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Discussion Starter #1
So, after adjusting the timing, tuning the carb, and then replacing the battery I try to start her up. POP!!! a 2 foot flame shoots out of the carb again, and again and again every time I try to start my beast up. WTF!!!
I'm doing all this while it's in the garage and I give up, I'm so frustrated I don't know what it is. THEN, as I leave to go out of the garage, I walk around the back of her to see a green sooty liquid puddle under my left muffler tip. FUK, blown head gasket. Well... not so bad cause now I have a perfect reason to recam it and put a different intake manifold on it to remedy my hood clearance issue and turn if from a drag race motor to a TORQUE monster!!! Now, I need a cam (yes this was posted before) that will put a permanent smile on my face. I want 600ft/lbs or torque and 550ish HP. I have a 468 big block and I want to go hydraulic roller. I now have a solid mechanical cam and oval port heads. I'm going to stick with the oval ports cause they flow way better than rectangle until .625ish lift so the heads are good to go. Post your suggested setups and we'll all decide together.
 

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Discussion Starter #3
Grumpy, what are the things you need to know for you to accurately guesstimate what cam I need to get 600 torque and 550ish HP? Also where do I need to look when I get the head off to see where the crack is?
 

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if those heads were ON my car ID suggest taking them to a good local machine shop and have them cleaned & inspected and if necessary MAGNAFLUXED

post everything you can about your engine combo and drive train and ILL run the data thru my software and personal notes and see whats obvious



as I said before, call a minimum of 5 to 7 cam companys you trust, DON,T TELL THEM ANYTHING ABOUT WHAT YOU WISH YOU HAD OR EMBELLISH ANYTHING TELL THE EXACT TRUTH ABOUT YOUR COMBO< NOW!!

write down the durration , lift and LCA they suggest after giving them all your info and concerns ...DO NOT DISCUSS with them anything another cam company suggested, as that will alter the results. once youve got a minimum of 5 cams, (7 is better) average the results and buy the cam closest to that average, the great thing about that method is it basically eliminates the ocassional morron you run into at times on help desks from totally screwing up your choice
BTW when in doubt its better to be very slightly under cammed.

you could also buy this, software to play with, and imput your data, but its only one of many sources for info

http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=180950&Category_Code=

now personally I think the softWARES USEFUL, FOR COMPARING RESULTS.
BUT I would tend to buy a cam elseware

CRANE
http://www.cranecams.com/

CROWER
http://www.crower.com/

LUNATI
http://www.holley.com/division/Lunati.asp


ERSON
http://go.mrgasket.com/pdf/Chevrolet.pdf

OR ISKY
CAM

http://www.iskycams.com/
 

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Discussion Starter #5 (Edited)
3.73 gears, chevrolet iron oval port matched heads to a Victor Jr intake (wanting to change intake) and don't know too much else about them, Mighty Demon 850 carb, 468 cubic inch block. Don't know about compression ratio or pistons. That's about it. Is there anything else that you need? Stock tires and TKO 600 tranny with 0.64 5th gear and like you Grumpy I would love to smoke'em going 60mph!!! Gimme some torqie numbers!!!
 

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if those heads were ON my car ID suggest taking them to a good local machine shop and have them cleaned & inspected and if necessary MAGNAFLUXED

post everything you can about your engine combo and drive train and ILL run the data thru my software and personal notes and see whats obvious



as I said before, call a minimum of 5 to 7 cam companys you trust, DON,T TELL THEM ANYTHING ABOUT WHAT YOU WISH YOU HAD OR EMBELLISH ANYTHING TELL THE EXACT TRUTH ABOUT YOUR COMBO< NOW!!

write down the durration , lift and LCA they suggest after giving them all your info and concerns ...DO NOT DISCUSS with them anything another cam company suggested, as that will alter the results. once youve got a minimum of 5 cams, (7 is better) average the results and buy the cam closest to that average, the great thing about that method is it basically eliminates the ocassional morron you run into at times on help desks from totally screwing up your choice
BTW when in doubt its better to be very slightly under cammed.

