Spent the day with my engine builder buddy. Over dinner we talked about your build among other things. He mentioned a 400 short block could be built for around $3500 and that's what he'd recommend.. A 427 version requires many special parts, that all cost double normal SBC parts. Even the brand new 1700 block needs machining. The trial fitting & clearancing is much more etc.. So a 427 short block would run about double that. He wouldn't recommend it and said you could probably not even tell the difference between that and a 400 anyway on a mild street build. He could even make your 350 pull real strong if you wanted to try that, for way less. Said it needs to be de-LT-1'd. Hah!

PS I forgot his son runs a 400 SBC in his S-10 and runs 10.50s with it! He does wind that one a little higher than what you are talking tho, about double, to 8200 rpm.
OTOH (& extreme) he has an already built 620 cu in BBC for sale at $11.5k Roughly 900 HP. & maybe 750 ft lbs? Enough? LOL

 

Thanks Leigh. I will call him this coming week, I just got too distracted this last week. I have started a spreadsheet listing everything on a 427 and 406, and there is no doubt that the special labor, and special parts for a 427 escalate the price substantially. After all the input, and further reading on other forums, here is my current newly educated position on a 427 SBC versus 406 SBC:

- 427 is substantially more expensive, as Jeff said. Although CNC Motorsports will build either for nearly the same price, but you have to compare the components. I won't cheap out.
- 4.0 inch stroke requires extra machining on an SHP block, and pushes you into special parts. If money was no object Dart and World make better blocks for a 4.0 inch stroke, raised cam, etc. The SHP is already machined for 3.75 stroke so easy on a 406.
- 427 requires a small base circle cam = compromise= more money. 406 can use standard base circle cam.
- 6.0 rods require low compression height piston, oil ring support = compromise, but I think it is a small compromise. When you scour the forums, the pros / cons between 5.7 and 6.0 seem to wash out in all aspects. I prefer the longer rod because the issue with 5.7 rod is increased side load on pistons and rings. The downside to small compression height seems to be less an issue, especially if quality pistons and rings are used.
- I am not starting from clean sheet - I have a $2000 set of 1-5/8 inch stainless headers into 2-1/2 stainless mandrel bent exhaust that I have no interest in replacing. I wanted to use my AFR 180 heads. But both of these would choke a 427, but would be more acceptable in a 406. However, I might step up to AFR 195 heads or Dart Pro 1. Carb and intake also may go to Holley Double Pumper with Edelbrock RPM Air Gap...more just cause thats what I want to do, and because it has been highly recommended.
- The one practical and real limitation is my car and my unwillingness to "improve" certain features to accomdate massive torque, which include 225/R70/15 tires, stock drive train components, 355 rear end and Borg T10 transmission. At some point, you can have too much torque, and it is unusable. I think some of it can be offset but how hard you push the pedal, but??
- Finally, when you look at the entire picture, a 406 provides a massive increase in torque and power capability, if built right, over my 350, but stays just clear of most of the compromises a 427 requires. Add that to my interest in what most consider a "mild" power need, it seems going as big as 427 is overkill,.....especially when it cost substantially more i.e. not a good value..

As for my 350, it is built with all quality parts, and I did get to do a cranking compression test last week and all cylinders with 195-200 cranking pressure!! They were so good, I verified with another gauge my old Lisle compression tester was accurate. With those great numbers I did leak-down compression test on only Cylinder #1 and it measured only 5% loss at 100 PSI. So its a very tight engine. It should be. I broke it in properly, treated it right, and was very methodical about getting the quench right, and compression right on the build. Unless the plan changes, which it might, I want to get it back together and sell it to help pay for the big inch. Money wise it would be smart to just make it work, but I am not yet sure that it can be made into what I want. I will talk to Jeff about it. I think what would help my 350 is more lift, with higher lift cam and 1.6 ratio rockers, and possibly a more single pattern cam. I have read the AFR heads have such a good intake / exhaust ratio that a dual pattern is not needed and possibly is over scavenging. I could also stroke it to 383, but I cannot yet convince myself it is going far enough versus a 406.

