my granpas diamond reo dropped a shaft, it was in a few inches of frozen water. my dad says that it dropped it on the ground like it was nothing.(before my time)

 

I have a mild built 400 with 351c heads on it with 351c intake 351c pistons aprox 500 horse with not much spent you need to buy the adapter plates to make it work and it really opens up the motor depending on what your motor can turn depends on which chamber (open or closed) depending on the rules because my buddy does the pulls and they are some rules like how many cubes you can run and what heads you can and cant use find out the rules becuase major mods might jump you up to a different class

if interested the web site for the plates are http://www.flatlanderracing.com/

 

[QUOTE=buttnuttn8]I have a mild built 400 with 351c heads on it with 351c intake 351c pistons aprox 500 horse with not much spent you need to buy the adapter plates to make it work and it really opens up the motor depending on what your motor can turn depends on which chamber (open or closed) depending on the rules because my buddy does the pulls and they are some rules like how many cubes you can run and what heads you can and cant use find out the rules becuase major mods might jump you up to a different class




What heads are you running 4v or 2v? I am just trying to findout what heads would be best for my motor to make more torque.

 

4v heads have to big of valves to make any torque down low. The best combo for torque is a set of ported 2V heads (what you have now) with flat top pistons.

 

I disagree, I think the 4v heads would be fine on a 400. They only lack torque on small displacement 302s. I had a 351c 4v in my circle track race truck and it moved, didnt lack anything, i switched to a 351w and i think the 4v cleveland pulled harder. the 4v clevelands make 20-30 more lbs of torque than the 2vs its just at 800rpms higher.

 

the problem with torque on the 302 was that they were not big enough to breath through those heads till they got up in the rpm range, thats why alot of people say that the boss 351 was better. it had the displacement to breath right. the biger 4v heads would probably work excellent on a 400,especially with the smaller combustion chambers.

 

I've only messed with one 400M and it was years ago but I was very impressed, My girlfriend bought a 78' F150 longbed 4x4 with no engine, then her perents bought her a Kregan shortblock, so the bottom end was completely stock, had a set of stock 400M heads cleaned up (little portwork) stock valves and heavier valve springs (cant remember what they were) then installed a crane 272 cam & pedistal mount roller conversion for the stock rockers, the truck came with an edelbrock performer intake and 600 cfm carb, so we installed them along with a set of headman fenderwell headers, after lifting and painting the truck she ran 36" tsl swampers & 3.50:1 gears and had no problem smoking the tires, also while driving back and forth to school, ( aprox. 120 mi) every weekend she was getting 14-15 mpg, Just goes to show the potential thes engines have, they are way under rated I think,

 

For torque you need port velocity and flow. If you run 4bbl heads you might lose what you've got below 2500 rpm. Above that they should be similar till around 4500 then the 4bbl heads will come on hard.

Port the 2bbl heads, install the 4bbl valves. Make sure you clean up the exhaust and take out the smog bump. Leave the floor of the exhaust alone. It already flows backwards at low lift. Lowering it more will only hurt. You need more cam. Try the comp extreme cams around 265 deg duration or better. Desktop dyno will tell you a lot more than my rusty memory. Fenderwell headers are o.k. but you can have clearance problems with 4x4 with big tires. Summit sells a set for your truck for around $100. The performer intake is good till around 4500-5000 then it runs out of capacity. Adding a 1-2" spacer and a 750 carb will help the top-end out if you need more. Adding a set of quench type heads will net you around 1.5 points of compression and build a lot more low-end torque, but then you will have to have premium gas or it may knock too much. Launching around 4000 will work, but you can't dump the clutch, you have to pre-load the drivetrain and slip it out of the hole if that's what you have to do to get a good launch. If you do this, I would highly recommend adding a 1/4" steel enclosure for the bellhousing. If nothing else, cut it to fit inside the cab under the carpet to protect you if the clutch explodes. Pulling is very hard on parts and an exploding clutch or flywheel can literally cut your leg off.
Good luck and post back. If you live around Vegas I have a set of 351C 2bbl heads that I don't need anymore. One is ported, the other is stock. You can use the ported one as a template and do it yourself.

 

Good luck and post back. If you live around Vegas I have a set of 351C 2bbl heads that I don't need anymore. One is ported, the other is stock. You can use the ported one as a template and do it yourself.[/QUOTE]



Are the 2v cleveland heads better than the stock 400 2v heads?

 

They are the same head as well as the 351M head as well.

Yeah the 400's have good power in stock form as well, and i can smoke my 35x16" boggers no problems and that is with a 3.50 gearwith a very well working limited slip as well. But if one does use the 4V heads i would be a goof idea to use a set of gears slower than 4.10's, a set in the 4.50 to 4.88 range would be great and they would give you the benefit of the higher powerband of the 4v heads.

Yes the 4V heads will make more torque, but that 800rpm difference can make the difference between a full pull and a mid pack finish, that is unless you re gear to make up for that powerband difference. The best head if you use a 4V will be the quench head cause it will give you more compression so you can take advantage of the bigger valves, but the open camber heads are ideal for forced induction.

 

i pull with a 73 highboy it has a stock 390 in it down to the cast iron 4v intake.i use 33" tires i have 4.10 gears. if your truck is lifted i would suggest taking the lift off.i have seen a lot of lifted trucks try to pull and all they do is hop down the track.

 

Last that I knew, if you used 4V heads on a 400, the intake ports would be too large for ANY 400 intake to seal. There might be adapter plates to put a 351c 4V intake onto the 400.

 

perhaps it would take an aftermarket intake???

 

There is the edlebrock performer, and there's also a weiand 4barrel intakes for the 400/351M. The intakes ports aren't to large to seal, the higher deck hieght of the 400 needs a wider intake manifold to fit the wider gap. And yes you can buy spacers and this will allow you to run any 351 cleveland intake manifold.

 

Book I have says aftermarket 400 intakes wont seal up the 4V ports- even shows pictures of an intake that has extra material welded to it and machined flat to seal port.