Open chat thread for Buick 350 Camshafts

Another, more 'practical' rendition of the Buick 350 "Stage1 stock" cam:


GF 204-14H "Stock Stage1 Cam" Practical

.392/.408 @ 1.55 lobe .253/.263

266/280 @.006 116/112 I/E 114 LSA
2*R
112/116 I/E (4*A ICL)


62/66 lobe intensity

IVO is 21.0 BTDC ( - indicates ATDC)
IVC is 65.0 ABDC
EVO is 76.0 BBDC
EVC is 24.0 ATDC ( - indicates BTDC)
Overlap is 45

204/214 @.050 110/114 I/E 112 LSA
2*A
106/118 I/E (4*A ICL)


IVO is -4.0 BTDC ( - indicates ATDC)
IVC is 28.0 ABDC
EVO is 45.0 BBDC
EVC is -11.0 ATDC ( - indicates BTDC)
Overlap is -15
--------------------------------------------------------------
Power Range (Shift Point): 1500-4400 (4900-5100) "1500-5000"

Wide power band, with HP peaking around 4400-4600 RPM, fading
slowly to 5100 RPM, then nose diving somewhere around
5300-5600 RPM.

Peak torque should be around 3300-3500 RPM, with a very wide
torque curve, particularly from 1800 to 4800 RPM. Main torque
focus will be between 3000-4500.
--------------------------------------------------------------
For use with Premium pump gas:

Static compression ratio of 10.05:1.
Effective stroke is 2.98 inches.
Your dynamic compression ratio is 8.00:1 .
Your dynamic cranking pressure is 158.97 PSI.

Static compression ratio of 9.72:1.
Effective stroke is 2.98 inches.
Your dynamic compression ratio is 7.75:1 .
Your dynamic cranking pressure is 152.55 PSI.

Static compression ratio of 9.40:1.
Effective stroke is 2.98 inches.
Your dynamic compression ratio is 7.50:1 .
Your dynamic cranking pressure is 146.16 PSI.

Recommended static compression ratio for Premium: 9.5-9.75:1
-------------------------------------------------------------------
For use with Regular pump gas:

Static compression ratio of 8.43:1.
Effective stroke is 2.98 inches.
Your dynamic compression ratio is 6.75:1 .
Your dynamic cranking pressure is 127.24 PSI.

Static compression ratio of 8.11:1.
Effective stroke is 2.98 inches.
Your dynamic compression ratio is 6.50:1 .
Your dynamic cranking pressure is 121.02 PSI.

Static compression ratio of 7.78:1.
Effective stroke is 2.98 inches.
Your dynamic compression ratio is 6.25:1 .
Your dynamic cranking pressure is 114.85 PSI

Recommended static compression ratio for Regular: 8:1-8.25:1
------------------------------------------------------------------

Camshaft takes the general idea from the stock centerlines and LSAs, but applies them to a more practical usage without so much 'hair splitting' on the numbers. The idea is to build about 2* retard into the .006 durations while having the durations at .050 with 2* advance built in. This creates a design similar to the stock cam's intentions of making an otherwise small cam behave larger than it actually is, with asymmetrical lobes for faster lift side ramping (though still within very safe parameters) while slowing down the closing side for a smoother, safer transition and longer-lasting valve seats.

Another feature of this lobe design is helping the compression stay within realistic ranges for street and pump gas usage.

I'm creating these myself, and posting them for others to use, critique, analyze, or otherwise use as reference. If anyone decided to make a camshaft from these specs, it would be way cool if I got credit for its design. It's just another small way I enjoy contributing to the community and the Buick 350.


Gary

 

GF 192-08H "Stock Cam"

.392/.408 @ 1.55 lobe .253/.263

268/284 @.006 116/112 I/E 114 LSA
2*R
112/116 I/E (4*A ICL)

IVO is 22.0 BTDC ( - indicates ATDC)
IVC is 66.0 ABDC
EVO is 78.0 BBDC
EVC is 26.0 ATDC ( - indicates BTDC)
Overlap is 48

192/208 @.050 110/114 I/E 112 LSA
2*A
106/118 I/E (4*A ICL)

IVO is -10.0 BTDC ( - indicates ATDC)
IVC is 22.0 ABDC
EVO is 42.0 BBDC
EVC is -14.0 ATDC ( - indicates BTDC)
Overlap is -24

