Last summer I posted a thread titled "Disappointed", on the engine below that I built in my 77:

- New GM ZZ4 factory hydraulic roller short block
- AFR 180cc Heads, 65cc Chamber 10:1 Compression (015 gasket)
- GM Factory Hydraulic Roller Lifter system
- Comp Cam Extreme Energy XR270 Roller Cam (218/224, .500 lift, 110 LSA)
- Comp Cam Ultra Pro Magnum Steel Roller Rockers
- Edelbrock RPM intake
- Quadrajet rebuilt by Lars (with the above engine specs)
- DUI Performance HEI Distributor (timed to 35 degrees)
- Stainless Works 1-5/8 inch long tube headers / 2-1/2 mandrel bent exhaust system
- Borg T-10 Rebuilt Original 4-speed transmission with 3:55 differential; New Spec Stage II Clutch

I drove the car about 4200 miles last year and while it produces great power and torque at 4000 plus RPM, truth is I am the type who likes big block torque, and I just feel let down by the engine at lower RPM's. The car is scary fast when you get it wound up. What I want is quick acceleration up to speeds I drive without running it to 5000 in every gear (Borg T-10 4-speed).

NOTE - I do NOT want to change this motor for a big block....simply too much of a change, weight and money.

So, I am thinking of building another motor to push the torque curve up at lower RPM, like a big block. but with stroked SBC. This is my plan:

- New Dart SHP 406 block
- Scat 3.75 crank with 6.0 inch rods and pistons for 10:1 compression and .040 quench
- Use my current AFR 180 heads....or go to 195 AFR heads??
- GM Factory Roller Setup
- Cam?? Something like hydraulic roller 230 to 240 @ 0.050, and maybe single pattern rather than dual pattern. I keep hearing the AFR heads do better with single pattern because of excellent exhaust flow. I would consider custom grind from Comps like Extreme Energy lobes on single pattern or Lunati??.
- Comp Cam Ultra Pro Magnum Steel Roller Rockers
- Edelbrock RPM intake
- Holley 750 Carb or stick with my Lars built Quadrajet
- DUI Performance HEI Distributor (timed to 35 degrees)
- Stainless Works 1-5/8 inch long tube headers / 2-1/2 mandrel bent exhaust system
- Borg T-10 Rebuilt Original 4-speed transmission with 3:55 differential; New Spec Stage II Clutch -

Many questions.

If I stick with my current AFR heads, I now have a short block to sell.....if I buy new 195 AFR heads....I could sell the engine complete....many of you said it was a great engine.....how much could I sell it for? Anyone interested?

My goal is to have a strong and flat torque curve starting down low at 2000 RPM . Hot Rod Impersonator 406 used Vortec heads, Impersonator II used AFR 180 heads. Both created the torque curve I want. Pushing up to 195 may start to take away from that just to have high RPM horsepower that I really don't care about. I am sure the car will go 75 mph very easily, and I am not racing anyone.

I also worry that a 1-5/8 inch headers is pushing small on a 406, and the AFR 195 heads will also be limited by it. Another reason to stay with my 180 heads. I do not want to buy another set of StainlessWorks headers at $1000.

The Hot Rod Impersonator series, and some of the builds in the Big Inch SBC book show that Vortec 170 and AFR 180 heads produce Big Block torque, and HP that is well within my needs.

Lastly, is my 355 rear end right for this engine? Would a 336 be better once I have the torque down low?

Thanks in advance for any input....Mako, BK Broiler, Lars, Gkull, Straub and 427...looking for your input.

 

I would get a 383 stroker kit and use what you have. Building a 406 with a dart block would be quite a bit more expensive. Imo the stroker kit will give you what you want and be a better value for what you are doing.

 

Yes, I have seriously considered a 383. I could use most of what I have, and do the work over next winter.

My concern is that it will NOT be a big enough torque gain with a 383, and I don't want to be disappointed again. There is a limit, and I am not going past 406 like some may suggest. At some point, I have to be satisfied and do not need a 572 Big Block....even though that would clearly make me smile.

