Cam specs


Departed Member
I have been spending a lot of time with a cam manufacturer trying to establish a line of camshafts specifically suited to our small six rebuilds. This is pretty tough considering the endless combinations that are possible. I was just wondering if you guys have any suggestions as to what you would like to see. Here are my general thoughts for four different shafts.

1) stock rear gears (270-320), C4 or manual, 2V or multiple carbs, headers, 1.6 rockers. Strong bottom end and midrange (1000-5000), good idle, used for daily street driver with some highway.

INT DUR 260 DUR@.050 200 DEG VALVE LIFT 1.6 .464
EXH DUR 270 DUR@.050 206 DEG VALVE LIFT 1.6 .450

2) stock rear gears (270-320, C4 with modified stall or stock manual, 2V or multiple carbs, headers, 1.6 rockers. Strong mid to upper rpm range (2000-6000), good idle, used for daily driver with extended highway.

Recommended: verdict still out

3) minimum of 320 gears, C4 with modified stall or manual, 2V or multiple carbs, 1.6 rockers. Good bottom and strong midrange (1800-5800) lopey idle, occasional driver (mostly street with some highway).

INT DUR 268 DUR@.050 208 DEG VALVE LIFT 1.6 .453
EXH DUR 274 DUR@.050 218 DEG VALVE LIFT 1.6 .480

4) minimum of 320 gears, manual only (T5 recommended), 2V or multiple carbs, 1.6-1.65 rockers. Strong midrange and upper (2000-6500) lopey idle, occasional street use only (no highway).

Recommended: verdict still out

Any thoughts, changes, or recommendations would be greatly appreciated. After these are hammered out, I will be working on shafts for the big sixes, so feel free to comment on those as well.
The specs look good . Are these all hydraulic lifter design?

I would most likely be looking at the larger cam for my drag race effort in my 62 Falcon. Perhaps I would try the next size smaller cam from the big one listed.

I will be running a C-4 tranny, but the converter has been modified on the level of 4500 rpm stall. What the converter will actually stall to with the 200 cid motor is most ly unknown at this time.
Sounds right on. The overlap and total duration with both intake and exhast valves open is the key to drivablity with any cam. The high intensity nature of these cams looks okay. The truth is, any cam like these will be a huge skirt lifter to a normally latent engine.

One other thing to consider. Is the piston moving away from the piston at maximum speed when the intake opens? This is based on the rod ratio (yes, Rod Ratio crusade again, do I ever let up?).

Most programs analyse this. For 1.51 to 1.53 ratio 200 and 250's this must be optimised.

Failing that, the 202/3.3 liter Holden Six has a raft of very good cam grinds for the 9 and 12 port Aussie General Motors engines. Checking actual stats of the performance grinds from these engines with a better 1.65:1 rod to stroke ratios should be show similar results.

Aussie grinders have been active on these grinds since the early 1960's, and lead the world on OHV sixes only because Australia is even more six-cylinder orientated than the US of A. Those Holden patterns, as made by Wade, Speco Thomas, Bert Johnes, Crow, and Chevy Offroad and Marine, optimised to suit the proportionally shorter Ford rods, would most likey be the same as what you looking at. 1971 to 1979 HQ-HZ Holden sedan racers run 260 degree cams like the first suggestion, and these hugely under carbed single venturi Bendix 9 port head sixes run over 165 hp and top 115 mph on oval ciruits in 3000 pound mini Pontiac 4-door style bodies. That cam is a brilliant road cam, and that is the one most of us would want to use. Not all of us can afford 2v's, Alloy heads and all the drama. The adding anchovies to the pizza base is the cornerstone of good speed equipment!

Heatseaker, an American company, also did some early work in the 1990's, but the Aussie market is very fickle because it is spread wide, and V8's and ricers are starting to cut into this time-honoured market. The volumes just didn't shift. They were published in Aussie magazines for both Holden and Falcon sixes, and I can post them if you wish. Just holler!. My Falcon runs one of the sub 256 degree grinds for the cross flow head.