(Numbers in parentheses indicate what the lobe intensity would
look like if the lobe slope were symmetrical)

32(64)/44(88) intake valve slope intensity for lift/close
36(72)/40(80) exhaust valve slope intensity for lift/close

34(68)/42(84) lift/close average lobe intensity for I/E
76/76 I/E average lobe intensity for average I/E durations

Power Range (Shift Point): 1200-4200 (4700-4900) "1200-4800"

Wide power band, with HP peaking around 4000-4400 RPM (depending
on head flow and valve size), fading slowly to 4900 RPM, then trailing
off fast somewhere around 5100-5300 RPM (should be capable of revving
to 6,000 RPM, though obviously not recommended).

Peak torque should be around 3100-3300 RPM, with a very wide
torque curve, particularly from 1400 to 4600 RPM. Main torque
focus will be between 2200-4200.

For use with Premium pump gas:

Static compression ratio of 10.14:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 8.00:1 .
Your dynamic cranking pressure is 158.97 PSI.

Static compression ratio of 9.81:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 7.75:1 .
Your dynamic cranking pressure is 152.55 PSI.

Static compression ratio of 9.48:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 7.50:1 .
Your dynamic cranking pressure is 146.16 PSI.

Recommended static compression ratio for Premium: 9.75-10:1

For use with Regular pump gas:

Static compression ratio of 8.51:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.75:1 .
Your dynamic cranking pressure is 127.24 PSI.

Static compression ratio of 8.18:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.50:1 .
Your dynamic cranking pressure is 121.02 PSI.

Static compression ratio of 7.85:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.25:1 .
Your dynamic cranking pressure is 114.85 PSI.

Recommended static compression ratio for Regular: 8:1-8.25:1


Paying closer attention to the 'weak point' of these cams, which is the lift slope on the intake lobe (which was a bit tighter than I'd rather for the last camshaft, the "Stage1 Practical"), this "Stock cam" (which closely follows the parameters and overall spirit of the Speed Pro stock cam) is my rendition of a stock camshaft for the Buick 350, with a few improvements for performance and economy without worrying too much about emissions, though the differences are subtle.

This camshaft would better compliment cleaned up heads than the Speed Pro stock cam, with more effort on my part to make the cam a bit more symmetrical in other aspects aside from the lobe dimensions, or at least 'geometrically' friendly to each other.

Enjoy.


Gary

 

More info for reference:


Speed Pro's Stock Buick 350 camshaft:

.243/.253 I/E lobe lift
.377/.392 I/E valve lift @ 1.55 stock rocker ratio

270*/293* duration @.006
189*/208* duration @.050 81*/85* I/E lobe intensity

112.75* LSA @.050
109.5*/116* I/E centerlines @.050

114.25* LSA @.006
116*/112.5* I/E centerlines @.006

This equates to a 1.75* retard setting @.006 and 3.25* advance @.050

Specs for stock cam with a 4* advance on timing:

270/293 @.006
112/116.5 I/E 114.25 LSA
4*A

IVO is 23.0 BTDC ( - indicates ATDC)
IVC is 67.0 ABDC
EVO is 83.0 BBDC
EVC is 30.0 ATDC ( - indicates BTDC)
Overlap is 53

189/208 @.050
105.5/120 I/E 112.75 LSA
4*A

IVO is -11.0 BTDC ( - indicates ATDC)
IVC is 20.0 ABDC
EVO is 44.0 BBDC
EVC is -16.0 ATDC ( - indicates BTDC)
Overlap is -27

(Numbers in parentheses indicate what the lobe intensity would
look like if the lobe slope were symmetrical)

34(68)/47(94) intake valve slope intensity for lift/close
39(78)/46(92) exhaust valve slope intensity for lift/close

36.5(73)/46.5(93) lift/close average lobe intensity for I/E
81/85 I/E average lobe intensity for average I/E durations


This last bit on lobe slopes is particularly important, since it's the basis for my latest 'stock' cam rendition, and plays a key role in the cam's effectiveness.

