irocz

I was pretty much committed to building a 6.0" rod 383 for my new engine. The price tag, though, was going to be around $2000 by the time I bought forged pistons, 4340 rods, 4340 crank, boring, balancing, etc.

Now I have a lead on an original 400 w/ the factory 2bbl still sitting on it as it came out of an impala. It's never been touched & the guy is willing to stand behind it in case something is cracked, but he said it ran good when pulled. Price tag on it is $500.

Anyone have any thoughts as to which way I should go? Oh yeah, what is the difference between a 400 & a 383? The bore? What rods do they use?

thanks,

Dan
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87 IROC-Z, 5.7,auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, Accel .219 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon- Fasttrack/Accell DFI(?), Dart Iron Eagle 200cc heads, 6" rod 383

1987 Camaro Z28 - 5.2tpi, auto, 3.73s, tb airfoil, ported plenum, !cat, !tbcoolant, !smog, !4th gear :/

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N - SOLD

[This message has been edited by irocz (edited May 19, 2001).]

FAST LiFE

iTrader: (3)

If you can go with a 400, go with the 400. There’s no replacement for displacement I always say. The main difference between the 383 and 400 is the block. The 383 combination is very powerful. But with the right heads, the 400 is even more powerful. The additional increase in displacement produces more torque and the increased bore diamter allows more incoming airflow potential. The 383 uses a 350 over-bored from 4.00” to 4.030”. The 400 block is a siamesed block with a larger bore diameter of 4.155”. The 400 also have steam holes in between the cylinders to aid in low rpm cooling.
I doubt this is the main reason why most people go with the 400 but, along with the displacement increase, going with the 400 and it’s larger bore diameter, will allow you to have the chambers of your cylinder heads “unshrouded” farther out to match the bore diameter. Unshrouding the helps allow more airflow around the valves and in/out of the chamber. It’s a common practice for NASCAR type motors to be build with engine blocks with 4.125” to 4.165” bores (400 style block) even though maximum legal displacement is 358cid (usually 4.155” w/3.30” stroke crank) to take advatage of the airflow increases unshrouding the chambers to the bores diameter will give.
As far as rods are concerned, go with 5.7” or 6.0” over the shorter 400 5.565” rods. The shorter rods puts more load against the cylinder walls.


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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

[This message has been edited by FAST LiFE (edited May 20, 2001).]

88IROCs

Coupla things:
- a 383 is a 350 with a 0.030" overbore and a 3.75" crank(vs 3.48" stock). This stroke comes from the 400 cid engine, though few 383 kits use an actual 400 cid engine's crank. The 400 uses 2.65" main bearings, which require turning down the 350's mains by 0.020". If you go with the 383, definitely go with the 6.0" rods, as this will give you the same rod/stroke ratio(1.6: 1) as the 350. A higher rod stroke ratio causes the piston to dwell near TDC for a longer period of time, which helps build cylinder pressure, which lowers the tendency toward detonation while building power.

- the 400 cid engines had 4.125" bores and a 3.75" stroke. Overboring this engine by 0.030" - to 4.155" - yields 406 cid. The 400 engines used a unique rod length of 5.565"(all other small-blocks used 5.7" rods). It does share a common deck height - 9.025" - with the rest of the small-block family. Because of the 400's larger bores, water passages between cylinder pairs were eliminated and steam holes substituted. Steam holes cool less efficiently than water passages, but if the cooling system is properly set-up, this shouldn't be a major problem. If you plan on using any non-400 heads, you will have to tap the heads for these steam holes.

- the 400's larger bore will naturally unshroud the valves without modifying the combustion chamber. If you decide you want more flow, remember changing the shape of the combustion chamber will lower your compression ratio and may change the burn characteristics of the chamber.

- $2000 for an all-forged assembly doesn't sound like that much(try ordering Lunati's catalog and putting together an all-forged assembly for $2K). Additionally, cranks for 400 blocks are not very common(because of the 400's larger main bearings) and usually cost a little extra.