What I would like to see is some dyno graphs of a 406, maybe with AFR 180 and 195 heads, as well as graphs of my 350 with whatever Jeff would do to it. What Desktop Dyno are you using? I have been talking with Chris Straub, and whatever I do, I most likely will be buying his recommended cam.

Thanks to all. This thread has been long, but useful to me. ....exactly what a Tech Forum should be.

 

I think it was by David Vizard. A 383 SBC was tested with 3 sizes of dart heads all things being equal,180, 200 and 215, or so. If IRCC, they were all pretty similar, until about 5500 rpm. At low RPM the small heads had the advantage. I have seen the test as few times, but my quick search didn’t provide it.

 

You guys want to talk about grafts and computer generated dyno charts. I posted real dyno sheets from my cheap Chinese headed 383 are you not reading them. This thing is ridiculous in my 64. You don't need anything more trust me the car can barely handle it. It makes 464ft lb at 3000 rpm and 498 at 4200. Look at the sheets. You can not hold it to the floor and go through the gears you will crash. You don't need a 427 and an ls5 is no comparison although it would work great in a motor home or dump truck

 

I had Dart Pro1 180 heads on my other 383 and it ran good, BUT when I built my new 383 motor with a much bigger cam and CR being a bit higher I went with AFR 195 heads and love them. The motor runs great. I also get that you are not looking to break ANY HP records which I get. Good luck with your choices and build. I want to build a Dart SHP 421 motor next which would be cool IMO.

 

I saw a similar test between a small block and big block Chevy years ago with the same displacement - can't remember if it was 427 or 454. But the small block beat the big block in low rpm power because of the smaller heads.

 

That's a great 383 and makes a lot of power and most vette owners would love it a motor that strong that revs that well. Strong and very fast too, I bet. But it makes peak power at 5800 and peak torque at 4400. It's down 36 ft lbs by 3000 and there are no numbers lower. It's probably down at least another 40ft lbs at 2000, maybe more, and that's 76 down from the peak.
The OP is looking for the strongest possible torque from 2000 to 4000 rpm. Peaking closer to the middle of that, or about 1000 rpm below yours.
Yours will always be faster if you rev it up. But if both of you shifted at 4000, then maybe not.

 

With so much talk about a big cube smallblock, I happened to stumble across this 406 cuin short block (4-bolt main) on the Raleigh CL and thought someone here might have an interest... Looks like it's located just NE of Raleigh between I-85 & I-95

406 SBC short block - $800 (Louisburg)

https://raleigh.craigslist.org/pts/d/louisburg-406-sbc-short-block/7019275328.html




I have a 406 SBC short block.It has around 500 miles on it.It is a 511 four bolt block.It has new Keith black signature series pistons with 5.7 bushed rods.It has a new cast steel crank with chamferred oil holes and lighting holes drilled in all rod throws.The block has been tapped for lifter valley breathers and deck plugs.It has a Melling oil pump and Clevite rod and main bearings.$800.

 

For a clever fellow who KNOWS what he's looking at ...& if truly is as represented ... Snap It Up!

 

Again....just do the 400.
AFR 195 st head or Dart equivalent, dont go nuts on cam overlap use your dual plane, 750 DP 1-5/8 headers that will be more than youll ever need.
No need to punch the throttle to push ahead of most people. Yes same stroke as 383 but that little extra bore on the 400 really makes a nice difference. It will last a long long time as youre keeping it under 6k so cast bottom end parts are ok.
HEI and a HP carb or at least a modern one with electric choke will make you happy. Doesnt sound like youre trying to extend your powerband so a single pattern cam ought to be just fine. If it were me a HR in the high 220/low 230 intake 112lsa something like that. Ramps designed not to beat things up but still enough to make power. Will still sound like a hot rod but not radical & have real good manners.
Call Chris Straub he can get you the right one the first time as lsa isnt something you really choose
straub technologies dot com

Another route if you can spend a little more is a mild 400 with a small st blower. Talk about massive part throttle torque! Those things work great.

