I have read lots of threads on big inch big blocks, but am starting another one. I have some threads going now about my quality built 350 with oil in runners and the engine for sale in classified, so I have decided I am building a big inch small block. What I want is big block torque, and really do not care about HP numbers at 6000 RPM. I want an engine that pushes me back in the seat with factory 4-speed WITHOUT having to go to 5000 RPM to do so.....I want it to happen at 2500-3000 RPM, which I gather a real big block does.

I have already decided a 383 will not do it, so I start at a 406. But there is something desirable to me to go to a 427, just because of the number! What my question to all of you is, what is the downside to stuffing a 4.0 inch stroke into a SBC? But there are some requirements......I need the engine to be reliable, and have longevity to take it till I am done. I am 61, plan to retire at 66, and I do not want to ever have to remove it and rebuild it again. I drive 5000-6000 miles a year, and when I retire I hope that number goes up. I want the engine to outlast me. So with those qualifications, does a 427 fit? Does the higher piston speeds wear the rings faster? Does the reduced compression height on the pistons (just over an inch) cause issues? Does the large stroke crank cause issues with the oil, as I understand I will need an oil pan with kickouts and scraper. What other considerations based on this would make a 427 a bad idea? What else? Talk to me.

Please don't start, as always seems to be the case, with the inevitable thread direction of going bigger and bigger and bigger. I will not go over 427 as I already think it is too much. I want bottom end torque, not an engine that wins a drag race or even a street race. I need it to be a well mannered, street friendly engine. I would consider a real big block, but just don't want to go there, and forget an LS engine. I enjoy the appearance of my car being original, and will not make upgrades to 5-speed transmissions, big blocks or LS engines. I have 15 inch wheels, manual steering, 355 rear end, love my factory 4-speed, etc.

Lastly, I am getting the engine dyno'd before I install it, so I am looking for someone to build it this time, rather than do it myself. The problems I am now having with my 350 really have frustrated me, because I am worried I did something wrong. While I have 40 plus years of mechanical experience behind me, I am by no means an engine builder.

 

consult tpi421vette in the c4 tech he doesthem all the time for guys here, afr dealer also
He has a street driven manually shifted sbc that runs 9s..right air may even crack an 8.
He can get you something that will do what you want and wont take your retirment.

 

OP FB
? Why not put your city in your visible profile ? ...

With that, someone might suggest a competent builder in your region.

 

I am no expert, but... From what I have read and seen, I think a 427 small block is doable. Those are readily available from the major crate engine manufacturers. I think that would be a great option. I went with a 383 but a 427 would be better. I would think you would want really good bottom end, and possibly start with a quality block like a Dart or something. What's your budget?

 

I built a 434 for my 69 4 years ago and have been averaging about 4000 miles a year on it. It's turning a 200r4 in front of 3.08 screws and like you I didn't care about high hp numbers at 6000+ rpm. I don't thing the engine has seen 5000 rpm, but when I want to pass some cars it steps right out, can't say if I ever pushed the pedal all the way to the floor. I'm 65 and expecting this engine to outlast me. The short block was machined, clearance, and assembled by a local speed shop [C&S PREFORMANCE], it's a stock 400 block bored .040, 4-bolt studded mains, all forged internals with a custom ground roller cam to deliver low end torque Crower lifters, toped by Dart 195 heads. This past year it was treated to a Holley Sniper system and runs so smooth you can almost stand a nickel on the air cleaner when the engine is idling. One of the things I like the most is when I walk behind the car the exhaust ruffles my trousers, first one pipe then the next. The 434 sure has made the car fun, good luck with your build. T

 

You can buy 454 SBC's If I had it to do all over again I would have bought the 4.125 stroker crank and built a 441 or 447. I also like the 3.875 stroker 4.125 bore Dart SHP blocks. You put in a H-roller cam and have a very powerful motor. That could be made to peak at some lower rpm.

My 7500 rpm 434 has enough TQ that if say I was cruising down the freeway at 2000 rpm in 4th gear. I can just floor it without shifting down and out accelerate 95% of the cars on the road. I have the 5 speed od and rarely shift down.

 

Couple more qualifying statements for my questions.

My car has 355 rear end, Borg T-10 4 speed manual transmission, and I am running YJ8 factory aluminum wheels with 15 inch 225/70/R15 tires (currently Coopers). I had 255/60/R15 tires, and I did not like them. I have no interest in changing any of these items with an big inch SBC engine. I understand these are limitations. I also want to the car to idle at 800, without issue. It can be rough, but I don't need it rough and I don't want to have to set it up at 1000 RPM to run. With all this, will a 427 be too much....? Will I have be careful shifting to avoid spinning the tires? Any torque past spinning these tires makes it worthless to me. I also rarely exceed 70 MPH anywhere, so speed is not my goal nor relevant to me. My goal is about pushing me back in the seat so the car feels like a performance car, under 70 MPH, instead of just making a bunch of noise, as my current 350 does.

