Thanks! Yes it's a turbo, and rather modified with a lot more hp than stock too... This is that car:

 

Ouch. You did a great job ghosting him.
To the OP.....please excuse the hijack.

 

After this long winding road thread, I have come to many conclusions and here is my current plan on the 406 build:.

- Dart SHP Block bored to 4.155, 2 piece rear main
- Callies Compstar Forged 3.75 inch crank
- Callies Compstar Forged 6.0 inch forged rods
- SRP Pistons that provide best compression height, with app. 10.5:1 compression, and will get deck blocked as little as possible to get 0.040-0.045 quench
- AFR 195 Heads - either street heads or competition heads - see question below
- Cam will be hydraulic roller Comp, Howards or Straub low to mid .220 duration, mid .500 lift, 110 LSA - possibly single pattern cam - remember I am looking for low end torque primarily, without killing good average torque. I know its a milder cam than most would choose, but I want that torque curve to go high early.
- Comp Pro Magnum steel or Aluminum Gold 1.6 ratio roller rockers - should put total lift in the mid .500 range with
- Holley Double Pumper, mech secondaries, no choke - its what I want, don't bother telling me vacuum secondaries will be better for me
- Edelbrock RPM Air Gap manifold, ported to match heads - remember I want low end torque
- Unless I am able to sell my $1100 Stainless Works 1-5/8 headers at a reasonable loss, I will use them. If I did sell them, I would go American Racing Headers 1-3/4 inch

Questions for you:

- My builder is pushing me to go with the AFR Competition heads rather than AFR Street head, which are fully CNC machined, 2.08 intake valve, 7/16 inch rocker studs and springs for .0650 lift VERSUS the Street heads, which come with 2.02 intake valve, 3/8 inch rocker studs and springs to 0.600. I just talked to Chris Straub about a cam, and he thinks I should NOT go with the larger intake valve on the competition heads because intake velocity will be less, and will be counterproductive to my desire for low end torque. My builder says the competition ported heads flow way better, but not sure it matters in my application. What do you think? Would I still be better off give the better flow, even down low?

- As for the cam, I want torque to come on strong and the primary reason I am building this engine, ….and willing to give up HP at my 6000 RPM max. You and others have educated me that a better average torque, and allowing motor to RPM up higher is going to give me the push back in seat feeling I am looking for, but I want to be careful to not let this engine turn into a high RPM engine like most of you want. Not sure if I should go single pattern or not - many say AFR int / exh ratio is so go, dual pattern not required......but I may end up with 1-5/8 inch headers??

- As you can see, I conceded to not use my AFR 180 heads on this 406. I will be reassembling my 350, cleaning up its issues, and selling it.

Looking for any of your expertise on any of this. This is an expensive build, with lots of expensive parts that may exceed my application, but I prefer to have an overbuilt engine, that will go the distance that cutting corners. I restored the entire car to a higher level than necessary, and its what I do.

 

Agree with your builder too big a valve can shroud. The comp ports dont give a lot more....they are for the guy that wants every bit. The guy that wants ALL of it will get some touch up work done, tricky on those. And expensive. Comp uses 1206, at that point youre looking at a sinlge plane. You are planning a nice tire smoking driver with killer manners.
195 st heads with touchup. Finsihed @193cc intake
Exh were right on par if not a hair ahead of the comps. Intake still a little behind but the owner did not want any increased volume period, tough to do.

 

The rpm dual plane can except a 1206 gasket. If you decide to start with a bare head these valve springs would be great for a hydraulic roller. Comp cams single conical 1.290 at the bottom 1.020 at the top, 136 seat at 1.8 height, 412 open, 438 rate, can handle .650 lift. There not cheap $252.00 but the cream of the crop. Don't let anyone talk you in to a strait duel spring for this low rpm biuld.

 

Sounds like your "build plan" is coming together. Sounding more and more like a very strong engine, with very strong low end and midrange. You have gotten a lot of help and advice from experts here on CF and several strongly recommended builders.

