Going to get a SBC 400 this week that will be going into my 88 formula to replace the 305 thats in there.

Not sure of the year of the motor though, but I believe I get the heads with it.

So, anyone have any tips/advice on what to do to the motor before I put it in and what to look for when I go and pick it up.

I can't wait to get it in since the 305 is so darn slow. Runs a whopping 15.7 @87mph.

 

con-they're getting harder to find
pro-you can tell most guys it's a 305 and they won't know the difference

 

Are the parts the same as a regular sbc chevy like a 350?

I'll probably get some decals for the door that say Formula 400, but I can always say the doors are from another car.

 

Pros:

• 400 CID

Cons:

The heads that come on a 400 are terrible. If it comes to you with the stock heads, usually either 882 or 624 castings, throw them in the trash.

The 400 is the same externally as the 350 except for the "unbalance" of the damper and flywheel; and identical internally, subject to CID-related things like pistons.

All internal parts interchange, like cams, heads, rockers, etc. The only difference is that the heads should have the steam holes added.

Actually, I might have put too many cons in my list up there. Delete a couple of them.

 

2 bolts are preffered in 400s too, I think you might know that but just making sure.

The rest is if your trying to hide cubes....

Some have 3 core plugs, Some have 2. When we were racing we always looked for the 2 core plug 400s so people wouldnt notice it was a 400 as easily.

Im not a fan of external balance. If you buy an aftermarket crank pay a little more and get an internal balance one. Then no one could tell its a 400 block, because youd have a normal balancer/flywheel(and maybe 2 core plugs)

 

theres only 3 "gotchas"


steam holes
balancer
flywheel/flexplate


the steam holes can be made with a hand drill or done by a machine shop cheap.

the balancer and flywheel/flexplate have to be 400 ones... external balance, yadda yadda ya..


watch for overbored motors. alot of 400s have core shifts and that means you cant go past .30 over... but some shift the other way and have thicker walls lol... unless you have a sonic tester, just stick to std bore blocks.



umm, thats about it, everything else is common sence and you're no fool.

 

thanks for the tips.

I am going to call up a few buddies of mine since they are running sbc 400's with MiniRams on them, maybe they have some parts I can get from them.

 

sweetS10, you big cheater! we used to do the same thing

Really though, here's a fast and dirty combination that works well.
Forged dished pistons, shoot for 9.5 to 1 compression.
305 HO heads with 1.94 intake valves (don't forget steam holes)
350/350hp hydraulic cam. & valve springs
This will run all day to 6grand without breaking anything, it's simple, it works and is probably plenty for most street cars.
Are there better ways to do it?, I'm sure there are, this is just one of the many combinations, and it does work well for the street/ occaisional strip car.

 

I would use ANYTHING BUT that! I would throw one of those in the garbage (and have) and throw a quarter in at the same time, and figure I came out about even from not having to wonder any more how I was going to get rid of the cam without making somebody mad.

Catch me sometime when I'm in the right mood, and I'll tell you what I REALLY think about those old factory cams from the days when you couldn't get heads that flowed above 240 CFM or valve springs for over .480" lift without taking out a second mortgage.

The best 400 cam I've had for a street motor was a XE274H. Actually had some lift, aggressive ramps, not alot of wasted time with the valves barely cracked open (unlike GM cams). But at the same time, got 18 mpg on the highway with a Holley 800 CFM carb and 3.73 gears, and out-torqued a big block on the chassis dyno (373 ft-lbs to the rear wheels with the air cleaner on). How can you argue with that?

Think BIG. A 400 is alot of inches; as much as some big blocks. A cam or a set of heads that seems like too much for the street on a 350, will be tame on a 400. A cam that has a "choppy" idle in a 350, will sound like a 929 in a 400. 1¾" headers should be the minimum, like a big block.

