|07-15-2019 05:17 PM|
"Bob Falfa" was the driver of the black '55 Chevy, character played by Harrison Ford. "John Milner" was the driver of the yellow '32 Deuce coupe, character played by Paul LeMat. "Steve Bolander" drove the white w/red striping '58 Bel Air cruiser, character played by Ron Howard(Opie on "Andy Griffith", Richie on "Happy Days").
Anyways...Cam I referred to has near the same power band as what you currently have, as you've said before you don't want to turn this build higher rpm-wise. Just the 8° added intake duration @.050" and tighter lobe separation to get an earlier opening intake valve without drastically changing the intake closing point(nearly identical advertised intake durations).
You may think is seems ultra radical, but you have to dissect the numbers to get the whole picture.
It is 1° LESS total seat-to-seat intake duration, combined with 2° closer lobe separation actually closes the intake valve 2.5° SOONER than your current cam....so it is going to trap more mixture(higher DCR). This means the additional duration is all on the exhaust side, getting the exhaust overlap draw on the intake charge started earlier by about 10°. It is also a much more aggressive lobe profile, as it has 16° more duration at .200" lobe lift....which means a lot more "area under the lift curve", and that is a significant difference.
This is what the Lobe Master catalog description of the intake lobe is: "The QXI Series lobe profiles are designed to provide the highest available valve lift for modern cylinder head ports, along with excellent stability and the broadest possible power range in hydraulic roller applications. Designed for both street and racing use".
It's a match to the other board's cam choice advice. Toss this info to your other forum board and see what they think.
Idle will be a more radical lope, but power range is the same rpm window. Should just create a power increase across the entire rpm band. Same compression ratio suggested, same rear gearing, and BBC's always like more lift.
|07-15-2019 02:23 PM|
|55 Tony||Holy cr*p that's a huge jump. Did a search for that cam and Jegs lists the specs. I believe that's a bit more than what I want. As for the American Graffiti reference, I think I saw that in the movie theater and not since, and I sure don't remember the names. I know I should since my ride is a 55 chevy.|
|07-15-2019 10:17 AM|
Going to be hard to get earlier opening AND earlier closing points for the intake valve while at the same time trying to add duration.....something has to give somewhere.
I would have wanted a bigger cam from the get go, the smallest I would have considered would have been something at least 8° @.050" bigger than the factory LS-6 solid lifter stick at 242¯ @.050"....probably something more like the L88 solid at 264/269° @.050".
I'm far from convinced hydraulic roller is a successful way to go with a BBC, seems like there are just too many complaints of either lack of power or lack of RPM capability.
I've put 248/254° @.050 solid in 406 and 383 SBC's and they are mild enough your Mom could drive it, while still making good power..
If it was me, since you are close to 3/4 of the way there while doing a cam swap, valvetrain is all loose, is pull the heads for a mill job at the same time.
Id look to increase the duration while tightening the lobe separation down to 106°, trying to add no more than a couple degrees to the intake closing. This will add a bunch to the intake opening point.
"Less streetable"....lower vacuum for power brakes, higher idle speed so it drags harder on the brakes at a stoplight unless the stall rpm is higher, rough idle, poorer gas mileage, stickshift cars will need more downshifts as motor won't like being lugged down to low in rpm without chugging, same with an automatic but to a much lesser extent, might have to stay in 2nd at city suburb speeds.
All things that don't matter if you're really after performance.....you like the 1100 rpm choppy rough "fender shaker" idle, you have no problem tossing the shifter into neutral at every stop light or while creeping forward in a traffic jam or event entry line, you don't need power assist on the brakes
Mentality: Are you Bob Falfa/John Milner, or are you Steve Bolander. (for those of you who get an "American Graffiti" reference )
The only hydro roller that caught my eye in Comp cams list is Cam Part #11-870-11, grind # 3130NHR-08, in Drag Race Hydraulic roller section. I'd link it but their web site is acting really screwy today, can't get to several pages. 260/270° @.050" duration and .670" ish lift, 108° LSA Listed as 3600-6800 rpm bracket cam for 396, so rpm range will come down 400 rpm or so in a 454.
|07-15-2019 09:17 AM|
Not that I don't trust the help on this group, but I was asking the same questions about this heads performance on another group also. More advice can be better, or just more confusing, but I'm grasping at straws.
