Hey All,

I am finally getting ready to build the big inch small block I have always wanted. Lost or research and reading all over the place and years of getting into this position but I still have some questions. I was looking at some crate engines as there are several companies out there building these things in the specs that I want however, there is a lot of good and of course bad reviews. Understanding that is the case anywhere it just makes me uncomfortable spending this kind of money on an uncertainty. I thought about building it myself but I understand what I don't know and decided to let a buddy of mine that's a builder/racer do it for me. He's in my back yard and I can trust him so it gives me a level of comfort spending this kind of money.

I know there is a handful of you guys with these big inch sb's and I am curious about how they have been holding up, what kind of driving do you do? Discussing the build with my buddy he stated potential issues with valvetrain longevity due to the aggressive cam that will be in it along with a lot of stroke. He also suggested looking at an LS swap since the platform is just better in terms of design and effcicentcy. If I did an LS it would be a stroked LS3 to 416-420ci.. I do like the idea of shaving more weight off the car with an aluminum block and LS's do make some power however I want to keep the car old school.

Here is the build layout for a sbc, it will be a Dart SHP block, of course all good components and anywhere from 12:1 to 13:1 cr to make the power goal. I will use the AFR 245 heads with a solid roller cam. From what I have seen shaft mounted rockers, off set and a .903" lifter is needed. Cam specs will be determined once we decide to go this route. Haven't decided on going FI or carb setup but leaning to a crab for the "old school" appeal.

The car is not a driver, this thing sees less than 5k miles a year really it maybe sees 2k. It is driven to put around town, car shows and then hit the drag strip. It will be pushed and built to rev 7k so its 100% a street fighting toy.

If the biggest issue is adjusting valves a few ties a year for maintenance that's not an issue as I do that now with the current setup. I am more concerned about it eating cams or any other issues that may arise from a build like this. All the "issue" related things I can find in searches revolves around using the correct block, rods etc for the big stroke. Of course other discussion on having to use a small base circle cam and smaller lifters but I think that's covered. Anything else you guys are seeing? As stated this engine will be pushed and not babied but its not seeing hwy miles, the car never really gets driven more than 45miles at anytime just short drives and burst and then of course dragging.

Thanks for the input!

 

My 440 sbc is built similarly to your goals and usage. What is your horsepower goal?......that would determine some things in your build. Auto trans or manual?.........need vacuum accessories to operate ok? Also, 12:1 to 13:1 is an in-between ratio nobody really wants. That is because it is not pump friendly (requires race gas) so you might as well do 14:1 for full power potential. Mine is just short of 700 hp, but at 11:1, uses pump gas, and is street friendly.

 

looking to make 700 with this combo, Schafiroff has one making 700hp with pump gas and so does CnC motorsports so the power goal is not out of reach. I do know that both of their builds making this power on pump relies heavily on the cam, CNC does list this their specs. I'm not concerned about pump gas usage since the car is a hot rod street fighter, it can run on fuel for the amount it gets driven. The car will be a manual using a G-force trans which is about the only thing that will hold up from what I have researched. If I for sure go this route we will spec out the cam for the needed power along with needed compression, there is no vacuum requirements on my car, its about as bare bones as it can be.

how long have you had your combo and what cam do you run? I am mainly concerned with the valve train making this power as I am comfortable knowing the bottom end will be solid I dont for see any issues there. Its the top end that has me raising questions.

 

I've had the present combo a little over 2 years now, and before this one I had a 427 sbc with 628 hp. built in 2009. Both similarly built, with Crower Stainless Steel shaft rockers (don't skimp here, get the good stuff). Lock 'em down once and you will never have to adjust them again. (At least I haven't had to).......I check them once a year and they have always been spot on......street driving friendly, though I don't put many miles per year on the car. Actually, 700 hp for the street relies heavily on the heads, then the cam doesn't have to be as radical, keeping the horsepower peak below 7000 rpm. A 700 hp 11:1 compression engine is just as quick as a 700 hp 14:1 engine. Check out my signature for cam specs and car info. The 628 hp engine went 10.40s at the strip. This current combo definitely feels quicker, though I haven't strip tested it yet. I went with a locally known good engine builder also, rather than buy a crate, and I'm glad I did. It makes it easier to personalize your build. I made 2 concessions on my build from the original plan....1, shorter intake because of hood clearance, and 2, slightly milder cam for more vacuum. Good luck with your build!