My take:

• The double pumper when tuned properly will give strong & "instant" power on throttle movement. A plus for your app.
• The 180 or 195 heads have a "relatively small" volume for a 406 and will keep port velocity high and throttle response very sharp.
• The 1.6 rockers should help power with almost no impact on driveability. May only be at higher rpms tho.
• Any dual plane is a perfect choice for low end tq, and the Performer is a very good one. I would not consider any single plane for this engine.
• I would check with other SBC Vette owners on the Air Gap manifold and confirm hood clearance on a vette and with which air cleaner. I am assuming you have a stock hood but never asked. It gets tight very quickly when you go taller than factory. The factory LT-1 manifold does not leave very much clearance.
• I would not worry about the headers at all, the smaller ones may even be beneficial in keeping exhaust velocity up. I don't believe they'll be restrictive until high rpm.
• DPs are very size sensitive, in your app, be careful not to go too "big"
• Good quench figure, should help retard detonation.
• Basic cam duration sounds ideal for your app. Personally I'd leave the rest of the cam details up to your engine builder and the cam designers, someone who has done this 100s of times, if not more.

Should be a STRONG Build and you should be happy with it. WAAY stronger than your current 350. Like 100 ft lbs or 25% more.
Good Luck with it.

 

You might have missed that he said he is building a 406 (4.155 x 3.75)
But great summary otherwise.

 

idk about all that. In my research and understanding.. Siamese are very strong. Cooling is the only issue I know of with the 400s.. and that can be managed. The tiny steam holes can get clogged. But I know if 2 406 c3s that can do wheelies. One is just a 817 core with chinese heads and a cam.

 

I agree - the Comp version of the AFR heads costs more, and I highly doubt you'll notice ANY difference in torque at under 4,500 PM. If you're racing and there is a head size limit - by all means go with the Comp version - that's NOT what you're doing. BTW - The AFR 195's are NICE heads....

If you want the Holley DP - go for it - but go small - I know for a fact that a 750 DP will support 500 HP, so I'd probably be looking in the 600 - 650 cfm range.

My only comment is that the 220 duration may be just a touch bigger than you want. You got one opinion - now get a couple of others ... Give the guys at Comp Cams a call on their 800 number and talk to them - see what they say... Maybe try Crane Cams as well. Think of it this way - the cam basically controls the torque peak of the engine...

A few friendly suggestions - 1) Go with good Head Bolts and a good set of MLS Head Gaskets. They cost a bit more in the beginning, but are definitely worth it in the end.
2) Use the BBC 7/16" dia rocker studs and the appropriate rocker arms. The 7/16" studs are definitely stronger than the 3/8" studs.
3) Go with a good High Volume Oil pump, and have the builder tack weld the pickup to the pump after the pickup height is set.
4) Use a Good 4340 Oil pump driveshaft,and spend the less than $10 for a good oil pump stud.
5) Most factory distributors get somewhat worn after 50K miles - when they get worn, the timing gets erratic. Replace the distributor with a good aftermarket one if there is even the slightest question.
6) IF AT ALL POSSIBLE - Break the engine in and get it tuned on an engine dyno !!!!! This is the absolute best way to set the timing and get the jetting right. (The single biggest advantage to the Holley DP is it's adjustability - use that adjustability intelligently !!!)

 

OOPS! Senior momment.....

 

Been there, done that....seemingly often lately.....pushing 70 next year...lol

 

I don't understand why you would start out planning to use 1.6 ratio rockers instead of just increasing the cam size a bit. Many people on forums seem to think that 1.6 ratio rockers increase lift without changing duration, but that's not true. Duration is measured at a lift value (220 @ .050 valve lift for example). A 1.6 ratio rocker will reach that .050 valve lift sooner and lower the valve to .050 lift later, increasing the duration that the valve is open at that given lift value. I would plan on keeping the standard 1.5 ratio rocker and then increase to 1.6 if you decide the cam is just a bit too small.

Regarding the Air Gap intake, the air gap seems to be designed around the principle that having the air gap will keep the intake charge cool. However, that's only important at WOT for maximum power. At part throttle, a warm intake charge is better for fuel atomization, which gives better part throttle response (which is what it seems like you want) and efficiency. I had a 160 thermostat and an always cold air intake on my 79 with a Performer RPM intake. When the weather got cold, part throttle response was awful and punching the gas to WOT was disappointing until the engine caught up. When I got the ThermAC system working that warmed the intake charge, part throttle response was much improved. I'm now running a Quadrajet on a ZZ4 intake with a functional exhaust crossover and functional ThermAC system. Part throttle response is quick and snappy, and WOT stabs are met with instant power.