you could also buy this, software to play with, and imput your data, but its only one of many sources for info

http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=180950&Category_Code=

now personally I think the softWARES USEFUL, FOR COMPARING RESULTS.
BUT I would tend to buy a cam elseware

CRANE
http://www.cranecams.com/

CROWER
http://www.crower.com/

LUNATI
http://www.holley.com/division/Lunati.asp


ERSON
http://go.mrgasket.com/pdf/Chevrolet.pdf

OR ISKY
CAM

http://www.iskycams.com/
:agree: Wise words spoken here.
 

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that backfire/ fireball from the carb on a new start-up is very often caused by being 180* off with the spark timing...the timimg mark on the harmonic balancer lines up with the timing pointer when ''set to fire'' BOTH #1 and #6 cylinders...pull #1 spark plug and put your thumb OVER the plug hole while someone cranks the engine over -- you'll definitely feel the compression as that cylinder comes up firing position, only light pressure if its in ''exhaust'' cycle...or just switch the plug wires around 180*, pretty good chance that is the prob based on your description.

the ''green'' stuff on the floor may only be old condensation+algae in the muffler/evhaust pipe...get it running , if you get ''white cloud'' out the exhaust or push lots of coolant out it will be time for ''off with 'er heads''
 

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that backfire/ fireball from the carb on a new start-up is very often caused by being 180* off with the spark timing...the timimg mark on the harmonic balancer lines up with the timing pointer when ''set to fire'' BOTH #1 and #6 cylinders...pull #1 spark plug and put your thumb OVER the plug hole while someone cranks the engine over -- you'll definitely feel the compression as that cylinder comes up firing position, only light pressure if its in ''exhaust'' cycle...or just switch the plug wires around 180*, pretty good chance that is the prob based on your description.

the ''green'' stuff on the floor may only be old condensation+algae in the muffler/evhaust pipe...get it running , if you get ''white cloud'' out the exhaust or push lots of coolant out it will be time for ''off with 'er heads''
algae? I don't think so.
 

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you NEED to KNOW your true compression ratio!
theres several ways you can measure or at least get a very close educated guess as to what you have, and without it its going to be more difficult to sellect correctly but I can garauntee that the cam your currently useing has more durration than would be ideal for your current application.


HERES WHAT YOU SAID YOU WERE RUNNING CURRENTLY IN THAT 468BBC

"I've got a solid tappet Isky cam in my 468 big block that's .630 .630 and is 264 264 intake and exhaust at .050. Victor Jr intake, oval port matched heads and headers and dual chamber Flowmasters. I thought with this cam I would walk away from damn near anything that pulled up to me, but this isn't the case! Is this too much cam for me? I know with oval port heads the max lift you want to run is .630, but is .630 too much?"

read thru this, NOTICE they are running 11.83 and 13:1 cpr with a cam similar to the one your currently running....if you were running that cpr and it was a race only application the cam might work with the matched components, but with significantly lower cpr it won,t work!

http://maliburacing.com/patrick_budd_article.htm


since your looking for a hydrolic roller cam, ID suggest something closer to these but like i stated do the research and know< don,t guess about your combo,before ordering the parts and follow the plan,id bet they all suggest even milder cams

http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=01405&x=40&y=9

http://www.cranecams.com/?show=browseParts&lvl=2&prt=5&Vehicle_Type=Auto&Cylinders=8&Engine_Make=CHEVROLET&Year=1969&Engine_Size=396-454 C.I.&partNumber=139651&partType=camshaft
 

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Discussion Starter #10 (Edited)
If I were to stay with the solid set up (way cheaper!) I would definitely go the Crower cam you suggested. I would assume that I'm around 11ish for compression, but I'll try my ass off to call the engine builder who built it to find out. It'll be likely that I'll keep the solid cam route. I'm curious to see if I can get a higher lift in there while those valves are open. Also if you have time Grumpy, can you gen up some numbers for me with 11:1 CR for the cam that you suggested? This would get me fired up and on the right track.
 

