drwet

I finally took the plunge and ordered a 427 small block short block. I have a couple of questions for the guys who have been running one of these for a while.
1) What heads are you using? I figure I will need 220-240cc intake ports. Looking for a torquey street motor. Probably never see more than 6000 rpm. More often a lot less.
2) What camshaft are you using? I am looking at something in the 230-235 degree intake duration range. Again more interested in torque than big horsepower numbers.
3) Did you drill the steam holes in the heads?

stingraymax

bogie4speed

+1 I want to see this too.

cooper9811

I caught a little grief over my head and cam choice from the "bigger is better" crowd. No doubt, I could have built this to rev to 7000+ RPMS, but my goal is to stay under 6K RPMs and have a butt-load of torque. This is a daily drive (when it's dry out).

If you are using a Dart SHP block, you don't need to worry about steam holes.

• Dart SHP short block with 4" stroke, mahle forged pistons and forged rotating assembly
• AFR 210 heads - These are not a bad choice but you can go bigger with no real penalty IMO. I will admit that I know I could have gone a little bigger on the heads, and have thought about either comp porting the 210s or going to 220s. However, AFR 210s flow better than some other brand 220/230 heads, so not sure how much I would notice the change. In this case, more flow is not really a down side. Even with slightly small heads, my "butt dyno" says the ole 79 has plenty of torque.
• I have run 2 cams, and minimal difference in the two in terms of power. Both were in the 230-235 degrees @.050 range. Power band really similar between the two, and I feel it really come one just over 2000 RPMS through mid 5000s. One was a clay smith designed for AFR heads, the other was a Comp Magnum HR286. Vacuum was somewhat better with the Comp (wider LSA), but I would bet the Clay Smith is a better cam for the quarter mile. Keep in mind head choice will influence the best cam choice. Some here will tell you go bigger - And you can go bigger here too, keep in mind it may push your power band into higher RPMs. I say let your desired powerband and head choice dictate the selection, so research may be required.
• Hooker comp sidemount headers (don't go under 1.75 inch primaries);
• You can throw a single plane and not lose any torque down low. I've played with both a Vic Jr and a 7501 air gap (dual plane) and both can work. Vic Jr is probably a slightly better choice for this combo.

Desktop Dyno says this will exceed 500 HP/500 TQ - as I said before, that was my goal and I am in the ballpark. I was looking for that kind of torque in an RPM range that I drive in regularly, and I am there.

You can go over 600 depending on your choices, but would bet you need to exceed 6K RPMs to get there. If I raced, that would have been my goal (it wasn't - I do have torque on demand in my desired driving range).

My advice would be to do your research, and make choices based on your preferences.

rklessdriver

The engine in my 84 (yes thats it in my avatar) was orginally a pump gas 427. 4" stroke x 4.125" bore 6" rods. JE pistons with a 4340 Eagle crank and rods. 10.1 compression.

Top end used box stock Dart Pro1 230s, Edelbrock 2925 Super Victor, 950 QFT carb. Comp 312R solid roller 279/286@.050 .680 lift 108 LSA.

This engine made 603HP@6500rpm and well over 550TQ. It pulled like a tractor from 2500RPM up.

I did not orginally build the engine. A customer brought it to us to fix some valvetrain problems, which we did and few years later when he was done racing, I bought the car turn key. I presonaly would not have built that combo. I feel due to the box stock heads/intake, shelf cam and low compression it showed mediocer HP/TQ numbers. It did however make good TQ, had great driveability and it was totally reliable. You would think with a cam that seemingly big, it would be terrible on the street but not so at all.... 4" stroke SBC eat up big cams and need lots of induction to show good power. It actually drove around great and had a very mild lick at idle. Car was driven all over and driven weekly much like I use my 72 LS5 today... just a fun kick *** weekend car.

The car had a 3.73 gear in the stock D44 IRS, a TH350 trans and a 9" PTC converter that would foot brake about 3000rpm. I would stall it up to 2500rpm and it would flash about 4200rpm on motor. 1.41 60ft on motor. It would flash about 5800rpm on a healthy shot of nitrous and went a best 1.24 60ft.