PETE

iTrader: (1)

you could go one step further and make a 377 fantastic for horsepower look into using a forged 350 crank fairly cheap bearing spacers still cheap 6.0 in rods and special pistons more horsepower and rpms than the 400 and same brute tourqe of the 383 just a suggestion to think about needs to be matched with big heads though like 210 cc or so

Z-BOSS

I've had both under my tpi.....
I likes the 406. enough said

jovialevil

Which ones cheaper to build?

Slow Iroc

The 406 is cheaper to build as long as you can find a complete motor.

The 406 will spank the 377 or 383, every day of every week, all things being equal. Bore is about the best thing on the planet when comparing it to the 383. Why? I don't know, those little unknown cars like Porsche's, Ferrari's, and Lambo's, all use motors with HUGE bore and tiny tiny strokes. However, if they increased their stroke, they would increase their power everywhere in the RPM band, so keep that in mind when comparing the 406 to the 377.

ImportsRsloths

Hey,
I was planning on going with the 383. But you guys make it sound like the 400 is designed better. My friends got a complete un bored 400 sitting in his garage. What do I have to do to get the Tuned port to fit on?
Thanks,
Matt

JoelOl75

If you use the stock TPI heads and drill them for the steam holes the TPI will drop on, but compression would be quite high with 64cc chambers. This isn't a bad thing since you can remove quite abit of material porting the chambers and help drop the cr.

305 suffer from the difficulty of getting compression high enough to make power and the 400's the opposite.

I would definatly ditch the 400's short rods and use at least 5.7 rods in the buildup and make sure to get the right pistons for them, and if your doing this why would you use the TPI's small valves on this motor. I think bang-for-the-buck would point to an aftermarket aluminum head with 200cc or better intake tracts.

There's no replacement for displacement...

IMO there's no reason to destroke a 400 when you could get longer rods to gain the RPM potential and keep the cubes to boot.



[This message has been edited by JoelOl75 (edited May 25, 2001).]

89ProchargedROC

go tell kenny duttwheiler that 377s dont run

also as a side note, if you build a 377 right it will make more hp that 406 because a 377 is meant to rev HIGH with a solid cam and about 9,000rpm or even 9,500rpm. now this isn't a street car, BUT anything over 5250rpm equates to higer hp and a 377 will rev faster and freer that a 406 will.

for a street car and ease of cost and power, go with the 406

graebz28

iTrader: (5)

377's are will rev higher, but of coarse you lose lower end torque. I had a friend w/ one in a 67 bird, running 108 octane and it screamed. He felt the power drop at 8200.

I have a 406, 6" rod motor. My power-band on it is from 4500-7800. Lots of torque.

You have to begin w/ the end in mind. First question is how fast do you want to go in the 1/4(if you are building a drag car). If you are looking to break into the 10's or faster, go with as much cubic inches as you can.

------------------
Michael Graeber

My Garage

1)83 Z-28 T-Top: Full cage, 9" w/ lad.bars, Midwest Engine Tech 406sbc,Strip Dominator, 1000-CFM Demon Carb, Phase VI Chevy Bowtie Heads 2.05/1.60, .630" Crower roller set-up, 1 3/4 coated Hookers 3" true dual exhaust th400, fuel cell & still not running

2)89 Formula WS-6 305 TPI Auto Daily Driver: minor motor mods, more suspension stuff. MODS

graebz28

iTrader: (5)

Remember:

HP gives you a higher trap speed.

Torque is more important when it comes to acceleration. Everyone always puts too much emphasis on HP, when torque IMO is more crucial..... that is for 1/4 mile times.

Peace

Slow Iroc

HA HA HA HA HA HA HA HA. LOL! FUNNY **** YOU JUST SAID THERE!

