Open chat thread for Buick 350 Camshafts

I read in a Buick performance book Bulldog was working on 350 heads.But I see MTS Cadillac bought Bulldog according to their site.I wonder if they would be interested and how far bulldog got with their head. Just a thought.

 

(UNexhaustive) Comparison (present observation) between the Crower level 3 and the TA 212 for the Buick 350:



TA 212-350


.454/.456 @ 1.55 lift

@.006 280/285 62/55 lobe intensity

@.050 218/230 110 LSA @ 4*A = 106/114 I/E centerlines

IVO is 3.0 BTDC ( - indicates ATDC)
IVC is 35.0 ABDC
EVO is 49.0 BBDC
EVC is 1.0 ATDC ( - indicates BTDC)
Overlap is 4

Pros:

The TA 212's intake valve opens sooner and closes later than the Crower level 3, which means a larger permissible intake charge. Exhaust opens sooner, however, and closes later, meaning a longer evacuation period to get the larger charge out that the intake gave. Headers will accentuate this. Coupled with the larger lift (compared to the Crower level 3's lift), will aid the longer intake charge period. Larger valves and/or intake port work will be a benefit.

Cons:

It also means less dynamic stroke and CID, less intake vacuum, less combustion stroke, and is more dependent on long tubed scavenging exhaust design for optimal performance. Less exhaust lobe lift (compared to the Crower level 3's lift) means the valve is more dependent on the longer duration for exhaust evacuation, which could have been reduced with more lift.

Conclusion:

For the Buick 350, a pretty well-rounded performance oriented camshaft best used with other performance parts, particularly headers, though not completely necessary. NOT using headers would cut into the performance based on this camshaft's design intent, however. This cam seems as though it would perform well in any engine ranging from stock to heavily modified, though optimal performance would hover in the 'moderate' range when used with moderately ported heads/larger valves and headers with matching compression for premium pump gas.

(Jim Weise shows us an excellent example of this in one of his 350 builds)




Crower level 3-350


.446/.468 @ 1.55 lift

@.006 276/281 66/61 lobe intensity

@.050 210/220 112 LSA @ 4*A = 108/116 I/E centerlines

IVO is -3.0 BTDC ( - indicates ATDC)
IVC is 33.0 ABDC
EVO is 46.0 BBDC
EVC is -6.0 ATDC ( - indicates BTDC)
Overlap is -9


Pros:

By having the intake valve opening later and closing sooner than the TA 212-350, the Crower level 3-350 cam affords less overlap when coupled with its shorter duration exhaust lobe which gives better intake vacuum, longer dynamic stroke which means more dynamic CID. Exhaust opens later, providing more combustion stroke and an overall greater combustion cycle making more efficient use of the fuel charge while providing adequate exhaust evacuation coupled with the extra exhaust lobe lift emphasis, making headers less necessary.

Cons:

Is likely to make a little less power when compared to the TA 212-350 (despite its cons) when the 212 is optimized with scavenging accoutrements and will have a smooth idle, which many consider unattractive when choosing a performance camshaft. May not be quite as 'ideally suited' vs the TA 212-350 when the Buick 350's rod/stroke ratio is considered.

Conclusion:

This Buick 350 performance cam is almost the perfect match for moderately modified engines who still wish to use the stock exhaust manifolds, though a port and polish on those would provide obvious benefit. With more dynamic CID, it depends less on scavenging to make power, instead focusing on more efficient use of the somewhat smaller intake charge. This camshaft would better suit a street engine that could fit into any application where a direct fit header is unavailable and cost of custom headers is prohibitive. When compared to the TA 212-350, would probably make MORE power if both engines were in a similar, closer-to-stock environment. This cam would be best suited using mildly ported and contoured heads with or without oversized valves, over plain untouched heads.