 

I've read through this thread. If you don't ever want to exceed 5000rpm, then you want to build an engine with a horsepower peak around 4500rpm with as much hp as possible to get best use out of it. 180 heads should be fine regardless of capacity and will give you the most of what you want. As others have said, a short duration higher lift cam is what you want (hydraulic roller will be best for what you want I think). And displacement, especially stroke, the bigger the better for the down low punch. Having said all that...

You keep speaking about low rpm, but a couple of times you mentioned not wanting to have to push your foot to the floor and having heaps of torque/hp at low throttle. What you are talking about here is response. I think maybe going to a fuel injection setup that cracks all 4 barrels at once would give you what you are looking for - they offer huge response with the throttle just barely opened, and you have to modulate the throttle carefully - to the point that many people dislike them and go to a progressive linkage instead, but personally I love it. I have Fitech on my car, but there are other systems too (Holley Sniper etc). I wonder if this is actually what you are looking for.

 

P.s. If anyone doubts that 180cc heads will be plenty at that rpm, as I've had my engine apart I recently measured my heads. I hadn't measured the intake runners previously as I got the heads and intake off a known engine (10.3 compression ratio 383 with hydraulic flat tappet that ran 10.9 @ 121 repeatedly, bracket engine) that I knew worked, and I could see they were ported, and so I didn't worry about it too much. I didn't have history on the heads, but I've been spinning them to 7000 regularly on my 388 still making power, best shift point around 6500. Not dynoed but all performance measurements have pointed to a bit over 500hp at the engine. Anyway, the engine is apart and I'm looking for improvements, so I measured the intake runners. All 4 that I've measured are just over 170cc... Yes, I'm going to a bigger head because I want more hp and I'm happy to rev the engine harder to get it, but often small ports work better than they're given credit, and they are ideal in an engine where low rpm power and response are the aim. There's plenty of videos of my car on the track on YouTube if anyone is doubting its performance with those tiny heads...

 

thanks metal head. If money was no object, and I didn’t already own the 180 heads, would you still choose those over say a AFR 195? I may just try selling my 350 as a complete engine with the AFR 180 heads, and if so would need to buy new heads. Or would the 180,s actually be better than the 195 heads for my application.?

 

I'd have to do some simulations to be certain, but yes, if you don't ever wish to rev the engine above 5000rpm then I suspect the 180cc heads will probably be ideal. They wouldn't be my choice, but I have very different criteria. Again, consider whether it is actually part throttle response that is your aim rather than low rpm full throttle power too.

 

Someone wanting a 400 to make more hp and torque up higher then you want a 195 head would actually be considered a little on the small side. If you use the Wallace racing calculator let's say you wanted to build a 427 and have it make the most power it can clear to 7000 rpm. It should have a minimum cross section area of 2.43. To accomplish that you would have to use afr 245cc head. You will be fine with either a 180 or 195 head, but if you do decide to sell the 180 go for the 195. Only thing that can mess you up is the wrong camshaft it's the brain of the engine. If you work with straub or mike jones they will put you on the right path for the camshaft no doubt.

 

there are futurity races for younger horses

ho hum, seems this is a slog to futility

 

What title will find the Youtube videos? Thanks


And to the OP...Flyboy...don't get discouraged. So many variables tossing around while trying to define the actual usage of the engine can be frustrating.....I know, I am.....

 

This should work: https://www.youtube.com/playlist?lis...UYyXlIChIKyeiQ Alternatively google "metalhead 140 youtube" and you'll find the channel.

 

I guess we know you were having fun ... door key stretched out nearly ninety degrees from column

 

I remember one of the rally videos you posted awhile ago.
Nice to see these others.
Chasing the Audi was cool.....was that a turbo?
Your car definitely handled the curves as well as he did.
Thanks