Open chat thread for Buick 350 Camshafts

:laugh:

 

I tried to improve the TA 212-350 cam and couldn't (in its latest design), based on the spirit of the cam's intentions. I thought I did a decent job at making a smaller 'torque grind' cam that beat the Crower level 2 and 3 (IMO), but last night found a way to improve it.

I took this improved rendition and tried to improve upon it based on its spirit of design, and found it's pretty much as good as it's going to get.

Here's what I did:

I tightened the lobe separation angle (LSA) from 112 to 110, then widened the intake and exhaust durations @.050, and kept the .006 IVC point @58*, the same. This also puts the intake lobe intensity to 64*, while the exhaust is set at 56*. This seems to be an ideal zone that the Buick 350 likes (and is similar to the TA 212-350), according to this dyno simulator.

The new cam now makes 4 ft. lbs. and 12 HP more than the old one, with a wider plateau on the power peaks for HP and TQ, using the exact same engine as the old cam (only thing done was a cam swap, like in the comparisons I did earlier).

It makes 428 ft. lbs. peaking at what seems to be 2000 RPM (that's as far down as the simulator goes), stays almost perfectly flat to around 3500 where it starts to slowly trail off. HP raises fast until around 4500 RPM, then plateaus off, peaks at 5000, and slowly trails off to 5500. From 5500 to 6000 the HP dips down fast, but not as fast as the peaking to 4500. This means the overrev capacity of this cam is tremendous (you could feasibly shift this cam at 6000 RPM, though 5200-5300 is probably the best place).

Peak power numbers are 428 ft. lbs. @2000 RPM and 342 HP @5000 RPM.

Huge torque off-idle and would pull strong all the way to 5500 RPM. If that's not a wide power band, I don't know what is!

This is quite impressive considering the cam's specs:

200/220 I/E @.050 (this shows my previous theories correct with the Buick 350 iron head wanting much more exhaust emphasis on smaller cams)
264/276 I/E @.006 (64/56 I/E lobe intensities)
110 LSA @ 106 ICL

Lobe lift: .280/280 (.434/.434 @1.55)

SCR: 9.5:1 for 8:1 DCR

Intake: stock
Exhaust: small tube headers
Carb: 750 CFM
Heads: "Stage1" cleaned up with oversized valves of 1.92/1.55 I/E
Overbore: .030




Gary

 

I'd like to add some more comments about this cam (and others like it).

The reason it does so well despite the low intake duration (and in fact does better with it--I tested many variants and this is what it ended up being) is because it seems the wide exhaust duration, coupled with its increased lobe intensity when compared to the intake's, acts like a 'siphon' at higher RPMs, much like how overlap on a larger cam would act with scavenging.

I suspect this is why the TA 212-350 does so well, and that it does better with less exhaust duration emphasis than this smaller cam because it has overlap to help with the 'siphoning' effect via scavenging. The smaller cam needs more exhaust duration emphasis because it can't rely as much on scavenging.

This helps to extend the RPM range and boost power levels beyond what a tighter I/E ratio cam would, while retaining the lower RPM 'torque grind' aspects.


Gary

 

Here it is again with considerations taken to replicate the Buick 350 stock intake with torque mods implemented, and a .060 overbore instead of .030:





Shows 455 ft. lbs. @3000 RPM and 337 HP @4500 RPM.

This is with small tube open headers. Real world numbers will be less.

Very wide torque band that will start well below 2000 (probably around 1200-1300) and continues nice and flat up to 3000 RPM where it finally peaks, then trails off nice and slow.

I have tried other variants of this cam, including a straight pattern cam, but only results in losing power, either torque or hp, or both. (Yes, the straight pattern cam makes less power than this wide, split-pattern cam (both TQ and HP), and has narrower bowerband).

Even if the real world numbers are off by a lot, this cam STILL makes some impressive power. I can choke it down and still can't get the torque numbers below 406 ft. lbs., even when the HP goes all the way down to 282.



Gary

 

Looks like a great overall cam to me.

My question is: Have you decided which cam profile would you want to use in your engine?
I'm betting you are having a difficult time deciding. LOL

Paul

 

I get closer every day Paul! :laugh:

I think it's a toss-up between this cam and going a little more ambitious with the TA 212-350. If I don't use this custom cam, it'll be that cam most likely.


Gary

 

Here's the latest custom cam, yet again, but with bone stock heads and valves. Stock ports, not even so much as a cleanup. Stock valves.