Using the information above one could modify valve timing events to suit the application, or simply use either Crower level 3 or TA 212 and come out with an excellent choice for your typical street performance engine. Obviously, the TA 212 is a hotter cam and will benefit from additional performance add-ons, while the Crower level 3 is an excellent choice for a stock-sounding engine with exhaust manifolds that will perform well and get great gas mileage.





Potential variants for discussion:

Custom example 1

.434-.453/.443-.465 or thereabouts

@.006 27?/28? ??/?? lobe intensity

@.050 212/228 110 LSA @ 4*A = 106/114 I/E centerlines

IVO is 0.0 BTDC ( - indicates ATDC)
IVC is 32.0 ABDC
EVO is 48.0 BBDC
EVC is 0.0 ATDC ( - indicates BTDC)
Overlap is 0

A sort of 'in-between' cam which could potentially possess the best of both worlds from the Crower level 3 and the TA 212, with either the specs given above or some mild variant thereof.


More potential variants to come, and will range from mild to wild.


Gary

 

OK Gary. still trying to understand this. So if your cam has intake centerline of 102 and you advance it 4 degrees its at 98?
So if intake is meant to open at 40btdc then it will open at 44?and if so would this cam be better at zero or even retarded 4. To be at 106? Here is the specs lobe sep 107 intake center102 duration 287/305 intake opens 40 btdc close at 67 abdc. Exh open 80 bbdc close 45 atdc . This cam is aggressive.

 

That cam is beyond aggressive...


with your specs:

40
67
80
45

would be:

Your cam has an Overlap of 85.00 degrees
Intake Duration of 287.00 degrees.
The Exhaust Duration is 305.00 degrees.
The Inlet Cam has an Installed Centerline of 103.50 degrees ATDC.
The exhaust cam has an Installed Centerline of 107.50 degrees BTDC

103.5 plus 107.5 divided by 2 = 105.5 LSA


LSA is the angle that separates the lobes, measured in degrees. Intake centerline is where the cam is installed in relation to the crankshaft position (piston position), so advancing it will move intake centerline narrower while making exhaust centerline wider. This also changes the timing events (where the valves will open and close).


If you want a cam that has 107 LSA installed at 102 intake (5* advance), the exhaust will sit on 112*. (107*-5*=102* and then you add same number you subtracted from intake to the exhaust, so 107*+5*=112* for ECL)

LSA stays same and never changes. It's the physical difference between the lobes, and can only be changed by regrinding the cam.

Centerlines are where the camshaft lobes are in relation to TDC, measured in degrees from the crankshaft.

So installing a 107* LSA cam 4* advance would put intake centerline at 103* and exhaust at 111* (subtract 4 from intake, add 4 to exhaust).

It's simply twisting the cam rotation relative to the crank position.

All this will change those timing event numbers around so that they will happen earlier or later, depending on whether it's advanced or retarded or straight up.


If your cam is 107* LSA with 287/305 duration with a 102* intake centerline, the numbers will look like this:


IVO is 41.5 BTDC ( - indicates ATDC)
IVC is 65.5 ABDC
EVO is 84.5 BBDC
EVC is 40.5 ATDC ( - indicates BTDC)
Overlap is 82

 

The durations you posted...those are .006 numbers, correct? If not, that's one massive monster cam! lol

This one seems to fit your description better:

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1454&sb=2

Thanks to Paul for pointing this out to me. :TU:


So the ICL is 102 and LSA is 107, which means the numbers you see there are @ .050 and are accurate when the cam is installed @ 5* advanced.

Here's the numbers @ .050 duration with 235/249 107 LSA 102 ICL

IVO is 15.5 BTDC ( - indicates ATDC)
IVC is 39.5 ABDC
EVO is 56.5 BBDC
EVC is 12.5 ATDC ( - indicates BTDC)
Overlap is 28


And here it is again @ .006 with 287/305 107 LSA 102 ICL

IVO is 41.5 BTDC ( - indicates ATDC)
IVC is 65.5 ABDC
EVO is 84.5 BBDC
EVC is 40.5 ATDC ( - indicates BTDC)
Overlap is 82


This tells me that the lobes are asymmetrical, based on what they list in their website

I just used online (website) calculators tonight, and it's late, so I'm going to tackle it tomorrow. Can use a regular ole calculator and get it straightened out.

