I've been looking around in the local bargain post and I've found a lot of good deals on 350's but I've also found deals on some 400's. Which motor would have more potential? If I get the 350 I'll have it punched out to a 383. So which motor would be better(hp and torque) to build? If it helps I'll be using a carb for the new motor. Thanks a lot.

 

Hey,
The 400 isn't a great hot rodding engine. It's basically a bored and stroked 350, but in order to get the large bore they had to make the water journals way smaller there is no longer room for water to flow between the cylinders only around it. Because of that, you need a very good coolant system, possibly drill steam holes in the heads

The 383 is a good engine that produces immense ammounts of torque. I would choose it over a 400 simply cause its more durable

Dan

 

Obviously spoken by someone who has never had a 400...

A 400 will produce more HP and torque than an otherwise identical 383, by about 5% (the CID difference).

Always go for the inches. The 400 is an excellent motor. None of the ones I've ever had, including the one that was in my 83 for about 10 or 11 years (and which will be going back soon) has ever had the supposed cooling issues that people who have never had one always talk about. I have the stock 83 L69 cooling system, except that somewhere along the line I ended up with the plastic & aluminum radiator, and I have a Stewart water pump. Stock thermostat, stock fan switch, stock fan motor, etc.

You do have to drill steam holes in the heads if you use non-400 heads. That's something you can do yourself in less than 5 minutes with a hand drill. Hardly a reason to throw away 20 cubic inches.

 

I got a '70 Impala 400 from my dad. At 50k, a heater hose broke on it and it overheated, cracking the block. A new bare block was put in it (old guts put in the new block), and it continued on. At 95k, a piston broke, it was replaced but the others reused. I got it when it had 170k on it. At about 195k, the lower radiator hose burst on me, and it overheated.

Hardly things to call a systemic 400 overheating problem.

I gave it to my bother with a little over 200k on it. He put new rings and bearings in it (still stock bore, 7 original pistons, original heads) and drove it a couple more years. He gave it to his son, who drove it for another couple of years before the rest of the car fell off around the engine. He abandoned it in Wichita about 5 years ago.

Sure wish I had that engine now...

 

So you're saying the 400 is just as good(if not better) than the 383. Would it be just as much to hot rod it or would it be les since I won't have to have it bored and stroked. I don't know much about the 400, I would like to be educated more on it though . Thanks guys.

 

Since they stopped producing 400's in 1979 the amount of good cores is decreasing. If you're going to build a 383, you're going to waste a 400 crank to put it into a 350 block (machining is required on the mains). Since you'll already have the 400, just build a 400.

Throw away the factory 400 heads though. They're all junk and caused most of the overheating problems when they cracked. Find a good set of 350 heads. Use a 400 head gasket and drill the steam holes into the head. 1/4" drill bit.

The best way to build a 383 now is with an aftermarket stroker crank.

 

"There's no replacement for displacement."

Go with the 400.

 

I'd definately go with the 400, but make sure you use 6 in. rods in it. At the very minimum use 5.7 rods. It's more expensive than just putting the stockers back in, but the performance is worth it. Plus it leaves room for future mods. Never skimp on the bottom end.

 

Cool, there're plenty of 400's in bargain post for pretty cheap. Where do you drill the steam holes exactly? I know on the heads, but where? When I have the money I'd like to get some AFR heads, would you do the same to them? Also, I"ll be doing my auto to manual swap as soon as I get everything, will the bellhousing bolt right up to the 400 or will it need modification? Thanks for all the info guys, any more will be greatly appreciated.

 

The bell housing bolts up; all SBCs have the same BH bolt pattern. You might need to have one starter bolt hole drilled. You'll need to use a 82-85 305 flywheel (12¾" 153 tooth) and have it "unbalanced" to the 400 spec, or get some other flywheel of similar specs from Centerforce or wherever.

Lay a 400 head gasket on the heads, mark the holes with a center punch, and drill them with a 3/16" bit.

 

Anyone know where to get a good 383 or 400. I want to build an engine that will get me in the 11s anmd I have 5k to do it in hand now.

 

I dont know In my honest opinion I give a big praise to wingnut
for stating there is no replacement for displacement. The only two things in motor building are cubic inches and rectangular dollars. the 400 heads suck so throw them in the trash and drill steam holes in a decent aftermarket 2.02 head id go with prolly 72cc chambers from what ive been told cuz you run lower compression which will keep you pump gas friendly. If you get some time scope this out http://www.scatcrankshafts.com/news02.html 500 lb-ft of torque and 450 hp isnt too shabby good luck man. and please dont think about a 377 lol

 

I decided to go with the combo in my sig. The engine will be done next week and desktop dynos at 580 HP 523LB TQ.

 

Neither the 383 or the 400 is a good motor. 350 or 406 is the best way to go. 383 is too costly and the 400 is not a good drag motor.

 

Ya, my 383 cost me way too much. I have $2400 in it with a brand new Hotcam, all steel Eagle stroker kit, Keith Black Pistons, 1.6 aluminum rockers, and Vortech heads. It sucks for a drag motor because it only pulls mid 12's with that small cam. Seriously, if you don't have a clue, then don't post here. As for your question either a 383 or a 400 will make you happy with all of the torque on hand, but if you can get a 400 cheap buy that.