If I pull this motor and do whatever, I want there to be no doubt that what I do is the final step. While it may sound like money is no object, it is, and I just want the car to deliver what I expected from all the money I put into it.

 

All other things being equal, torque comes from stroke and hp comes from bore. That is a gross generalization but basically true.

Both the 383 and the 406 have a 3.75 stroke so the peak torque numbers and rpm of peak would be similar.

the "value" would be to put a 3.75 crank in your current engine. If money is no object then go for the 406 or even a 427 small block!

R

 

It seems to me that you already built a true lower rpm motor

These are the ways to increase TQ: superior cylinder filling which causes higher compression testing cranking pressure

So the intake track has to have good flow for the ci. The cam should have very little over lap. The highest practical compression. The most ci possible

A ci is a ci no matter what it is packaged in. A bbc has lots of cc heads and valve size in comparison to the sbc

So you need to figure out what is the restriction points of your system. Maybe go to a cam that creates higher cylinder pressure and go to a 3.875 crank to increase the ci

 

Nothing will help more then displacement. If you Use a sbc 427 u end up with a 4" stroke and a ton of power that will make the ZZ4 modded short block a joke. I know I went this way from a ZZ430

 

It would be feasible to use all your parts on a new dart shp block with a 3.875 stroker rotating kit. I've built a few 415 ci motors

The other possibility would be to put the 3.875 kit in your block and make a 396 ci

 

I am happy to hear you think my AFR180 heads will work on a 406, as well as the 1-5/8 inch headers. I am willing to spend the money on a 406 block and crank, but would like use all the other expensive parts....but it has to work and make sense.

 

At what point do you stop? As I said, I would like to keep my 1-5/8 $1000 headers. I would like to keep my AFR 180 heads if possible. So when do they become a restriction that does not just continuously goin up in cubic inch? I think a 406 will still work, but higher, I don't know?

 

I love my 406.......
Driving home from Friday burger cruise at 70 mph.....a kick to the throttle gets you to 120 QUICK......
Any more power than this is either for bragging rights or street racing.....
I think I want a little more RPM as this seems to be done at 6000......but that is where the Jebby meter pegged it when I built it and the Desktop dyno said the same thing......
500 horsepower and 470 ft/lbs. is a lot of power........don't let anyone tell you it is not......
Detroit builds all of these high horse cars now but none of them weigh 3150 pounds either.....
A 406 is a good way for brute strength on a budget......
I have this car at a solid 11.50 if it will hook.......it is that fast and that is as fast as I think it needs to be.....

Jebby

 

If you don't want to rev it to 5000 rpm or above, the heads, intake and headers are exactly what you want with more cubic inches. A 4.155 bore with a 3.875 stroke will give you 421 cubic inches. With a moderate duration of no more than 230 degrees and a compression around 10 to 1, you would have massive bottom and midrange power and it would sign off at just over 5000 rpm and it should still make plenty of horsepower.
Just what you are asking for.

Mike

 

Why not just change your cam? I'm not a cam expert but isn't that 110 lsa bleeding off low end power?
I have 406 with 234/244 @.050 .488/.510 112 flat tappet, alum L98 heads, 11:1 compression 700r4 w/3k stall an 355s...its a fun car and have new heads waiting for it.

 

Take a look at a comp cams cam card. They show the overlap as a shaded area where both I&E valves are open and you also have to to look at the valve event numbers. As intake duration goes up the more the intake valve is opening before top dead center causing intake reversion and less cylinder filling at lower rpm.

If you have identical duration cams and just change the LSA the 110 would have more overlap than the 112.

the poster has a tiny in comparison 218/224 duration

 

Here's a 400" we did a few years ago using an SHP shortblock and untouched Dart 200 cc heads. Still running strong in the '61 Vette it went into.

It's 11.0 compression (93 octane in the heat is fine) and uses a 248* solid roller cam on a 109 LSA. Drives great.