At the time the 84 weighed 3200lbs and it ran 10.50s@125mph on motor. I put the plate kit on the car and it went very low 9s@148mph for a couple yrs before I found a local small tire, stock suspension class and started racing it more seriously.... then I tore it apart, sold almost everything but the Dart Little M block to build the 436 I have in the car now.
Will

terrys6t8roadster

My 69 got a daily driver engine build. 434 cid, Dart Pro 1s 195 runners 64cc, custom ground solid roller cam from Camotion, Mahle pistons 10.5 C/R, Scat 6 inch rods, K1 forged crank. 200r4 trans and 3.08 gears. Rear tires are 285/40/18, the engine probably hasn't been over 4500 rpm, but it sure gets there in a hurry and lights up the rear tires. The steam holes were drilled. T

drwet

Thank you all for the excellent input. I AM using the Dart SHP block. What is different about it that I don't need the steam holes? My understanding is they are required because the cylinder bores are siamesed.

gkull

Your compression ratio determines what cam duration you need. The second factor is Auto or manual transmission. As to heads it is not the CC that is important, but the CFM of flow.

Speaking for the majority of on here with 415 or larger ci SBC's and roller cams, both solid and H-roller. The mild builds H-rollers are like off the shelf extreme roller series in the 242/248 with auto trannies is the norm. People that want more top end and have manual transmissions or 3500 plus stall street drive with intake durations in the 250's

427 is not in the same league of rules that apply to wimpy 383 builds or even 400 ci. The 4 inch stroke has high piston speed and creates high vacuum even with 250+ duration. Look at the CC size of BBC heads.

My first 427 was bolted on the front of a racing 700R4 and 3800 stall with 4.11 rear end. Comp cams 242/248 extreme H-roller. I never installed the H-rollers and put solid rollers instead. For heads I went with 227cc. It was a nice daily driver, but if you pushed the go pedal the 3800 stall made it traction limited even with my big 335/17 rear tires. It was actually a learning curve on how to drive it. I let my wife drive my Vette when it had the over 500 HP SRoller 383, but the 427 was feasibly dangerous with the rear end moving around.

I saw right away that my cam choice was too mild to take on my co workers 69 Camaro with a 496 BBC other than high speed. I also smoked my multi clutch lockup in my 9.5 inch racing TC. So I was done with the mild cam and auto tranny. I bought the TKO 600 and a custom billet steel SRoller with the 4/7 firing order swap. My duration is something like 252/258 .680/.714 lift and 110 lc. To hear it, it doesn't sound radical or racy. On the road racing track I would pass BBC equipped vettes and just smoke the modded 427 Z06 vettes. The 427 Z06's were only stock 505 hp and the guys with the modded motors were still talking about under 600 hp. That is why I could pass them.

My heads needed a refresh because my lift was hard on valve guides. So I had a pair of fresh AFR 210 heads. So I threw them on one afternoon and took my 227cc to the head shop. The AFR 210 heads have over 300 cfm of flow intake, but I noticed that they were a limiting factor even with my big single plane intake. I left them on for about a year and they still whipped up on the c-5 and c-6 crowd

Oh my light and brakes were fine with 252/258 110. I'm still driving it around like that all these years later. I wouldn't change a thing!

c3_dk

SHP 427 here, AFR 220 competition and AFR composite intake (EFI)

cooper9811

Steam holes were drilled in the heads when using the old GM blocks. Dart blocks have a better design in the water jackets to allow free flow of coolant in those areas.

