112 cam likes a 4 degree advance in your combo, a .16 sec (about a carlength) edge in the 1/8 mile, which actually is significant and you can even begin to feel that difference from one day to the next.
As far as I can tell from my Gasolator, which is semi-empirical, based on numbers and experience:
9.30cr for the 214-214-112 at 0a
9.18cr for the 214-214-112 at 4a
9.05cr for the 208-208-110 at 4a
All these three setups have the same "octane requirement" which is right around 87 octane, or what they call regular out here in Cali.
The other thing as best I can estimate it is that decking the block, while it raises the CR, actually doesnt change the octane requirement, the higher CR is just about offset by better quench and swirl so as usual, zero decking is a win.
Of course, octane requirement depends on a lot of other stuff like piston material, intake air temp, engine temp, chamber shape, etc but I'd say if your chambers are all 65cc youre pretty much "there".
Just a heads up , The later 200 and most of the 250's have an open style combustion chamber that is VERY Detonation prone , it was designed to be used with EGR , I know the consensus on here AND in a particular book touts all the Benefits of the BIG LOG Head , BUT that part ( the detonation prone )is sadly missed , theory and calculators are nice , BUT they are NOT always right , they are a help , just as an education and shop manuals are , BUT the biggie is EXPERIENCE and that is sadly ignored by MOST , not ALL on this site , especially from some of the Longest time members !! with that said , I am always open to new knowledge , I spent 7 months in Tennessee last year working with a 2nd generation Super stock / Stock Ford Engine builder , I am 54 , he is 44, and with his combined Knowledge from his Father, It was a great Learning experience for me and Humbling at times, he would call the cam company and tell THEM what he wanted for specs , we are talking FE Fords and Engines that make 530+ on a 390 to 930+ 427 and larger Combos all Naturally Aspirated, I left there a smarter person and hope if willing anyone reading this can understand my frustration at times with the rehashed magazine articles that pass for technical knowledge, ok done now
The only good info is from those who have done it. Hang in there. It's taken me three years just to understand Holley 2 and 4-bbl fuel atomisation flow patterns from your first response to my posts, and I'm Still Not There.
Sad thing is, you explained it right the first time you told me. :arg:
time
:boom: :fume:
Sad thing is, you explained it right the first time you told me. :arg:
time
:boom: :fume:FalconSedanDelivery":2jwkkugy said:
FSD,
Well now I'm hunting for chamber pictures and cant find the right ones.
Are you saying some of the heads were the dreaded full-open chambers like the
351c-2v
351cj
400m
429 in 1972 only
If so which years, I remember looking into this a while ago but now forgot. You have a point though, when I estimate a "safe" CR, if its one of the dreaded no-quench chambers I knock off about 0.5 points, maybe 0.6 even
Do you want a street engine or a track machine. Take your choice, one or the other.
A nice street combo is an engine with close to 10-1 compression or slightly over.
Cranking compression with 93 octane would be about 195#
Ideal camshaft with a C4 would be 262 degrees Intake, Exhaust 280 degrees.
L/C close to 114 degrees. Lift at least .535" spring pressure 300# open, 130# seat. Of course solid lifters with at least a 1.6 roller rocker arms.
Converter close to 2500 stall speed. Rear gear with a 250 close to 3.50, 200 at least a 3.80 or more.
Headers with a crossover or an X pipe dual exhaust.
If you don't run 93 octane fuel don't even go any further.
On the 200 holley 4412, on a 250 a holley 4412 with enlarged venturi's.
Last but not least is the distributor advance curve. DSII with a MSD-6AL box.
With my sun distributor tester & knowledge I can set your distributor curve the best for power & economy.
A nice street combo is an engine with close to 10-1 compression or slightly over.
Cranking compression with 93 octane would be about 195#
Ideal camshaft with a C4 would be 262 degrees Intake, Exhaust 280 degrees.
L/C close to 114 degrees. Lift at least .535" spring pressure 300# open, 130# seat. Of course solid lifters with at least a 1.6 roller rocker arms.
Converter close to 2500 stall speed. Rear gear with a 250 close to 3.50, 200 at least a 3.80 or more.
Headers with a crossover or an X pipe dual exhaust.
If you don't run 93 octane fuel don't even go any further.
On the 200 holley 4412, on a 250 a holley 4412 with enlarged venturi's.
Last but not least is the distributor advance curve. DSII with a MSD-6AL box.
With my sun distributor tester & knowledge I can set your distributor curve the best for power & economy.
On a Boss or Cleveland 302, Boss and Cleveland 351, or 351M and 400, yes. The alloy head X-flow 200 and 250, yes, but not on a 170, 200 or 250, no. Circumstances alter cases.
