Head Games!

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Captainkirk said:
not sure why that should happen now?
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You said you had a 4-speed; I assume that 4-speed has a 2.66 low gear;
have you idled it down to 500 and tried to drive it there.
If you did and it didn't buck, then
1) it wasn't Idle timed in the usual place (15 to 25 deg). and/or
2) your 298/308 cam is not rated in the usual way.

Even a 220*@.050 cam will buck at 500/550 with the usual 15 to 25 degrees of Idle Timing...... because the transfer slot sync is in the wrong place.

The only other way that it won't buck, is if the cylinder pressure is in the basement, and then the thing will be embarrassingly low-powered from idle to 3000 rpm or more, which you didn't mention.
 
AJ/FormS said:
You said you had a 4-speed; I assume that 4-speed has a 2.66 low gear;
have you idled it down to 500 and tried to drive it there.
If you did and it didn't buck, then
1) it wasn't Idle timed in the usual place (15 to 25 deg). and/or
2) your 298/308 cam is not rated in the usual way.

Even a 220*@.050 cam will buck at 500/550 with the usual 15 to 25 degrees of Idle Timing...... because the transfer slot sync is in the wrong place.

The only other way that it won't buck, is if the cylinder pressure is in the basement, and then the thing will be embarrassingly low-powered from idle to 3000 rpm or more, which you didn't mention.
Click to expand...

I don’t let anything idle at 500 and my stuff doesn’t buck.
 
I disagree with 99% of what you wrote.
AJ/FormS said:
Race only?

12 second implies just into the 12s, with unlimited suspension, you only need a P/W of .081 to get there so, at 3400 pounds race weight, that would be 275hp

But on street tires, and with street suspension, you might need a P/W of .094 so 320 hp.
But if you want a low 12 second in street trim you could be looking at a P/W of .115, so 390hp

So obviously, each of those builds is gonna be considerably different.
@Rumble said you had some decision to make, and I agree.
Cuz 400hp in a streeter is way overkill. Even with 3.91s, if the tires hook, you can't get to peak power in Second gear until just before you are speeding. And the ride takes about 5 seconds from a dead stop. But more than likely your street tires will NOT hook,and they will spin all the way....... and spinning ain't winning.
If that is what you are after, and you have the money, I find no fault in the doing, on account of that was what I wanted, and did,lol. But I didn't have any track goal in mind.

To say it in another way, 400hp at 3400 pounds is a P/W of 400/3400= .1176, and with unlimited suspension, has the potential to go about 11.5@116 mph. But with street suspension and tires expect to be a second or so slower.

Now, to make 400hp with XJOUorZ heads
for use with pumpgas
is gonna cost you a wheelbarrow of money and and, flippin' AND; a crazy for street, cam.
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Well OP, the jury is in. Two of the brightest fellows on FABO, are clipping my feathers. And I'm not playing the facetious card, they really are. So before I embarrass myself any more than I already have; I'm gonna back into the bleachers.
 
AJ/FormS said:
Well OP, the jury is in. Two of the brightest fellows on FABO, are clipping my feathers. And I'm not playing the facetious card, they really are. So before I embarrass myself any more than I already have; I'm gonna back into the bleachers.
Click to expand...

I know I ain’t one of them but I’ll still throw my two duckets into the hat. So you better too!!!!
 
I want to thank all the members here for their copious amounts of SBM knowledge. CaptainKirk and I have very much in common, but I guess I'll try to figure out how to start my own thread to get SPECFIC recommendations for my build. AJ, Rumble, YR, and other have been a wealth of knowledge to me, and I guess it's time to quit lurking and put my pair on the chopping block. You're a good man, Rumble, you helped me out years ago with tire advice. Paul.
 
Thanks man. Anytime Paul.
70dart340 said:
I want to thank all the members here for their copious amounts of SBM knowledge. CaptainKirk and I have very much in common, but I guess I'll try to figure out how to start my own thread to get SPECFIC recommendations for my build. AJ, Rumble, YR, and other have been a wealth of knowledge to me, and I guess it's time to quit lurking and put my pair on the chopping block. You're a good man, Rumble, you helped me out years ago with tire advice. Paul.
Click to expand...
 
