Not sure what you mean by "rarely done". They're built all the time - they just don't get featured in magazines as they're significantly more expensive to build and there's less aftermarket support (*cough* ad revenue *cough*).

Regarding high RPM, the factory heads don't support it (and the ProComp/Edelbrock castings flow the same), the mains are huge at 3" diameter, and the rod journals also large at 2.5" diameter. That leads to some very high bearing speeds when you try to spin them up. They also tend to have long intake runners at a relatively flat angle. Given the limitations of the design, people build them for low-end power, quite successfully (when not set up with tight Chevy bearing clearances).

Finally, 455 is not the only Olds big block. A 425 Olds has a 4.126" bore and a 3.975" stroke. Unlike the 427 SBC that almost perfectly matches that though, the Olds does have a much taller deck height, allowing a longer rod and more compression height.

Still, this seems to be more the OP's speed: https://www.hotrod.com/articles/ccrp...elbrock-heads/

Good low end power, good street manners, no need to rev high. I didn't spend a ton of time, but I did dig around to try to find a similarly built Chevy - no dice. They're all spinning 6000-6500 RPM and set up far more aggressively - even the "street engines". So looking at the above build, you don't need 220cc heads - those Edelbrocks on the Olds are 188cc, and I'll pretty much guarantee the OP's AFR heads flow much better at any/all lift. You don't need a ton of lift or duration (though I'd definitely bump up to a modern roller cam). You don't need a tunnel ram - a performer or performer RPM will do fine.

Using that Olds as a template, the OP can use the better Chevy parts available and exceed that engine's performance in the RPM range he wants to settle in.

 

Considering its displacement class, Buick 455 is comparatively light.

 

Ignore the 7k dyno sheets they are not good st motors...got one
Look up tpi421vette in the c4tech sec he can make this easy for you. Does em all day do it right the first time and no corvette tax
Dyno sheets dont mean much on the street.

 

You will have good torque at low rpm and it will accelerate well with a low RPM engine. What I am pointing out is the most torque you can expect is 450 to 500 ftlbs out of a low RPM 406 to 427 CU engine. That will accelerate the car but if you are going 40 MPH and want great acceleration it will not happen at 2000 RPM because the gear ratio will be to high at that low RPM to allow great acceleration. If you downshifted to allow the engine to rev to 4000 RPM it would be great acceleration (4000 RPM is still low RPM) Any of the big cubic inch engines can be built to make good torque at low RPM like 2000 but the limit will be around 450 to 500 ftlbs of torque and that may be exactly what you want. It will climb hills and pull away from stops with no issues.

 

 

[QUOTE=CSIROCZ;1600493467]Not sure what you mean by "rarely done". They're built all the time - they just don't get featured in magazines as they're significantly more expensive to build and there's less aftermarket support (*cough* ad revenue *cough*).

Regarding high RPM, the factory heads don't support it (and the ProComp/Edelbrock castings flow the same), the mains are huge at 3" diameter, and the rod journals also large at 2.5" diameter. That leads to some very high bearing speeds when you try to spin them up. They also tend to have long intake runners at a relatively flat angle. Given the limitations of the design, people build them for low-end power, quite successfully (when not set up with tight Chevy bearing clearances).

Finally, 455 is not the only Olds big block. A 425 Olds has a 4.126" bore and a 3.975" stroke. Unlike the 427 SBC that almost perfectly matches that though, the Olds does have a much taller deck height, allowing a longer rod and more compression height.

Still, this seems to be more the OP's speed: https://www.hotrod.com/articles/ccrp...elbrock-heads/

Good low end power, good street manners, no need to rev high. I didn't spend a ton of time, but I did dig around to try to find a similarly built Chevy - no dice. They're all spinning 6000-6500 RPM and set up far more aggressively - even the "street engines". So looking at the above build, you don't need 220cc heads - those Edelbrocks on the Olds are 188cc, and I'll pretty much guarantee the OP's AFR heads flow much better at any/all lift. You don't need a ton of lift or duration (though I'd definitely bump up to a modern roller cam). You don't need a tunnel ram - a performer or performer RPM will do fine.