The closed chamber 'quench' 57 and 62 cc Cleveland heads are exactly what the Yates A3's were based on, and they are perfect when the right type of piston is used to promote flame travel in high hp situations, Australian V-Eight Supercars are still using a 1969 Boss 302 knock off head, and it loves a good squeeze. So are the Ford NASCAR engines. When used on 302C with stock 2v , they were unable to turn them off due to dieseling. That doesn't happen with the closed chamber 170 and early 200 heads, they love the wall, and it just liberates hp, cfm and flame progression.
The closed chamber V8 and Aussie I6 X-flow canted valve heads don't put much spin on the mixture and the close proximity of the close chamber walls creates a demand for higher octane on the 256 and 268 duration cam engines. As the cam timing goes up, the octane sensitivity drops off, and you make more power, although the detonation threshold on all canted valve engines is in a very tight margin.
The non cross flow is more like a messed up FE, after all, they were designed by the same team who did that engine, and at that time, the closed chamber 144 and 170 were made for very low duration cams of about 240 degrees, where octane sensitivity is high. The engineers were experimenting with Ricardo and Weslake ideas, and the so they spent time making the bathtub heads flow well by canting the valves over to make a wedge on one plane. As soon as 1966 rolled around, the 200 and later 250 were going to have to contend with air injection into the exhaust in CA, and the whole line of non 170 heads were opened up to as octane sensitivity was less of an issue than emissions. They just knocked off the compression ratio a whole point.
The valves on the small sixes are canted in one plane, and the mixture motion with a close wall is aided by it, very much like a Max Wedge, and the shrouding, quench and squench is favourable. The opposite is true with the 2v and 4v closed chamber Cleveland heads, they hated to have walls near the valves when the compression ratio was high and the cam duration was so low, and there were major problems in the Aussie 1972 to 1982 with there inability to cope with anything other than leaded super (our 96 to 97 octane high lead gas). When a nice big cam was used, they just loved it, and power grew. In the 351c, adding 302 2 or 4v heads made them pink like crazy, and the only solution was one of the five Ford high lift cams, and then they'd cope with 11:1 compression and standard gas as the early 1971 330 hp Panteras with the Autolite 4-bbl proved. As soon as the cam duration was back down to 2V level, 256 or so, it would detonate like crazy.
The reason I know all this is that the Repco development engineer who did the 250 2v non cross flow, the 351c 4V HO QC sedan car racing engines and the reworks of the early Alloy Head I and II X-flows found the early Cleveland canted valve heads needed a composite gasket, different pistons and the Boss 351 style head; Fords Dearborn engineers like Lee Morse found the same thing when experimenting with the 91 unleaded versions which were going to have to be used for 1973. So big chamber open heads and softer cam profiles with huge piston caverns were rolled out with the 400 and later 351m. Charles Landers and Bill Santaciccone, Mick Webb, Kevin Bartlett and Bob Pinnell discussed this at length in 1988 to 1990 articles in Australian Street Machine, and it took them years to find out that the reason for crankshaft and rod failures and over heating were just poor detonation sensitivity on all engines with the small chamber canted valve heads.
The closed chamber 'quench' 57 and 62 cc Cleveland heads are exactly what the Yates A3's were based on, and they are perfect when the right type of piston is used to promote flame travel in high hp situations, Australian V-Eight Supercars are still using a 1969 Boss 302 knock off head, and it loves a good squeeze. So are the Ford NASCAR engines. When used on 302C with stock 2v , they were unable to turn them off due to dieseling. That doesn't happen with the closed chamber 170 and early 200 heads, they love the wall, and it just liberates hp, cfm and flame progression.
The closed chamber V8 and Aussie I6 X-flow canted valve heads don't put much spin on the mixture and the close proximity of the close chamber walls creates a demand for higher octane on the 256 and 268 duration cam engines. As the cam timing goes up, the octane sensitivity drops off, and you make more power, although the detonation threshold on all canted valve engines is in a very tight margin.
The non cross flow is more like a messed up FE, after all, they were designed by the same team who did that engine, and at that time, the closed chamber 144 and 170 were made for very low duration cams of about 240 degrees, where octane sensitivity is high. The engineers were experimenting with Ricardo and Weslake ideas, and the so they spent time making the bathtub heads flow well by canting the valves over to make a wedge on one plane. As soon as 1966 rolled around, the 200 and later 250 were going to have to contend with air injection into the exhaust in CA, and the whole line of non 170 heads were opened up to as octane sensitivity was less of an issue than emissions. They just knocked off the compression ratio a whole point.