 

yes and thats the "middle" cam

 

Gary,don't forget to take in consideration valve clearance,having a valve closing at TDC would get VERY close to the piston or the piston would already of crashed into it.

Remember the crankshaft is rotating twice as fast as the camshaft,and the piston moves up and down two time per one full rotation of the crank,but good stuff all in all.:TU: (although a tough read,LOL):eek2:

Derek

 

I noticed That no one mentioned trying solid lifters to get a little more out of there cams has it not been tried ? I maybe entering the 350 world of performance Enhancement!!:TU:

 

Ok let's see...

Those 'Muthathumper' cams are asymmetrical for sure for max effect on performance, though I imagine they'd be hell on the lobe longevity, but hey if you only run the car every so often who cares right? It becomes more of a toy at this point. :Brow:

Let's compare the duration numbers as given on their website.

We see 235/249 @.050 and 287/305 @ .006.

Let's start with the intake lobe. 235 subtracted from 287 is 52. This is the lobe intensity for the intake lobe. It represents the angle the lobe is at between .006 and .050 lift. The smaller the number the less difference there is between the two, making the lobe lift faster which puts more strain on the lobe, but increases performance.

(This is probably the main reason for roller cams, as lobe intensity can be at values far greater than with flat tappet and wears out much, much slower with no risk of failure at break-in because it doesn't require breaking in. In fact, roller cams last practically forever as long as nothing catastrophic happens with the lifters, which should be changed every so many 10's of thousands of miles, possibly even 100,000 miles, simply for preventive maintenance. Keeping spring pressures to a minimum with milder grinds and using grooved cam bearings with adequate oil pressure would ensure a very long-lasting engine, even at performance levels. Money well-spent. Less friction also = more power...the pros go on and on)

For exhaust it's 249 subtracted from 305 which is 56* lobe intensity.

There is really no way to discern the lobe profiles other than the equal distance between the two sides (lobe lifting and lobe closing points), which according to those event numbers on their site, differ. This tells me that the lobes are probably lifting faster and closing later, making the camshaft easier on the head seats...or vice-versa. OR the shape is different. Could be anything really, though you can bet it's to milk every last drop of possible performance out of the profile as possible, based on the cam series' name and reputation.

There is one way to find out the variance for .006 since they list the timing events for those, but we'd need their timing events for .050 to get a better picture of how the lobes are shaped. Plus they could alter even more further up the lobe, so there'd be no way to know beyond .050 lift...
unless maybe one could take the lifts and contour a probable shape using a computer simulation program.

Or just buy the cam and have it measured.

---------- Post added at 06:23 PM ---------- Previous post was at 06:21 PM ----------

Good observations Derek. :TU:

Even better to have shorter lift on intake than exhaust when a camshaft is advanced...

---------- Post added at 06:38 PM ---------- Previous post was at 06:23 PM ----------

Or maybe I'd just question the info you see on that website, since the exhaust lift numbers are off.

lobe lift shows .327/.315 I/E which is .50685 (rounded up to .507) and .48825 (rounded down to .488) @ 1.55

On the website it shows valve lift to be .506/.491, when it's actually .507/.488 @ 1.55

@ 1.6 it's 523/.504 I/E

---------- Post added at 07:10 PM ---------- Previous post was at 06:38 PM ----------

IVO is 15.5 BTDC ( - indicates ATDC)
IVC is 39.5 ABDC
EVO is 56.5 BBDC
EVC is 12.5 ATDC ( - indicates BTDC)
Overlap is 28


And here it is again @ .006 with 287/305 107 LSA 102 ICL

IVO is 41.5 BTDC ( - indicates ATDC)
IVC is 65.5 ABDC
EVO is 84.5 BBDC
EVC is 40.5 ATDC ( - indicates BTDC)
Overlap is 82


There's 1.5* difference for intake and 4.5* difference for exhaust on this info from Wallace's website (which splits them evenly) to the information @.006 on Comp's website for this cam.

