I have a 77 f250 with a 351 m, and a c6 automatic tranny. I also have a 78 f250 with a 400 and a c6, anyway, both have been machined and have performance mods, all of which were done by the previous owners. The 400 is so much incredibly more powerful than the 351 that I got a 400 just to rebuild, and I want to go high performance. But I don't know if I should do a few things to the block when I have it machined. I was thinking about having it drilled and tapped so that it would have four bolt mains. Is this a good idea or a waste of money? I don't know much about rebuilding motors, but I do know I want the cylinders over bored. I don't know how much though. And that brings up a pretty big problem; I can’t find pistons at all. Where can I get them? And should I go with flat topped pistons? And should I reuse the stock connecting rods? I'm going to use the stock heads, but I’m going to have them ported. For a cam, I don't know what to use, as far as numbers go, but I want to use a cam from crane cams. Lifters, I want to use solid lifers. That’s almost definite I’m going to use an edelbrock intake and a Holley carb, mechanical secondary, probably around 700 cfm. I’m not sure if I’m going to use the c6, or if I’m going to use the 4 speed that I have in a parts truck. What do you think? All help and suggestions will be greatly appreciated. Thanks. And sorry it’s so long, I had a lot to say.

 

There is no need to have the block tapped for four bolt mains, The 400 was a lower rpm engine that never turned fast enough to worry about it coming apart. If you want to bore the engine out go .030 over. I got my pistons for carquest. Just about any parts store should be able to get them. For the cam i went with comp cams #268 extreme energy cam. There is no needed to install a solid cam because the engine doesn't rev that high to worry about the lifters floating. Stock connecting rod should be fine. 650cfm holly four barrel and headers should give you upwards of 320 horsepower and almost 500 lb. ft. of torque. keep us informed.

 

There is no XE268 cam listed on the Comp Cams website. I did find XE256 and XE 262 cams.
With 8.5:1 CR:

• XE256 T=434@2000, 404@4000 RPM, HP=308@4500 RPM
• XE262 T=431@2000, 408@4000 RPM, HP=321@4500

• [*]
• [*]

You need flattop pistons to get 9:1 CR. You may need 89 Octane or higher with 9:1 CR and the XE256 cam.

 

blockson98, so even under very hard accelleration, as in drag racing and burnouts, the stock 2 bolt mains are fine? not a high risk of lower end failure? solid cam and lifers is one thing i want, i understand that its not neccesary. But through personal experience i've found that a solid cam and lifters produces a better running engine. its louder, and you get the clicking sound, but hey, it add to the coolness factor. im glad i can save a few bucks and use the stock rods though. one last thing, why 650 cfm? i've been shopping around a bit and most people recomend 700 or 750. infact, i knew someone with an 850 on a 351. so now im just confused. headers, i forgot about that, they are definate, along with an h pipe and dual flowmasters. thanks for the help.

danlee, i would like the 9:1 cr, so i guess i'll be getting flat topped pistons. i dont have a problem running on 89 octane, thats what i run my trucks on now. they dont really need it, but it makes me feel better putting a better quality in there. those numbers you posted, do those change much if i go with a solid cam and lifters?

ohhh and i almost forgot, should i use rollerrockers or the stock rockerarms? rollerrockers if i can find them that is. i remember seeing them somewhere.

 

With 9.0:1 and ported heads and 600 CFM carb and a Comp Cams 270S will produce T=438@2000, 454@3500, 415@4500 RPM. The HP=356@4500 RPM.

A Comp cams 270HR will produce T=466@2000, 476@3500, 441@4500 RPM. The HP=379@5000 RPM.

You can get Scorpion Roller Rockers for pedastal mount. You cannot use stock rockers with a solid lifter cam. You need to adjust the clearance on a solid cam.

You can use any size carb that you want at WOT, but you will have a tough time getting a big carb to run right at part throttle. The recommended carb for a 400 motor is 600 CFM.

 

i'm having a little trouble understanding this whole camshaft thing, because i checked the comp cams website. it said the 270hr is a roller hydraulic cam, and the 270s is mechanical, whats the difference? and can all of these cams be used with solid lifters? which gives better tourque and hp?

 

The cam has 268 duration sorry! Yea there is no need to run four bolt mains. I know a guy that drag races a 400 and he has never had any problems. For the 650 cfm carb, there is no need to over carb. people who put the big carbs on there usually don't do research. You only actually need 610 cfrm for the combination i talked about. If you look back in the forum there is a link to a article in hotrod about the 400 and every thing i have said is explained in there and they have the numbers to prove it.

 

Just my opinion, but I think you need to start with a clear idea of the performance you want, and from that you can determine what you need to do to your engine to get it (i.e., how much torque/power, and in what rpm range). I can't tell from your posts what you really want, other than a cool solid lifter sound.

Starting with an assumption about using solid lifters, regardless of the performance characteristics of any off-the-shelf solid lifter cam, means you might have to design (or pay somebody else to design) a custom cam that has the characteristics you want. Otherwise, you risk building a cool-sounding engine that doesn't run very fast, and it might not be much fun to drive.

Hard acceleration doesn't require 4-bolt mains, but high rpm does. (Hard acceleration and burnouts are not the same thing -- one requires traction, the other does not.)