With such a disparity between the durations @.006 and .050 lifts, this creates a gentle slope upon which the lifters have a smooth ride. While not particularly performance oriented, it will ensure maximum life of the valvetrain. To offset the weaker lifts and durations, an asymmetrical lobe is utilized which creates a faster lift speed than closing speed. This design idea is ideally suited for maximizing the lobe's effectiveness at any lift, and is particularly useful for the stock (or any low-lift) cam.

This also creates the illusion of having a larger camshaft, since the increased duration between .006 and .050 is useful on the lift side of the lobe, it is especially useful on the closing side of the lobe, which is exactly how these lobes are designed. This 'two cams in one' design is subtle but effective, creating a valvetrain that will outlast any other while permitting the engine to make power beyond a typical symmetrical lobe design, which effectively widens the power band and general overrev capacity, particularly when used with a carburetor that adjusts the fuel/air delivery as the engine needs, i.e., Rochester Quadrajet.

It does seem, however, that when lifts and durations are increased (as with larger 'performance' style camshafts) this lobe style becomes less necessary and can actually get in the way of performance characteristics by making the cam act too big, or making the lobes too intense for the lifters to safely follow on flat tappet designs, depending on the symmetry design. Camshaft manufacturers already do this using computer programs for their special brand of camshafts, which unfortunately tend to wear out too fast or fail upon break-in.

I did come up with a hotter version though, and is still within safe parameters of lobe wear. The exhaust lobes are symmetrical, and the lift side of the intake lobe is of the same symmetry as the exhaust's lift/close intensities, but I made the intake closing side longer in duration to increase the effective intake duration, all while keeping the actual intake duration lower for better I/E symmetry for air flow.

These cams are basically just ideas, and I don't use a computer program to configure them, only my mind and some calculators. The idea is to create a lower-lift cam that will have decent longevity, gas mileage, wide power band, and yet optimize the air flow strengths and weaknesses of the Buick 350 heads, while making it worthwhile to create and use over a basic stock cam.

I haven't decided whether or not to increase the lobe duration for exhaust or leave it as is, but I wanted to list the idea here for future reference and comments/ideas/input/critique.

Lobe Separation Angle is greater at .006 than it is at .050, and would continue on this path until reaching its peak lift, rounding off more for a smoother transition and effectively increasing the duration at peak lift. It starts off at 2*R and goes to 0*, having the camshaft installed at 4* advance @.050 to the given valve timing events listed below.


GF 202-18H GS-350

.403/.434 @ 1.55 lobe .260/.280

270/278 @.006 115/111 I/E 113 LSA
2*R
111/115 I/E (4*A ICL)

IVO is 24.0 BTDC ( - indicates ATDC)
IVC is 66.0 ABDC
EVO is 74.0 BBDC
EVC is 24.0 ATDC ( - indicates BTDC)
Overlap is 48

202/218 @.050 111/111 I/E 111 LSA
0*
107/115 I/E (4*A ICL)

IVO is -6.0 BTDC ( - indicates ATDC)
IVC is 28.0 ABDC
EVO is 44.0 BBDC
EVC is -6.0 ATDC ( - indicates BTDC)
Overlap is -12

(Numbers in parentheses indicate what the lobe intensity would
look like if the lobe slope were symmetrical)

30(60)/38(76) intake valve slope intensity for lift/close
30(60)/30(60) exhaust valve slope intensity for lift/close

30(60)/34(68) lift/close average lobe intensity for I/E
68/60 I/E average lobe intensity for average I/E durations

Power Range (Shift Point): 1500-4400 (4900-5100) "1500-5000"

For use with Premium pump gas:

Static compression ratio of 10.14:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 8.00:1 .
Your dynamic cranking pressure is 158.97 PSI.

Static compression ratio of 9.81:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 7.75:1 .
Your dynamic cranking pressure is 152.55 PSI.

Static compression ratio of 9.48:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 7.50:1 .
Your dynamic cranking pressure is 146.16 PSI.

Recommended static compression ratio for Premium: 9.75-10:1

For use with Regular pump gas:

Static compression ratio of 8.51:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.75:1 .
Your dynamic cranking pressure is 127.24 PSI.

Static compression ratio of 8.18:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.50:1 .
Your dynamic cranking pressure is 121.02 PSI.

Static compression ratio of 7.85:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.25:1 .
Your dynamic cranking pressure is 114.85 PSI.