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Just on the CHANCE that it's CRACKED head, I'd pull all the plugs and turn it over after it sets. Be a big BITE in the azz to have a cylinder full of coolant and try to turn it over. That ol' coolant will just not COMPRESS. It'll bend rods, break pistons, split cylinders, but it will not compress. Be really FUGLY to get as far as you have and then need a bucket full of new parts that were good parts 30 seconds ago..


:cheers:
 

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Discussion Starter #13
Grumpy, with that cam and my setup (11:1 comp ratio) and everything else being the same, what numbers does your program say that I'll be putting out? I see that you keep going back to that cam. I love it that you take the time to expain the way you come up with what you put out to the rest of us. As for me I learn something from every post that you do.
 

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my software makes its wild guess (based on totally in complete data...no true cpr, head flow or header flow info)
at about 500 peak hp and 450 peak ft lbs for your old combo and 500 peak hp and 550 peak ft lbs with the new crower cam and an EDELBROCK RPM intake,
(those are all flywheel #s not rear wheel)
but the main gain is at just off idle to mid range where your easily 100 ft lbs better with the new combo of intake and cam over the old combo for most of the low and mid rpm band...youll notice that:thumbsup:
 

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Discussion Starter #15 (Edited)
YES! Getting a hell of a lot closer to what I'm wanting. Could I eek out a few more ft/lbs by going to a 1.75 rocker ratio to get a little more lift? Also does that thing gen up a dyno graph and if so then what RPM is my torque the highest and what RPM is my HP the highest on the new set up?
 

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I only wish I could post a graph, but being computer skill deprived IM still working on THAT little skill,
BTW I played with the combo some, changing rocker ratios or advancing the cam a few degrees was TOTALLY wasted effort, RETARDing the cam a few degrees helped very marginally, tq crurve was fairly wide anf fairly flat from 3000rpm-5500rpm near 550 ft lbs, power peaked at about 5900rpm but held on well to about 6300rpm then dropped off,keep in mind BOTH the PERFORMER RPM AND CROWER CAM change were necessary to get the correct curve and retarding the cam 4 degrees will help only slightly so ID try it at factory install specs first



as I said before, call a minimum of 5 to 7 cam companys you trust, DON,T TELL THEM ANYTHING ABOUT WHAT YOU WISH YOU HAD OR EMBELLISH ANYTHING TELL THE EXACT TRUTH ABOUT YOUR COMBO< NOW!!

write down the durration , lift and LCA they suggest after giving them all your info and concerns ...DO NOT DISCUSS with them anything another cam company suggested, as that will alter the results. once youve got a minimum of 5 cams, (7 is better) average the results and buy the cam closest to that average, the great thing about that method is it basically eliminates the ocassional morron you run into at times on help desks from totally screwing up your choice
BTW when in doubt its better to be very slightly under cammed.

THATS THE CAM ID INSTALL BUT FOLLOW THE PLAN


http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=01349&x=21&y=4

http://www.competitionproducts.com/prodinfo.asp?number=651080DL
 

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Discussion Starter #17
Here's what I got so far:
Crower
@ .050 is 244,246 with .517,.532 with 114 LSA
Crane
@ .050 is 238,248 with .544,.567 and don't know LSA, but the dude said that this would be good for my set up
Isky
@ .050 is 250,254 with .560,.590 with 108 Lobe center

Grumpy, I'm at work all night and most of tomorrow (military on watch) and I don't have my computer to download that software to do what you're doing. I would if I could though. If it doesn't take too long can you maybe plug that other cam that you suggested in and see where it's at as well as these specs to see who has their info correct. Also the LSA thing seems to be of a mystery. Isky suggests 108 and Crower suggests 114 and I don't understand why such drastic differences between the two. Also does the more valve lift mean that the power will come in later in the RPM band?
 