The valves on the small sixes are canted in one plane, and the mixture motion with a close wall is aided by it, very much like a Max Wedge, and the shrouding, quench and squench is favourable. The opposite is true with the 2v and 4v closed chamber Cleveland heads, they hated to have walls near the valves when the compression ratio was high and the cam duration was so low, and there were major problems in the Aussie 1972 to 1982 with there inability to cope with anything other than leaded super (our 96 to 97 octane high lead gas). When a nice big cam was used, they just loved it, and power grew. In the 351c, adding 302 2 or 4v heads made them pink like crazy, and the only solution was one of the five Ford high lift cams, and then they'd cope with 11:1 compression and standard gas as the early 1971 330 hp Panteras with the Autolite 4-bbl proved. As soon as the cam duration was back down to 2V level, 256 or so, it would detonate like crazy.
The reason I know all this is that the Repco development engineer who did the 250 2v non cross flow, the 351c 4V HO QC sedan car racing engines and the reworks of the early Alloy Head I and II X-flows found the early Cleveland canted valve heads needed a composite gasket, different pistons and the Boss 351 style head; Fords Dearborn engineers like Lee Morse found the same thing when experimenting with the 91 unleaded versions which were going to have to be used for 1973. So big chamber open heads and softer cam profiles with huge piston caverns were rolled out with the 400 and later 351m. Charles Landers and Bill Santaciccone, Mick Webb, Kevin Bartlett and Bob Pinnell discussed this at length in 1988 to 1990 articles in Australian Street Machine, and it took them years to find out that the reason for crankshaft and rod failures and over heating were just poor detonation sensitivity on all engines with the small chamber canted valve heads.
WerbyFord":17jg9jg9 said:FSD,
Well now I'm hunting for chamber pictures and cant find the right ones.
Are you saying some of the heads were the dreaded full-open chambers like the
351c-2v
351cj
400m
429 in 1972 only
If so which years, I remember looking into this a while ago but now forgot. You have a point though, when I estimate a "safe" CR, if its one of the dreaded no-quench chambers I knock off about 0.5 points, maybe 0.6 even
ok, here is the early styl combustion chamber;
here is the late combustion chamber, not a clear a picture, but all i could find;
hope this helps.
Mine are more elongated than in the early picture, but not like the later picture. In between those two. C9DE-M casting large log non egr motor. Funny thing is everything I read say's these are 62 cc chamber heads, but I measured the volume of chamber #1 twice and it is 65 cc's. Measured with alcohol, grease and plexiglass with a spark plug installed.
Werbyford, I was out for the evening, I'll get back to you with that info, just checking in now before bed.
Werbyford, I was out for the evening, I'll get back to you with that info, just checking in now before bed.
WerbyFord":88as075z said:
I'd say that's about right for curb weight, this van shipped was around 2600lbs. 250 is heavier, I'm around 200lbs, it has a 12 gal tank and I'm adding a heavier rear end.
Right now it has 3.5:1 gear ratio, the rear end is getting swapped to a larger one though.
I am planning on putting headers on with the rebuild, probably single out 2.5" through short resonator/glasspack AND dynomax turbo style muffler. Right now it's single out 2.25" + resonator + dynomax
Not sure what you asking for in deck height? If I assume the centerline to deck before milling was 9.469"(which I doubt, virgin block never decked/bored ect, all original, deck height from piston @ TDC measured .103") then it would be 9.449" after decking. The pistons I'm using are 255 pistons with a compression height of 1.583" custom milled with a chamber shaped D dish.
Thanks for the help everyone
Econoline":wjb27819 said:Not sure what you asking for in deck height? If I assume the centerline to deck before milling was 9.469"(which I doubt, virgin block never decked/bored ect, all original, deck height from piston @ TDC measured .103") then it would be 9.449" after decking. The pistons I'm using are 255 pistons with a compression height of 1.583" custom milled with a chamber shaped D dish.
Thanks for the help everyone
So I then get deck clearance = 9.449-1.583-5.880-3.910/2 = .031"
You had mentioned deck clearance = .001" above so I wasnt sure how you got there.
Then again, I would have calcd your original deck as
9.469-1.511-5.880-3.910/2=.123"
Since you got .103" I figured maybe your block had been cut .020" already, plus .020" more that youre cutting it...
