Stan's Customs

Thank you sir...you may be right...and yeah torque is where it's at on the Seat-O-Meter!

By the way..I sent your buddy tpi421vette a pm...

Westlotorn

If your 400 can be bored one more oversize there are forged lower ends using internally balance cranks with a 6 inch rod. With good heads that would make a nice monster for under $5,000. If you do the work.

Stan's Customs

It was done in 1984 so I don't remember what I had it bored to the last time...probably as far as it could go. I need to find out what the maximum over bore a stock 400 can stand. Then I'd need to dig it out of storage and tear it down...that's probably going to be more work than building the engine, ugh! ..and that old barn is like an oven this time of year (Texas).

What "brand" of forged stuff are you thinking of? I have looked at some of the Eagle and Scat assemblies...but I'm really too far out of the loop to know what's good and what isn't these days.

Thanks...Stan

GearheadJoe

I'm with you on the desire to maintain the correct Gen I vintage look. The LS is an amazing engine but to me it just doesn't look right in a C2 Corvette like my '67.

I recently built a very correct looking 383 "stealth L79" using a correct 1967 block. This build is described in the July 2017 NCRS Restorer issue that will be out any day now.

I think that 383 CID is about as far as you can reasonably go with a 327/350 block. If I had it to do over again, I would build a 427 small block using either the Dart Sportsman block or a 1970s 400 block with a 4.125" bore. I just think there is something really cool about a 427 small block.

To maintain the period-correct appearance, I would use a Z28/LT1 Winters intake, and aftermarket heads that are externally machined to look like the iconic "double hump" vintage heads. Brzezinski Racing can do this machining to Dart iron heads, and I recently found a shop in California that says they can do this to AFR aluminum heads.

With 427 CID and a medium hydraulic roller cam, you could easily generate more than 500 HP with such a setup. Yes, a well-built LS could beat that, but it wouldn't have the same cool factor as a Gen I small block 427.

Stan's Customs

Thanks Joe...

I am big into the era correct look with a few visible mods like Vintage air.. It is is a 1961 has a after market chassis.It has stock appearing custom made Stockton wheels with Diamond Back wide white Michelins. Looks stone stock on the outside even with the Corvette Correction Chassis.


However..I never had a bone stock car in my life...so I'm good with a few changes as long as it is reminiscent of days gone by...especially with some big changes in the way it runs and drives.

Cams and headers and aluminum intakes etc..were the first thing we did back in the day...and maybe mags and tires.

So what else is new..heh heh!

Thanks for the input...I do like the idea of a 427!

Thanks again..Stan

cv67

with a good sized head I dont think those old intakes would cover the port..and would strangle his motor big time
Eagle and scat are ok but really entry level stuff. Callies Crower and others make the real good stuff

AZDoug

Eagle and Scat stuff is heavy.

Callies makes a good crank. I used Manley h beam rods. The rotating mass of the rods is much less than the other brands mentioned.

Doug

Stan's Customs

Agreed...I just got thru looking at the new intakes Dart is making...

Height is my problem...as was Dougs.

CORRECTION: NEW INTAKES "AFR" IS MAKING...

Stan's Customs

10-4 Doug and thanks. Callies seems to be the crank of choice from a couple of other builders too.

GearheadJoe

Hi Stan:

If you decide to build a 427 small block, please keep me in the loop as you plan the build. I think that a 427 small block would be really cool.

Since building my 383, I have amused myself thinking about how I could build a 427 small block. I've done quite a bit of research on how to get the rotating assembly to fit properly. While it is possible to accomplish, there are some key challenges and also some tradeoffs to consider.

The first problem is rod clearance at the base of the cylinder bore. With a properly selected rod this can be accomplished with a stock 400 block without hitting the water jacket. It's easier with the Dart block because the area that needs to be clearanced is solid material with no water jacket behind it.

The second problem is rod-to-cam clearance, which is harder to resolve. If you think about it, the spacing between the crank centerline and the cam centerline has remained unchanged since the Gen 1 small block came out in 1955 as 265 CID. Every time the stroke is increased, the clearance between the rods and the cam gets smaller.

The problem is manageable with a 383 (3.75" stroke), but it gets very difficult with a 427 (4.00" stroke). And, if you use a roller cam, the inherently fatter lobes of a roller cam further reduce the rod-to-cam clearance.

This makes the choice of an appropriate "stroker profile" rod critical. And, it often requires using a cam that is ground on a small base circle.

I had samples of several stroker rod candidates left over from the research I did on my 383 project, so I bought a used 400 block, and I have made a variety of comparison measurements. I still haven't figured out what I think would be the best combination.

The good news is that a 427 small block is definitely feasible if you use the Dart block because clearance at the base of the cylinder becomes a non-issue. That leaves just cam clearance to sort out. The Callies Ultra rod and/or a small base circle cam can usually solve the cam clearance problem.

What I'm not yet sure about is whether a stock 400 block can be successfully stroked to 427, but I hope to figure that out when I get time to make additional measurements.

Lastly, whether you use the Dart block or a GM 400 block, you will not have the rear crankcase vent that makes it easy to use original un-vented valve covers. There are several ways to resolve this problem, but it requires some thought and planning.

Stan's Customs

I'm just getting into all that myself Joe.