Let's start with this, the longer the stroke, the more power that will be produced per combustion event because the flame front will have more distance to push the piston, and distance multiplied by time is force, which is torque. Being that HP is a function of where torque peak occurs, HP is more about torque than RPM. So you can take your statement about a 377 making more HP than a 406, and shove it...someplace.

The 377 meant to rev higher? Meant to do so buy who because last I checked GM never released a 377 small block... Nothing in the hot rod world is "Meant" to do something, it's all experimental. The 302 was MEANT to rev higher than the 327. The 427 was MEANT to rev higher than the 396. Designers at GM never drew up plans for a 377, or 383, so how can you say they are meant to do anything besides be aftermarket experimentation?

Will the 377 rev faster and freer than a 406? Sure maybe like you said, at 9000-9500 RPM, but only because of piston speed at that piont in time. A 406 CAN be built to rev that high, infact, without a problem! Steel crank, lightweight 6 inch rods, lightweight pistons, and a mechanical cam, and a set of SERIOUS Brodix heads, and a 406 can rev there and while it's there, it will be out powering the 377 because of the combustion event efficiency being increased by the stroke. In fact, it will be increased to a greater extent than piston speed pumping loses.

377's run, but 406's sprint!

(By the way, at a local circle track there is a 430 cubic inch small block that redlines (electronically controlled limitation) at 8900 RPM...it can be done, and if a hillbilly like that guy can do it, so can anyone and probably better. By the way, if he removed the rev limiter, I think the motor would spin another 1000-1100 RPM.)



[This message has been edited by Slow Iroc (edited May 28, 2001).]

the roc

Slow Iroc - You've been doing a lot of reading since this post asking which way the crank rotates,, huh? I really enjoy reading posts from guys like you. Now,, that is funny.

https://www.thirdgen.org/messgboard/...ML/007686.html

Slow Iroc

So how does that prove anything I said to be invalid? It dosen't, which maens you are simple using a tool of the inferior to point the finger someplace else besides yourself, without making a meaningful contribution. THAT IS FUNNY!

FAST LiFE

iTrader: (3)

Duttweiler has built many 7 second 377 motors, albeit they are twin turbo charged. I know of two third-gen’s in the San Jose area and one of the has broken speed and ET records in the PSCA. Duttweiler also built many 8, 9 and 10 second 302, 350, 383 and 406ci Chevy’s. Although it’s not built by Duttweiler, I know of another 377ci IROC that runs 10’s normally aspirated.
It doesn’t really matter what size your engine is, what matters is how you achieve that power, whether it be through high RPM 377’s or torque monster 434’s. It also matters on who builds it because any half-@ssed monkey machinist can build a great motor on paper but doesn’t have the know-how to bring it to the real world. Does size really matter? Hell yeah, the size of your wallet.


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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

PETE

iTrader: (1)

in all of these postings nobody mentioned anything about using longer rods,why?for 1 a 406 is hard pressed to use a 6.125 in. rod costs a lot of cash for special piston with relocated pins and ring seats by increasing the rod length you increase the amount of time the piston is @tdc (dwell time)which creates better combustion and a better flatter tourqe curve for an hipo motor that wont break your wallet a 377 chevy with a 6.125 rod will make close to what the 406 does and yes if anybody researched gm archives you'd see chevy made a 377 it was in 1970 it never made it to production due to the cost get this it even had modified hemi heads with hemispherical combustion chambers

FAST LiFE

iTrader: (3)

