Hi,

I read one of the articles about the High Performance Options for the 351M/400 Engine. My question is on the pistons. I have the stock pistons in my 351M and am planning on putting in the Comp Cams K32-221-3 High Energy Kit.

The article talks about flat top pistons. My pistons are the dish pistons. If I rebuild my engine for higher compression, should I change my pistons to a set of flat top pistons with a high CR or should I use my stock pistons?

Here is a link to my stock pistons.

https://picasaweb.google.com/cdawley...79938443160194

Thanks,

Chris

 

Get tim piston to get better than stock lower comp about 8:1 for the better one from tim meyer to have 9.3:1.TMeyer, Inc. Precision Automotive Machining He's the men to talk for 400. Get a 400 crank with piston to convert 351m to 400, the only difference between a 351m and 400 are the crank and pistons.

 

X2 mustang. Tim is THE guru for the 351M/400. On its own the 351M is an OK engine, BUT do some simple mods ( crank, piston timing chain & gears 4BBL intake and 600 CFM carb) you're rebuilding anyway, and volla you to can have a torque monster. Talk to Tim, tell him what you want to do and let him advise you on the parts.

 

You need to decide what you want out of your motor and just how much you intend to use it. These gas prices are going to the moon with no end in sight. Exxon's greed is really going to show in the near future, and if you need to use the motor in the vehicle a lot then I would get the 400 crank for the extra cubes and maybe leave the comp ratio down so you can run the low grades of gas.

 

If just doing a simple rebuild nothing tricky? what is you piston deck height with your engine now. Need to know these things. If the only thing you do is bump up compression and run your comp cam and good timing chain you will notice a big difference in your power/torque. These motors are easy to make power compared to factory hrspwr numbers. 9 to 1 compression would be a big help compared to factory.

 

IIRC there are no higher compression pistons available for the 351m. That is why people change them to 400s, for which the flat top pistons are readily available.

More cam with low compression isn't going to work very well.

 

run a cleveland piston and have your rods small end bushed down to fit the cleveland piston pin which is smaller than a 351m/400. Not a difficult process but a extra expense. this little keithblack flat top will get you into the mid 9's in compression alone with open chambered heads and a factory .041 head gskt. If your around .040 down in hole with piston. will need to balance the rotating assembly after doing this but would reccomend this anyways with this older Iron. Believe their is a dome piston available also if wanting more compression. So yes their are options available for the 351 M. I doing a 400 ford with cleveland pistons flat top one valverelief and about .033 deck height and will be at 10 to 1 compression now this is where my cam comes into play on changing compression. Look at 400 4v wyoming site her in 351/400 and more info. catch you later!!

 

Since this post, I have went back and re-read the article on projectbronco and noticed that it said that if using pistons with a higher CR, a 400 crank must be used. I guess I read over that part too quick and it didn't register at the time.

So far, in order for me to convert it to a 400, I would need to obtain a crank, pistons, and harmonic balancer. I guess it wouldn't hurt to replace the crank bearings either.

Since I am on the subject of replacing bearings, would it be beneficial to replace them, since the engine has about 78K original miles on it?

Also, is there a kit I can buy that will come with the crank, pistons, and bearings?

I am also going to send an email to Tim Meyer to see if he has any kits with a 400 crank.

 

Always replace the bearings when you're into it this far.

 

Good advice about complete bearing replacement.Also consider cam bearing replacement as these engines produce a lot of wear in that area.Oil pumps are also easily replaced and are not expensive.Sounds like a good build you will have going,and well worth the time and effort.You will be pleased with a good 400.

 

If you go the 400 direction you will have a stout 400. won't go wrong with tims guidance. Several good ford guys out their and tim is one of them. would reccomend a 400 just because of the easy torque to be gained. Sometimes you spend money and only gain minimal results and this upgrade you will really notice the difference. crank piston and dampner are the only difference between the 351m and 400 pretty much. Your 600cfm carb might be a little on the small side but will work.

 

Even the dampener will serve for a breathed on application to a point.There are plenty of stock replacements out there.If the old dampener doesn't show signs of the rings slipping on one another,nor the center seal between the rings bulging or deteriorating,use it.There are timing or match marks on each ring to show alignments.If you can watch it run on an engine or on a lathe watch it for wobble.600 cfm should be a good carb match for a reasonable engine.You won't have the altitude problems that some of the rest of us face.Air is a premium for induction,cooling,etc. here!Let us know about your progress.

 

Does anyone know where I can get a good quality crankshaft pretty cheap around the McDonough, GA area? I thought about going to Pull-A-Part and pulling a crankshaft and harmonic balancer.

A couple of things that concern me about salvage yards, is I wouldn't know what kind of condition the crank is in until I pull it out. My other concern is pretty much time. Say for instance, I go to the salvage yard, find a 400 engine and balancer. Is it worth the 2-3 hours of work to hassle with trying to get it?

Would it be better for me to buy a new one from Summit Racing, Jegs, or Rock Auto? I found one a couple days back on Ebay for like $65 with 40 shipping, so around $100 total for a factory crank that stated it was already magnafluxed.

What are some of your opinions?

 

IMHO an already-magnafluxed crank delivered to my door for $100 is pretty decent!

Think of the pain & agony & grief & dirt & mess & contorting of your body to extract a
crankshaft from a junkyard in the most convenient & optimal conditions (drips of
sarcasm) possible.

Granted, I'd prolly still want to have a pro machinist check it out, but you'd need to do
that regardless unless you purchase one from a reputable machine shop/engine builder.