AJ/FormS said:
Well OP, the jury is in. Two of the brightest fellows on FABO, are clipping my feathers. And I'm not playing the facetious card, they really are. So before I embarrass myself any more than I already have; I'm gonna back into the bleachers.
Click to expand...
Well, I'll still PM you when I need advisement on how to get a bunch of mismatched parts selected by someone else to play along nicely with one another. That last tune you helped me baseline in was very nearly spot on (it would have been if we had known the actual head gaskets used and thus the true compression at the time). We're in process of some upgrades (It's going a little farther over the top than before, too much is never enough for some people :p) so you'll probably be hearing from me again. :thumbsup:
 
AJ/FormS said:
Well OP, the jury is in. Two of the brightest fellows on FABO, are clipping my feathers. And I'm not playing the facetious card, they really are. So before I embarrass myself any more than I already have; I'm gonna back into the bleachers.
Click to expand...
@AJ/FormS
No need to go back to the bleachers, sir...everyone's opinion is appreciated on this thread, and your opinions are highly regarded by yours truly. All I was saying is that the former build of this motor did not act up despite heavy pistons, high compression, 4-speed, 3.91, single plane w/Holley DP and a modded dist curve. I can't recall ever having had to "walk" the car at 5mph and if I did, I was probably clutching it. This build will not be a "daily driver" and hopefully will not see much in the way of traffic. It's more for finding an open stretch of country highway and letting the horses out of the corral to play, or maybe to park at a car show. So get back in the saddle and pitch your wares.:poke:
 
To me, a streeter, If I couldn't drive 4 mph, or less, with a 4-speed, I'd not get much driving done in a summer. I've got her down to 3.6 mph.
I'll tell you what 3.6 mph cost me;
three transmissions, two rear ends, three cams , two clutch discs, three carbs, one timing retard box,and countless hours of tuning, to get;
So you know I'm serious.
When's the last time you saw a 4-speed 367, cammed with a 276/286/110@.008 tappet-rise, idle at 500 rpm, with 180 psi cylinder pressure, on 28/24psi tires, in gear and pulling itself with; no toeing of the clutch,NOT loading up, cranking modest turns thru the SureGrip;
AND,not donkey-kicking!
Ba bump-up, ba bump-up, ba bump-up,
ba bump-up, ba bump-up, ba bump-up
Suhweeeet.

Sometimes I'll leave it in Second gear, or Third, and start retarding the timing, until it wants to stall, and THEN toe the clutch,lol. Downshift, repeat. Downshift,repeat.
Big fun coming to stoplights, and entering Pony Corrals; you got those down there?
BTW
I had most of those replacement parts in the shed. The things I actually had to buy,were; the cams, the Commando 3.09-low gearset, and the 340 clutch discs.
 
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AJ/FormS said:
To me, a streeter, If I couldn't drive 4 mph, or less, with a 4-speed, I'd not get much driving done in a summer. I've got her down to 3.6 mph.
I'll tell you what 3.6 mph cost me;
three transmissions, two rear ends, three cams , two clutch discs, three carbs, one timing retard box,and countless hours of tuning, to get;
So you know I'm serious.
When's the last time you saw a 4-speed 367, cammed with a 276/286/110@.008 tappet-rise, idle at 500 rpm, with 180 psi cylinder pressure, on 28/24psi tires, in gear and pulling itself with; no toeing of the clutch,NOT loading up, cranking modest turns thru the SureGrip;
AND,not donkey-kicking!
Ba bump-up, ba bump-up, ba bump-up,
ba bump-up, ba bump-up, ba bump-up
Suhweeeet.

Sometimes I'll leave it in Second gear, or Third, and start retarding the timing, until it wants to stall, and THEN toe the clutch,lol. Downshift, repeat. Downshift,repeat.
Big fun coming to stoplights, and entering Pony Corrals; you got those down there?
BTW
I had most of those replacement parts in the shed. The things I actually had to buy,were; the cams, the Commando 3.09-low gearset, and the 340 clutch discs.
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How can you tell you are going 4 MPH or less?

All I’m saying is it’s bad policy to let any engine with flat tappets idle at 500 RPM. You use a cam that is even remotely aggressive and that slow idle will kill it in short order.
 
Because people can walk beside the car?
Walking 4mph is a 15 minute mile. you gotta chug along pretty good at that rate.
3.6mph is a mile in 16.7 minutes, easily doable for a younger person. In my 40s I was still easily walking 4 mph. I haven't tried it for a few years now.

I put my trust in the HV pump, the oilmods, and the oil itself.
Since the last freshening in about 2005 or 6, the engine has not been apart.
I would guess my cam is therefore
Not,
remotely aggressive.
 
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