Check out grinds from these companies. The only real way to make them work well is to do very expensive dyno runs on junk yard sixes with control modifications. That's how all good cam grinders do it. Failing that, you play percentage shots based on good computer programes and grinds that work on similar engines. I'd bet 40 years of GM-Holden experience would short circuit that process. The 202/3.3 Holden is that bench mark!
Do you have any flow figures on a stock head?

Cam specs for a 300:
Computer compatible, including OBD-II
Smog-legal or at least capable of passing a tailpipe test if not paperwork compliant.
A towing cam with more performance throughout the stock RPM range (800-3700 for automatic trans.) with biggest gains at 2000.
A performance cam with biggest gains primarily in the 3000-3500 range.

Other than the smog issue, there are already cams out there to do this and many of those will sneak past a sniffer, so I'm not all that sure there's a market for additional sources
I don't do log headed 200's or even 2V hybrids, so my flow figures would be meaningless.

There were some flow figures posted earlier by one guy on a 2v Aussie 250 head. Some have suggested a 2V 250 with the a big cam would need to flow 175 cfm at 450 thou to get 250 real flywheel horsepower. Raise the lift, increase the CFM.

The 3.3 and 4.1 Aussie Falcon Alloy Head in 1980 was rated at 145 cfm at 25 inches of mercury at gross valve lift, although some thought this was the exhast figure.

Those deceased Heatseaker cam specs I promised have 18 fields for everything from a stock GM Holden to a Cross-flow Ford. You will have to wait until I type them all out, but they go like this:-

Holden 149/186/202:(These are pipe [|] delimited if you want to pass them in a spreadsheet)
Order is:-
Part No.|Performance LevelSeries|Application|Idle|Operating Range|Trans|Running Clearanace|Gross Valve Lift|Cam Lift|Adv Dur|050 Dur|Valve Event|

HS10E|Stage 1 Economy+|Improved mileage and lower RPM torque. Good vacuum, improved economy, daily usage.Suits STANDARD or SLIGHTLY MODIFIED engine|Good Idle|1400/4800|Any|Hyd|368 371|230 232|248 251|182 185|15-53 52-19|

HS20E|Stage 2 Street SportsEconomy+|Good Idle|1400/4800|Any|Hyd|368 371|230 232|248 251|182 185|15-53 52-19| rah rah rah rah.

See you when I'm done!
Still getting my act together. I've sent Azcoupe a copy of the 1991 September Street Machine Mag which contained some Heatseaker cam specs. They are American grinds for the Aussie market, and were discontinued after lack of response form the local (Aussie) market.

The 6-cyl market can be a fickle place, best wishes for getting some proper market share!
Thanks XECUTE, I just got them. A little hard to read, but doable. Thats perfect timing as I am visiting with my cam supplier on Monday and it will give us some good info to go over.

I hope that this will work out OK. I'm not looking to make much on the profit end as this is mostly just for fun, I just don't want to loose money. I like being able to beat the prices of my compeditors, if nothing else, hopefully it will force them to keep their prices down. :LOL:

Thanks guys for the ideas and input.
Roller cam would be nice. I'm planning out a performance six rebuild on a 200, and I found everything I need, but have not found anyone who makes or is developing a roller cam.

David 8)
az coupe,

Isnt that lca on the first cam a little shallow for a "good' idle. I would think to keep it in the 110-114 range. 109 will definately let you know that you have a cam and might be too rough for some. Just a thought!

Todd Fields
The Ford E303 roller cam has these specs just for comparison:

Advertised duration: 282 intake/282 exhaust
Duration at .050 in. cam lift: 220 intake/220 exhaust
Gross valve lift: .498 in. intake/.498 exhaust
Lobe separation: 110 degrees

This would be a fairly hot cam in a 200 ci engine.
I just had a look at that Isky site and there negative comments on the trend toward dual pattern cams. According to them it seems that the rule is dont use them unless you need them.
Recently I had cam sheet specs sent to me by Crow Cams on a new cam for the EA through to AU Falcons. They stated that this cam was dynoe tested to make more power all through the rev range with better highway economy and it has LESS duration on the exhaust that on the inlet not more as most dual pattern cams do.

Thanks for the tip interesting reading.