Same .060 overbore, and I even choked it back further still by adding mufflers to the dyno simulator to make the numbers seem 'more realistic'.

Still produces massive low-end torque.





Produces 429 ft. lbs. from 2000-2500, then drops 1 ft. lb. at 3000 to 428.

HP peaks @4500 RPM with 296 HP.


Gary

 

Here's the TA 212-350 for comparison, choked down as well with the stock, untouched heads, .030 overbore for matching with the different pistons (which don't come in .060 overbore) which sit in the hole innately higher, for considerations of less machine work done to the block to achieve the 10:1 compression this cam feels most comfortable with to match its IVC point of 66*.

So even though it's .030, the comp has been bumped .5 a point to better match the camshaft.

Also added were the large tube headers, which this cam seems happier with even in the choked down status with mufflers attached.

Also removed was the torque mods for the stock intake, making it flow a bit better to help compensate for the extra lift and duration this cam has over the custom one I made. This drops torque a bit, but adds HP and increases the power band by a couple hundred RPMs.

I did it this way because this might be the typical scenario that an average engine builder might encounter while building his own Buick 350, with little machine work and no head porting, but making sure the timing is correct and compression matches the camshaft.

Notice the torque comes up slowly from 2000 RPM, then slowly climbs from 2500 to 3500 where it peaks, then trails off slowly. An otherwise nice, broad torque band that peaks just over 400 ft. lbs.

Hp climbs from 148 @ 2000 RPM to 324@4500, then planes off and trickles out another 2 HP @5000 before trailing off to 5500 and then nose-diving after that. Nice wide HP band from 4000-5500 RPM.

Peak numbers are 404 ft. lbs. @3500 RPM and 326 hp @5000 RPM, with 390 ft. lbs. @2000 RPM.

A mild stall would help this combination, say a 2000 or 2500 is all that's needed, with a gear from 3.23 to 3.73, depending on how aggressive one plans to drive.





These numbers are probably pretty close to real-world (flywheel) numbers in this combination, providing steps are taken to make sure the engine is tuned properly.

For the "Budget" minded, this combination isn't unrealistic. No head work, .030 overbore with some shaved off deck and heads to achieve around 10:1 true static compression, netting about 7.8 or 7.9:1 DCR. Compression could be dropped slightly to compensate for more of a buffer zone with pump gas premium and have minimal impact on the power.

TA's 212-350 cam with their Stage1 single springs @100/260 # closed/open should work fine. Get the big tube (1 3/4" primary, 3" collector) headers, 2 1/2" exhaust with good flowing mufflers and maybe an H or X pipe.

With head work and bigger valves, the numbers go up nicely. This cam responds well to mods, so the more you put in, the more you'll get out.

(A "High-flow" intake, such as the TA Stage1 intake, will drop torque and increase HP, according to the dyno simulator. This aligns well with the numbers seen on Jim Weise's dyno results, when the head flow numbers are set to match his)

Gary

 

When comparing TA's 212-350 camshaft with the custom one I came up with (which outperforms all other 'grunt' to 'mild' grinds I've tested in both HP and TQ), the two cams seem to swap HP for TQ with each other, and about 1000 RPM difference in peak torque, while only 500 RPM difference in peak HP, when compared in stock-mild environments.

You can adjust the TQ and HP up or down, and/or higher or lower in the power band by doing some adjustments as far as where the ICL is installed to (though both work best @4*A IMO), or by adding/removing add-ons, such as intake, headers, etc.

I noticed in another thread how much power roller rockers seem to give by simply bolting them on, so that's another option if one has a spare 700-800 bucks lying around.

Another good option would be to upgrade to a roller cam version of these two, along with those roller rockers. :TU:



Gary

 

Dude you rock! I am contemplating on throwing in a roller. Please help me understand why it is that they make more power. ;-)

 

Main reason is less friction. The roller tips allow it to move over the parts much easier, which restores lost power the engine wouldn't otherwise have due to friction. The engine should run a bit cooler too as a result.

Roller cams and lifters also have higher lifts, which helps somewhat with these milder applications, but would make a HUGE difference with a set of heads that flow well at higher lifts, like heavily ported irons or those aluminum heads due out.

One or the other or both would be ideal, providing your wallet can be persuaded to agree with you. :grin:

With the introduction of the new aluminum parts on the way, a roller cam, roller rockers and headers, anyone could bolt together a good running, powerful Buick 350 as long as they had the money.