Rod ratios are important in many ways. Increased rod ratios due reduce angular thrust against the cylinder walls. Increased rod ratios due allow longer piston dwell times at TDC. However, longer rod ratios do decrease instantaneous piston velocity (longer dwell time at TDC also means longer dwell time at BDC, more time at BDC is not such a good thing) and it makes the engine more sensitive to cylinder head port dimensions, particularly larger ports. For example, low to mid port velocity of an 180cc head can slow down to the port velocity of a 200cc-210cc head. Basic rule of thumb, longer rod ratios equal increased mid to upper RPM power, shorter rods increase low to midrange torque. That’s why there’s such a big debate whether longer rods make more power or not. Some tests show an increase of an 8-20HP and others claim more, across on the top end, but some tests see a gain as little as 1-2HP and some even no gain. The tests results vary too much on HP gains, but all do agree that angular thrust wear is decreased.
Since 5.7” and 6.0” rods are more common and cheaper in price, so are off the shelf pistons for those rods. 5.8” and 6.125” rods on the other hand are not as common, are priced higher and do require more of a specialty piston. Let’s use the price of a Keith Black piston in the Summit catalog. The price for the 377 domed piston set w/5.7” rods is $245. Price for the 383 domed piston set w/5.7” rod is $234. The price for the 406 domed piston w/5.7” rod is $234. Looking at other catalogs and other piston manufacturers show similar pricing differences. Building a 377 is going to cost about as much if not more (don't forget about the bearing spacers for that 3.48" crank) than a 383 or 406.
The thing about the 377 is that, yes it makes a ton of HP. On the down side, it makes that HP at higher RPM’s (up to 8000-9000RPM), which means you’re going to want steeper gears to keep the motor in it’s power band during a run. It’s not uncommon to have to use gear ratios of 3.73 to 4.10 to really make the 377 shine. A 383 or 406 on the other hand will be just fine with as little as 3.08 to 3.45 gear ratios. A 377 will feel a bit sluggish on the low to mid RPM range with those gears as apposed to a 383 or 406. I’ve had one of my IROC’s with a 383 do high 12.8’s on 3.08 gears.
I’m not bagging on the 377 and I’m not glorifying 383’s or 406’s. In fact I’m even considering it for a light 63’ Nova of mine. I’m just saying that no one motor or its size is better than the other. It’s basically going to come down to a personal preference of what you want to use, where you want your powerband at and how good your engine builder is.


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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

[This message has been edited by FAST LiFE (edited May 29, 2001).]

the roc

Sorry IROCZ,, I don’t want to turn your thread into a flame war. However, there is not much more one could say that Fast Life hasn’t. He’s pretty much dead on.

Slow Iroc – You laughed at someone’s comments that could not have any less engine building experience than you have. If you can’t take it, don’t dish it out. Be considerate of others and maybe they’ll be considerate of you.

irocz

One other thing I was wondering is what's a good price for a 400? I can get a stock bore long block for $500 and a stock bore shortblock for $300. Was wondering which I should get or maybe both?



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Dan
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87 IROC-Z, 5.7,auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, Accel .219 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon- DFI or prom burner, Dart Iron Eagle 200cc heads, 6" rod 383 or a 406

1987 Camaro Z28 - 5.2tpi, auto, 3.73s, tb airfoil, ported plenum, !cat, !tbcoolant, !smog, !4th gear :/

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N - SOLD

FAST LiFE

iTrader: (3)

Get the short block and put some better heads on it. Honestly, $300 for a short block or even $500 for a long block, that is very cheap and would make me wonder what they skimped on to get that price low. I can foresee inexpensive cast or hypereutectic pistons, cast piston rings, standard rod and main bolts and nothing balanced. I’m not saying that you’re not getting a good deal, just be careful now so you don’t have to shell out more money later.
I myself would rather just get the block bare ad build from there. What exactly are you shooting for with this motor? Is it going to be daily driver that will see the track on occasion, a street/strip car that you’re going to take to the track all season or a full on weekend cruiser/race car? What you intend to do with the car dictates what type of work and parts you want in your motor.


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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

BadSS

The stock 400 heads are not worth $200. I'd go with the short block also,, if you can buy it under the condition that it's a usable block and crank that will go 30 over or less and the crank doesn't have to be turned more than 10/10. If you don't have someone that can go with you that can eyeball it and know what and where to look for trouble spots, see if he'll agree to those conditions with you (or both of you) taking it to a machinist for the "yeah,, it should go" estimate.