It has been recommended that I get a cam with a longer duration. Also said was a cam with an earlier opening and more important closing of the valves. Any thoughts on that? The current cam is a lot more mild than I had hoped, so I don't mind if a new one is a little less streetable. Don't get me wrong, I'd still like to drive it on the street more than the track, but I don't mind if it doesn't purr like a kitten at 750rpm like it does now. Also with a cam change to a longer duration, if you could explain to me in what ways will it become less streetable? Thanks so much with this mile long thread!
For you convenience, here is a link again to my current cam specs. http://www.compcams.com/Company/CC/c...?csid=438&sb=2
Oh, and Ericnova, at this point I really don't want to pull the motor, so decking the block is off the table for now. Is just milling the head getting maybe .75 point gain worth the hassle?
|07-13-2019 10:08 AM|
On the open chamber head, roughly 1cc reduction for every .006" removed....so .040" is about 7cc.
Since it is also roughly 1cc per every tenth of a point for compression in the cubic inch range you are in, you will raise compression 0.7 with .040" removed.
Cutting the deck surface, since you are removing volume from the entire bore diameter when you do, results in about 1cc for every .0045" removed.
Between both a .040" head mill and a .020" deck cut to get to zero deck you could swing compression change by 1-1/4 points.
|07-13-2019 09:34 AM|
I'm working on the fan deal but would like more than that will give me.
I just sent Skip White a question about milling the heads and got this response:
"Tony you can take 50 or 60 thous. off them, and this will reduce the chamber size by about 6-7cc approx. try to take as little as possible so you don't have a funny fitting intake manifold. maybe take 40 thou. and call it a day."
Does that sound about right? Any guesses at what .030 or .040 milled off might reduce the chamber size? I don't want to go too far. Even at that level I'll have to do a little work on the valve reliefs.
So maybe a bigger cam and have them milled? Does this make sense to anyone?
I just thought of one drawback, milling the heads instead of decking the block isn't going to help the poor quench I have.
|06-28-2019 06:15 PM|
Reason you can't just re-use your current 454 piston to do a 4.25" stroke stroker build is because the longer stroke will have it sticking out the top of the block by 1/8" more. Only way you could get around that would be to shorten the connecting rod, like Chevy did with the 400 SBC....but nobody makes a shorter rod for the BBC and it would not fit anyway.....with a shorter rod in a BBC the piston would not clear the counterweights on the crankshaft at Bottom Dead Center.
The way they fix the issue is raising the pin in the piston, and if they use a longer rod at the same time they raise the pin even more(called shorter compression height in the piston spec's)
You can build a "496" stroker at just .030" over, it would be a 489", standard bore is 482", .100" overbore is 505", .125" over is 511".
Seems like at just 10,000 miles on the current rebuild a re-hone would be all that is necessary along with the stroker rotating assembly....decking would be an added value option but if you were to use one of Skip's kits with the .010" taller Wiseco "custom" compression height pistons he has(when compared to industry standard heights on stroker pistons) it would eliminate the need to do any decking.
If the bores are I good enough shape to not need boring to .060" over, there is no smart reason to do it, the extra 7 cubic inches certainly doesn't return enough added power to be worth the cost or hassle.
Cam bearings and freeze plugs would still be fine....ball hone it, wash it, and go.
Heck, I wish every used engine I get would have bores good enough to just hone and go, and never have to re-bore anything ever again .....the tiny power gain from the added cubes of just an .030" overbore doesn't even come close to offsetting the dollar cost. Boring is basically just a necessary evil you are forced to accept when rebuilding old production crap.
Your WOT vacuum reading shows the carb to not be a major restriction.
