just want some reassurance on combo choices

Strictly Attitude said:
Looked at comp lobe catalog all are similar .050 and advertised gotta say Isky here. Pretty close all specs reality comes to who you want cam from I like the Isky but that's me Brian loves Isky also what we have ran and used in past. Just as grumpy Rick used crower and crane. Has Crane added any grinds lately I have not been on there site in long time.
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Not that I am aware of. I haven't seen much in the way of added grinds lately. I guess lunati has added a few, and comp has those 4 pattern grinds.
 
no mater what roller cam you select, youll need to get ,
the valve train geometry, clearances and spring load rates correct,
youll ideally want to get the quench distance in the .040-.042 range ,
port match the intake selected to the heads, and do all the other related checks and clearancing.
keep in mind scavenging the cylinders correctly requires a properly designed set of headers,
and open or at least very low flow restriction exhaust
 
Grumpy said:
no mater what roller cam you select, youll need to get ,
the valve train geometry, clearances and spring load rates correct,
youll ideally want to get the quench distance in the .040-.042 range ,
port match the intake selected to the heads, and do all the other related checks and clearancing.
keep in mind scavenging the cylinders correctly requires a properly designed set of headers,
and open or at least very low flow restriction exhaust
Click to expand...
Quench will be .039". I'm gasket matching everything. The Doug's headers I have are pretty decent. 3" exhaust with an x-pipe is the plan. Id do larger, but no one bends larger close to me. Grumpy, how do you feel about that strange dip that's there in all the runs? What's your thoughts about what's mis-matched. Thanks for all you guy's input. And clearances will be carefully performed and springs will be placed at cam manufacturer recommendation
 
Im looking over the parts list and software to try to locate the probable cause, currently I don,t see anything obvious ,
it will be rather interesting to see if you build the engine similar to the listed info, if the predicted software dyno result and reality are close to similar!
 
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Grumpy said:
Im looking over the parts list and software to try to locate the probable cause, currently I don,t see anything obvious,
it will be rather interesting to see if you build the engine similar to the listed info, if the predicted software dyno result and reality are close to similar!
Click to expand...
I didn't either, although the software is pretty foreign to me.
 
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Does a 950 aed help or hurt me? I have one on the shelf. Headers have a bung welded in so I can do a/f mixtures on each bank. I think that and is actually rated at 820-930 cfm and has good street manners
 
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Grumpy said:
Im looking over the parts list and software to try to locate the probable cause, currently I don,t see anything obvious,
it will be rather interesting to see if you build the engine similar to the listed info, if the predicted software dyno result and reality are close to similar!
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Port Velocity Air Speed Dip I believe Grumpy.
 
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no port air speeds will be closely related to engine rpms ,
and as rpms increase flow tends to increase and stabilize,
as the number of increasing induction pulses per second increase,
thus the individual intake pressure waves become less pronounced,
individually submersed in the total flow rate,especially as the exhaust scavenging ,
and ram inertial tuning also tends to increase in efficiency as rpms increase,
If it was related to that, the most likely cause would be a carbs secondary throttle bores rapidly opening, dropping the plenum vacuum momentarily,
but That would not, likely too be a factor in a vacuum secondary carb,
as its secondary throttle bores open, smoothly in direct response to plenum vacuum.
I don,t see software's inducing and recording and predicting that potential tuning flaw,effect
 
A reverse shock wave is created as the intake valve opens and closes.
Then partial moment happens.
The higher overlap of the HR306 may disturb the process till rpms catch up.

Looking at BSFC numbers may clue in.
 
if thats the case its something that can be tuned out through indexing the cam timing ,
header design changes, like a different collector diam and length,
or intake manifold design changes,( theres dozens of different options)
like adding a open spacer (changing the plenum volume)
or swapping to a different intake, or if you went to stack injection,
its simply swapping to different stack lengths.
one of many reasons software dyno results are best at predicting trends,
but not always accurate representations of a well tuned combo,
Ive seem many engines where a bit of advance or retarding cam timing,
ignition advance curve, and changes in header collector length,
made a very noticeable change in the power curve.
 
Grumpy said:
if thats the case its something that can be tuned out through indexing the cam timing ,
header design changes, like a different collector diam and length,
or intake manifold design changes,( theres dozens of different options)
like adding a open spacer (changing the plenum volume)
or swapping to a different intake, or if you went to stack injection,
its simply swapping to different stack lengths.
one of many reasons software dyno results are best at predicting trends,
but not always accurate representations of a well tuned combo,
Ive seem many engines where a bit of advance or retarding cam timing,
ignition advance curve, and changes in header collector length,
made a very noticeable change in the power curve.
Click to expand...
Not a single person here in my memory has ever built custom 1 off headers Grumpy.
I would like to.
Its possible now in Eds Garage & Him Tigging.
Still need that Fancy Plastic Donought Header Tube Mockup kit.
Recall it was $700-800.

Stack injection is Nice.
Screwed if it rains.
You had Morons pour soda pop down the IR Cower Stack injection on your 1968 Corvette 496 BBC.
 
yes I had morons try to screw with my crower stack injection,
but I personally have build several sets of custom headers,
now in many cases it was basically, rather extensively modifying existing headers
cutting them off and significantly lengthening them with pre-formed collectors like linked, below
, at times adding the collectors and 4 short lengths to primary header pipes,
you simply do the required math and figure out how to build what you need from what ever your budget options and skill level permits,
at times thats with a header flange and the collector, placed where you want it, then routing each primary as required

http://garage.grumpysperformance.com/index.php?threads/building-custom-headers.961/

http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/

http://garage.grumpysperformance.co...-exhaust-system-for-your-car.1166/#post-30424

http://garage.grumpysperformance.co...for-a-metal-cutting-miter-saw.3184/#post-8478

http://garage.grumpysperformance.co...bbc-muscle-car-engine-combo.10084/#post-39412

theres readily available calculator info in the links posted below so take the time to read thru the linked info and sub links as it can save you days of work and a bunch of cash
theres pre-cut header flanges

one reason I own both a miller MIG and TIG, welder
http://www.summitracing.com/parts/HOK-11622HKR/
hok-11622hkr_w.jpg

theres pre-welded collectors, its really not all that difficult
flowre2.jpg

http://www.summitracing.com/parts/FLO-C134218234/
FLO421.jpg


I generally just buy the set of these and weld them on,to the primaries cut to 36"-38" as it saves a great deal of work and the results have proven to be similar, ideally the two collectors feed into an (X) pipe with fairly long tail pipes as this seems to help the torque curve be a bit broader , even if it does cost a few peak ft lbs
http://www.summitracing.com/parts/FLO-C134218234/

flo-c134218234_w.jpg

http://www.summitracing.com/parts/DTC-80-01514C/
dtc-80-00514.jpg

collectors.jpg
 
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