I totally agree with Fast Life - Depending on your budget and it's intent will determine the rest of your combination.

[This message has been edited by BadSS (edited June 02, 2001).]

whiterocz

i would seriously like to see someone that has a 406ci that can rev up to as high as a destroked 400 block (ie 377ci). one of my good buds has a 85 vette with a destroked 400 (377) with a mini ram sitting on top of it and it will rev all the way up to 10.5k rpm, and has usefull power all the way up there. its funny hearing a v8's rumble at 10.5k rpm.

FAST LiFE

iTrader: (3)

For a street motor, which is what I thought we were talking about, spinning a motor up to 10.5k RPM’s is kind of ridiculous. For a racecar, that’s fine, but for a street motor I don’t see any reason to justify why you would want to spin your motor that high since it reduces the longevity of your motor. If you read the rest of this post, the understanding that the 377 and the 406 are two totally different motors with two totally different powerbands.

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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

irocz

That's what these are...rebuildable blocks. They are original engines that have not been apart. I would have to rebuild them and go from there.

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Dan
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87 IROC-Z, 5.7,auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, Accel .219 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon- DFI or prom burner, Dart Iron Eagle 200cc heads, 6" rod 383 or a 406

1987 Camaro Z28 - 5.2tpi, auto, 3.73s, tb airfoil, ported plenum, !cat, !tbcoolant, !smog, !4th gear :/

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N - SOLD

FAST LiFE

iTrader: (3)

My apologies irocz, I thought you were talking about newly rebuilt long and short blocks. If you can, see if you can get them to lower the price if you just take the block only. Getting the stock 400 crank ground and polished will be around the same price as the newer nodular iron 400 cranks available on the market now. They are definitely better cranks than the stock unit. And as far as rods, you want to go with a 5.7" rod. There is more angular thrust wear with the shorter 400 5.565". You can get newly rebuilt Chevy 5.7"rods for around $100 (maybe less) and if you want something a little better, you can get new GM PM rods for around $175 or Eagle SIR's for around $299. I’ve bought all 4 of my 400 bare blocks (virgin bore, no machining) for $100 each.

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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

[This message has been edited by FAST LiFE (edited June 02, 2001).]

camarokev400

Hey Fastlife ive got a question for ya on those 5.7 rods, (sorry this is kinda off topic) I bought everything for my 406 except the rods, i have keith black signature series 30 cc dish pistons made for 5.7 rods. And i am running a comp cams extreme energy 268 series cam with a stock crankshaft. What kind of rods could i get so i wouldnt have to do any grinding or clearancing work? Is there such a rod out there that i wouldnt or i am pretty much screwed and have to clearance everything?

hectorsn

We built two 400's at work with the same GM PM 5.7 rods and Comp X276? cam. One needed no clearancing but the other had rod and cam interference. The rod stud was hitting the lobe at the peak. A little grinding and it was good to go. I don't know if the fact that the block had a main saddle problem was to blame but it's a possibility as the other block was in pristine condition. I built my 400 with a Comp X286 and Eagle rods (which have bolts and not studs) and had no interference with the cam but had clearance issues around the block. Basically, you have to check everything when you make changes like that to avoid having to take things apart later. And not to add to the debate but I've had both a 377 and a 400 (both had the same AFR 220 heads) and I'll take the 400. Not because the 377 lacked torque down low but because there really is no need to rev to high heaven on a street engine. By going with a slightly smaller cam on the 400 as the 377, I got better drivability and made as much power with the extra CI. Truth is the torque/hp characteristics of an engine come from the head/cam combo, not because of 23 CI, but I could see 123 CI making a difference.