 

Looks like you have a solid build, I am also looking at a little more stroke to go 440, figure why not if there is no real downside. Did you consider the AFR 245 heads? It seems that is the head of choice for most all the 700hp crate engines I have seen. Sounds like the maintenance is about what I do now, I check my lash a few times a year and very rarely have to make adjustments. I will absolutely go with goo rocker shafts and don't plan on skimping anywhere. As stated I have a local builder that is going to do this for me, I have a power goal of 700 as that's what I figure its gonna take to go 10.0-9.9 in the 1/4 basically I need 620ish whp. I do see that several crate engines offer this power in a pump gas engine but they also state running some good fuel when racing, these engines are 11.5:1 and of course do not state the cam specs which is the magic.

Glad to hear you have not had any problems, like you my car does not get driven a lot, when its nice out it will get used most every weekend but its little short trips and then to the strip. What are you twisting the engine to? If i can accomplish my goal on pump gas I think it will also help heat issues versus a 14:1 build but again for the amount it gets driven I'm not concerned with running some fuel in the car.

 

You may want to consider an iron eagle block with a raised cam tunnel to get away from small base circle cams. That would most likely give you the valvetrain stability you are looking for. You can also get custom cam journal bores going that route.

 

My engine's horsepower peak is 6500 rpm, and torque peak is 5000 rpm, (the previous 427 sbc peaked at the same rpms), and I shift at 7000 rpm. I have an auto trans, so a 4500 stall converter works nice for street and strip. You can only put so much cam in an 11:0 c.r. engine, so really no magic is involved for an experienced builder. Your compression ratio, your desired hp peak, and your heads/intake airflow will determine the cam specs. 14:0 compression can take more cam for more power but will peak at a higher RPM which may not be wanted on the street. I personally like my 700 hp to be under 7000 rather than 7500+ for a street engine. I considered AFR 245 heads. Both Dart and AFR are excellent heads and either will work as well. I got Darts because my engine was built by Box Performance, and Gary Box is a head porter, whose CNC program is used on the Dart/Box 245 Pro 1 heads. He personally did the finish porting and testing on his flow bench......and, yes, they flow better than AFR's advertised specs. Box also customed the cam for this combo according to what my driving would be. (I wish now that I had went just a bit more on the cam, as there were 2 choices considered and I thought about vacuum and chose the milder one !)

 

you know I never even thought about that block and I don't know anything about it as I have never looked at it but you make a good point. However, most all these crate SBC,s run either the SHP or the Little M which neither have a raised cam tunnel I believe. Curious to know how those engines hold up running the small base circle cam, they are basically what I want to build but as I've stated I am curious on the longevity.

Thanks for the tip, I will look into the other block and see whats the deal with it.

 

I will let my builder figure out exactly what is needed, I am just trying to educate myself as much as possible to fully understand what works and what doesn't. I have read pretty much all the threads on this forum and others regarding big inch small blocks and some of the info is conflicting that's why I am researching. My builder is also friends with Jon Kaase who is also a well known head guy, as a matter of fact Kaase is the one who ported my current heads on the engine I built 16 years ago. He helped me spec out the cam i used in my current build and I will let the pros spec everything out on this build I just want to fully understand what is going on. I have read lots of posts stating to use the SHP or Little M and other say not to when running 4" stroke or bigger, same conflict with small base circle cams as a lot of these engines do which is why I posed my original question.

I will keep digging, thanks for sharing info!

 

I know there is a handful of you guys with these big inch sb's and I am curious about how they have been holding up, what kind of driving do you do?

I started with the Motown SBC block. 427 ci 4.125 bore and 4 inch stroke. If you attend any circle track racing where all the cars are 800+ hp they are all running 441-447 ci with 4.125 bore and 4.125 stroke or some bored out variation. My crank shaft with 400 mains was over $4000 about 15 years ago because I broke my original Eagle lightweight forging with 350 mains. It my 4th refresh I think. 7500 rpm many times a day is hard on rings and valve guides.


Discussing the build with my buddy he stated potential issues with valvetrain longevity due to the aggressive cam.

My first 427 at a claimed dyno of 600 some hp had Motown 220 heads and a 242/248 Comp Cams XE solid roller. Even though it had a dyno sheet it just didn't have much more jam than my 396 with Dart 227 cc heads. Then I went to a 248/252 custom billet that I designed with engine simulation software. Then I was up against the 650 hp track queen Porsches and decided that "No more getting sand kicked in my face!" I had CC make me another billet steel solid roller of 252/256 with road racing lobe profile lifters and .685/.714 lift with 1.7 rockers. I could pass the lighter turbo Porsches in the tighter infield because of my now monster big TQ 434.