However tpi421vette on the C4 forum is the guy to talk to...he builds these small block strokers every day...and has all the answers to those questions. In fact I just had a conversation with him about the different ways to approach some of the very things that concern you.
There several ways ...but turning down the rod journals and using a small block rod helps on the cam clearance issue (using high quality rods and so on). ...then there is the small base circle cams that are available.
Everything ...depends on exactly what engine you plan. In my opinion...the Dart block is a no brainer...even though it's costly...it's the foundation you build everything else on. Forged internals add up to big $$ quickly....so you really need a comparable quality block. Then there's the heads and on and on...

The cost between one of these motors like I'm considering with some kind of fuel injection...is nearly as expensive as a new LS3 with a new transmission and wire harness...then you have the accessory drive package and all the "little" stuff. There's no end to the little stuff on the LS it seemed to me. Last I tallied...about 18K and climbing for all I would need on an LS3. I'd be curious if anyone had some real LS numbers has done it on a C1 or C2...(all new engine /trans etc.). I built my cars out of wrecking yards all my life, but this one is the last one for me, and I wanted it to be all new or built with top quality forged internals in this case.

I will keep you posted on what I do on the stroker if I do decide to take take the plunge.

Like every thing has been on this car..it is a d##n hard decision. I'll sure be glad when it gets easier.

Stan..

AZDoug

I used a hyd roller cam with a .050" smaller base circle to give a little more cam clearance.

With my 3.85 stroke, just a tiny bit of clearance work (less than .010" IIRC) was needed on the pan rails, and I had to ever so slightly dimple the sides of the pan, at the mounting surface in four or five areas. That was fitting the pan with no gasket. Once the gasket was installed, it increased the clearance even more.

I am not sure you could really do a 4.00" stroke without extra hassles, or going to a raised cam block.

Doug

GearheadJoe

If you use the Dart Little M Sportsman block, you will be off to a great start. The problem of rod clearance at the bottom of the cylinders will be comparatively easy to solve because the Dart block has more available space in that area than the stock GM 400 block. Yet, the Little M accepts all the standard Gen 1 parts such as oil pan, timing cover, intake, etc. It's a great platform for building a stealth 427 small block.

In theory, the Callies Ultra XD rod will help with cam clearance. This rod has an innovative canted parting seam between the rod and the cap to provide extra cam clearance. Unfortunately for someone trying to use a stock GM 400 block, the extra cam clearance comes in exchange for less block clearance, so the Callies Ultra XD is not a good candidate for a 427 that uses the stock GM 400 block. Here's a link to a video on the Callies site that shows the Ultra XD rod clearing a standard base circle roller cam:

http://www.callies.com/connecting-rods/ultra-xd/

I'm not convinced that the Callies Ultra XD rod completely solves the cam clearance problem for all possible roller cams, but it's probably a good place to start. For some cams, a bit of material on the rod might need to be removed.

You mention using a 2.0" small journal rod as a way to gain some cam clearance. I have looked at this too, and it is tempting. My only concern is weakening the crank when such a long stroke is being used at high power levels. This could probably be adequately addressed by using a high end race crank made out of really good material.

I don't think the Callies Ultra XD rod is available with a 2.0" journal, but based on my measurements the Manley Streetmaster I-beam rod with a 2.0" journal looks like a good candidate.

Please keep me posted on how this project develops. I just love the notion of a small block 427!

cv67

Keep us posted Stan
Jim has one hell of a machinist his stuff never breaks. As you can tell honest guy really knows his stuff and can tune very well if you go EFI

Stan's Customs

I'm running to issues regarding room for big enough exhaust with my independent suspension and custom chassis on the c1...same as stock issues I guess. I know wmf62 (Bill) had to deal with clearance issues on his stock frame.

If I had deleted the trunk pan I would have been able to do more...I guess that's why so many do delete the trunk.

I'm not sure I can get 2 1/2 " pipes installed.. from the rear axle back? Plenty of room forward to the engine...

MY BAD FOLKS...bill said he DID get 2 1/2" exhaust all he way back. I misremembered..."old timers disease" I guess....sorry Bill

cardo0

Don't understand why everyone post's 427". Every time I do the math using 4" stroke and min 4.125" bore I get 428 cubes! Using a 3.85" crank you need a 4.2" bore and Dart doesn't have a normal bore spacing small block for that. 3.85" stroke with max 4.185" bore only gets you 424 cubes.
What I'm saying is why the focus on 427 cubes when it's not technically correct?

Stan's Customs

Good question..and I had not done the math. But they are advertised every where in the long and short block crate motor ads as 427, so I assumed that they were really 427"s.
I'd like to know the answer to that myself...?

I remember back in the day that a 396 Chevelle wasn't really a 396...but that's different, it was Ok for GM to say anything...LOL!!
Just goes to show ya, that where ever you go ... there you are!

Stan's Customs

Cardo0 you are right...technically a 4.125 bore with a 4.00 stroke is 427.65 cubic inches which "would" round up to 428 c.i.
Evidently most Chevy guys call it a 427. That is the same bore and stroke GM uses in their C6 LS7. GM calls it a 427. So if GM calls it a 427 I guess we are supposed to as well. LOL..so what else has changed..right?
Stan

AZDoug

Technically my motor is 425, or 424.xx.

But it sound too, well, Buick, and its close enuf to 427, and 427 sounds better anyway. Whats 2 CI between friends?

I suppose I could have ordered the crank with a 3.86" stroke, but, well, hindsight and all.

Doug

wmf62

Stan

stock frame, but 2-1/2" end-to-end; not sure how your frame is made

Bill