1TUF92Z

You mentioned 2 3rd Gens from San Jose that are really fast. Who are they? When are you going to take your car to Sac raceway again? I have a similar engine combo. Let me know if you are going.

as for the topic, everything has been said. But here's my .02 cents:
1.) If the car will mostly see the street go for the 383. Reason is the 350 block has a less tendency to crack since it is not a siamesed bores.
2.) If the car sees more of the tracks, well, any of those combo will work. Figure out how fast you wanna go or how many HP and TQ you are looking for then see which one will be cheaper to build-BEST BANG FOR THE BUCK.

BTW, I have a 406 in my 92 Z28.

FAST LiFE

iTrader: (3)

Camarokev...if you want a rod that you don't have to grind the shoulders for clearance, you want to go with a connecting rod that's "K" cut or stroker clearanced. Usually those rods do away with the bolts and nuts combination and just use a bolt or a stud and nut combination. Alot of manufacturers make them. Most of the "H" beam style rods are usually "K" cut or stroker cut. Look at the Manley or Eagle "H" beam rods and you'll the type of rod bolt/cap style you're looking for. There are "I" beam rods with that type of rod cap configuration. Pro-Tech Engineering, Elgin and Scat make rods with that type of rod in different materials to suite your budget (5140, 4130, 4340 steel). Usually rods made of 5140 are at the $380 - $450 range and are good to about 400 - 500hp range and 4340 being the more expensive and good to higher levels of hp.
I attached a picture of an Eagle "H" beam rod to give you a better idea of the rod cap design you are looking for and how the bolts are configured. You can see fromt he photo how the shoulders on the big end of the rod is clearanced. On a standard rod, bolts would go through from the shoulder side and the threads would be bolted down with nuts on the cap side. You would need to grind down the head bolts at the shoulders for clearancing.
1TUF92Z…they’re guys from Unlimited Racing car club, they were local hero’s to all the street racers at the time. You don’t happen to know them do you? I don’t really know them personally, but saw them all the time at the street races way back in the day and at the track. I wish I could be going to Sac to do a few runs, but I’m hating it here in S. Cali and missing the Bay real bad, so I’m going to have to settle for LA Raceway or Bakersfield. Usually I went to Sears Point. Only went to Sac a few times. I see you’re in Elk Grove…pretty lucky living close to Sac Raceway. We had to drive from Frisco and that was a long drive for us.

1TUF92Z

Reason I asked is curiousity got me about those two 3rd gens in San Jose who you were referring to. Actually, I am one of the Unlimited Racing crew since way back then when we used to street race alot and yes I used to lived in SJ but I move to Elk Grove back in '97 to buy a house and of course closer to the track. Well at least that's how my wife convinced me to buy a house here in EG. hehehe Yeah, when it is really quite around my neighborhood, I can hear the race car outside and that is 16 miles away. Let me know when you come up hear and we can meet at the track. I am still breaking-in the 406 then hit the track maybe next month.

BTW, I have an 8 pt roll cage, MSD 38LB injectors, brand new Lakewood struts and shocks, subframe connectors and a 10"TCI 3500 Stall TC(700R-4)brazed for anti-balooning and balanced for NOS or Boost. Let me know if you know anyone who's interested.

FAST LiFE

iTrader: (3)

1TUF92Z...lol, I kinda knew you were with Unlimited because of your forum name and I'm sure you know how I kinda figured it out. LOL hehehehe. I'm glad that you guys were able to keep it together and running the Firebird with Jose at the PSCA. Tell him that there's alot of proud guys in SF when we heard about him setting the records he did with the PSCA and representing N. Cali. Hopefully I'll see you guys around at a PSCA race in S. Cali.

Beefy89

Like Fast life said,
There is no replacement for displacement....
Now the TTA guys will argue that,but they're using a power adder.....

u r sofa king we tah did

you can bet if i had a mini-rammed 377 in my car, id be turning 10.5k rpms on the street. if you can do it and make power doing it, what would be so bad about doing it on the street too? nothing. all that 10.5k rpm is unstreetable is crap. id like to see the look on someones face when i ran up to 65 before shifting to second, pulling hard the whole way.