Here is the build layout for a sbc, it will be a Dart SHP block,

Entirely wrong thinking! Shp is kinda limited to 3.750 stroke. The smartest big SBC has to be the raised cam Dart blocks. In fact the bigger journal cam model. Stronger and no rod clearancing problems. Motown splayed cap blocks with the bigger lifter bores is an option. My motown is so superior to stock blocks. and with the ability to go to 4.200 bore you can make 454 small blocks

anywhere from 12:1 to 13:1 cr to make the power goal.

I have 11.7, but it requires some thought to run on 93 pump gas without a problem. Good cooling, well thought out ignition timing, thermal coated piston domes

I will use the AFR 245 heads with a solid roller cam. From what I have seen shaft mounted rockers, off set and a .903" lifter is needed.

All of us kinda use 227 - 235 - 245 cc heads, The smarter person would go to a spread exhaust port design head. Or even smarter skip right to 18 degree heads. But with a lowly 7000 rpm just spread port 23 degree heads is fine

Cam specs will be determined once we decide to go this route. Haven't decided on going FI or carb setup but leaning to a carb for the "old school" appeal.

Anything over 252/256 is too much with a 7000 rpm red line. But use 1.7 to get all the cylinder filling that you cam

The car is not a driver, this thing sees less than 5k miles a year really it maybe sees 2k. It is driven to put around town, car shows and then hit the drag strip. It will be pushed and built to rev 7k so its 100% a street fighting toy.

If the biggest issue is adjusting valves a few ties a year

other discussion on having to use a small base circle cam

Good valve trains rarely need adjusting. My cam base circle is something like .980 inch in diameter for max cam strength. I've driven my vette from Las Vegas to Chicago in one day straight through or smaller 1300 mile jaunts

 

Long as you use premium parts and the ramp rate isnt too aggressive it should live for a long time.
Shaft rocker are where its at that lash wont budge. If it ever did youll hear it...early warning system somethings up.
Dont skimp on lifters...looking forward to seeing this come together. Do like the 18 deg suggestion talk about big power.
Wish Id gone that route

 

I have a 421 Combination that makes 630 horsepower at 6800 rpm and is setup to take a 175-250 shot of nitrous like it isn't there. I like the 421 better as you can pull the top ring down .060 and though that is not a big number.....it is huge on ring longevity and heat. This is a pump gas combo too. 10.7 to 1.
As far as valvetrain goes....spend the money on a Jesel or T&D sportsmans system.....the shaft system adds stabilty which keeps frequencies from killing the valve springs. Trend .100 rad wall 5/16 pushrods and PAC valve springs and Isky Red Zone lifters......now there is some money there, but stone reliable. I keep lift in the mid/high .600's......you are not going to see huge gains with bigger lifts on a 23 Degree head setup.....just not enough ultimate flow.....not there are some whiz bang heads out there now that claim huge flow.....but at what cost? The intake width is the problem.....to make a port wide enough to flow.....you have offset the lifter and the rocker.....which the more offset.....the shorter the life of the rocker and ultimately the lifter.

Jebby

 

All, thank you for the info! This is exactly why I posted here because I know a lot of you guys have done this, and been running them a while. I am pretty sure I have read every thread on this forum about big inch small blocks. Like I stated before, most all these crate advertised 427,434's etc run either the Dart SHP or Little M block so I figured that works if these guys are using them and selling with a warranty. I will look into the Motown block as well as the Iron eagle for raised cam tunnel as you guys have suggested. I have thought about an 18* head but have zero experience with them, does the exterior demission's stay the same? I want this thing to appear as a "small block" and if I do stay with a 23* head with will for sure be a spread port design.

I am prepared for the expense as i know it will not be cheap but its what I want and I absolutely do not want an LS in the car. I was just a a local car show Saturday at the local Summit and there was a lot of cars with LS power in them. I know they are efficient and make a ton of power but it just doesn't look right. Plus I think the extra cost in swapping this thing to an LS will equal the additional cost for building a solid big inch sb and it will drop right in the car without any modifications except for headers.

 

Right in the SHP block directions and disclaimer it says "Max Stroke 3.750" While working at the race shop it would take me about 6 hours to hand grind and clearance the pan rail for a 3.875 crank with big "H" beam rods. Including running it through a wash cycle to get all the metal out in the block cleaner machine. I also had a spare 3.875 forged crank that I wasn't worried about. You have to grind down the bottom pan rails for all 8 cylinders rod bolts. Going to 4.00 stroke would just mean taking off even more material. But I thought about setting another block up on a vertical mill after I did the first one by hand and you could make the job very repeatable after plugging it all in for CNC.