People will tell you all about "torque monsters". That is bull droppings. The only "torque monsters" are CUBIC INCHES. Cylinder pressure times piston area times stroke times the number of cylinders = torque! Nothing else matters. And if you're paying atention, you'll notice that piston area times stroke times the number of cylinders, is the formula for CUBIC INCHES. The hot gas does not wake up and look around itself and gauge the cast-iron owner's fondness for that particular brand or vintage of cast iron, and produce energy accordingly; that whole idea, that a Brand P or Brand B or Brand M motor is a "torque monster", simply because of its brand, is ludicrous. Those of us who know better will build our small blocks and laugh all the way to the bank. The only way to beat cubic inches (apart from nitrous or a blower, both ways of increasing cyl pressure) is with MORE cubic inches.

Don't use small valves, small exhaust, small cams, small head ports, small intakes, or small carbs, in the name of "torque". It doesn't work that way. All that happens is, you move the RPM at which the torque peak (max cyl fill, which in turn produces max cyl pressure) DOWN in the RPM range, thereby slowing the car down.

A MiniRam is a great idea. So is a solid roller. Hmmmmm...............

 

I've got a set of stock LT1 Aluminum heads in the garage and I can aquire an LT1 intake. Should I put those heads and intake on the 400?

 

I think if you search about the LT1 head conversion youll find its a lot of work. I would sell those and search other avenues.

 

Oh RB left out these :hail: AFRs

You wone belive the difference they make. I sold my S-10 with 195s and I will have them again.....

 

I'm running a 400 in my 86 TA. My biggest fear was tearing up drivetrain parts because of the torque from the 400.

I happened to be sitting on a virgin 400 2 bolt block and started building it after one of my rods let go in my 383.

The block is bored .020. The machine shop said that the walls are thin and they don't recommend boring over .030. Watch out for cracks around the mains with any of the 4 bolt blocks.

I did not drill steam holes. Brodix does not recommend them with their heads.

I am running a Comp solid roller with a MiniRam. Don't have 1/4 mile numbers yet but it does feel stronger than the 383/AFR combo I had.

Downside to the 400 - violent wheel spin from a 20 roll resulting in premature tire wear.

Advice - Go for it!

www.geocities.com/dzperf

 

:rockon:

 

you really dont need the steam holes in the 400 heads ive been told it will only run a little bit hotter

 

What the steam heads actually do, is to allow any steam that develops from heating between the cyls, to percolate upward through the system, and to condense (turn back to liquid) rather than collecting in pockets right below the deck, where they can't flow out easily.

Steam makes an excellent heat insulator, rather than a conductor of heat, like coolant is supposed to be. So if it accumulates, it creates some potentially VERY hot spots in the cyl walls and deck, whcih warps them, which doesn't promote good head gasket or ring performance or lifetime.

It's really only a problem in street-driven motors, where they have to idle or otherwise run at less than 3000 RPMs or so alot. In something like a sprint car motor, or even a strip-only straight track motor, I don't bother with them. But in a street motor, they don't hurt anything, and can help prevent catastrophe, so they're cheap insurance.

 

Whoa, don't 305 heads on a 400 engine give you something like 11:1 or 12:1 compression? I knew a guy that tried this, but his engine was never in good shape to begin with, and he had some monster cam in it, so I don't know how it would've held up in the long run regardless of the heads.

 

305 heads, lol.... I wouldnt put #416s on a 400 unless I ran out of money and jsut wanted to get it running.

Probably have like 150cc intake runners.

People use compression as a crutch. Heads are the most important thing in power potenital of any motor. You have good heads, you make good power almost always......

 

you guys left one detail out, the 400 block has 2.65 " main journal crank vs 2.45 in all other small blocks.

if you have a restricted budget go with the scoggin-dickey style vortec heads, they have made over 500/500 ftlb hp in several buildups. i would also recommend a solid roller over a hydraulic roller or flat tappet if its in the budget. With a good head on a 400 its hard to not make good power but in a thirdgen you will have to put some planning into the exhaust, as cid goes up so does exhaust flow.

 

Now why would you do that? Some nice GM 305 valve cover stickers on top the VC's would look much nicer.