IVO is 40* and IVC is 67*, which means the lobe is actually angled more toward opening faster and closing slower (as I said earlier) by a difference of 1.5*. This would put the lobe looking more oblong leaning toward TDC. What this would also do is change LSA at different lifts. This is where it gets complicated, since the LSA will get narrower as it goes up in lift.

Faster intake ramp = even more performance, though slower exhaust closing creates another dynamic dependent on RPM, and that's the 'bleed-off' or 'blowby' (between .050 and .006 lifts) that would exist at lower RPMs but would decrease as the engine revs...(this is a feature the stock Buick 350 cam seems to have based on my observations, and contributed to some of the confusion I had earlier on its design)

What this design does, however, is create a cam profile that seems to generate a wider power band than with symmetrical lobes. Improves power down low, coming on sooner and stronger, but remaining strong throughout the entire power band. In stock form, the lifts and numbers are so weak that it doesn't really affect longevity much, though it does help the stock cam perform better than one might imagine upon initial examination.

With LSA being narrower as the lift increases, this also means it widens to its max at .006 or seat. A camshaft could start off retarded slightly and end up advanced as the lift progressed, as the stock camshaft does.

This means that at lower RPMs where the blowby is prevalent, the cam uses more of the lower lift duration in its power band (which is always wider), permitting the retarded intake setting to be more obvious, making the cam act like it's bigger than it is at lower RPMs, while after it revs up past a point where the blowby becomes less and less apparent, the cam begins to behave as though it has a tighter LSA.

Anyway that's the theory I have. I'm sure there's a computer program out there to sort this all out.

EVO is 80* and IVC is 45*, showing an even greater emphasis of this aforementioned effect on exhaust at 4.5* instead of only 1.5*.

This is of course my theory on this cam design, and I may be giving it more credit than it actually has. It could be something as simple as a typo or some errors with some online info...


Anyways, something to think about anyway! Maybe this info will help more than confuse.

Gary

 

The dominate parameter of the "Mutha Thumpr" is the overlap.
With 28* of .050" overlap there isn't any power till after 2500 rpm and when the power does come on it's like turning on a switch.

This cam is best used with long tube headers or else the power band will get cut short on the upper end as well.

Intake manifold vacuum will be very low and probably not enough for power brakes.

With the aggressive leading lobe ramps it might not be a bad idea to use solid lifters.
I've seen a few people complaining about the Mutha Thumpr cam not making enough power.

Paul

 

Couple of observations I'd like to make for open discussion on a particular cam.

Revisiting this engine rebuild: http://www.powerblocktv.com/episodes/HP2011-13/building-the-other-350-small-block-engine

I noticed they used the Big Mutha Thumpr Camshaft Kit K92-602-5, which is this cam: http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1455&sb=2 and uses this timing gear set: http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=3215 which as you can see, is a single keyway gear set.

The cam's specs are set up for 5* advance, which may or may not be where this timing gear puts it (I'm guessing no since it's supposed to be a 'replacement' for mild/stock engines).

That could be a bit off, since in this kit http://www.ebay.com/itm/Competition-Cams-K92-602-5-Big-Mutha-Thumpr-Camshaft-Kit-/141103408354 it shows the timing gear/chain as looking a bit different, though still with a single keyway (or it could just be a representative image).

Issue #1: IVC @ .006 is 71* with 5* advance, which means it needs 10.56:1 SCR for 8:1 DCR, even more if it's advanced less than 5* (which it probably is). Also, advancing it less will mean putting power band higher in RPM range, which with the heads used (more on this later), would work even more against this combination.

