Thread: Is a sbc 400 worth time or a waste

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Hello All I'm new to the forum and wanted to throw out a question that some of you engine building experts can help with;

Goal: In the future I want to build a HOT purely fun to drive motor which puts out >400hp as a fun muscle car only not daily driver, (something to beat rice burners in the city)

Parts I have currently; Stock rotating assembly crank, rods and (slightly larger) pistons oiled in a plastic bag with maybe 15K miles before disassembly.

The Block is a ~1976 400 w/ 2 bolt mains, bare, untouched since last machine work still bagged and coated in oil kept in attic. The machining was .40 over, taper/Cross-honed (??? Machine shop ran by friend recommended it ???) and he matched it with some flat-top hypereutectic pistons and rings unmounted still in the box. (I still have receipts)

Background: 10 years ago I spent a bundle on building up a 76 chevy with a 400 small block but when I decided to sell the truck I pulled the motor since it was what I sunk my money into and replaced it with a stock 350 so I wouldn't loose what I spent on the motor when I sold the truck. I have since needed money and have sold the double hump heads, intake, carb, and all the other accessories off of it. Then did the machine work a few years ago with hopes to start building again but that fell through

Again, From the engine block and pistons I have is it strong enough for what I want or should I sell it for what I can get for it and anything else and start fresh when needed? I was thinking I would mount pistons on 6” rods on forged crank, with some High performance heads.

I know I haven’t been clear but …Is my block worth anything, is it worth me sinking money into, or is it worth only a core! I’m concerned b/c its not a 4 bolt main.

Thanks for your time…I’ll work on the lengths of my post in the future!

JT

I don't think there was a 400 4 bolt. Not sure, but I just don't think there was. if it were mine I'd build it.

There was a 400 4-bolt block, but it proved to be weaker than the 2-bolt block in the main bearing web area. Not enough material to prevent the crank saddles from pulling out of the block at high hp levels.

This will make an excellent platform to build a rice killer if your intention is to build a small block motor. If you need money right now, sell it. If not, hold onto it and build it later. You don't necessarily need a forged crank either, depending on the rpm limit and the cam you use. See combo #15 here. Although it's a 383, the same parts would apply to a 400, it's the same stroke....
http://www.ryanscarpage.50megs.com/combos2.html

Raisedinal,
There is nothing wrong with a two bolt main block. They were used for years and years. Techinspector1 is right about the crank. Cast cranks will work just fine, unless you plan to turn in the 8- 10,000 RPM range. Then in that case the 400 would not be a good choice anyway because of the short rod. If you replace the heads, make sure that you drill (or have it done) the steam holes in the heads to match the block.
Ed

You mentioned the short rods...The stock is 5.7" right...would the 6" rods make a difference. For some reason I think that was the plan.

My friend the machine man has since died so he used to be my guide on ideas and recommendation when I was into this stuff. I am glad to get a helpful resource like this. Keep the suggestions coming I really appreciate it!

JT

Stock 400 rods are 5.565". If you can come across 6" rods at a reasonable price, use 'em, but if you already have the pistons and short rods all matched to the motor, use 'em. You won't be able to use the pistons you have if you change to a longer rod.

[QUOTE]Originally posted by raisedinal
[B]Hello All I'm new to the forum and wanted to throw out a question

…Is my block worth anything, is it worth me sinking money into ?

Welcome to CHR. and to answer your question------ABSOLUTELY!

You have 408 cubic inches there. 400s make tons of torque and the seat of the pants feel is like no other smallblock. They do like a good set of heads,so I wouldn't go spening too much on an old set of double humbs. Something like a set of Iron eagles might be a good choice . A short rod 400 does not need a lot of gear like a 327 or a 350 would need and with the short rod you will want to make all your power at 5800rpm or less. You could go to the 5.7 or 6 inch rods and matching pistons but you might just as well use what you have.400 horsepower iswithin reason and it will not cost you a fortune. Can You tell? I like the 400s and have been more than pleased with the ones I have built in the past.
You will be able to find lots of help from many knowledgable CHR members.

I recently had a 400 assembled
it is .030 over bore with the 6" rods it makes gobbs of power
i rev mine about 6000 rpm for now but its gonna get the 7000 rpm rev chip in it 400's are easy power. JMO.

...i have a 415 small block sitting in my garage that put out 448 HP @5250 & 499 Ft Lbs @ 4000 {flywheel dyno}. Its bored .060 over, cast crank, stock rods, TRW forged pistions {#L2467}, AFR 195 heads with 2.05 intakes & 1.625 exhausts, 76 cc heads, Crane cam {224/234 @ .050"}, lift is around .520 with 1:6 roller rockers, Edelbrock Performer RPM manafold with a 850 double pumper..... It was a really great torque motor! Was??? well, it sat for 9 years and rusted. Now I'm up in the air about what to do about it. I want to supercharge it but after asking on the board and now after pulling the heads I see that the distance between the cylinders is only about .1875" and thats not enough for a supercharger. I wish now that I didn't bore it so far or at all!!!}. Anyway, NO problem at all with over 400 HP...... {oh, my engine could have handled a bigger cam. Would have put out A LOT my HP with one.......