Recommended static compression ratio for Regular: 8:1-8.25:1



I was rather pleased with the outcome of this camshaft's symmetry while creating a longer slope on the intake closing lobe.


Gary

 

Here's one based on the one above, only calibrated a bit larger, for those fans of everything bigger...

This is the largest I'd recommend with safe lobe ramps. Larger than this and it's just going to wear out too fast.

It came out to be 2* smaller and 2* larger than the TA 212-350 cam on I/E durations @.050, with 111/109 LSAs @.006/.050 (TA's 212-350 cam is 110 LSA symmetrical).

Lobes are asymmetrical for longer intake closing ramp. The rest is pretty symmetrical and safe on valve seats and lifters. Should be quite a performer with a nice wide power band, starting off sooner than you'd expect for a large cam (means no stall needed, but one would help), with a pretty lopey idle and just enough vacuum to handle the power brakes (similar to TA 284-88), all while being easy on the valve train.

Will have a rougher idle than the TA 212-350 cam, but with power coming on sooner and extending to around the same on upper RPM. Stage1 valves and valve springs recommended. Small primary headers recommended (though not required--but at least port/polish the exhaust manifolds). Head work recommended.

EDIT: Small primary headers with an exhaust system conducive for scavenging (H or X pipe with 2 1/2" mandrel bent pipes) will help wake it up even more in the mid range-top end with the symmetrical overlap characteristics, with the use of a 2500 stall and shifting around 5700 give or take.

Here it is:

GF 216-32H GS2-350

.434/.449 @ 1.55 lobe .280/.290

284/292 @.006 113/109 I/E 111 LSA
2*R
109/113 I/E (4*A ICL)

IVO is 33.0 BTDC ( - indicates ATDC)
IVC is 71.0 ABDC
EVO is 79.0 BBDC
EVC is 33.0 ATDC ( - indicates BTDC)
Overlap is 66

216/232 @.050 109/109 I/E 109 LSA
0*
105/113 I/E (4*A ICL)

IVO is 3.0 BTDC ( - indicates ATDC)
IVC is 33.0 ABDC
EVO is 49.0 BBDC
EVC is 3.0 ATDC ( - indicates BTDC)
Overlap is 6

(Numbers in parentheses indicate what the lobe intensity would
look like if the lobe slope were symmetrical)

30(60)/38(76) intake valve slope intensity for lift/close
30(60)/30(60) exhaust valve slope intensity for lift/close

30(60)/34(68) lift/close average lobe intensity for I/E
68/60 I/E average lobe intensity for average I/E durations

Power Range (Shift Point): 1900-5100 (5600-5800) "1900-5700"

For use with Premium pump gas:

Static compression ratio of 10.56:1.
Effective stroke is 2.82 inches.
Your dynamic compression ratio is 8.00:1 .
Your dynamic cranking pressure is 158.97 PSI.

Static compression ratio of 10.22:1.
Effective stroke is 2.82 inches.
Your dynamic compression ratio is 7.75:1 .
Your dynamic cranking pressure is 152.55 PSI.

Static compression ratio of 9.87:1.
Effective stroke is 2.82 inches.
Your dynamic compression ratio is 7.50:1 .
Your dynamic cranking pressure is 146.16 PSI.

Recommended static compression ratio for Premium: 10-10.25:1


Gary

 

I like this one Gary. If we could get it run thru a desktop dyno to see some estimates on what it might do that would be cool. Or grind one and throw it at a 10 to 1 350 with 2500 stall and 3.73 gears ,

 

Yeah I just edited it for additional info.

Any cam can be made obviously, I'm just goofin around with some ideas. Maybe I'll come up with something cool eventually. :grin:
Get people to thinking, maybe someone else will use this info or it might help them in some way with some of their own ideas.

Lift can be adjusted to match head flow too. This is just something I put down 'on paper'.

I know how people like that nice horse-gallop idle sound. This cam should have that in spades. Plus be easy on the valve train and not need a whopper stall to be functional.

By comparison, the TA 212-350 and TA 284-88 cam has the same exhaust valve opening @.050 (49*), but closes a bit sooner at 1* after top dead center @.006. This cam closes 2* later at 3*, for a little more extended exhaust cycle and will help with scavenging if someone decides to go that path with the headers/exhaust I mentioned above, but is in a position where it wouldn't be detrimental if they didn't.

