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  #196 (permalink)  
Old 06-26-2019, 09:23 AM
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Well, if all is about as good as it can be, I guess it is what it is.

Machine shop jail sucks for sure.

Valve size should be 2.06" intake and 1.72" exhaust, or close to those numbers.
You ought to be doing better than what you are since your heads were stock, valves alone strangle the flow.

I'd say skip a factory block, and go with a dart or merlin, get a 540 or 555 kit and put it together, it's not that much more expensive when you figure in rotating assembly, machine work, etc. Takes the same 4.25" crank as a 496 anyway. I've learned my lesson on my deal, no more fixing up old blocks.

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  #197 (permalink)  
Old 06-26-2019, 05:57 PM
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I would not worry about a 2-bolt main block, even with a 496 stroker kit, until you intend to push rpm up over 6800.

A lot of folks don't realize this, but the 2-bolt BBC main cap is just as wide as the 4-bolt cap, just lacks those two extra bolts....and the number of bolts isn't where the strength is.
It isn't sheer bolt strength that keeps problems from developing in a main bearing, it is surface contact between cap and block....the more surface in contact, the less apt the cap is to squirming around("cap walk" and bore go out of round and leading to a spun bearing.
Good ARP bolts or studs in a 2-bolt BBC will hold 650-700 HP without a problem as long as the RPM is reasonable.

It is a lot different than the problem the SBC has with the 2-bolt caps being half as big as the 4-bolt caps....do a 383 stroker in a 2-bolt block and turn it 6500+ RPM and you'll soon find out what cap walk is.

Interesting note, the 400 SBC is like the BBC, 2-bolt and 4-bolt caps are the same size, 2-bolt 400's don't have the same cap walk problem the 350 and smaller 2-bolt blocks have.
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  #198 (permalink)  
Old 06-26-2019, 06:33 PM
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Dump trucks and boats need 4 bolt caps, hotrods not so much.
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  #199 (permalink)  
Old 06-26-2019, 07:42 PM
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What are you calling reasonable rpm? I'm curious as I've read of people turning 2 bolt block and cast cranks into the mid 6000's no trouble. You mentioned 6800, that is getting it to me.

Only reason I mentioned aftermarket block is to get a real seat of the pants frightening experience, and that comes from displacement. Wouldn't have to rev it to the moon to get the power, depending on what your looking for of course. 555 cubes that should drop in where the 454 is now. I think like a grandpa though and don't like high revving engines on the street.

Something still isn't right, I know your compression dropped some, but crap you ought to be doing better than that. Those heads are in rectangle port territory on size and probably flow better or at least as good as the factory rectangles.

Have you checked to see if plug wires are arcing, sounds stupid, but I've seen that cost some ponies. What's your vacuum at idle? What's your water temp look like?
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  #200 (permalink)  
Old 06-27-2019, 10:13 AM
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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 Energy™ Hydraulic Roller Camshafts
And here is mine again:
11-450-8 - Magnum™ 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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  #201 (permalink)  
Old 06-27-2019, 02:53 PM
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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.
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  #202 (permalink)  
Old 06-27-2019, 06:10 PM
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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.
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  #203 (permalink)  
Old 06-27-2019, 07:49 PM
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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.
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  #204 (permalink)  
Old 06-27-2019, 08:37 PM
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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.
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  #205 (permalink)  
Old 06-27-2019, 11:02 PM
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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.
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  #206 (permalink)  
Old 06-28-2019, 10:23 AM
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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.
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  #207 (permalink)  
Old 06-28-2019, 05:57 PM
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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.
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  #208 (permalink)  
Old 06-28-2019, 06:15 PM
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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.

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  #209 (permalink)  
Old 07-13-2019, 09:34 AM
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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.
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  #210 (permalink)  
Old 07-13-2019, 10:08 AM
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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.
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