Issue #2: No mention was made about any deck or head surface milling to bring compression up. Pistons used were the 'shallow dish' cast pistons, which if they are anything like these http://www.summitracing.com/parts/slp-340p30/overview/make/buick would sit .040 below deck by default, with a 10.18cc dish size. This comes to 9.73:1 SCR with .040 head gaskets, 58cc head volume and .030 overbore, over 3/4 of a point less than where it needs to be. Less advance on the ICL would make this even worse.

Issue #3: While the valves are "Stage1" size (1.92 int, 1.55 exh), they are in '75 heads, which are notorious for having smaller and less ideally suited runner designs (without porting), and the only head work that was mentioned in the video was the 'Stage1' intake runner port work (no mention of exhaust, where it would be crucial (UPDATE: I re-watched the video, and you can see on the exhaust ports that they are in fact untouched). No mention of CFM flow parameters or I/E ratios to match the camshaft (which is WAY too big, more on this later). If we assume nothing was done to the exhaust runners, the engine would need a camshaft with a lot of exhaust emphasis (suitable mainly for smaller camshaft profiles) and would make the camshaft used grossly mismatched.

Issue #4: The camshaft used probably makes less power than if they would have used a stock one. Why? Because it is so grossly mismatched in every aspect that the engine is working against itself from idle to redline. Observe A) in the video how sluggish the engine throttle response is. My stock 350's had 3x this throttle response, and this should be much, much crisper. Notice B) when they rev it up how the choke flap is just vibrating away like it's going to start flapping and fly away. This (to me) indicates severe intake reversion. You can hear it as it revs and makes its dyno pulls too. My ears tell me when I listen to this engine that it's working against itself. The dyno numbers pretty much tell the story.

This is with all due respect to the builders. I'm somewhat familiar with the scenario that went on surrounding this build, and they did a fine job with what they had to work with. My only point to this post is to point out how camshaft mismatch can cripple an engine's performance.

Feel free to point out any mistakes I made or to add in your own thoughts or ideas.


Gary

Notice the super narrow torque band (tight LSA is doing this) and overall wimpy performance:

Also notice that the HP trails off after around 5200...I smell issues with lobe intensity and hydraulic lifters. Probably borderline lifter crash. The cam's specs are supposed to pull to 6400 RPM, according to Comp...

Plus the cam will wear out quickly, get crappy gas mileage, and probably doesn't have enough vacuum to operate a vacuum advance, much less power brakes.

Another classic 'build it like a Chevy' Buick.

 

I thought power block build had am&p custom 1.94 intake valves. a d I believe they used the biggest of 3 cams and 10 to 1 piston in a late block with a taller Deck. Which means at least. 5 lower compression. Plus they ran 38 degrees of timing. Something is off there.should not need that much timing.

 

Ah yeah the taller deck. So that's no less than 1.25 compression points off.

Listen to it run, watch the throttle response, the timing position, and the movement of the primary choke flap...

Notice the exhaust port when he's talking about the heads. They're untouched. Combustion chamber is untouched. Only port work I see are intake runners. It doesn't show bowls or anything.

By the way, what's the difference in deck height between those later blocks and the earlier ones? I'm showing 10.187".

 

Well, that explains why the engine did not have as much power as I would have thought. I thought this thing was going to pull closer to 400 HP but you are right it was built like a Chevy. Like I said before, If this thing was built more like my motor with good porting, it would have been closer to that 400 number, but we just could not beat the Chevy with the Buick now could we.