You could get a stud girdle made for your 400 for a lot less than the cost of machine work for 4-bolt mains, and the stud girdle would be stronger (because you don't weaken the main bearing supports in the block by drilling them out). If you are serious enough about high-rpm performance to justify a stud girdle (and solid lifters), then you might well need something stronger than stock rods, and maybe even a custom steel crankshaft.

You really can't use a pedestal-mounted rocker, stock or roller, with solid lifters, unless you want to completely remove the rocker arms or swap the push rods every time you adjust the valve lash. The only practical way to accommodate solid lifters is to machine the head for stud-mounted adjustable rockers, and use guideplates with hardened pushrods (just like the Boss 351C and 351C HO).

The 270HR requires hydraulic roller lifters. The 270S requires solid flat-tappet lifters. I don't have a desktop dyno like Dan, but just looking at the cam specs (lower lift and longer duration @ 0.050" with the 270S) I'd bet the torque and power don't really come in until considerably higher rpm with the 270S, which will give weaker low-rpm performance.

The only significant advantage of the 270S over the 270HR would be at engine speeds over 5K rpm, which barely (if then) justifies the solid lifters. OTOH, if you really want good performance at 5K+ rpm, I'd go with the 284HR (same duration @ 0.050" as the 270S, with the higher lift of the 270HR). With the low-friction advantage of roller lifters, I'd bet the 284HR would easily outperform the 270S, at least all the way up to whatever rpm the valves start floating with the 284HR (probably well past 6.5K rpm), which is well past the 270S power band anyway.

So what's your objective for this engine?

 

yeah, sorry about that, i was so excited to find this website, i couldnt say everything, anyway, i want a tourque powerhouse that is super powerful at low-mid rage. but not lacking, and perfectly capable to take on the 6+ rmp spin. well i guess what im building is a drag racing plowtruck, to put it simply. thanks for clearing up the 4 bolt main issue. i dont think i'll ever rev it so high that i blow out the bottom end. i know i will probably never need solid lifters either, but i've had good experiences with them. how often do you have to ajust them anyway?

 

The last time that I adjusted a solid lifter it was in a Mushroom tappet 'Y' block. That was enough for me for a lifetime. Usually you have to adjust them 'hot.' That is the engine must have been run enough to expand all the elements of the valve train before you can set the clearance.

The best way to get an engine that works well at low and high RPM is to improve it's ability to breathe. A four cycle engine is an air pump (stroke 1 and 4) that sandwiches a power generator (stroke 2 and 3). The power generator depends on compression and volume. The air pump controls the volume. The greater the volume of air that gets into the cylinder the more power it makes. It is easy to fill that volume at low RPM, but at higher RPM the time to fill it gets shorter. Therefore to fill the cylinder at high RPM you need more air in less time. Since the air speed is limited to the speed of sound, you can't get it in the cylinder any faster. So you need to get a larger volume of air into the cylinder in that short time. The same is true for stroke 4, the exhaust stroke, only the hot exhaust is being removed from the cylinder. The volume of air that is fed to and removed from the cylinder in a given time is called the head flow.

A cam can help the high RPM power by extending the number of degrees that the valve is open, allowing more time to fill and exhaust the cylinder, but this is at the expense of the low RPM power.

A wide power band can only be met by having excellent head flow and only a moderate cam with as much lift as possible. My motor has a custom 281 degree hydraulic roller with 0.595 lift, and CHI-3V aluminum heads. My heads flow 319 CFM at 0.600 lift. The cam is a little long for maximum low RPM power, but I wanted more power at 6K, and to be able to use 93 Octane with 10.35:1 CR. A better grind for broad power would be a 270/280 dual pattern hydraulic roller.

 

As far as the pistons go you have to take into account what heads you will use. If you stay with the stock heads then you want to get the Badger flat tops. Try tim meyer in a search on hear and he should be aboe to get them for you but I would have the block checked first to see how much overbore it needs to get trued up. Sometimes he can't get all of the over sizes in pistons. Also get the block decked if needed. When I got mine back and had the bottom together I discovered it hadn't been checked and there was a .004 variance.

 

im probably going to call around tomorrow and find out how bad the damage will be. LOL when i got the motor it was partially rebuilt, the kid lost interest, the heads have allready been machined, but im still going to have them checked, and probably ported. the motor was running fine when they pulled it, so im hoping the block is fine. ohh btw, the badger flat tops, are they hypereutectic or cast? or are they available in both? forged is out of my price range but thats not really neccesarry anyway.

 

The two bolt mains in most Ford blocks are at minimum as strong as 4 bolts in a Ch**y. You want 6k+? No problem, 6500 doesn't even tax it. Spend the time and energy tuning in a larger carburetor, 750 cfm min.

 

that was my original plan, go with a 750 cfm holley. but then i found a formula that told you the right size of a carb for the displacement of the motor, and it worked out to something like 675 cfm so i decided on 700. but everybody says that 650 is fine.

 

the 400 likes big carbs, they will breathe better. also depends on carb choice. a 750,800, or 850 d.p. with downleg boosters are very tuner friendly and are not overkill on a moderatly built 400. people dont realize holley's formula is just a basis to start for a street engine and not performance