How to build a better inline six???

[bookworm007]

So I have been poking around the forums here for awhile learning what I can on how to build one of these engine up for good horspower. I have already decided that I would like to do the crossflow head swap. I have found build from FTW racing that put you in the 250 horspower range with mostly stock parts. My question is since I currently have a 200 in my 65' stang would it be better for me to swap up to a 250 for the ease of bellhousings, extra cubes, and better rod to stroke ratio. Second part is I have read in my falcon hand book about putting chevy pistons in to the 250 to bring the piston closer to zero deck height but it says mill the deck past there is a bad idea as it will increase compression too much. So which engine is better in respects to haveing good quench and ability to swap in other pistons and rods for a good ratio. I have heard about modfiying 302 connecting rods attached to ACL pistons to get a good ratio and with the ability to get good quench. I would rather stay naturally aspirated and will source a carb after getting all the other parts together. I also know that I will need a grocery list of parts to swap the crossflow head in. Does anybody know of a current importer of the alloy crossflow head??? Basically I want an awesome inline six so I don't have the same thing as every other guy and I can beat my brother and his 86 trans am. Thanks for the help guys u are awesome for keeping this engine alive

 

[Explorer]

Go to the parent site, classicinlines.com and read the tech section. That'll keep you busy for awhile.

 

[Gene Fiore]

You can also use pistons for the Ford 255 V8 which has a higher pin height than the stock 250 pistons but is identical in every other way and will push the piston up in the bore about .085 Classic inlines carries these pistons. On my motor this put the piston .027 down from the deck.

 

[rocklord]

So I have been poking around the forums here for awhile learning what I can on how to build one of these engine up for good horspower. I have already decided that I would like to do the crossflow head swap. I have found build from FTW racing that put you in the 250 horspower range with mostly stock parts. My question is since I currently have a 200 in my 65' stang would it be better for me to swap up to a 250 for the ease of bellhousings, extra cubes, and better rod to stroke ratio. Second part is I have read in my falcon hand book about putting chevy pistons in to the 250 to bring the piston closer to zero deck height but it says mill the deck past there is a bad idea as it will increase compression too much. So which engine is better in respects to haveing good quench and ability to swap in other pistons and rods for a good ratio. I have heard about modfiying 302 connecting rods attached to ACL pistons to get a good ratio and with the ability to get good quench. I would rather stay naturally aspirated and will source a carb after getting all the other parts together. I also know that I will need a grocery list of parts to swap the crossflow head in. Does anybody know of a current importer of the alloy crossflow head??? Basically I want an awesome inline six so I don't have the same thing as every other guy and I can beat my brother and his 86 trans am. Thanks for the help guys u are awesome for keeping this engine alive

Be careful about transferring upgrades from FTW on their 4.1L to our 250; MustangSix when he rebuilt his crossflow 250 described the Australian 250 and the US 250 as more like cousins, not siblings. Read this: http://www.fordsix.com/XFswap.php
Is the modified 302 connecting rod for the Aussie 250? If so, the ACL piston is no longer being produced and are hard to find.

You can get HP easier going with the 250 (there is no replacement for displacement); the 200 will rev better, so personal preference. The bellhousing does give you greater transmission choices, the AOD being the main one. The US 200 and 250 have the same rod to stroke ratio (1.50); the Aussie 3.3L crossflow has the rod/stroke ratio advantage over the 4.1L. As for a current importer of the alloy crossflow head, there isn't anyone right now. Bayrunner and I have a couple spares, but xrglen lives in Australia and could ship some of the parts for you. Here is a website you can get in contact with him: http://www.hotsixes.com/forum/

Hope this helps. If there is anything else, let me know.

 

[Bayrunner]

I do not know how many more un-modified heads XRGlen wants to deal with! But, if someone asks nicely, I am sure glen will do what ever he can to accomodate.

Now. The pistons and acl rods are no longer available.
I do believe that the last ACL gasket set I have purchased.
I can tell you, all of the good head gaskets are gone!