I feel pretty confident the sleepy headed Buick 350 will wake right on up with a pissed off vengeance once those are bolted on and tuned.



Gary

 

Ah yes I'm confident we will see some power monsters when those heads are produced. I bet you can't wait to design cam combos for them

 

Yeah I'm pretty anxious to see the flow numbers on those heads. :TU:


Gary

---------- Post added at 09:22 PM ---------- Previous post was at 09:21 PM ----------

On the stock heads with the TA 212 cam, notice how it gets choked down @4500 RPM. The cam wants to pull better to 5000 and beyond, but is restricted by the heads.


Gary

 

That power limit reminds me of Chevy tbi heads... Great for tq. But not a stomp em head.

 

Your right,the sbc tbi heads have swirl ports(almost half of the port is blocked bycast iron shaped to make the A/F mixture rotate as it enters the chamber) which really restricts high rpm flow,at around 4,500 rpm they're maxed out. That is one of my many side project I have,to see if there is enough material to machine out of the sbc swirl port to make those boat anchors flow some cfm!


To an extent a sbb 350 head also has a swirl port design but not as restricting and not as swirled as the sbc heads.The sbb swirls the A/F mixture with an offset valve to port that ramps the A/F in the chamber from one side to rotate the incoming mixture. Swirling the A/F mixture as it enters helps promote low end torque,but limits high rpm HP,but not as much as those crappy sbc tbi heads.LOL

If TA can spread the valves apart enough to have the center of the port more inline with the the center of the valve,it will help tremenously with flow,bigger valves would also as long as they're not overly shrouded.


Derek

 

Ah so that's what's holding sbb heads back. if like to see some vortec and hemi head traits implemented into the reconstructed sbb heads

 

Bump... We need to re-do this work with the alum heads now

 

The real reason a roller cam makes more power than a flat tappet. Gary really missed the mark on why they are better. Found on the internet. The second paragraph says it all.

So what is a roller cam? Quite simply, a roller cam is designed to use roller lifters. There are tons of benefits to rollers. First, is the reduction in friction. Because the lifter rides on the camshaft through a roller ball, there is very little friction. This means that the zinc additive has no effect on the break-in of the camshaft. Roller lifters do not have to be changed when a new cam is installed either, reducing the cost over time. This is only part of the story though, as the real juice is in the camshaft design.

Because the roller tip can easily follow a steep ramp, roller cam design changed radically. Instead of a slow ramp that opens the valve over 15-or-so degrees (same for closing), a roller can pop the valve open very fast, keeping it open at full lift for much longer and then slam the valve closed quickly. This allows more air and fuel to enter and leave the combustion chamber than possible with a flat-tappet. This makes more power, and does so more efficiently. This is also the reason that roller cams require much heavier valve springs to control the valve’s movement.

If you ever see a flat tappet cam comapared to an identical roller the roller is much fatter. Gets that lifter up and open and keeps it that way for longer. Something like an old school Stock Eliminator cam except the roller lifter can follow it easily.

 

So what would be the closest roller equivalent to a stock oem cam?

Jim

 

Soon I'll be doing my first 350 SBB after doing BBBs since the mid '80s. It's going in my '79 Estate wagon, beater and parts runner, with a TH350 and 3.23 gears. I had really good experience with a Crane HIT266 grind (216/228@.050", .456/.480", 112*LSA) back in the '80s in my '72 LeSabre Custom 455 with the TH400 and 2.56 gears, so I wanted something similar. Crane has redone their lineup and no longer offers that grind, and their pricing has kinda gone crazy too, so I impulse-bought a Lunati shelf cam. It's a "High-Efficiency" 215/225@.050" with .469/.493" on a 110*LSA, which I hope will compliment the long stroke 350. I think I'm going with milling the heads maybe .030" and 8.5:1 replacement pistons, as I'm not racing and it's a regular gas build. Scored a T/A dual plane and want to run a Street Demon 625 carb, and stock exhaust manifolds with 2.5" duals. The stock motor scoots pretty well with the 13" factory converter, but I'm thinking of going with a 12" Chevy-style (bolt and nut) converter behind the fresh, cammed motor. We put a mild-cammed (218@.050") 403 Olds in a Pontiac Formula and used the Chevy-style converter and it worked perfectly, so I'm thinking it's the way to go. Thoughts?