Thanks...sounds like the block is a keeper.

Also in looking at the combo links ya'll provided that 400HP is very conservative. Maybe I needed to raise the bar for a purely fun motor that I don't have to worry about fuel mileage.

The new pistons are still in their retail box unmounted and the rings in theirs with receipt so I may be able to sell them with no worries. Then I'll just use the block as a blank slate to start fresh (if what I have isn't productive to my goals) The last time I fooled with it I was thinking High compression daily driver. My goals are changing with fuel prices.

I really enjoyed the links ya'll passed on...are there any other resouces you an recommend for a rusty fellow wanting to get involved with engine building (and doing it right the first time) Thanks.

<billlsbird> Supercharging (or turbocharging) sounds like fun! That means easy horsepower but you have to have lower compression right? What are the normal weak points that prevent a motor from supercharging with medium compression?

Excellent all, I'm getting real excited!

Thanks
JT

What is wrong with the pistons that you have? Save money and use them. Find you a nice set of heads, drill them for steam holes and take off.
Ed

I guess nothing is wrong with the unused flat-top Hypereutectic pistons I currently have... I just need to read up on pros and cons of different subjects like Rod lengths, compression ratios, RPM ranges, etc. Any recommendaions on resources?

A question on terminology; My old advisor had a 350 that preformed well by the seat-of-your-pants dyno, and he always talked that he liked to build a "tight" motor and explained it as when throttled it was crisp and was quick to return to idle. It didn't take 2-3 sec for it to rev back down to idle like stock motors do. Is a "Tight" motor actually mean anything performance wise. or is that just motor building talk. I don't think he was talking about throttle response but the time it took to return to idle. What did he mean, how do you get it, and what do you get out of having a "Tight" built motor?

Sorry More "wet behind the ears" questions.
JT

The speed of acceleration and deceleration of a motor is determined by the static compression ratio and weight of the reciprocating assembly (crank, rods, pistons, damper and flexplate/converter(auto trans) or flywheel(stick shift).

Lightweight parts such as flyweight cranks, aluminum or titanium rods, flyweight pistons and such are necessary if you are competing against others who have these parts and there is money involved, such as in the professional ranks of motor racing, but would be an unnecessary expense in a street or street/strip motor.

There are guys who run aluminum rods on the street, but you must inspect them often for signs of failure. They don't have the fatigue resistance of a steel rod. I have heard from several sources that Bill Miller makes an aluminum rod that will survive on the street, but I have no first-hand experience with them.

Hope this helps.

When you go shopping for heads, consider these from Air Flow Research. 74 cc chambers will give you 10.5:1 c.r. with your flat-tops, zero deck and 0.039" gasket.
AFR 195cc SBC Street Cylinder Head
The Ultimate Bolt-on Emissions Legal Street Weapon
The AFR Emissions Legal (versions from 1969-94 with heat riser, CARB EO #D-250-2), 195cc intake port small block Chevy cylinder heads are available in your choice of straight or L98 angle plug versions. These heads feature a 74cc or 68cc combustion chamber with a 64cc exhaust port and a 3/4” thick head deck (ideal for nitrous or blower applications). The 68cc chambers are designed for flat top or dished pistons; domed pistons will require additional machining. Standard valves are 2.020 intake and 1.600 exhaust with AFR’s hardened ductile iron interlocking valve seats. The exceptional flow characteristics, ideal operating range of 2000 rpm to 6500 rpm, 23º valve angle, and standard valve spacing make this the perfect street head for 350 cid to 400 cid engines from 1955-86. Available for 1987 to present engines with center bolt valve covers and 2 center intake bolts at 72º angle. No special parts are required.

That does help, When you say aluminum I see dollar signs and increased maintaince. So I think I'll stick with reliability.
Your right in that I won't be making money or loosing money by racing it I just want the thrill to drive! (and tire smoke, and make the passengers wet their pants! :-) Ok I'm not that mean...I'd warn them first!

This should be renamed help the newby post! Cause I have another question. (ya'll let me know if I need to start new post for new questions?)

Has anyone spent money on some of those computer virtual dyno programs. where you can put in your specs and see the output of your planned motor? I see prices of $40 and up Thats alot if they aren't accurate and just a toy. I saw some reviews on some online magazines and some were good some bad in comparing results to actual built motors? Do any of you builders recommend them?

Thanks again!

JT

I'd suggest keeping all your questions on this same thread so the other board members can keep up and offer their suggestions.

I have no input on a virtual dyno. There are others on here who use them and I can see where they can be very helpful in selecting a combination of parts that will work well together.