I wish the fan test links were still good. It was a 496HP 383 SBC, they tested it driving a bare mechanical water pump, then plus alternator to see what drag was from just keeping a ignition box(6AL) running and battery topped off(less than 2HP), then with electric fan( minus 7HP is what I remember), then all the mechanical fans they could find, 12-13 versions. Right up to 6500-6800 rpm IIRC. All of the flex fans were well down the list, surprising just how much power they would eat....no comparison at all to a clutch driven fan, typically 15 Hp to as much as 40 HP difference.
|06-28-2019 05:57 PM|
|lmsport||For oval racing I always took a 6 blade all-plastic flex fan and cut two blades off, 180 degrees apart. And trimmed the remaining 4 blades to be more rounded on the engine side. Still moves alot or air and if the fan gets into the radiator in a wreck it might not destroy it, and if a finger got into it the finger would remain attached.|
|06-28-2019 10:23 AM|
No it didn't ping on pump gas with iron heads. And lord knows how, but cranking compression was 210psi with the iron heads. Now it's down to 180psi. Still respectable I believe, but a big drop. There wasn't a speck of evidence that the old build was pinging/knocking on the pistons or plugs.
I just looked it up and see that for a 496 it only gets a 454 bored out .060 over. Still not ready to do this, but if my bores are still good at .030 over, couldn't I just put in a crank and rods to stroke it? Oh, and get the block decked and honed! Save a lot in machining and pistons. Well I just did some reading and see that builders prefer to use different pistons with a different pin height, so with new pistons, may as well go .060 over I guess.
I question that HP loss with the flex fan. I'd love to see the test and what rpms they were testing at. The blade flatten out pretty easy as the rpms go up, and once I got rid of the shroud, it's very quiet. And anyway like said, it was the same before the new heads.
I went for a drive this morning and re-tested the WOT vacuum, it stayed below 1psi until it got over 5500 rpms, then although it was still pulling hard, the vacuum went up but less than I thought before. I'd say just a little over 1 psi.
|06-27-2019 11:02 PM|
With 210* water temp and your compression was 10 something:1 with iron heads, and it didn't ping? On pump gas?
Newer big blocks means you get rid of the button and use a retainer plate to hold the cam in, that's the way mine is. But you'd better make sure is has a fuel pump lobe if using a mechanical pump. Those empty bolt holes on each side of the cam nose are where you bolt the retainer to.
Well sure, more cubes, setup best not to detonate, I'd still try and figure out what's wrong with yours. Even high 9:1 ought to be a real handful, plus you still have that weird timing thing going on. You don't have the wildest 454 ever assembled, but it ain't the mildest either.
Even with the fan dragging it down, shouldn't it still make more power than before? Maybe not a linear rise, but there ought to be something.
|06-27-2019 08:37 PM|
If it isn't a clutch fan, just a straight drive flex fan, it could be costing you anywhere from 25 to 65 hp.
I use clutch fans on everything, use the stock 7 blade air conditioning clutch driven on my Nova.
Every link I've got to the 2003 Car Craft magazine test comes up dead(which sucks...but they dyno tested a dozen or so stock and aftermarket mechanical clutch and flex fans on a 500 Hp small block....the 6 and 7 blade clutch driven used the least, 8-13 HP, some of the stock mechanical fixed blade and aftermarket fixed and flex were awful, including the 4 blade "rail road cross" factory fan. The wide blade flex and wide blade fixed straight drive were among the worst, a couple were in the 50-60 Hp range, the worst was 66 Hp IIRC.
That fiberglass/reinforced nylon thing a lot of the circle track racers use was pretty bad also.
If you can hear it roar you can bet it is eating a good bit of power.
|06-27-2019 07:49 PM|
If I go to the trouble of replacing the cam, I'd like for it to be a good one, not just something that popped up cheap. Besides, I now see that cam is for the newer BB's.