Lastly, the 250 HP build you are refering to was the one XRGlen had built. Well, that build has been uped to 365HP but you really have to import an ausie motor in order to get the steel crank to make this possible.

Cheers.

 

[bookworm007]

So I have been scouring summit racing trying to find a replacement piston that would work but the miracle cure has yet to be found. I was wondering about some of the dimentions of the 2.3 HSC engine. How did they mange to have an engine with 5.2 rods and a piston with 1.5 compression heighth? Did they raise the deck? It would seem ideal to use parts from those engines since they are more or less the same. I also heard some people looking into custom pistons. Would that be outragesly expensive? I mean I don't want to blow a ton of money trying to perfect the rod ratio for this engine but I think it would be cool to do especially if it doesn't take too many customized parts. Does the Aussie 250 have a better rod ratio? Also as far as quench goes how do u know how close u are to it? I hear about getting to zero deck height which I understand but do u want to go farther than that to get a small quench??? also how hard would it be to modify a connecting rod to accept a larger pin? Thanks again guys

 

[rocklord]

Ford was able to use 5.2 rods in the 2.3HSC engine by having a taller deck height than the 200, but don't ask me what it is.

Other parts of the 2.3HSC has been used, some have retrofitted the TFI distributor to run in the six.

Custom pistons would be expensive; but if you can find someone who will do a set for the 250Xflow with 200 conrods for less than $400, I'd be interested.

The Aussie 250 Crossflow has the same rod ratio as the US250, 1.504. The Aussie 200 Crossflow has a rod ratio over 2.0; that's why stock they can rev 700rpm higher than the 250. An Aussie 250 Crossflow with 200 conrods has a rod ratio of 1.60.

When dealing with quench, zero deck height on a 200 would be the most you would want to go; pistons above the deck could be a problem with valve interference when using a performance cam (higher lift).

You could enlarge the pin size of the conrod slightly to accept a larger pin, but don't go overboard or you will weaken the rod.

 

[bookworm007]

So I just found these pistons for a jeep 4.7 V8 on summit racing that are the same bore as out engines but with a compression height of only 1.240 in. The only draw back is the pin size is different, but it is only .02 in bigger than the rods I think I could modify to fit. This set up would only work in a ford 250. The rods are 6.4 in sbc rods and the pin end would need to be bored out .02 and the big end would need to be .00236 larger. This seems rather small and doable. Also the right gasket would need to be used in order to attain proper quench as the modern gaskets vary from .046 to .057 for the log head. What gaskets are still availible for the Crossflow? I found a full crossflow gasket set online for $130, but it used the graphite gasket from ACL and they don't list a compressed thickness for it. Is this a good gasket? You were saying having the piston coming above the piston would be bad for the vavles do you mean the block or the block plus head gasket? My Ford Falcon Perfomance Handbook states that the ford 250 has between .120 and .150 between the top of the piston and the deck. why this is??? All in all this would give me about a 1.6 rod ratio a slight improvement over the stock 1.5

 

[rocklord]

I'm talking about the piston sticking out of the block. The reason it's a bad thing is that the piston is getting closer to the valves and clearances would be tight.
Pistons touching valves - Bad
The engine would have to be test fitted to determine valve clearance.

The piston recess in the 250 is to keep the compression down.

There is a problem with your proposed setup. The US 250 has a block height of 9.469'. If you use a 6.4' rod and a piston with a compression height of 1.24", the piston will stick out of the block 0.126"
block height - centerline of crank to top of block
(stroke/2)+rod length+compression height+deck height=block height
(3.91/2)+6.4+1.24+ deck height= 9.469
deck height = -.126 (negative number means it sticks out of block)
With the flat top 4.7L Jeep piston, even with a combustion chamber of 62cc, your compression is over 14:1 - Bad

The ACL racing piston that is used in the Australian 250 crossflow with 200 conrods has a compression height of only 1.169, with a recess. This is to keep the CR down.