The 180 heads are good..but they're going to run out of breath early and the 1-5/8" headers will do the same thing. If you never go over 5000 RPM then I suppose they'll be fine. The above 400 with a dialed back cam could easily do what you want.

Ever thought about just putting in a 5 speed with a steep first gear to wake up the bottom end? It really works.

JIM

 

This. A 5 speed or a 6 speed transmission might help.

Also how much does the car weight? Loose as much weight as possible. It will make the car much fun to drive.

 

With all due respect you want to use the very parts that chocked off the motor you have which you now want to put on a 406 ci short block ?

I am sorry but that defies logic

 

I am not following your comment?? If you are suggesting that AFR 180 Eliminator heads, Edelbrock Performer RPM with a Lars build Carb, and 1-5/8 inch long tube headers into 2-1/2 inch stainless exhaust system is somehow CHOKING a 350 built for low end torque, then I guess that is your logic. But many would disagree. Using these same parts on an engine with more displacement will create more torque, but will limit 6000 RPM HP, which I do not care about. Note: I would probably use a slightly bigger cam in the 406.

I am going to guess that your idea is to use big CC heads, like 210 or more, a single plane manifold and 1-3/4 inch headers, and THAT would give me MORE bottom end torque, and 7000 RPM HP???

This type of debate never ends, because one side only thinks about MAX HP at big RPM. For those on that side, answer this simple question. With your big RPM engine, will the actual torque numbers be higher at 2000-4000 RPM than a 406 with my current parts. That is really the bottom line. IF you can get MORE torque at 2000-5000 RPM, especially at the lower end of this range, then that is what I want.

But, from everything I have read and learned you trade torque for HP in this 2000-5000 RPM range, you can't have both. Explain how I am wrong.

I want a torque curve that starts high at 2000 RPM, stays flat or rises up to 5000 RPM. If the HP is less at 5000 RPM and above, but still will easily sustain 75 MPH in a 4-speed with 355 gears, then that satisfies all me needs. Top speed means nothing to me, as I am not racing anyone. I want acceleration, like big block acceleration, at the shift points I use on the street.

I can tell you that with my current motor, I can feel it starting to really come alive above 4000 RPM, so with my 4-speed, I can run it to that number in each gear, but will be doing over 55 MPH by second or third gear. So, I have what I want, I just want it at lower RPM. And frankly, it does not push me back in my seat as much as I expect out of a muscle / sports car.

 

I do need to weigh the car to know. But I expect it is pretty light for the following reasons:

- Aluminum heads and intake manifold
- No emissions
- Aluminum Dewitts radiator
- No heat - core is installed, but no hoses, valves, controls, etc.
- No radio, wiring or antenna
- No electric windows and motors
- Electric headlights - all vacuum parts removed
- Soon to be manual steering - i.e. removing all power steering parts
- Aluminum factory wheels
- No spare tire (do have the spare tire mount)
- 4-Speed Borg Transmission (lighter than automatic)
- Thinking about converting power brakes to manual - would eliminate booster.
-

 

Thanks Jim, I was hoping you would provide some input. The idea of 5 speed has merit, and the cost would be less than another motor, but I really like the crudeness and character of the old 4-speed. It may be a tradeoff I am unwilling to make.

 

Couple "tips" to maybe help meet your goals better, assuming you do the 400" platform.

Keep most of your pieces you now have, change the cam over to a Comp #08-466-8, this will get rid of that "narrow" L/S and get you up to some "decent" lift numbers.

With the "SHP" block you'll be able to use a cam thrust plate to control the cam end-play. Block's already set up for the plate!

The larger bore (4.125") will help increase the Torque by design. With the above cam, the "smaller" intake runners, and "smaller" exh pipes you will produce some nice low-end Torque and still have a very decent HP number.

Thanks, Gary in N.Y.

P.S. We've recently began using these "XFI" lobes on a number of carbureted "streeters", guys are very happy so far with the results. You'll end up with a 113* L/S and .570" intake/.565" exhaust lifts (1.6 rockers). You can use 1.5 rockers if you like and still have some respectable lift.