Fan is ... don't freak out ... a flex fan. Rated at 10,000rpm. I think most of the flex fan catastrophes come from fans that are underrated. Anyway, It's seen some use, and although the factory says it will be fine, I just may get a new one exactly the same and toss the old one. It works so darn well and without a shroud. My old 6 blade in a shroud didn't work as well, and it was noisy as all hell. The current fan in the shroud was also very loud, and it too worked better without the shroud and the sound level went down A LOT.
Do any of you see Skips idea about building a bigger CI motor, with the block decked as a REALLY GREAT solution? Just asking, not ready for it.
|06-27-2019 06:10 PM|
Being below a recommended compression ratio for a given cam just impacts low rpm performance and "driveability". Once you start into the cam's power range it doesn't matter nearly as much.
I never cared much for the Magnum cams and their equal durations on both lobes, but I'm not sure the Extreme Energy you've linked is enough better to make the switch worthwhile....I need to think on this a bit.
If you can get it cheap on Craigslist, it could be worth a try, it is higher lobe intensity and a little more intake lobe duration(4° @.050") but just 1° later intake closing if you are one of those guys who chases dynamic compression calculations. So just advance the cam another degree when installing it...or 2
A decent amount more exhaust duration.
Valve to piston clearance should show almost no change at all, nearly nothing.
Carb could be a little bigger, but I know guys who have gone 2 seconds faster with a 454 and just 750 or 780 cfm carbs. It wouldn't be the first place I would look.
Just curious, what are you using for a engine cooling fan?? Wondering if you are using a HP eater.
|06-27-2019 02:53 PM|
Yeah, they're $2400 or more dollars. A torch, welder, Vaseline, and a prayer, anything will go anywhere.
Shouldn't wot vacuum be 1in or under meaning the carb is sized right. That's leaving some power on the table.
It's got more duration, and it has a dual pattern which Chevys like( more exhaust than intake duration) lift you could compensate with 1.8 ratio rockers, but that may be another can of worms.
I'm guessing carb is costing you way more than the cam.
|06-27-2019 10:13 AM|
Dfish, the kind of block you are talking about is most likely out of my price range. You say it "should" drop right in? Right now I have short valve covers and it barely fits, that is with some major hammering on the firewall already, with no room for more without getting real serious removing the heater inside and cutting the firewall. I know, what the He** do I need with a heater?! Well I drive it on the street all year round so that's a nice thing to have. Also defrosters are nice for the times I get into some rain and things get foggy inside.
My vacuum is about 12-13psi, it sort of surprised me that it was that high. I had just checked it for the first time when checking the vacuum at WOT. And speaking of that, the ~2-2.5 vacuum didn't make anyone say I needed a bigger carb or not. Wires are good and pretty new too. Runs as high as 210* on the highway cruising at 3500rpm (maybe higher when the temps are higher but it's no fun to drive when it's much over 80*) and drops 5 or 10 degrees in town. I have a new radiator to install that may lower it more. (it even has a 60 day not cool enough warranty) Only bought it because the old one keeps popping up with leaks.
So when installing the new radiator it's not *that* much closer to the cam, but a little. That had me thinking about the cam being advanced 2*, if I should try setting it straight up? Then just now I did a little search on craigslist for blocks and found a different cam for sale, it's new,unused. It has less lift than what I have but it says for street or strip where my current one says something like "hot street machine". I don't know anything about the rest of the specs, it's all greek to me. The one drawback is that it calls for 10:1 and I'm under that now, I think it's still above 9.5:1 But here it is:
01-421-8 - Xtreme Energyâ„¢ Hydraulic Roller Camshafts
And here is mine again:
11-450-8 - Magnumâ„¢ Retro-Fit Hydraulic Roller Camshafts
So what/how do the cams compare? And any new cam isn't out of the question, but at this point I'd really not care to have to pull the heads and cut into the valve reliefs. I have the measurement here somewhere from the clay and I don't have much room to spare. Maybe in a while I'd be into pulling the heads, but just don't want to get into it now. Just remembered that Skip told me I already have too much cam?? He kept figuring less than 9.5:1 and I keep calculating a little more.
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