See if you can find out the compression height and wrist pin size on the 94mm stroker pistons used in aircooled VWs.

 

[Bayrunner]

I'm talking about the piston sticking out of the block. The reason it's a bad thing is that the piston is getting closer to the valves and clearances would be tight.
Pistons touching valves - Bad
The engine would have to be test fitted to determine valve clearance.

The piston recess in the 250 is to keep the compression down.

There is a problem with your proposed setup. The US 250 has a block height of 9.469'. If you use a 6.4' rod and a piston with a compression height of 1.24", the piston will stick out of the block 0.126"
block height - centerline of crank to top of block
(stroke/2)+rod length+compression height+deck height=block height
(3.91/2)+6.4+1.24+ deck height= 9.469
deck height = -.126 (negative number means it sticks out of block)
With the flat top 4.7L Jeep piston, even with a combustion chamber of 62cc, your compression is over 14:1 - Bad

The ACL racing piston that is used in the Australian 250 crossflow with 200 conrods has a compression height of only 1.169, with a recess. This is to keep the CR down.

See if you can find out the compression height and wrist pin size on the 94mm stroker pistons used in aircooled VWs.

Go Dan, that is some serious math! Cheers

 

[rocklord]

That's what happens when you have a spreadsheet, you can play a bunch on "What Ifs" on it.

 

[Bayrunner]

Those darn Excell Experts!

 

['68falconohio]

bookworm007,
I'm exploring piston options as well. I find this earlier today: Stan Weiss' Piston Page

Stephen

 

[bookworm007]

I started looking into the VW pistons but and I am still searching for compression height and pin size number, but all the pictures I have seen make them look like they are flat top pistons which would pose problems in the compression ratio category

 

[bookworm007]

I just found some info on the VW pistons this online book has lot of info
http://books.google.com/books?id=NPJVPI ... q=&f=false
It would seem that the VW pistons stock pin size is only .866 inches which a bit smaller than our stock size of 0.912 in. There are some aftermarket VW pistons that used a .990 in chevy wrist pin. They also come on compression heights ranging from 1.21 to 1.4, but I'm not sure what the stock height is.

 

[bookworm007]

Alright I think I may have an option for all of us building a 250. It would seem the 200 rod is so short that there are not many options still availible. First of all the block would need to be bored out by .056 which is getting very close to the safe max for our engines, but I think that will be the buld of the mods needed.

I found these sbc (small block chevy) pistons with a compression height of 1.261 and you can get a set of 8 for only $375
http://www.summitracing.com/parts/UEM-KB153-STD/

As for rods these sbc 6.2 in rods should do the job and they are only $315 bucks for a set of 8
http://www.summitracing.com/parts/SCA-26200716/

Since both rods and pistons are for a sbc there should be no fitment problems attaching the two and they are made to use floating pins. The crank end of the rod has a diameter of 2.100 and our engines have one of 2.1236. So some slight machining or honing might need to be done to get proper clearences. The rods are forged steel and the pistons are Hypereutectic aluminum.This should stick the piston .033 from the deck of the block after milling .01 off the head and block to make them level. Also with a 62 cc head and .05 headgasket you should only have about 10:1 compression and a rod ratio of about 1.59. With all the combustion chamber size options from classic inlines you could crank the compression ratio up as much as you want. With the 57cc Aussie Alloy head I should be in the 11:1 range still within reason for a street car. As far as quench is concerned this set up is not much better than the 255 chevy pistons, but it would give you similar quench with a better rod ratio.

This piston which is also for a sbc could be switch in. It has a slightly taller compression height of 1.265 and only 3.250 cc dish, but is the same bore. It is made of forged alluminum which I know is a requirement for boosted applications. Also H beam rods could be found if stronger ones were needed.

Now if only my brother would stop laughing at me about putting chevy parts in my ford (fyi he is a chevy guy). Hopefully kicking his rear with an inline six will shut him up 8)

So what do u guys think?

