Anyone have the full specs for the TA 284-88 and/or 290-294 SB cams? PLUS DesktopDyno results!

I have that Desktop Dyno program (2003, took me a while to find it) and I input the specs of the comp 268 cam and with the headflow files of stock 1970 350 heads, a 350 built to the specs of a stock SP 350 with the stock manifolds and mufflers option checked I got 288hp at 4500 and 375ftlbs at 3500. I know things like these are meant to give a general idea, but it's fun to theorize. Anywho, I was wondering if anyone knows all the specs of either of these two cams, as they are the two I'm considering stabbing into my SP 350 soon. Any help is appreciated.

 

Gary would have those specs if the TA website can't give you much more. If you can change head flow and valve size to 255 flow/1.96 valve try this crower mechanical cam with a 3.903 Bore and 3.975 stroke and single plane intake. Zero deck 33 cc Pistons dish 9.0 compression

https://www.crower.com/camshafts/buick-350-compu-pro-solid-cam-282-fdp.html

 

Have to be careful with that program. You can put in optimistic stats and get unrealistic prognoses.

Assuming the program is 'Chevy friendly', I generally use the 'HP manifolds and mufflers' option along with the 'dual plane high torque' settings for (all iron) Buick engines. I've run hundreds, if not thousands of simulations with this program and have found, when comparing to real world dyno figures and track results, that this setting is the most accurate, though can still be a bit off.

There's another program I use (Larry uses the same one) for calculating DCRs. It comes in very handy when comparing two combinations with the same DCR, even though SCR's can be different.

Specs for the TA 284-88H and TA 290-94H cams are:

TA 284-88H
Duration @.006: 284/288 I/E
Duration @.050: 223/230 I/E
LSA: 110
Lift: .460/.460 I/E @1.55

TA 290-94H
Duration @.006: 290/294 I/E
Duration @.050: 226/235 I/E
LSA: 112
Lift: .476/.486 I/E @1.55

Both cams are good choices. The larger one will have a lower DCR on the same SCR when set at the same install point, due to the larger intake duration number @.006.

 

As a side track note, relevant to how 'on paper' numbers can be misleading, I have a document printed in April of 1967 on the (then) new Buick 430 engine.

The engineering team pulled a new Buick 430 from the assembly line and took some measurements...

Compression was supposed to be 10.25:1, but according to sonic displacement analysis, the engine showed an average of 9.4:1 static compression, with all cylinders ranging wildly from about 9.25:1 to 9.75:1 (actual difference wasn't a true .5 point, more like .38--this is me rounding up and down, but is pretty close).

Cam specs showed different on two separate measurements, both close to low .400's on intake and exhaust (.413/.430ish I/E), with rocker ratios ranging as well, from 1.55 to 1.57 to 1.59.

Then they strapped the beast to a dyno.

Performing a 50 hour run in process at 5200 RPM (!), they blew one up (spun a rod bearing, destroying rods, crank, and block), detonated one to death (using 95 octane gasoline--it was only one piston affected, probably the one that had an unusually 'high' compression ratio closer to the advertised 10.25:1 rating), then found one that could hold together under these severe conditions, before measuring power figures.

Advertised power on this engine was at 360 hp @5000 RPM and 475 ft. lbs. @3200 RPM.

Actual power figures ended up being 344 hp @5000 RPM and 453 ft. lbs. @3200 RPM.

Considering the compression ratio was almost a full point below advertised (average), and check this out--they dyno'ed it with the water pump and alternator installed and operating, at the flywheel, and using single exhaust. Not just any single exhaust, but a super restrictive 2.25" single, and ran it through a full sized muffler with a 2" exit and resonator!

The engine was slated for a B body 4 door Wildcat.

All those cubes and power pushing through a tiny exhaust system on the dyno.

It lost 16 hp and 22 ft. lbs. compared to the advertised numbers, and with lower compression. Still, according to other figures, 16 hp lost should have equated to about 16 PSI of back pressure. I'm amazed that all it had was 16 lbs.!

By comparison, that type of exhaust is the one used on small blocks, which still had some back pressure using it.

(((Edit: imagine what that assembly line engine would have produced with a true 10.25:1 compression ratio (block and heads milled so the compression was much more equal across all cylinders), and ran through a better exhaust (hell, even a press bent dual 2" system would have been a vast improvement!), such as a common 2.25" or 2.5" dual exhaust, leaving everything else the exact same. This would show that 'blueprinting' is super effective, even on bone stock engines)))


Another case in point was an article about a 1970 GS350 with that SP code, which was supposed to produce 315 hp and 410 ft. lbs.

Well, they put the 30,000 something mile, factory assembled engine on a dyno.

It showed an average of 270 hp and 385 ft. lbs., using the same cam as the earlier '68 and '69 engines, which were rated at 375 ft. lbs. and 280 hp.

So go figure. lol

Everyone sexed up the power figures. Mopar, Ford, Chevy, etc. etc. so it wasn't just Buick doing it.
The same article on the GS350 took power figures from a '325 hp' Chevy 327 and the '300 hp' Chevy 350 and showed that the 327 (rated at 325 hp) only made about 10 more hp and around 10 ft. lbs. less than the 350, which made the exact same power as the Buick 350, but at a slightly higher RPM than the Buick.

 

Gary, just goes to prove everyone is very liberal when quoting HP and TQ, even Buick Engineers, good stuff, thanks for posting.

 

My pleasure.

 

The stock 1970 SP engine is NOT 10.25 as it is listed. More like 9.25. If it was to blueprint spec it would be 10.25 and make the rated power.

 

May be why my '68 stocker that had a true 10.13:1 ran so well.

 

Very good discussion Garry thanks.