But the problem with SHP is that it's not as strong and robust as the more expensive block models. You can just see the difference in how they are made. So there would be some HP and rpm limits with a cheap SHP block. The 600 - 700 HP crate motor guys are cutting corner to maximize profits. So you are not going to have great, rods, pistons, billet steel cams, top shelf lifters or rockers! Many years ago a customer brought in a 600 something hp crate motor 427, It came with a dyno sheet and you could not even rotate the motor?????? every rod hit cam lobes. So it tells me to cut corners and maximize profits that they dyno one motor and print the next 500 to be sold. But they got some standard base circles cams and threw it together somehow without ever rotating the motor after the cam went in.

Look up thermal coating pistons. Motown blocks are real quality with sleeved lifter bores........

Do not even think about getting an off the shelf cam. You want to get billet cams with sleeved on dizzy gear. I have the 785 gram Manley H beam rods good for over 1000 hp. For comparison Oliver I beam rods rated for up to 600 hp weigh only 570 grams. My cam base circle is .980 which is vastly superior to a small base circle of .900 inches

 

Yeah I bet you are correct, most shops do one build and dyno it and use that as the base for all others power rating however, Schafiroff states each engine comes with its own dyno sheet so maybe they go a little further. Schafiroff also uses the Dart Little M block so it for sure looks like the SHP block is off the table. I see Schafiroff builds their 434 using the Little M, according to darts web page is a 4.00"-4.125" bore and up to 4.185" but they do not mention how much stroke. It does say that you need to run a small base circle cam and rod clearance is needed but can also run a .9004" lifter.

Now when Schafiroff lists their 454 it still says Little M2 block which has a .391" raised cam and 9.065 deck height with a max bore of 4.185" and stroke of 4.25". It says it still uses stand sbc cam and oil pan so it appears this would be more of what I need if I chose Dart block. It does also say you can use most standard oil pans and of course id need one with a kick out for rod clearance. I will look into the Motown block to compare both and see what's a better fit for my application.

 

I wish that Shafiroff 454 sbc was available when I got my engine.......I certainly would have gotten it, or have my builder duplicate it if he would. There was a 454 sbc in the shop (in a c3 corvette,too) beside mine when it was built. It dynoed 730 hp and well over 600 TQ. But it was built using the tall deck block. Custom headers had to be made for fitment.

 

The iron eagle block has 9.325 deck height, pan rails opened up .400 inch per side and the oil pan holes lined up with the main caps.
It will support 455 cid and comes with billets main caps with 4 bolts in every position. I also believe it comes with BBC cam bore as std. Crank to cam centerline is raised .394 of an inch.

 

For sure this is appealing, BBC power in an SBC platform is just awesome! I am now looking into this option using the Dart Little M2block since it has a raised cam you can use a standard cam and not a small base circle. It shows a max bore and stroke of 4.185x4.250 so that's like 460+ ci which is nuts! I will for sure be using a spread port head design and I run side pipes so a custom made header is in my future no matter which combo I build.

 

The only thing I question on the eagle block is that it has no setup for standard oil filter, you have to run a remote setup. That's not a huge deal but i do want this thing to appear as a standard sbc. I also do not know if all other exterior dimensions are the same for accessories and engine mounts to be the same. It doesn't specify in the description so Ill have to call Dart. The biggest thing is I just want the new setup to drop right in and not have to change or modify anything externally, with the exception of headers. The Little M2 seems to fit the bill pretty good for a solid 434 or bigger. I'm still looking at the advantages/disadvantages from 427-434-440-454 setups.

 

Stay away from the Iron Eagle block......this is the Pro Stock Truck "Rocket Block" that was released in 1996 and although it is indestructible......it is barley a small block Chevrolet as there are so many differences.
Also stay away from strokes bigger than 4.00".......it becomes 10 lbs. of **** in a 5 lb. bag after that point......just unnecessary unless you have to have the bragging rights.
421-434 is the unit to build. 421 is 3.875 stroke and makes for a stronger piston and better ring stack. 434's run well too....just stay away from Nitrous or Boost.
Use a Little M block.....the iron splay is plenty. Raise cam is great but be prepared to source the timing cover and longer timing chain set.
Big small blocks like the 454+ are pretty much worthless to me in a standard pro arrangement.......it simply will not be enough head. Going to high end Brodix type stuff just makes a $$$$$$ Money Pit.....you can have 10k in the induction before you buy a carb.
Use the KISS principle on these big small blocks.......you will be better off in the long run.

Jebby