Using that Olds as a template, the OP can use the better Chevy parts available and exceed that engine's performance in thesengine RPM range he wants to settle in.[/QUOTE

 

...so you’re just going to ignore the 425 with almost the exact same bore and stroke as the SBC 427...

As I said, the 455 is not the only big block Olds...

 

I hear what you are saying about wanting torq. That’s the big reason I went with a 427 sb. However, I did overcam it when the shop got 1.6 ratio rockers by mistake and I told them to go ahead. I’ll likely downgrade to 1.5 ratio this year and will likely pick up a little hp and tq. I think the cam is too much for my 210 cc AFR heads. I should have gone much smaller on the cam. Solid roller, 630 lift, 250 deg. at .05, 111 lobe separation if memory serves.

regardless, I would still get as many cubic inches as you can afford if you want tq. For a 5000-5500 rpm peak ho motor I think those heads are fine but frankly if you ever want to upgrade you can easily upgrade the heads, but not the lower end. Also, afr might be able to port your 180 heads for a reasonable amount. Might be worth asking.

 

Also, I got the Scat I beam rods with 7/16” bolts. I think they were around $300-$400 and are commonly used in striker motors. I’m not sure about how much modification they need. I think they were rated at 750 hp. Mine is a Dart Little M block so it’s a different casting than the shp you are looking at.

 

what I said had nothing to do with old-mobile engines just used it as 1 example that's well known undersquare, my point was engines are rarely built under square. The olds engine has over a 10.6 deck and 6.73 length rods. Putting a close to as much stroke 4.00 crank in a block 9.025 deck and 6.00 rod length not really good. The olds did not have muniscule compression height pistons, rods rediculous short in length for stroking something. You could never compare the olds with 3.90 stroke or the 4.250 stroke to a 427 sbc build. They sure as hell did not try to stuff even a 3.90 stroke in a 9.025 deck height block. When chevy decided to build larger engines they increased the deck height to 9.8 even for 3.50 stroke 409s, increased the bore centers. All was done for good reasons.

 

Found this below on Z28 forum....and pretty much supports what I have been trying to do

Lingenfelter was right...

For a street car, torque is king, period.

What we need to bear in mind is that a 195cc intake runner head is actually a pretty large head for a typical street 350. If it were me I would opt for the head with the highest flow #s with the smallest intake runner. High-velocity airflow makes all the world of difference when it comes to throttle response and low to mid-range torque, and that makes the car fast on the street and fun to drive. For that purpose and your compression ratio, I would opt for the 180 heads and a smaller cam, like the XE 262. In my opinion the car will accelerate harder and have better throttle response than the 195 head with the XE 274 cam.

What Lingenfelter always stressed -- and where 95% of guys either fail to appreciate or just lack the knowledge -- is that torque is king especially for a street car. You design the engine for what you will be doing with it 90% of the time -- and most guys are not winding the engine to 6000+ RPM in that 90%. If you take two engines of 350 ci and both have that same 9.5:1 compression ratio and 3.73 gear -- the quicker of the two will be the engine with the smaller heads and cam.

Back when Lingenfelter wrote that book -- which I bought years ago and have read through numerous times -- AFR, Brodix, etc heads were all around back then. What John did was try to educate the reader in just how important designing the engine for the intended purpose really is. He was using his considerable experience and knowledge to try to educate the reader into the reality that high-RPM parts -- ie bigger is better -- does not work nearly as well as the properly matched components working together. Even with so-called 'better' heads available, JL would use factory small-port heads like the aluminum L-98 head, port it, and build very powerful street 355 and 383 ci small blocks with nearly big-block torque #s. As a result, whenever the magazines did road car comparison testing, his cars usually either won or were near the top in performance -- and usually if beat, only by a small margin and by cars with much more $ into them. He would regularly allow his 383 and 355 LT1 Firebird and Z28 Camaro street builds to go up against forced induction cars and he would still beat them. In the Silver State Classic many years back, he raced his late 1980s-era Corvette with a 406 and SuperRam intake to well over 200 mph. The engine made so much torque it literally melted not only the built 700R4 transmission behind it, but also the Gear Vendors overdrive unit behind that.