 

Im a heckuva lot less experienced than most guys here, but bigger numbers sounds better to me. I like the 400. Besides, it sounds less expensive to me.
Matt

 

jamesbern. You're right. I dont have a clue. I've only been building drag cars for 8 years. I'm glad your 383 was cheap and runs mid 12's. My latest 350 runs low 11's and it cost about the same as your 383. I have a 1989 formula with a 383 stroker. I wouldn't say anything about it if I didn't have one.

 

I'm surprised you didn't pick on the fact that there are about $700 worth of roller parts that aren't absolutely necessary for a drag car in my stroker. Also the entire engine other than the block is brand new. I don't want to pick a fight, but I bet not very much of your 11 second 350 is brand new. In all actuality if I had put a bigger cam in my stroker it would pull 11's easily, but I want a street car.

 

jamesbern. I don't want to pick a fight either. Just don't criticize my knowledge and experience, because it is far more than you can imagine. We are all entitled to our opinions. Thats what its all about istn't it. I'm just happy you are racing american muscle instead of a crappy rice burner. If your wondering why I am a junior memeber, it is because I hadn't been on for awhile and I lost my logon and had to get a new one.

 

Well the original question is which would have more potential. I have to assume he means for a street motor because he doesn't mention all out drag racing. A 350 is cheaper, but won't make as much power as a 383 or a 400, there is no arguing this point. To make a 350 run as well as a 383 or 400, you will have to cam it beyond street use. Many of my hotrod friends have such combos and I can still hang with them in my mild 383. For all out drag, yes a 350 may be the cheapest, but it also has the lowest potential. Also the money saved by using a 350 engine will be used to buy high dollar 3000-4000 converters and other nonsense not needed in a low r.p.m. torque monster such as a 383 or 400. The only reason 350's are so popular is the availability, not the power, though they have some. Out of every smallblock I have built, none was more impressive than the current 383. By the way mine cut 4.5 seconds off my e.t. with no suspension mods and they will probably give me another 3/4 to 1 second.

 

jamesbern. Out of curiosity. You said you dropped 4.5 sec. What motor specs did you run previous to the 383?

 

305 tbi stock with 214,000 miles on it.

 

i betcha with the right combo you can send a 400 into the 11s and still keep it streetable. those 400s are quite the torquers i hear. when i had that rusted out monte carlo with the 400/2bb it FLEW for what it had.

but the 400 will have more potential period.

get some good flowing heads, a roller cam with lots of lift, and a bit more duration.


oh yeah TA5LiterHO i don't want to pick a fight eighter but you stated....."Neither the 383 or the 400 is a good motor. 350 or 406 is the best way to go. 383 is too costly and the 400 is not a good drag motor." if you have all of this knowledge about drag racing and stuff, you should know that the 406 is just a 400 with a .030 overbore. now what does this overbore do to the block that makes it so much better than the stocker? could you please clarify this for me.....

 

ACE_Murdock. I am aware that the 406 is a bored 400. I am speaking of the cherolet 400 not the pontiac 400 which was a big block or is the size of a big block. This motor was used when pontiac made their own motors. They are two totally different motors. The 400 I speak of is not a well balanced motor to begin with. That is my point. Even with a 406, it will take you more workup to get the performance you want from it. I have personally built each of the motors you speak of and have witnessed their performance first hand. I am just giving information based on experience. I work for a company that does top end work on performance engines. Heads, TPI, Etc.

 

alright, i believe you. and i do know that the pontiac 400 was the same block as their 455 and the 3** i belive.

but wouldn't the 383 also be unbalanced because it is using the externally balanced 400 crank?

 

jamesbern. 305 tbi eh. What cam did you say you had in your 383?

 

also i am building up a 400, what are some tips and secrets to making power on these motors?

i am thinking of using the new motown heads with the 220cc intake runners, i also picked up an offenhauser 2x4 intake manifold that i want to use.

also could i take and have the 400 crank internally balanced at my local machine shop? I do know there are after market 400 cranks that are internally balanced.

 

ACE_Murdock. The 383 can have some balancing problems as well, hence the 400 crank, but with some good machine work its not a bad motor. Just takes a bit more machining to build up a stroker motor like that. Infact one of the guys I work with has a C4 Vette with a 390 stroker that runs 11:60's. He ported and polished the heads at our shop. It took him 2 months to get those heads the way he wanted them and to run those times, not to mention the balancing and blueprinting he did on the motor himself. The work payed off, but it took awhile.

 

cool thanks for the info

 

Ace_Murdock. One word AIRFLOW. Put the best damn flowing heads you can on that motor. They don't even necessarily have to be aftermarket. Like a set of heads off a 305 for example. I can get those to flow as good or better than many after market heads of thast size. Again that cost $. That is what my company does in fact. We do top end kits that increase flow. You'd be surprised at the power you can get just from increased flow. As far as balancing the crank. Some machines shops do balance them, but I am unsure of the one you are thinking of using. I have run into some that do and some that dont. You'd have to just give em a call and see what they say.