Also the .031" deck gives me CR=8.79
Just collecting details for the Gonkulator, but it might affect your decisions too -
If this block has ever been decked it would be astounding, the motor is all original, ford bearings, orginal bores etc. The clearance with oem pistons is .103" checked and rechecked before dissatssembly. Funny thing is this motor supposedly was 9:1 from the factory, but if you run the numbers with .025" gasket, .103 deck height it's 8.2:1, even if the chambers were 62cc's, which they aren't, it would have been 8.5:1 
xrwagon
Well-known member
my 67 200 in the wagon is apparently 9.2:1, the head comes off next week so i will post up a new thread with pics of my aussie 200 head and take note of my head gasket thickness, my question is how much more power does one get when milling the head? my new 2V head is stock height and unassembled so milling it will be easy, i have yella terra roller rockers so will need new lifters and pushrods.
I have found that most rated compression ratios from the factory ( pre computer age )are usually off up to and sometimes over a full point or more , that is why I use a conservative number when I see people saying that a 9.5 motor is fine on 87 octane , a true vs factory number can lead to problems , SAFE IS A DECIMAL MOVE ONE PLACE TO THE RIGHT 87octane will handle 8.7 perhaps more , but detonation ( and you cant always hear it ) is the biggest killer of an otherwise healthy Engine
Ak Millers original page 42 and 43 post of the Tricks with 6 in the Complete Ford Book were posted by pacer back in 2009 in this post viewtopic.php?f=2&t=59308
They are the 5th and 4th link in pacer's post.
This is where the 30% better than the large chamber info came from. One other poster said that the 30% flow rate increase is when compared to the early small log head.
I'll let you guys read the article on page 42 and 43 to decide yourself...
They are the 5th and 4th link in pacer's post.
This is where the 30% better than the large chamber info came from. One other poster said that the 30% flow rate increase is when compared to the early small log head.
I'll let you guys read the article on page 42 and 43 to decide yourself...
pacer":1w7dqi4a said:http://img2.imageshack.us/img2/8262/mailvuf.jpg
http://img40.imageshack.us/img40/3310/cutarticle.jpg
http://img40.imageshack.us/img40/9858/i ... 100012.jpg
http://img43.imageshack.us/img43/4426/i ... 010001.jpg
http://img40.imageshack.us/img40/3082/i ... 020001.jpg
http://img9.imageshack.us/img9/7797/imgy05110200012.jpg
http://img30.imageshack.us/img30/3339/i ... 030001.jpg
Hopefully these links work!!!
pacer":2gfqsqe5 said:http://img40.imageshack.us/img40/8343/i ... 300012.jpg
http://img39.imageshack.us/img39/5065/i ... 040001.jpg
http://img11.imageshack.us/img11/1649/i ... 400012.jpg
http://img43.imageshack.us/img43/2235/mail0002.jpg
http://img40.imageshack.us/img40/5744/mail0003o.jpg
http://img9.imageshack.us/img9/8074/slyonetbucket.jpg
http://img517.imageshack.us/img517/8449 ... erhead.jpg
Hopefully these links work!!!
So I've decide to go with the Erson E280101 cam and am wondering about figuring dynamic C/R so I can settle on a static compression ratio for the motor. I've used a couple of online calculators and have come up with 7.3-7.6 or so depending on the static c/r used. Not sure if I'm doing it right. I'm using the listed and calculated ivc of 67 degrees.
Motor is almost done at the machine shop. What I ended up doing was having it bored .040", decked .032", and I'm using 2.5 HSC pistons that will be milled w/ D dishes once I have the final numbers. If I did my measurements correctly I should end up with a deck height of .015" plus whatever head gasket I use.
Motor is almost done at the machine shop. What I ended up doing was having it bored .040", decked .032", and I'm using 2.5 HSC pistons that will be milled w/ D dishes once I have the final numbers. If I did my measurements correctly I should end up with a deck height of .015" plus whatever head gasket I use.
I'm using the Calculator program downloadable here: http://cochise.uia.net/pkelley2/DynamicCR.html
Right now this is where I'm at:
Bore - 3.72
Stroke - 3.91
Dynamic Stroke - 3.00103274604159 with Erson 280101 Cam
Comb. Chamber - 62cc
Gasket Bore - 3.81
Gasket Thickness - .044
Deck Clearance - .015
Piston Dish - 8cc
Quench Distance - .059 not ideal but alot better than the .153" I started with
Static C/R - 9.6:1
Dynamic C/R - 7.6:1
Right now this is where I'm at:
Bore - 3.72
Stroke - 3.91
Dynamic Stroke - 3.00103274604159 with Erson 280101 Cam
Comb. Chamber - 62cc
Gasket Bore - 3.81
Gasket Thickness - .044
Deck Clearance - .015
Piston Dish - 8cc
Quench Distance - .059 not ideal but alot better than the .153" I started with
Static C/R - 9.6:1
Dynamic C/R - 7.6:1
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