What mods should I do to the bottom end of a 250.

Solid Roller can be done, has been done, i know of a local guy, just over one hour from me doing a roller motor, he works at Tighe Cams, they do solid rollers for Crossflows, finished or semi finished, anyway guys name is Murray, knows a lot on pre cross cam shafts, i wanted to buy one off them badly but went with Clive cams as the solid new billet was 100 bucks cheaper, i couldn’t justify the extra on my baby solid.
 
xrwagon":2vr622z4 said:
Solid Roller can be done, has been done, i know of a local guy, just over one hour from me doing a roller motor, he works at Tighe Cams, they do solid rollers for Crossflows, finished or semi finished, anyway guys name is Murray, knows a lot on pre cross cam shafts, i wanted to buy one off them badly but went with Clive cams as the solid new billet was 100 bucks cheaper, i couldn’t justify the extra on my baby solid.
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yeah I sent them an email today about some of their grinds in solid flat tappet and asked about roller grinds too.

I know crower roller lifters with side grooves have been mentioned but how do they machine the groove in the lifter bore and is that the most cost effective way to get roller lifters in or 302 style roller lifters?

Then I know excstacy has said .590 lift can be done with the 250 so what would max lift be im leaning toward the hastings flat tops with 1.5cc valve reliefs from silvolite

1.585 in the .120 deck would be .035 deck hieght .050 gasket 3.7 bore stroke 3.910 a small log modified 1.8 intake 1.46 exhaust stainless steel with dual springs and a 53cc chamber would be 10.91 to 1 and could maybe get the pistons milled out to just 2.5cc more is 10.57 or out to a 8cc milled in dish would be 10.06 to 1

kind of leaning toward that combo with stock rods, autolite 4100 480 cfm 4 barrel and headers. has lots of port work and custom aluminum intake.

I want to save money on the different rods and custom piston combo since I just did another engine build on a 200 six. I do want to put money into the roller camshaft and lifters if I can get some direction on that as well as what is the max valve lift with this combo im looking around the 280 duration range hi rpm use profiles mostly strip on pump gas but would like to be able to do weekend street driving.

851A 70 34 34 70 284 284 231 231 .480" .480" H H 3200-6800 rpm.
thats a tighe solid flat tappet grind for the non cross flow 250 with 1.5 rocker arm ratio

883C 66 30 30 66 276 276 240 240 .580" .580" .022" .020" Fast road.
thats a tighe crossflow 250 cam with 1.73 rocker ratio it get .580 so with a 1.5 ratio on this cam would be .503" 1.65 rockers would be .550" valve lift

I may go with 1.65 rockers on this build so what about max valve lift on the 250 with zero deck?

and how much lift can be gained from keeping the .120 deck with a seal power flat top piston combo id have to mill the head down to a 46cc chamber to get a 10.06 to 1 CR.

Would I be more prone to detonation having the .120 deck and a small 46cc chamber or better to have a close to zero deck for more quench which this way would have a higher compression but be okay and less prone to detonate?

I know it may only be a coulple hp if that having the zero deck. but an extra .120" inch of room for the valve is big and is that only what allows the .590 lift so you will still have .030 clearance for rock while under use and the rods is at high rpms.

So i loose the .120 lift and go with a zero deck to help detonation issues because thats a huge deck plus gasket .170 deck is a lot of area in a 3.7 diameter and will loose the quench or squish effect and will then with a zero deck be limited again to the .490 valve lift range?
 
xctasy":gwlitv39 said:
6.21" rod won't work at all with 255 pistons. 1.585" compression height, 6.21" rod, puts the piston 281 thou out ofthe 9.469" block. You'd need a block 281 thou taller to capture that in the block.

I like the custom 6.21 300 rod and forged Racetek or CP piston, but there are other options. It will work


Some rods, like the stock 1978-1980 D8's a re cast iron, don't use them. Use forged rods. Best option is 4 cylinder Taurus 6" 2.5 HSC rods and a deep dish piston so you can reduce compression. The 9.469" deck gives a 103 thou short. With the HSC rod, the shortfall is gone in one hit. Victor Reinz head gasket or actual deck will propably get the piston clear of the head.


Factory Aussie pistons with 27.9 cc deep dish are avaliable from Silvolite 3332H on page 33 of the catalogue.

6-250 4.1L 3.6807(IN) 93.49(MM) AUSTRALIAN FORD ENGINE Hypereutectic, Dish 2.843” dia. .276” deep 28.7 cc calc, but chamfered, so its 27.9 cc.060” Offset Pin Unleaded Fuel
COMP HT: 1.530

these are available in flat top version and smaller dish # 3328H
2.967” dia. .071” deep
.060” Offset Pin
COMP HT: 1.530 PIN DIA: .912 Offset
Not intended for racing applications
3328H
STD.
.020
.030
.040
.060
PIN DIA: .912 Offset
3332H part number STD. .020 .030 .040 or .060
top ring 2-5/64
Second ring 1-3/16
Assy Interchange no RA4106

can these be used with stock 250 rod and will offset deck to .090 clearance then 3.5cc dish on these ones with 46cc chamber would be 10.26 to 1 CR so what about that option too would that combo work? or still too much deck clearance unless you use the HSC 6 inch rod which i have not been able to locate a source for?

Ak Miller said the 250 piston short fall gave extra room for higher lift cams, but when closed up, you needed a custom Jahns piston. Well, this was Ford Australias cross flow piston, and it will help reduce compression, and clear the lift of a 490 thou cam. And its tough as.

And is US made.


Slot the 51 cc chamber, 27.9 cc #3332H dish, into a 20 thou over 250 with 6" rods and a Chevy LS1 like +16 thou piston stick out, and you still get a fairly good compression ratio.

http://wallaceracing.com/cr_test2.php

(Your displacement is 252.24 CID The Compression Ratio is: 8.72)


Problem solved.
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Hi I have a question about pistons for my cross flow. I'm from Australia and have an XE Falcon. I was wondering if the pistons are the same that would come from the US?
I am trying to up my compression ratio so am looking for dome pistons...
 
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