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wide LCAs like 114 tend to make the idle much smoother

tight LCAs like 105 tend to give better power but a slightly narrower tq curve

read again

http://www.digitalcorvettes.com/forums/showthread.php?t=66643&page=2&highlight=lca

remember these..

http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/index.html





to find the ideal LCA take a SINGLE CYLINDERS DISPLACEMENT and devide bye the valve dia.

example on his 468 /8=58.5 cubic inches divided by the valve dia. approximately 2.2 so we get........26.5, read thru the text

http://www.popularhotrodding.com/tec...ics/index.html

and we find that approximately 105 LCA on a bbc combo will be close to ideal, if youve got that LCA and it runs like crap its a good indication youve got too much durration, and EVERYTHINGS A COMPROMISE simply because the engine doesn,t opperate at a single set speed/rpm

most guys go about this BASS ACKWARDS, they sellect TOO LARGE a DURRATION, then spread the LCA to LOWER the OVERLAP to allow it to run correctly.

the iDEAL is to maximize the cylinder fill efficiency in the rpm band the engine opperates in most of the time,

torque times rpm divied by 5252 =hp
torque is mostly the result of displacement and compression ratio,
your cams durration and to some extent lift determines the rpm range, IF the other components are designed to opperate effectively at the same rpm range, and NOTHING gets compressed untill BOTH VALVES FULLY CLOSE



"
Lobe Center Angle is the distance in degrees between the centers of the lobes on the camshaft.
To increase duration, cam makers grind the lobes wider on the base circle of the cam. This makes the lobes overlap each other more, increasing overlap. More duration = more overlap.
To increase overlap without changing duration, cam makers will grind the lobes closer together, making a smaller lobe center angle. Less lobe center angle = more overlap.
Overlap and duration are the two big factors in cam design. More overlap moves the power band up in the engine's RPM range.
Longer duration keeps the valves open longer, so more air/fuel or exhaust can flow at higher speeds. It works out that increasing the duration of the camshaft by 10 degrees moves the engine's power band up by about 500 rpm.
A smaller lobe separation increases overlap, so a smaller lobe separation angle causes the engine's torque to peak early in the power band. Torque builds rapidly, peaks out, then falls off quickly. More lobe separation causes torque to build more slowly and peak later, but it is spread more evenly over the power band. So a larger lobe separation angle creates a flatter torque curve.
So you can see how a cam maker can tailor the camshaft specs to produce a particular power band in an engine--

Short duration with a wide separation angle might be best for towing, producing a strong, smooth low-end torque curve.
Long duration with a short separation angle might be suited for high-rpm drag racing, with a high-end, sharp torque peak.
Moderate duration with wide separation angle might be best suited for an all-around street performance engine, producing a longer, smoother torque band that can still breathe well at higher RPM.
Remember, there's always a compromise made in this process.

One last item to consider is the lobe centerline. The lobe centerline is the angle of the lobe's center peak, measured in crankshaft degrees when the piston is at Top Dead Center (TDC). In general (but not always), when a cam is installed "straight up," the intake lobe centerline and the lobe separation angle are the same.
The lobe centerline can be altered when the camshaft is installed, by advancing or retarding the camshaft's position in relation to the crankshaft. Advancing the camshaft by 4 degrees will move the power band about 200 RPM lower in the RPM band. Retarding the cam by 4 degrees will likewise move the power band 200 RPM higher in the RPM band. This allows you to fine-tune the engine's performance according to your needs.
But, if you have purchased the cam matched to your needs in the first place, your best choice is usually to install the cam "straight up." "
 

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Discussion Starter #19
So, after all that I have yet gain learned a great deal. One last question, with the 105 LCA on that Crower cam, won't that not build any vacuum for my brakes, headlights, and vacuum secondaries? I only ask because our cars have a needed vacuum source to operate some components. I do understand that having small valve to cylinder size is of concern (therefor the 105 LCA) but also the vacuum has to be considered.
 
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