Kacyc3

You should go with a cam around the 240ish I have a 234/244 in my 406, it pulls great and runs to 6k

C3 Stroker

I'd use a camshaft in the 250° range, heads around 220cc (though mine are AFR 210'S). This is not a large cam.....remember you have 427 cu. ins. to play with. Mine acts exactly like my 383 did with a 230° cam. Plenty torque beginning off idle, pulling to 7000rpm. (You can let up at 6000 if you wish but you probably won't).

c3_dk

BTW my cam is:

Comp Cams spec. grind 12-000-13 - CS 3194 / 3196 HR.
This has the standard front end (12), 4/7 swap, and the cast dist. gear on a steel billet core.

Neil B

You need to first determine your horsepower peak RPM. Then based on that RPM level, you need to calculate the minimum cross-sectional area of the intake runner required to support that RPM. Here is an example:

You can use this calculator to play around:
http://www.wallaceracing.com/chokepoint.php

If you use a 2.20" minimum cross-section (CA) on a 4.125 bore and 4.00 stroke, your airflow choke RPM is 5,600 rpm. That will determine the horsepower peak RPM of the engine (assuming you have enough camshaft intake duration). That might be a good cross-sectional area if you plan to shift at 6,000 rpm. What complicates things is that most cylinder head manufacturers do not publish this information, except AFR. Here is AFR's data:

210cc head = 2.10" CSA
220cc head = 2.18" CSA
227cc head = 2.34" CSA
235cc head = 2.47" CSA

So in the example, the 220 head might be a good choice. Keep in mind, on the bigger SBC heads, they require 60/40 valve splits and offset rockers which adds to the cost of the build.

Once you have your cylinder head and peak RPM determined, you can then start to determine the camshaft specs. In a 427, I think you'll need a 240-245@.050 intake lobe duration (hydraulic roller) to make peak hp in the 5,500-5,700 rpm range. The idea is to match the cam's duration with where the cylinder head is going to peak.

I'm sure other folks have different ways of picking the right parts, but that's how I start.

Jebbysan

Use a Dart 230 Pro 1 and the matching intake......round it off with a 250ish @ .050 duration cam at about .600 lift.
A 950HP Holley works very well on these too.

Jebby

drwet

OK, I'll bite. What do you mean by a 60/40 valve split?

Neil B

The valve centerlines are moved slightly on some of the bigger SBC heads:

drwet

OK. I see what you mean. I can see why they would do that to install larger valves. As long as I stick to 2.02/1.60 valves that shouldn't be an issue. Also don't see why a special rocker would be required. Certainly they would have to relocate the rocker studs and design their own guide plates, but a conventional rocker should work. What manufacturer did you get your diagram from?

Neil B

The picture came from JE pistons. You want at least a 2.08 intake valve, not a 2.02 for an engine this size. I believe most good aftermarket pistons will accommodate both standard and 60/40 valve spacing. Just make sure the valve reliefs in your pistons will work with the heads you buy. Offset rockers are needed when they relocate the rocker studs and pushrod holes to make the port bigger. I think the AFR 227 is when you start getting into more exotic valvetrain geometry:

AFR 227/235cc Heads: Due to the "60/40" stud and valve locations, shaft mount rockers are highly recommended, however if you're ONLY Drag Racing you can run a .050" offset intake stud mount rocker with the AFR supplied guide plate (exhaust will use a standard rocker). Please note that with the .050" offset rocker arms the roller tip of the stud mount rocker will not be perfectly centered and will not sit squarely on the valve causing increased side loading and wear. This option is not recommended for race/endurance applications and/or street engines that see a lot of miles.

Also be aware that most heads in this size range with have raised exhaust ports which can affect header fitment.

gkull

I'm using crane pro off set solid roller lifters. .200 longer valve stems. .150. Longer .080 wall comp cams pro push rods. Valve stem lash caps. ARP taller 7/16th studs with crane cams gold stud girdles

Nothing moves around, so you don't have to adjust the valves. It is more of a check on the lash

Ï do pull the stud girdle off and use my spring checker to see how much the springs have lost in pressure

To get big 300 plus cfm you have to have 2.08 or larger valves.

My 227 head's have 2.10 intake and 1.65 exhaust Manley proflow ss valves. Ï went with bigger exhaust because it was going to use lots of N2O