Okay, long story short. Pulled my stock 305 tpi and found a cheap 400 block to build. Just need some help picking out parts. It's my first engine, don't know everything needed to put together an engine but I'd like to try it to learn. I've heard about 6" rods and matching pistons, bushed and pressed wrist pins, hydraulic lifters etc etc.
What CAN I put together? I've heard 6" rods are better because they keep the piston up longer or something? Can anyone point me to a moderately priced combo for a .030 over 400? What's the benefit of forged pistons, dished, domed, etc?

I just want a few products/prices and optimal power choices to get the ball rolling so I can get my bird back on the road.

 

Hang on..stop!! The 400 will have plenty of power, if you want you can put the 305 L69 heads on the 400 block and it will bump up the compression. (lots of roundy round guys do this for bottom end power, it's cheap, it works) The big thing you will find is that the 400 is externally balanced, so you will need the correct flywheel and balancer. If the 400 is in good shape, I would just rebuild it with a mild cam and go with it. If you go too hog wild, it'll be part break city on the driveline.

 

Here's the setup I'm going with...

400 Block bored .030" over, 0 decked
Eagle Cast Steel 400 Crank
Eagle 5140 Forged Lightweight SIR 5.7" Bushed rods
Keith Black 22cc Dished hyper. pistons w/ floating pins
~9.8:1 CR w/ 64cc combustion chamber
Dart Iron Eagle 180cc heads (2.02/1.60 valves, single coil springs)
Comp Cams XE274 Cam
Edelbrock Performer RPM Intake Manifold
Holley 4150 DP 750cfm carb
Fluidamper 8" Ext. Bal. Damper

This setup should do about 450hp and 530tq. I'm going with the floating pistons because I can put them on the rods myself and I don't have to pay the machine shop like $6/rod to put them on. I went with dished pistons to lower the CR with the small chamber on my heads. There's no real need on expensive forged parts in a motor like this since it won't see over 5500 rpm. I would reccomend the 5.7" rods though insted of the stock 5.565" rods. With longer rods piston speed goes down which allows more rpm. The only reason to go with 6" rods would be if you're racing it and spin the motor up past 6k. With the longer rods you will have to clearance them for the cam unless you get a small base circle cam. The cam is a flat tappet hydraulic cam. There's no reason to use solid cams since you won't be spinning the motor very high. This motor will be fun with all the low end tq and will beat most cars that come up to you on the street.

 

I understand and agree with everything but this part. I thought that pistons speed would remain unchanged unless you were to change the stroke of the crank. If the 400 has a 3.76" (?) stroke at 1000 rpm, the piston travels 1000 x 3.76" = 3760"/min. Wouldnt that be the same with a shorter rod?

Also, using longer rods would enable you to get a higher CR without increasing the compression height of the pistons, leading to less friction in the cylinder bore.

Lastly, I always thought that using longer rods was bad for high revving motors, because they put more stress on the piston/crank. Please correct me if I am wrong. Just my $ .02.


--Dave

 

What about using flat tops with 68cc or 74cc with 200cc runners or something?

Also is there something wrong with revving the engine high as long as it's built to?

Blacksheep, I've got some lb9 heads from my stock 305 but I don't know I want to run that restrictive of a head? at least I thought they were pretty restrictive?

 

Well, it kind of depends on what you're trying to do. The 400 was never a real revver anyway, it was always known for torque. For this reason a lot of them showed up on stock cars that raced on short tracks with limited rules. These guys had to use a lot of stock parts and that combination of a 400 block with the 305 HO heads worked surprisingly well. It was just a combination that really clicked. These guys also had to run hydraulic cams most of the time and they used either a custom profile or the old 350hp 350 hydraulic. If you want to build a killer motor, then sure go ahead, but you may want to consider the driveline in this, those t5's weren't much and neither were the rearends. I think the auto would work ok. So if you want to build the killer 400, then step up to the Richmond 5speed and a 9 inch, that would work, but I guess that I'm getting too old to work on my stuff all of the time. I almost had my hands on a 400 just like you described but it got away from me at the last minute.

 

use your 305 heads on a 400 your gonna have to drill our the steam hole if not youll run hotter than normal

 

Yes in some cases, thanks, it's been awhile.

 

Well, I had to do some research to figure out which is correct. You are correct that the average pistons speeds will remain the same. However on long rod motors the piston speed approaching TDC is slower than a short rod and the long rod will have faster piston speed at BDC than the short rod.