Intake lobe is in the same place as the TA 212-350 @.050 when it's opening, and that's 3* before top dead center. My cam has a little deeper scoop for the compression stroke though, starting off at 33* (Same as Crower level 3) instead of 35* for the TA 212-350 and 37.5* for the TA 284-88, though takes longer to reach .006 @71* making a little shorter dynamic stroke, but helps the intake charge momentum get a bit more of a gulp using a smaller intake duration @.050. This is the asymmetrical lobe's strength, letting the power come on sooner like with a symmetrical lobe cam, but permitting it to extend a bit further.

Exhaust doesn't need as much as intake, so leaving the exhaust lobe symmetrical is fine, as long as it has more duration on it (which it does).

Gary

 

Came across a dyno program and been goofing around with it. One of the cams I came up with seemed to do very well in it. I questioned its accuracy because the torque numbers are so high, so I put in the specs for that Buick 350 with the TA 212 cam that Jim Weise did some time back, and it was pretty accurate...

So, I figured I'd post this here for others to see.

The cam is the same as the Crower level 2 on intake lobe, with modifications done to the exhaust lobe to extend the duration for added power band and the results surprised me.

I put in the stock cam and it does very well in this program too, though I'm not surprised.

Notice how everything turned out pretty symmetrical. Lobe intensities, overlaps, even the increase from .006 to .050 is even on both sides, at double the numbers (58 is twice 29, 74 is 29 more than 45, etc.).

Nice to see my guestimation on power band RPM approximations were pretty accurate in accordance with this dyno program, so that tells me I'm on the right track.


Here it is:

GF 202-18H GS-350 "Symmetric lobe"

.434/.434 @ 1.55 lobe .280/.280 (Flat tappet version)
.465/.465 @ 1.55 lobe .300/.300 (Roller version)

260/276 @.006 108/116 I/E 112 LSA
(4*A ICL)

IVO is 22.0 BTDC ( - indicates ATDC)
IVC is 58.0 ABDC
EVO is 74.0 BBDC
EVC is 22.0 ATDC ( - indicates BTDC)
Overlap is 44

202/218 @.050 108/116 I/E 112 LSA
(4*A ICL)

IVO is -7.0 BTDC ( - indicates ATDC)
IVC is 29.0 ABDC
EVO is 45.0 BBDC
EVC is -7.0 ATDC ( - indicates BTDC)
Overlap is -14

Lobe intensities: 58/58 I/E

Power Range (Shift Point): 1500-4400 (4900-5100) "1500-5000"

For use with Premium pump gas:

Static compression ratio of 9.53:1.
Effective stroke is 3.16 inches.
Your dynamic compression ratio is 8.00:1 .
Your dynamic cranking pressure is 158.97 PSI.

Static compression ratio of 9.22:1.
Effective stroke is 3.16 inches.
Your dynamic compression ratio is 7.75:1 .
Your dynamic cranking pressure is 152.55 PSI.

Static compression ratio of 8.92:1.
Effective stroke is 3.16 inches.
Your dynamic compression ratio is 7.50:1 .
Your dynamic cranking pressure is 146.16 PSI.

For use with Regular pump gas:

Static compression ratio of 8.01:1.
Effective stroke is 3.16 inches.
Your dynamic compression ratio is 6.75:1 .
Your dynamic cranking pressure is 127.24 PSI.

Static compression ratio of 7.70:1.
Effective stroke is 3.16 inches.
Your dynamic compression ratio is 6.50:1 .
Your dynamic cranking pressure is 121.02 PSI.

Static compression ratio of 7.40:1.
Effective stroke is 3.16 inches.
Your dynamic compression ratio is 6.25:1 .
Your dynamic cranking pressure is 114.85 PSI

Here's some screenshots:



May have to download the images to see the text more clearly.


Gary

 

In case no one can read (the photos ), it came to 313 HP @4500 RPM with a nice overrev shift point of around 5000 RPM, and torque peaked at 3000 RPM with 447 frickin ft. lbs...dunno how accurate that would be. Just sounds too high.

The curve is nice though, is nice and flat from 3000 down to 2000 and beyond.

Would have pretty hefty grunt down low.