 

Welp, across the 3 cams I input in, and with more math than I would have liked (but it's car math so it gets a pass), I have come to these conclusions, which may or may not be entirely possibly accurate. I also found the compression ratios (dynamic and static) for these three cams as well. The specs I put into the program for the engine were the stock 3.8 bore size (what my SP engine is, I based all this stuff of off that engine for simplicity, plus I own one so why not?), stock stroke, the rated 10.25:1 compression although the static compression calculated out to be 10.1:1 with stock everything, 55cc heads, 5cc piston dish, .040 head gaskets with 3.9 gasket bore, and the piston .058 down the hole, a 750cfm carb, dual plane high torque style intake, HP manifolds with mufflers, and the flow files for 1970 heads I found on the internet somewhere with stock 1.88 and 1.55 valves.

First up, the comp 268. It was the cam I had in my blue '76 350 and I loved the way it sounded and performed, even with the 7.8:1 that the engine had.

Results below are for the SP engine:

Comp 268H: 298hp at 4500rpm and 409ftlbs at 3000rpm. DCR: 8.35:1

TA_284-88H: 309hp at 5,000 and 390ftlbs at 3,000rpm. DCR: 7.86:1

TA_290-94H: 292hp at 5,000 and 342ftlbs at 3,000rpm. DCR: 7.5:1


I also did some with small and large tube headers, open and muffler exhaust. I wish we could add type of muffler, diameter of pipe, etc but I digress. In my mind, I equated the small tube option with TA's 1 and 5/8, and the large with the 1 and 3/4. The results are as follows:

268H: Small tubes (open), 348hp at 5k, and 444ftlbs at 3k. Small tube with mufflers was 331hp at 5k and 427ftlbs at 3k.

284-88H: STO: 361hp at 5k, and 427ftlbs at 3k. STwM: 346hp at 5k and 408ftlbs at 3500.

290-94H: STO: 368hp from 5-5500, and 423ftlbs at 3500. STwM: 352hp at 5k, and 406ftlbs at 3500.

-----------------------------------------------------------------------------------------------------------------------------------------------

268H: Large tubes (open), 353hp at 5k, and 444ftlbs at 3k. Large tubes (mufflers), 337hp at 5k, and 431ftlbs at 3k.

284-88H: LTO, 364hp from 5-6k, and 428ftlbs at 3k. LTwM, 350hp at 5k, and 412ftlbs at 3k.

290-94H: LTO, 379hp at 6k, 422ftlbs at 3k. LTwM, 356hp at 5k, and 409ftlbs at 3500.


And for giggles, my 7.8:1, .030, 268, manifolds, downpipes, 8" cherry bombs, and 800cfm '76 motor. 265hp at 4500 and 370ftlbs at 3000.



Phew. This took two hours lol. I have no idea how accurate this is, but from the results it seems like the 290 is the way to go here out of the 3.

 

Try the crower level 3 cam. https://www.crower.com/camshafts/buick-350-compu-pro-hydraulic-cam-276-hdp.html

 

302hp at 5k, 383ftlbs at 3k. 7.988 DCR.
STO: 356hp at 5k, 421ftlbs at 3k. STwM: 340hp at 5k, 403ftlbs at 3500.
LTO: 359hp at 5k, 421ftlbs at 3k. LTwM: 345hp at 5k, 406ftlbs at 3500.

 

That program will suck you in and have you spending hours on all that math. Don't worry, it gets easier with time.
What I generally do is take the values at .006 and add them to the values at .050 and then divide by 2 (averaged figures between .006 and .050).
You can also add a bunch of numbers up and divide by the number of numbers you added, both for .006 and .050 to get your averages within a certain RPM spectrum.
Then divide the results of any set of numbers by about .97 (anywhere from .95-.98) to get results from better flowing mufflers (when doing manifolds w/mufflers option).
It maths out approximately.
To get a more accurate comparison, put your static compression on each cam so that they all have the same dynamic (static compression will vary from cam to cam when comparing this way).
Soon you'll be spotting patterns and trends in power changes and RPMs, among other things.

Here's another cam for you to try. Put in these numbers into the cam manager in the 'valve event timing' tab, put lifts to specified, and don't change anything else, or the program will try to set it up symmetric. This 'tricks' the program into using two different values for .006 and .050, so when you average those, you'll get a more accurate reading on an asymmetric cam. This could be done with any custom grind cam (I've done a bunch of those too), but it can get complicated and time consuming after a while!

These will be the specs for the Federal Mogul cs647 Buick 350 camshaft. Put static compression to around 10.25:1 to get about 7.77:1 dynamic.

Average the values at peak for both .050 and .006 and see what it comes to.

It'll be easier to post a couple of screenshots:

 

300hp at 5k and 359ftlb at 3500. 7.66:1 DCR.

 

I get 380 ft. lbs. @3000 and 268 hp @4500.

Take your findings and add them to these, including RPM averages.

It'll look like 284 hp@4750 and 370 ft. lbs. @3250, which is probably closer to the truth. (factory specs)

But who knows? The numbers are all over the place, and that doesn't include weather conditions or elevation.

Just get a decent guesstimation and leave well enough alone I reckon. It does give a decent general idea of what to expect, but more importantly, it's a useful tool with which to make comparisons to different engine changes, particularly cams.

 

I would love to see this document Gary, can you scan and post it?

If not, make me a copy and mail it, and I can do that.

JW

 

Sure thing, Jim.
It's in PDF format. I just tried to upload it here, but it says the file's too big.
I'll email it to you as an attachment.

 

jim@trishieldperformance.com

Thanks

JW

 

Ok, sent.

 

Yep, not exact, nearly impossible to do so on a computer but it does give a fair idea of what to expect with whatever parts or combos.