 

ya street cars are heavy in comparison to race cars and have compromis built into gearing, so torque more needed for most of them.

 

One minor thing you failed to notice with his builds and Superram, he considers low RPM to be 6000 and less. the superram is designed to operate from 2500 to 6000 RPM making the most torque at around 4000 RPM and HP around 5500 RPM. The RPM you are discussing is 2000 RPM.

 

The main point was that "torque" is what matters on the street, and the recognition that high RPM driving is for race cars, and only hurts you on the street.

 

Yup! Ligenfelter was right! Engine math 101.... Torque and HP rotate around a 5250 RPM point. To gain on the high end...you have to give it up on the low end....and vice versa.
The OP prefers to build TQ under 5000 rpm because he never revs it higher than that. . So if we lift the whole TQ curve in that area, we hurt the top end, but we strengthen the amount of TQ right off idle. So as the 6000 rpm power drops, the 2000 rpm TQ increases. And at 3000 and 4000 and 1000.

No it's not racer fast, but it feels strong at any speed, cause you are always driving it 90+% of the time near the TQ peak. Or at least closer to the TQ peak than say an LT-1 with a 4800 RPM TQ peak. Don't get me wrong, I love LT-1s, I had one for 27 years, but it's not a motor you can comfortably cruise around on in any old gear, you have to keep the revs up with it. From 3500+ up it's greaaaat. Under that, not so much. Don't get caught in the wrong gear with that one, I did many times. By the time I downshifted they were gone... At those lower RPM levels my 300HP 350 would leave it in the dust! BTDT. And even tho it felt waaay faster than a 300hp, it wasn't really, it was a little faster, the ET didn't really drop all that much, because the overall TQ wasn't all that much different, only the RPM it hit at.. 97 MPH qtr mile vs 104 MPH qtr mile, about a sec ET. but the 300 hp SS 350 was a terrific everyday cruiser, that was also pretty quick. With a mild-*** 195/205 duration factory cam. Not so much the screamin' Z28 with 242/254 dur. factory cam.

Not everybody wants the fastest possible XYZ. Some people just want to cruise comfortably, and have it still GO when they punch it. Without having to worry to much about what gear they're in or how much RPM they've got up.

Honestly I think a Buick (or Olds) 455 would be perfect for the OP, but that would look a little strange in a Vette. The real problem here is his original "engine builder" built him an engine that doesn't fit his needs with a 6000 RPM 350, that peaks around 4500, shame on him for not listening well enough.

How about all those guys that drive stock 270/300 hp C3s? They like them. Are they all wrong too? This med-perf 427 version will be way stronger than any of them, and just as easy to drive.

By far the easiest to drive... but faast street car I ever driven was a wheel-standing Corvair with a W-30 455 OLDS in the back seat. Drove like Ma's station wagon, and quiet too, until you floored it! ....Killed everything on the street by several car lengths in the first block. Yes on real street tires. ...Nothing ever caught it. ...But it was never on a drag strip even once. I wonder what that thing weighed ... maybe 2700lbs? With what 530 ft lbs?? Almost at idle? Shifted at 5200 rpm BTW. I lusted after the Baldwin Motion L-88 engined 72 Trans Am street racer waaay more, but guess which one cleaned who's clock? By several car lengths? That race-cammed tempermental SOB made all the right noises tho, and ate transmissions, rear ends, mufflers,belched fire and melted hood scoops off...all before lunch.

 

Pretty clear you're focusing on the wrong thing over and over again. No one on this forum gives a crap how an Olds bottom end is built. The only thing anyone here needs to understand is that it is fundamentally limited in RPM potential, meaning all builds of the engine focus on low RPM power. In other words the engines are built exactly like the OP wants - lots of low RPM power. So you look at the heads, the intakes, the cams - all things you can easily find a similar part for in a Chevrolet style. Building a Chevy bottom end for just about any displacement is as easy as picking up a catalog, so why focus there at all?

This is a MUCH better approach than looking at the obnoxious number of high RPM Chevy builds that dominate magazines to generate the high power numbers (at equally high RPMs). That is much better than the people on this very thread saying 180 cc intake ports are too small to support 427 cid.