(A roller version of this would be simple to make too. Simply put the lobes wherever, probably as low as it can get, at .465" lift on each lobe)

EDIT: that last part in bold is emphasized because it's not necessarily true. I have to get out of that flat tappet mentality. Lift will be dependent on how much you have to spend on aftermarket rocker arms and better valve springs. Lift up to a point is always good, especially with no negative side-effects like with a roller cam. Excessive strain will still be present though, with higher lifts, rocker ratios, and spring pressures, which still can reduce the life span of your valve train, just not as severely as with a flat tappet design.


Gary

 

after a little number crunching I have found that with a set of stock 68-70 heads with the 1.92.1.55 valves true 10.25:1 static a 270/293 118LSA 113ICL HYDRoller would make a killer street cam... .392/.408 lift ... nothing spetacular as cams go but just utilizing as many stock parts as possible and just rollering that cam. intake and headers would really wake it up...

 

The lower lifts match the head flow, but the lift does need to be higher than that, I agree. After playing around with that dyno program I can see the sweet spot is a bit higher than .392/.408, though these lifts do not run very bad. Anywhere from about .430 to .450 seems to be the 'sweet spot' zone for lift on un-hogged heads.

Purely from a performance perspective, it's always best to raise lift. From a longevity standpoint, not so much. But this is about flat tappet. Roller cams are exempt from this consideration for the most part.

Understand though that increasing lift beyond what the heads can flow will result in insignificant gains, which is the case in the Buick 350 iron head with very little done to it. The lift reaches further into its plateau in my tests at around .434 lift, which is why those cams are there. It's still fairly low lift for flat tappet and would last a long time, even with 58* lobe intensities. Leaving the head flow alone, if I increase the lift to .650, the results aren't very impressive, and .650 is pretty extreme.

Power gains are about 1-2 HP per .050 extra lift. I also noticed other patterns with different camshafts.

Durations are good though, lift was always to match the head flow, and a bit above into the plateau, just not to get too crazy with it.

Check out the valve timing events on a camshaft that's 118 LSA. With smaller durations it's not bad, but it tends to go a little overboard when durations start to get up there, or so I've noticed.

The main thing is the exhaust will have to cut too deeply into the combustion stroke with it too far apart and with larger durations. This is why you (almost) always see large duration cams with tighter LSAs. I've discovered that the stock cams have the right idea, but to increase their size requires a bit more finesse and the LSAs tend to get a little narrower with the increase of durations.

Simply exponentially increasing the sizes results in a cam that's too severe on the valve train.

With lower durations, and a wide exhaust emphasis, not too crazy LSA (112-116), and the cam will come on early and stay strong until its peak, then trails off slowly after that. You could probably get away with 118, but you'd have to watch the durations, or for with use with larger cubes so you have more duration to play with.

Stock 455's cam is 117.25 @.050 LSA It gets crazy from there, but suffice it to say the valve closing events occur fairly high above bottom dead center, like a cam much larger would have. You don't even want to know the exhaust emphasis that cam has, because people will look at it in disbelief. lmao...

I know I did at first.

These mild cams I have posted would behave larger than they initially appear on the top end, without sacrificing low end grunt, mainly because of the asymmetric lobe design, though also becasue in no small part to wider I/E duration patterns, which a wider LSA can help achieve with lower durations.

Even so, I am still learning! Don't stop offering advice or input.


Gary

 

Hey Gary, I think you have this cams + Buick Engine performance stuff down to a Science,:TU::TU:

 

I'm workin on it bro, not quite there yet, but getting pretty close.
I've learned a boatload of stuff over the past few months, and have gotten the kinks ironed out for the most part.

Thanks for the vote of confidence!

Gary

 

Gary

I seem to remember a conversation about .450" lift on an unported head getting the intake valve curtain area equal to the port CSA close to the time of max piston velocity at 70* ATDC.

Could this possibly be a verification?

Paul

 

Gary, can you run that simulator with 3.860 bore and 4.00 stroke ,heads flowing 245 FM intake and ta310 cam?

 

Paul, I think I do seem to recall such a conversation. I do believe confirmation is a fair word to describe it.

I can plug in just about any numbers into that dyno program...

Uh, oh. Did I just open myself up for extra analyses?

I have some extra time, let me draw up that combo in the simulator. I'll post the results when I'm done.