The forum is always the same, everyone wants to go big, no matter how I try qualify my needs in the engine. So please comment based on me, not you. I want low RPM big block torque, i..e from a standing start, in first gear, push the pedal down, and NOT have to floor it, I want the car to move immediately, and accelerate quickly WITHOUT having to wait for it to rev to 5000 RPM to accelerate. My wife's 4 cylinder Toyota Camry can go fast if all I do is floor it ever time. To me, that is not performance. Then second gear should launch it again after a shift at 3000 RPM. Same with third, and by then, I am going well past the speed and as fast as I need to go. Each shift should push me strongly back into the seat without every seeing 5000 RPM and should scare me with the acceleration. I cannot get people to understand this and maybe I am the idiot and do not understand this is not possible. And maybe its not possible with an SBC. Maybe I need a BBC. So with that said, what do I need to do considering my limitations.

Will my AFR 180 heads and 1-5/8 inch exhaust do this on a 427 SBC? Skip White says it will give me exactly what I want. I expect the response here to be same as always, AFR 180 heads are only good for a 350, and I need at least 220 head on a 427. Again, .......not what I want to spend money on, and not interested in going 100 mph. I want acceleration.

 

Why did you not like the 255/60 tires? Just curious.

The 225/70 tires are one inch narrower so those might be more prone to spinning with a 427.

 

Its mostly just about how they visually fill the wheel wells better, plus I feel the ride is better over the rough western PA roads. I know all about how they do not perform as well with the supposed sidewall flex, but the car just felt better on the 70's. And while I enjoy spirited cornering, the 70's do just fine for me on the roads I drive. I am not trying to win any races. If the day comes the 15 inch tires are no longer available, I will step up to 17's with tires of the same diameter.

 

First off, I don't know how to do that. But anyway, its Western PA near Pittsburgh.

 

Same window you entered your gender ... we don't wanna know where you reside ... just enter Western PA ... close enough

 

lol just drove through that area yesterday visiting my stepson in Waynesburg.

 

I had a 427sbc making 623hp, 557 lb-ft torque in my 68 camaro for several years, big torque jump from the 358 I had in it before (540hp motor). Both motors had pretty agressive roller cams in them so the power was more in the 3000-6500/7k area but the 427 would do 2nd gear rolling burnouts where the 358 wasn't anywhere near as scary. (Currently the car has a ls7 in it making similar power on a much milder hyd roller cam).

Lessons learned-- I had trouble with an aluminum block where the sleeves were not long enough to stabilize the piston at the bottom of the stroke. 4" stroke and 6.0" rods do make for short pistons but in a steel block they seem to run fine. A taller deck would help this.

A few minor things to remember like needing an oil pan with clearance notches for the rods. A big roller cam gets really close on rod clearance so sometimes they use a smaller base circle cam. As far as ring wear it shouldn't be any different/worse than the LS7 (same bore/stroke). I sounds like you are after a low end stump puller for that instant throttle response so as long as you are willing to give up the high rpm area (say over 6k), a hydraulic cam will be fine and easier to live with. Cam and head selection are going to be critical, but I would not use the 180's on that large of a motor. One of the big advantages of the larger bore is unshrouding the valves and allowing bigger valves, 2-1/8 intake 1-5/8 exhaust etc, but a cnc ported 210 or 220cc head would be good with a performer air-gap intake again for torque. I'd also really consider efi for the throttle response. -Dan

 

I'll add two cents....avoid at all costs 400 cu SBC's with the siamesed cylinders....Chevy's darkest moment right there!

Unkahal

 

Low profile sidewall tires are nice for good handling the downside to that shorter sidewall height is they hurt ride quality. For what you describe you want the engine to do the 180 afr head is fine. Sbc factory blocks any of them were not known for thick cylinder walls. If you intend to really make this engine last buy an aftermarket dart block. Longer the stroke the more tq at lower rpms so go long stroke at least 4.00. Hydraulic roller cam will give you a much wider power band then a flat tappet cam. These are all things you can do to maximize the torque at low revs you want. Use a spread bore carb.

 

The block will be a Dart SHP, no matter what size I make it.

 

Granted, OE 400 have some shortfalls but they can make a stout motor ... $aftermarket 400 blocks$ are better ...
... both Le Mans champ C5R blocks and LSx blocks ... both also have siamesed cylinders .

 

The block will be a new Dart SHP, no matter what size I build, and will be a hydraulic roller cam. My concern are the compromises a 4.0 inch stroke requires, like a very small compression height on the piston, including the piston pin bore intersecting the oil ring land, the poor rod stroke ratio, the high piston speed that has to be a wear factor, and all the required clearancing, including a small base circle cam, which apparently is hard on the lifters. And if I took a poll on this forum......putting AFR 180 heads on a 427 would not be recommended by anyone. I have people telling me AFR 180 heads are too small for a 383.....!

As for the tire sidewall comment, I agree, but many people on this forum swear its the way to go......but its not for me till I have no other choice.

 

Thanks, I PM'd him.

 

A longer rod length-to-stroke ratio is generally considered an improvement and desirable.

A block with a raised cam helps resolve most any small base circle dilemma.

But if you're just gonna putt-putt around on skinny tires ... this looks more & more like an exercise in futility.