So RB do you think that combo would handle well with forced induction? The twins seem to be putting out a tad more flow then the 350 needs and a nice 400 builder just happend to float my way today.

 

Putting 416 casting heads on a 400 was quite common in the dirt track sector. Port them out and stick em on, and get plenty of power!!

I've heard of combos like the one Blacksheep referred to above.

 

I believe the oil pump driveshaft is necked down on a 400 as well.

 

Our racing team actually did the #416s on a 400, with a lot of time into them. I was jsut trying to keep his parts matched fairly well.

400 w/ Vortecs http://www.chevyhiperformance.com/te.../148_0306_406/

Same 400 with AFR 180s http://www.chevyhiperformance.com/te...imp/index.html

 

i vaugly recall that too.

my ARP pump drive is necked down, but i dont recall if it had to be or not..... i bought it years ago.



if you can get someone to tig over the coolent holes cheap, gofor it.
having seen some of the other projects you tackled, it shouldnt be a big deal for you.. just take your time fitting the alum blockoffs, and then have someone weld them on.

you'll still need to mod the intake for the distrib, but it will bolt up.. then you just use the tapped holes in the head for your coolent outlets.

 

So RB83L69 tell me what you really think of the old 350/350 cam..don't hold back
That combination I talked about works great and won't break the bank. I left the door open for other opinions. I do suppose someone may have come up with a better cam in the last 25 years, but sometimes I wonder if we're just rehashing old technology.
Speaking of old cams, has anyone out there ever run a first design off road Z cam?

 

Some time, I might do that. Until then you'll just have to guess.

The 346? Yes, I had that one once, in a .060" over 283 that was pretty much a 302 clone. I had a 2nd design one (754 IIRC), but I sold it; I think that would have been a better cam but I never ran it.

Cam designs have as much to do with the parts that surround them, and the expectations of buyers, as they do with just purely what works the best. The explosion of CNC cast heads and better valve springs and chassis dynos on every corner, has taken alot of the "Well my brother's Stage 3 cam will whip your brother's ¾ race cam" out of circulation. A change I'm glad to see.

 

Those are great articles.
I am building this as a really cheap upgrade for the 305. I just want to slap something in there that will liven it up a bit for relatively low cost. I don't want to pour too much money into it since my 86 Trans Am is my main project.

 

stock 400(406) shortblock with upgraded rod bolts
vortec heads
vortec carb intake
carb

or if you're sticking to efi:
same stock 400(406) shortblock with upgraded rod bolts
dart iron eagles
whatever EFI manifold you have.



that is of course if you decide to not go the LT1 topend route... somthing i would consider if i had access to the needed tools.

 

My friends dad owns a machine shop so getting some of the LT1 mods done is no problem, I just need to let him know exactly what needs to be done. He can also mod the LT1 intake as well.
I'll know more when I get the motor Friday since I haven't seen it yet,
Will just measuring the bore tell me if it's a 400 or not?

 

Yes. It'll tell you if it's a 400 bore (4.125" or more depending on if it's been bored out).

To find displacement you'll need to measure the stroke as well.

Or you can just get the casting numbers off both the block and the crankshaft and go to www.mortec.com and find out that way.

 

the bore or the casting numbers is the only way to be sure its a 400 block.

stock is 4.125 stock crank stroke is 3.75




in your case, id mod the LT1 heads, put the hole in the intake, and run it that way.

since hes welding on the heads, see if you can get him to weld a block onto the intake, and tap that for the distrib hold down bolt.

ive heard 2 storys now about people having the bolt threads pull out on them, causing the oil pump not to drive......

 

cool, thanks.
I don't want the oil pump to stop spinning/

 

i was just thinking about this....

if you swap to LT1 heads, im pretty sure the accessory bolt holes are diffrent...

so you'll need to figure out their mounting before you begin.
ive never messed with accessorys on a LT1, so i have no idea what you're working with... but somthing shouldnt be to hard to fab up.

 

I give........