Edit: on the head flow, there's a graph where I can edit in info @ any particular lift, up to .700 I think. I'll try to improvise on the numbers you gave @max flow based on an educated guess.


Gary

---------- Post added at 07:25 PM ---------- Previous post was at 07:02 PM ----------

Ok, first bit of info to prime everything:

Considering the increased stroke, lowered static compression nets desired dynamic compression:

Static compression ratio of 10.27:1.
Effective stroke is 3.02 inches.
Your dynamic compression ratio is 8.00:1 .
Your dynamic cranking pressure is 158.97 PSI.

Gives good dynamic stroke of @ or > 3"...

I'm going to put 10.25:1 in the simulator for its compression then.

brb

---------- Post added at 07:35 PM ---------- Previous post was at 07:25 PM ----------

I put in large primary (with open collectors, typical of a dyno environment), hogged out iron head specs, large valves (1.92/1.55 I/E), dual plane 'high flow' (TA Stage1), 800 CFM carb and got:

405 HP @ 5500 RPM, 424 ft. lbs. @ 4500 RPM.

This is just what the simulator assumes. I'm sure it could go in either direction depending on what all else was done, fine tuning, etc.

I can post screenshots if you want, those others came out kinda blurry.


Gary

---------- Post added at 07:36 PM ---------- Previous post was at 07:35 PM ----------

Also didn't seem too 'squishy' on the low end. 371 ft. lbs. @ 2000 RPM.

---------- Post added at 07:41 PM ---------- Previous post was at 07:36 PM ----------

Put a 1000 CFM carb on it, single plane intake, and HP jumps to 425@5500 and TQ to 438@4500. Bump the lift to .550 on both and reclassify it as a 'roller hydraulic' and HP and TQ jump to 435/444 respectively @ same RPMs.

Hp slopes sharply up to around 5000, peaks at 5500, then trails off slowly to 6000 where it starts to curve down faster. I imagine the shift point could be 6000-6200 or so. Torque curve is kinda peaky, though is a bit broader than the HP curve.

This also assumes iron heads with peak flow @.550 lift @242 CFM intake / 164 CFM exhaust.


Dunno how accurate this dyno is...seems to be a bit generous on the TQ and a little skimpy in the HP. --though not by too much.

Another thing to consider is the head graph doesn't show anything other than just flow @ lift. Doesn't take into consideration all the little tricks of contouring and flow quality, just to name one thing.

I imagine the simulator gives a decent general idea, and would probably be more accurate with designs closer to factory.

Gary

 

Say its about 15 to 20 numbers off 350 lbs at 2000 is pretty nice.

---------- Post added at 08:09 PM ---------- Previous post was at 08:07 PM ----------

If you can post the graphs that would be cool to see.

 

Well 371 @ 2000 was with the dual plane and smaller carb. It peaked higher and the low end slumped down to about 350 @ 2000 with the single plane and big carb.

---------- Post added at 08:16 PM ---------- Previous post was at 08:15 PM ----------

Tell me which version you want to see screenshots of.

Gary

---------- Post added at 08:24 PM ---------- Previous post was at 08:16 PM ----------

I'm seeing also that there's two different readings: the one at .006 valve events and the other at .050. I imagine you'd take the average of the two?

I'm new to this simulator so I'm not sure. I have found a couple of bugs in it already, which I've discovered a workaround for already. (cuz I'm nerdy like that)

Gary

 

I think dual plane. This would make a nice street motor with 3.73 gears and a 2500 convertor.

 

Ok I took one @.006 and the other @.050.

This is with the dual plane intake and 800 CFM carb.



The curves are wider with the dual plane and smaller carb, at least the torque is.

Looks like shift point would be a bit lower, maybe around 5700 with the .050 graph.

Torque looks damn good though, from 2000-4500 where it peaks.

Out of curiosity, I took the stroke back down to stock 3.85 and left the bore at 3.86 and it dropped the numbers down some, but moved them higher in the power band...which was expected.


Gary

 

The torque curve is nice but HP Alittle slow to come up,but I'm sure that's how that cam is anyway. How does it compare to a stock stroke 350?

---------- Post added at 09:33 PM ---------- Previous post was at 09:11 PM ----------

I didn't see you said you changed back to stock.so it just brings rpm down but pretty much same curve as stock.