The compression height would have no difference in the friction on the cylinder bore. Thinner rings would though. As for long rods giving a higher CR, that won't work since the pistons would be sticking out of the block with the longer rod. With the longer rods you would need a piston with a lower compression height so that it would fit below the deck of the block.

You are correct that long rods put more stress on the crank, but it reduces stress on the pistons. With a short rod the rod angle is greater causing higer sideloading on the pistons as compared to a long rod. This puts the stress on the rod and crank itself which can take more stress than the piston. It allows the motor to rev higher w/o the chance of scuffing the piston skirts and cyliner bores due to the higher sideloading.

Hopefully that sets everything straight, but I might have some incorrect information in there since it's about 2 in the morning and my thinking is pretty clouded.

 

You can use flat-tops with 74cc chambers (68cc chambers would yield CR too high unless you are using aluminum heads). I'm only using dished pistons because I got a great deal on the heads used. If I had bought them new I would have gotten the bigger intake runner (better for a big inch motor) and gotten the bigger chambers so I could run a flat-top.

As long as an engine is built right there's nothing wrong with revving it high. The engine I stated would probably redline at 6k, but if you went with all forged parts you could hit 6.5-7k without too much worry.

The LB9 heads aren't terrible, but I personally wouldn't use them on a 400. First off they have a 58cc chamber which would require the use of a big dish piston, and even with that the CR would still be fairly high. With a good port and polish they can flow about the same as stock Vortecs. You will also have to install bigger springs in them to handle the extra lift which will require machining down the valve spring pockets. If you plan on seeing any higher rpm (above 5k) you should install screw in studs and guideplates also.

No matter what heads you get make sure you drill steamholes or you WILL have cooling problems.

 

Thanks for the heads up on the steam holes I heard something about that before but forgot and just went out to look over a mismatched set of 400 heads I've got and checked over the holes and such.

I think there's a set of 74cc chamber, 210cc runner heads on ebay right now for decent price. I could theoretically use these with a 6" rod/piston (bushed and full float?) combo and forged flat tops to get some power out with also being able to rev the engine?

I've got the ****ty slushbox 700r in the car now but I'm also converting to a t56 at the same time (with the realization I need a custom flywheel and clutch) so the tranny hopefully will hold up for awhile. The rear...stock 3.2X 9bolt. Besides, I just have some crappy 255's with no ability to hook so I have a feel there won't be enough to break driveline parts yet.

 

Go with a light wheel, it will kill you with the 2.5, but you'll like it later when you step up to the 3.5 -4.1 rearend gear.

 

find a flywheel for a 400 your a lucky man thats a hard find a 350 flywheel wont work cause the 400 is externally balanced you might be able to get one from a 70-72 chev pickup but make sure its for a 400 or your motor wont balance out

 

200cc heads would be about the biggest id run on a street driven 400..

 

210cc runners would be a tad much unless you're running a bigger cam (230+ degrees duration). I would try to stay under 200 for the street with a mild cam. I wouldn't use 6" rods in it. It will be cheaper for you to use the 5.7" rods. Pistons for 6" rods and more exspensive than pistons for a 5.7" rod. Besides you would have additional clearancing on the 6" rod for cam clearance. As far as using floating pins you'll need bushed rods and pistons with pin retainers for floating pins (aka spiro-loks). If you want to rev the motor high I would look at a set of H-beam rods since they see most of the stress and I might look into a 5140 forged crank (not as exspensive as a 4140/4340, but strong enough for what you're going to use it for).


The Borg Warner 9 bolts are stonger than their 10 bolt counterparts. As long as you have street tires (no drag radials or slicks) you won't be able to hook, and hooking is what breaks parts. I would look into 3.42 or 3.73 (or equiv. in a 9 bolt) gears though. The 700R4 should last a little while as long as you don't abuse it.

Just find a 2 pc. rear main seal 305 flywhell and have it unbalanced by a machine shop. You will also have to have an extra hole drilled and tapped into the block for the starter to fit.

 

With forged flat tops(full float), 5.7" rods , 72cc chamber 200cc runner heads; what kind of cam could I successfully run with? (it'll be fed by a slighty beefed up tpi (larger runners, injectors, and maybe manifold) along with some 1 3/4 headers. Any suggestions?