TLDR - Chevy engines aren't typically built for low RPM power, so look elsewhere to see how it is done.

 

I definitely wouldn't recommend he build a BOP 455 - they're far more expensive to build than a Chevy, and will most definitely be more difficult to put into a Vette. That said, what the OP wants so obviously fits that bill it is hilarious to those of us with experience with high performance BOP engines.

I completely agree - a 350 built properly should have given him what he wanted. It is a shame that his builder, and so many on this thread, seem too stubborn to even listen. We've become so saturated with big numbers in magazines, on dynos, and at the drag strip that it seems many people forget the awesomeness of a healthy street engine.

 

Yes it should have. And he can reuse half his parts and gain 75 cu in and 100 ft lbs if he so chooses. Pretty good $ return vs starting all over.

 

I just got the (not optimally... heads are too big and cam is older design and probably too big as well) built up 350 in my wife's 76 with a TH350 and 3.08 (I'm assuming) rear gears and 225 tires running right. When floored from a dead stop on dry roads pointed straight, it will occasionally chirp the tires. If the wheel is turned, the wheels definitely chirp and I haven't taken it beyond that. I haven't tested it on wet roads, but considering it's at the limit of traction on dry roads, I'd guess there'd be some wheel spin.

I daily drive my 79, which has a 4-speed (currently close ratio with 3.73 rear gears, but gears 1-3 are exactly the same final ratio as the wide ratio and 3.36 that it used to have), a 350 with AFR Eliminator 180 heads, around 9.5:1 compression and a Lunati Voodoo 268 flat tappet cam, and 255 tires. If I drop the clutch at around 3,500RPMs, the tires will spin. At the drag strip, I made one pass smoking the tires through 1st gear. The engine will pull to 6,200RPMs (though power falls off around 5,800RPMs now that I run manifolds instead of headers), but it will idle steadily at 500RPMs. I've started from a dead stop on a slight incline in 4th gear with no problem. If the roads are wet, I drive pretty cautiously, as I've accidentally spun the tires on wet road accelerating from a dead stop.

I have a Buick GS455 with a 455 built with a torquey cam (rated to 5,500RPMs if I remember correctly), noticeable idle, 2.73 posi rear gears behind a TH350 (it was a small block car and we kept the transmission) with 255/60R15 tires. The engine is built similarly to how you say you want your big SBC to be built. If floored form a dead stop on dry roads (foot nowhere near the brakes), the tires just spin. The car doesn't really even move. If the car downshifts into 1st at speed when floored, it will leave two lines and some smoke behind it. I actually wrecked the car a few years back. I was merging onto a highway, pressed the gas a bit as I checked my blind spot, and didn't feel the transmission downshift because it just started spinning the tires. I started merging and the car was sideways before I knew what had happened.

You're right that torque beyond what the tires can handle is useless on the street, yet you seem to describe wanting an engine that will make more torque than your tires can handle. I might build a 383 if any of my Corvettes need a rebuild next, but I'm not sure how far beyond that would really make sense. A larger engine like a 400+ would probably need a cam geared towards top end horsepower to avoid wheel spin off the line, which defeats the purpose of getting a big displacement engine for lots of low end torque.

 

I understand what you are saying, as there is a point where an engine is just too big for a car. Based on nothing but what people say on forums and reading magazines, I believe anything past 427 is too big. I like my 225/70/R15 tires for the bumps of PA roads, and have no intention of "improving" my tires, so I do absolutely have a traction issue with too much torque.

However,......your post talks about "flooring" it. This is exactly what I do NOT want to have to do, to make the car accelerate quickly. So, with a big torque engine, you have to control yourself and learn to drive the torque appropriately. Learn what it takes to spin the tires, and then back off slightly,......so once the tires do grip, you can truly launch......WITHOUT having to resort to massive RPM. And primarily, I am talking about first and second gear on a manual,.......after that, I understand RPM will keep you moving. My 350 is built well, and in my opinion its no better than my wife's four cylinder Camry......if you floor it, it goes, all with a bunch of noise and abuse to the engine......woo hoo!