 

The difference between the later blocks and earlier ones is that the factory finished machined deck height is taller than the factory spec. Even the earlier blocks were taller than the factory spec. by as much as .035",and the later blocks were even worse,by as much as .060" taller than the 10.187" listed spec.,the listed spec. was left unchanged in all the manuals though.But I suspect that for emission reasons they left the deck height taller to bring down compression to meet the emission standards of the day without having to change the piston design.(a bean counter alteration)

If using a later block in a performance build using custom pistons,the added material on the deck may work in favor for gasket sealing? I will be working with a 77 block in the near future and will disclose the factory machined deck height of that block to know how much more taller it actually is,as well as magna fluxed and a sonic testing will be disclosed.(Stay tuned,the block will probably be cleaned this weekend,after that the processes of measuring and machining can start soon after.):Brow:

I will start a new thread when things progress more,all I have right now is a few before pictures of a dirty rusty block that were taken a couple of weeks ago.(didn't want to start a thread and leave everyone hanging while the block was waiting its turn in line to be started.)


Derek

 

To be fair, the Comp cam would have done much better if the heads had been contoured to better match it, along with raising the compression to match the cam's IVC point @ .006.

I'm not a big fan of more lift on intake type cams for Buick engines. This cam's higher intake lift emphasis would only exacerbate the intake reversion problem, and just compounds the issues the engine is experiencing.

The engine's sound. All it needs is another (milder) camshaft and compression match to that camshaft, along with some exhaust runner work and some bowl blending/guide boss contouring, and it'll see numbers much closer to 400 HP and 425 ft. lbs.

It wouldn't surprise me one bit if this same engine, with the aforementioned modifications were made using either the Crower level 3 or TA 212 camshaft (or some similar variant thereof), you'd see well in excess of 375 HP and 400 ft. lbs., along with 18-22 MPG (without overdrive), 15-17" vacuum, and a much longer lifespan all off of premium pump gas.


Gary

---------- Post added at 05:16 PM ---------- Previous post was at 05:14 PM ----------

 

Actually after the block passes the magna flux and sonic tests the first thing will be the block fill before any machining. And since we are going with custom pistons,not much deck machining will be required passed making both sides parallel at 45 degrees of the mains and cam centerline and that both sides are the same,then measured to help figure out what the compression distance the pistons will be made. We will also have to wait and see what the head cc ends up being to spec the piston dish volume so minimum will be machined off of the heads as well.:TU: (the magic of custom pistons)

As for valve train geometry and measuring push rod lengths,that stuff is easy enough and should be checked on any build. Plus I have a couple of tricks up my sleeve for rocker arms that should be ineresting that some will like and others won't but should work very well.:Brow:

And as for an intake,there will be no boat anchor intakes on this build,LOL!:laugh:

So thats a no on the extra machining,and with the block fill will end up weighing more,but if the fill wasn't in the block there would be coolant in it that has weight to it,so it won't weigh much more than a stock block(if at all) after its installed in the car.(actually that is a good question,what weighs more block fill or coolant?)o No:


Derek

 

I was speaking in general about builds, not the one you're doing specifically.

I know there'll be a different method you'll use with custom pistons and no boat anchor intake. :grin:

I also know about those 'tricks up your sleeve' about the rocker arms... :Brow: (you told me in one of your emails)

 

Oh,I wasn't sure if you were speaking in general I thought you might be replying to me. Thats ok though,I got to write about how custom pistons can be used to avoid a lot of machining.

To save about$75- $150 to not deck the block and another $75-$150 not to mill the heads would go a long way to buying some nice light weight forged pistons.:Brow:

Not to mention the $$ a new set of push rods would be on top of all the machining that could go to pistons and be less $$ if new pistons were in the plan anyway. And there is the intake to head alignment that wouldn't be an issue either that wouldn't need corrective machining.

Lets say as much as a $400 savings from not doing all that machining and not having to buy push rods one could buy those really nice AutoTec forged pistons and dial in the compression ratio by having them made to the builder's spec. "for no extra charge". Probably would cost around the same with cheap pistons with all the machining done to try and dial in a compression ratio of choice.o Noas long as the deck or head surface is in good shape and doesn't need to be machined that is)

Derek