Thanks ALOT guys for the info so far. Helps a novice out tremendously.

EDIT: I've got an 85 305 flywheel, which to my knowledge is 2 pc. Along with my stock 87 305 flywheel. Both autos. I've heard lots of conflicting opinions, would that would with the stock clutch assembly?

 

Got it.

 

With a TPI motor I would run a smaller cam than an XE274. You might look into Comp Cams Magnum 270H (224 dur. .470 lift). I'm not an expert on TPI cams so that's just a guess.

Are you talking about flywheels or flexplates? Flexplates are used on automatics and flywheels on manuals. You have me confused.

 

we are talking about a flywheel for a stick on the 400 thats one of the balance points so it has to be a 400 flywheel or you will run into problems you better call around to a few machine shops that specialize in engine builds and see what they can do cause i originally wanted to go to a 5 spd for my Z but no one had a flywheel that would work

 

First of all, I would have to fully disagree with the statement that 200cc intake runner heads are too big for the street...

Remember that you make your power with your heads...the camshaft helps determine powerband RPM range...and on a 400, there is a lot of low end torque that I don't mind getting rid of (under 2200 rpm)...but the cam limits the airflow enough that I will be fine...it depends on what you want.

Lastly, I only wanted to buy one set of heads for a LONG time and decided to go with my 220cc heads...granted I am biased here (see my sig) but for ***'s sake, don't put the 305 heads on your 400...they are more restrictive than the stock 400 heads, which suck.

 

I hadn't ever planned on 305 heads, I was thinking about some Dart aluminum heads now. 200cc runners, with 72cc chambers. I think that'd be someting like 9.9 or 10.2 to 1 cr with the forged flat-tops. Any other opinions on a cam that'll make some power? I'm not afraid to lose some low end or drivability to gain some more power up top or in the middle.

EDIT: Centerforce makes a 153 tooth counter-balanced flywheel for a chev 400. Would that work for a t56?

 

I think it depends on how high you want to rev your 406...the 274 is a pretty good cam for a 6000 rpm redline (even 5800)...and what the heads are capable of...

I think that a 406 doesn't need to be revved...the example I can remember is the xe274 cam, 1 5/8" headers, 750 holley, trick flow 195 heads and 450 HP, 500 lb/ft of torque...with an HEI ignition...

 

You can use a stock flywheel from a 2 pc. rear main seal 305 with a T5 tranny. All you have to do is have a machine shop "unbalance" it.

 

I wasn't suggesting that he use the 305 heads on a maxxed out 400, What I gave him was a combination that would make good power at a lower budget. That combination works real well in the context of the rules they were working under and also for the price. Is there another way to go?, absolutely, if he has the bucks then go for it.

 

No.

What you need to do is:
*Get a 400 flex plate (from anywhere) for a template
*get an LT1 flywheel,
*take both to a machine shop
*have them balance the LT1 flywheel to match the template sbc 400 flex plate. At the same time, have them re-drill the flywheel bolt pattern to match the 400 flex plate
*bore out the inner diameter of the flywheel flange, since the LT1 has a smaller flange and bolt pattern than your older 400.

I did this same process before on a 305 and it worked great. The LT1 comes externally balanced, so in that case, the machine shop had to neutral balance the LT1 flywheel AND drill the holes and bore the center for the older two piece rear main seal 305. Like I said though, it all worked fine.

 

Are there ways around buying both flywheels? I don't want to have to pay ****loads for both...Since the block is at the machine shop now can I bring them the LT1 flywheel and just have them use the crank as a pattern to match?

 

You can probably get all the machine work of the bolt pattern/flange done using the crank as a template, but you still need another 400 spec flywheel/flexplate to get the balance right. A busy machine shop might have a 400 flexplate laying around that they would use for you. If not, you should be able to get one used for about 5-10 bux that you can use and then throw away. They aren't anything special.

The other thing you could do is machine the flywheel for a neutral balance, and then buy one of those bolt on counterweight thins from Summit racing just for neutral flywheels on sbc 400's. It sandwiches between the flywheel and the crank, and balances the assy. HOWEVER, I used one once and could feel some slight vibration at ~1200 RPM AND, it cost around $30.00 IIRC, for which price, you could get several used sbc 400 flex plates to use as balancing templates.

 

Thanks, I'll just go pick up a 400 flexplate tomorrow then.