 

[Bayrunner]

"The Quinch is not important in a crossflow application, the design creates plenty of breathing on the intake side. The exhaust side needs improvement on any crossflow head." This is from the master himself! Some of you know who I am refering to but this fella has built these engines pumping over 350 HP with no power adders and a carb.

Spend your money on a great head, cam, header, intake cambination. The pistons, rods, crank will be just fine fgor up to 450HP even on some juice. You might want to get creative on heat despersion and maybe some better ignition. Other than that, why mess with the items that are not the problem. You can re-condition your rods, I would be happy to explain, get you some Silvolite Pistons and molly rings from Mike and rock the US 250 to over 6K RPM. Why bother with the internals. You are talking about spending $800 and pushing the Block to it's limits for no reason. .040 over is the MAX I would go on these castings. The walls are THIN!

Just my humble opinion, influenced by someone who has been experimenting with these for over 2 decades.

Cheers

 

[Anonymous]

Look at the Ford 300 Rods 6.2097 long stock crank Journal Dia and stock Piston pin dia Summit Racing Part Number FEM-R25AY , or Part Number: SLP-R25AY
Ken

 

[80Stang]

That setup with Chevy 305 (cd 1.261") with Ford 300cid L6 rods is a known yet not proven possibility, and with 1.59 rod-ratio makes a sure difference in rev ability of the engine.

Then you can look into aftermarket Chevy 6.250" small block rods with 2.000" or 2.100" journals, and 1.890" Honda journals. You'll get direct fit to Chevy piston and also ability to stroke / de-stroke the engine by offset-grinding the crank. With 2.000" rod journal you can de-stroke up to 0.1236" thus make the stroke 3.7864", and rod ratio to 1.65 and engine size to 249cid in its 0.056 overbore. I.e. stock size but 1.65 rod ratio. Starts to be nice...
Or stroke it up to 4.0336", with rod-ratio 1.55 and engine size being 265cid. Bigger engine, still better rod-ratio than 250cid std.

With Honda rod journals (1.890"), theoretically these stroke changes get about doubled if you want to max it out. 1.7 rod ratio requires 3.676" stroke with 6.250" rods. With Honda journals, you can get minimum stroke of 3.6764" which happens to be just aimed for 1.7 rod-ratio. Engine size drops to 242cid...so what. Piston cd needs be around 1.31" but you can play with offset grind (giving up some rod-ratio) and the amount of block deck mill to make up a sweet setup of your will. Now, where to get pistons for this latest combo?

Maybe the sweetest/most doable combo would be to use rods with Honda journals, offset grind crank so that 1.261" CD Chevy 305 pistons would make close to deck with some deck milling. You'll get about 250cid engine with 1.65+ rod-ratio, stronger aftermarket pistons and very strong rods. Negative points are somewhat dangerously big bore at 3.736" and moderate cost due to offset grinding the crank, K1 technologies rods (they have the 1.890" / 6.250" rod) and pretty costly KB pistons (costly for a hyper piston by KB, and they sure are not too good looking pieces).

Now who remembers the big end width of the 250 rod? Chevys are .940.

 

[drag-200stang]

I'm going by memory here, but I believe the 200, 250 and 300 big end crank journal width is 1.00". So subtract your side clearance for your rod width. I can't see how most V6 and V8 rods would work. 0.060 seems like too much oil loss to me. The big block Chevy rod is pretty close, but I believe the bearing is offset. I think the best way to get the right width would be to look at the single crank pin engines (I-4, I-6). Keith Black has quite a selection of pistons for the Chevy 305 at 3.736 if you don't mind the 0.56 overbore. I'd be OK with that overbore for any NA engine except for an extreme drag only. Wouldn't do it boosted unless it was just a 8 lb max. Wouldn't leave much room for rebuilding later.

I think Ford's new modular 5.0 engine may have a bore size close to ours. Not sure yet though. Also, the guys that are looking the 3.70 bore pistons, I can tell you it's difficult to find an engine that will clean up with only a 0.020 overbore.