 

True airflow is important, but equally important is the design of the cylinder head. You can port out a set of 442 heads till they flow as much as the fastburns but the fastburns will make more power, its a better design for the flame front. Several factors in good heads not just air flow...

 

Chrome. You are correct in that asumption. It is important. Thanks for bringin that up. I did not say that all stock heads can perform as good as aftermarket though. I said that they can be made to flow as good. The comustion chamber is important, yes, but improved airflow is also.

 

Chrome. I agree that the cylinder head design is important. But with out good flow it isn't going to make that significant of a difference. I was merely giving advice on what he can do with what he already has. But yes. I agree with you.

 

Chrome. Don't get me wrong, I am not trying to get him to change heads, just maximize their performance.

 

TA5LiterHO my exact engine is in last months Chevy High Performance along with the dyno figures. Everything is identical to theirs from carb to 1 5/8 Hedman headers.

 

jamesbern. Sorry. I don't get that particular magazine, but the motor sounds good to me. Good choice in Headers by the way. I have used Headmans on my Formula and my Trans AM.

 

are those headman headers full length?

i am wanting to use a set of long tube headers, but i am unsure of which to use.

 

Yes they are long tubes. Its too bad you don't get that mag. because it has some excellent articles, I subscribed yesterday. Anyway the numbers are crazy for a small block from 2500-5500 it never dips below 400 ft./lbs. of torque peaking at 3500-3600 with 466 ft./lbs. The horsepower is over 300 from 3400-5700 and peaks at 5600 with 416, the test ends at 5700. My numbers would actually be higher because my heads are ported and I use 1 5/8 headers which they didn't show test results with on my cam, but worked better on the bigger cam.

 

I might just subscribe to that mag to add to the collection. Wow. Those numbers sound good. Thats probably one of the best 383 jobs I have seen. I am impressed. Out of curiosity, have you dyno tested your motor?

 

ACE_MURDOCK. I have shorties on my Trans Am and my Formula, but I was thinking about going to longtubes and true dual on the formula. It is difficult to do though. But my exhaust guy said he thinks he can pull it off. The one thing I don;t do is collector back exhaust because it has to be custom bent and welded. Headman makes Longtubes and Shorties designed for fbodies and they are reasonably priced. I like them.

 

Speaking of longtubes and true dual. I was trying to figure out where to place the mufflers for a true dual system with longtubes, so out of curiosity I went to the flowmaster site to see if they had anything new. They now have low profile mufflers. I am not sure how good they sound, but those could be helpful for ground clearance in a true dual system. Either of you guys seen these?

 

No, I haven't dynoed my engine, but a rear wheel dyno is in the works about a month or so from now. If you guys want to see how to make a true dual system, I can send you pictures of 2.5" duals with dynomax bullet mufflers. Just e-mail me a jamesbern@hotmail.com. I would have liked to dyno the motor, but around here it costs about $400 and thats way too much.

 

i saw those mufflers on horsepower tv last weekend.

they said they are suposed to have the same sound and stuff, just smaller. but i cannot verify this.

 

Hey Ace, don't know if it is possible with the long stroke, but go with some longer rods. The short rod in the 400 leaves it with a pathetic ratio that promotes deflection against the cylinder wall. The 383 setup is better because it uses 5.7 or 6.0 rods that rectify the situation somewhat. I haven't built many 400's and have experimented with none, but if you can change the rod length in any other smallblock surely you can in a 400. This problem actually tries to shove the piston through the cylinder wall and takes away alot of power from friction.

 

I gotcha man. $400 is quite a bit.

 

I agree with jamesbern on the lengthening the rods idea. Would be interesting to look into doing that.

 

By the way I checked on the dual exhaust with my exhaust man Billy and my bud Vinnie at VG Customs in Fort Lauderdale. He said he could do true dual with tips, but it would be $2500-$3000. He would have to shorten the back floor pans remove the panhard bar, drop the tank and axle. Keep in mind this guy Vinnie is a chassis expert. All he would do is modify the car to fit the exhaust. Unless you want to attempt to modify yourself. Then the exhaust work would cost on top of that after the room is made to accomidate for it. You could do true dual with just dumps in front of the rear axle, but I don't think it looks as good and doesnt sound as nice. Heres the #'s in case you have any questions. Hopefully this will clarify the thirdgen dual exhaust issue.

Vee Gee Customs: in Fort Lauderdale, FL (954)561-0209
Ask for: Vinnie

Prospect Muffler: Fort Lauderdale, FL (954)564-4411
Ask for Billy

 

yeah, i am gonna use 5.7" rods for sure, if i can i would like to use 6.0" i am not going to throw the stockers in.

 

also for the dual exhaust, there is no chance in hel* that i would spend 2500-3000 to modify my car to run dual exhaust. i will dump it out infront of the rear wheels, because i want that type of exhaust.

 

http://www.camaroz28.com/~chris/mmexhaust/ Here is your true duals with minimum effort and no floorpan mods. He did have to remove the panhard support to weld the pipe up and relocate the fuel lines, but that is it. Those are Dynomax Bullet mufflers they sound good. Go to the exhaust board and download the clip.