Regarding the double pumper, I'd recommend running a progressive linkage rather than a 1:1 linkage. I had a 1:1 linkage with a throttle body injection system on my 79 for a short time. At any engine speed below around 4,000RPMs, half throttle was the same as WOT. The bottom half of the pedal travel was wasted, and the top half was overly sensitive. You seem to want the most control you can get with your right foot, and progressive linkage is the besy way to do that, IMO.

For your cam, try to get a flat torque curve. If you have too much valve overlap (like a Thumpr cam, at the extreme end), you'll get a rough idle, a peaky mid-range torque, and then high RPM power. The peaky mid-range torque is good for breaking tires loose, but not much else. Getting a flatter torque curve with less valve overlap will give you a better idle, good low end, off idle pull, and torque through the mid-range that will be strong, but not sudden enough to break tires loose (as easily). Your cam specs are probably right about there, but the 110LSA is as small as I would go with what you're looking for. I might even consider a 112LSA and could be something to ask about if you're getting a custom cam. Flat average torque over the target RPM is key to getting good drivability (maximum power that is actually usable).

 

I have communicated with Tony Mamo on the AFR Competition heads, and he made it clear that they are what I should buy for my application. His response was that the small increase in intake valve diameter is negligible compared to the overhaul improved velocity of the competition heads.

I also have purchased the Skip White custom Wiseco pistons with the increased compression height, which will minimize the amount of material that will need machined from the brand new SHP block.

I am down to picking a cam. I have been communicating with Chris Straub, but he will not provide me his cam spec's unless I send him money, so regardless of how great his cam may be, I will not buy something unless I know what I am getting. I just won't do it. So, that leaves me to pick a cam myself. Jebby gave me a recommendation of a Howards cam with 227/233 duration, .560/560 lift. With my 1.6 ratio rocker arms, that puts me at .590 lift. This is as big as I think I will go. Looking at Comp, Howards and Crower for something just a tad smaller to keep the torque low, but want to make sure I have mid .500 lift.....as the AFR heads supposedly like lift. I also heard that a single pattern cam would be another AFR gain. The AFR 195 competition heads come with 7/16 inch rocker studs, and springed to handle .650 lift.

 

Call Skip back and ask about the magic cam It's a comp cam but you can only get it through Skip. I think it will make the power where you want it
It's a HR

 

I could do that, but I believe his custom cams from Comp are all reduced base circle cams, and I specifically made decisions on stroke to avoid reduced base circle cams, so at best, I could find out information.

 

have seen mamo on speed talk always recomend the afr comp over the regular 195 head. Contact mike jones at jones design he will tell you the specs on a cam before you buy it. Just give him all your accurate parts you will end up using. WWW.jonescams.com. jonescams @ bellsouth.net. phone 704-489-2449. He also now owns speed talk forum.

 

TOo many guys ask chris for ballpark specs and go somewhere else cause its cheeeper.

Rough specs dont get you the same cam. Guys gotta make a living...yes you gotta know what youre getting but hes as good as anyone else getting it right. Straub, Jones take your pic they are both stellar.

 

I know, that is what he told me. Doesn't work for me. I am honest person, expect to be treated as such.

 

That is first thing I thought of also.
The problem is that the big cam companies all post up that info so we sort of expect it.
And after looking at their website where they post up what they do, it sounds like they don't have a manufacturing business. Most "shops" post up picks of their equipment, shop, etc.
So what you seem to be getting is a cam "designed" by Chris but made by someone else.
I AM NOT CERTAIN HERE.....just my impression.
SO...with all the suggestions from guys here on cam specs, why not just order a custom grind cam from Comp, Crane, etc, etc?
Couple hundred goes into something else.

Not knocking Chris at all. Heard good stuff from some guys here. He fills a niche.

I remember back in 1968 the hot cam was the new solid lifter cam out of the Z28. You could buy it over the counter from Chevrolet but had to order it.
If I remember correctly, specs were - 300 duration and over .500 lift. No idea about LSA, etc.
Just know that put into my 1967 Camaro with a 350, domed pistons, reworked heads with studs and larger valves, it definitely woke things up.
Cost was $50 (which you had to save up to get....LOL)

 

I have sent in cam recommendation requests to Mike Jones, Comp and Tony Mamo.......we shall see what they say.