I Need help 410 Stroker timing Carb Education
- Thread starter /6Duster
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/6Duster
Active Member
When I took something apart I always put it back the way it was but seeing a new light here not
always the best way of putting it back together
I agree a great deal of knowledge on FABO
always the best way of putting it back together
I agree a great deal of knowledge on FABO
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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FWIW
IMO
Every small blockLA (all I know) Chrysler ever built, was well-engineered to work well in it's environment, for it's intended purpose.
But when we, the HotRodders, get ahold of it, and try to make it fit in multiple homes, that's when trouble starts brewing.
When I first started, I aimed too high, and that 292/292/108 just wasn't working for me, in the environment I wanted it to. I went THREE sizes down in the camshaft, to find what I wanted.
That's a pretty big mistake on my part. Butum,I gotta admit, that while it was in there I learned a lotta things. So it wasn't a lost experience.
And, in a way, I was lucky, on account of I started with alloy heads and 11.3Scr, so adjusting to the earlier Ica did not hurt much. I had engineered some adjustability into the design, cuz I was sortof pioneering. The local speedshops recommended to me to build to 9.5Scr, but I was a bit pig-headed, having already made up my mind that 9.5 Scr was for chevy's, the thing they all specialized in. No, I had figured out in my head that Dcr was the thing that made the difference.
Back in 1998, nobody was talking about Dcr, and there were no on-line calculators, and the local to me builder had never heard of it. So I had to do all the math longhand. Yeah, so I was a little blown away when the numbers spit out 11.3 Scr for the 292 cam. But I sortof trusted the numbers, but not quite. So I did the math with the .028 gasket and set it up thinking I could manipulate the Dcr with a thicker gasket, cam-timing, and/or, if I had to, injection of an anti-detonant.
When it ran like a raped ape with no detonation and full-timing; you cannot imagine how excited I was. The cranking pressure on my guage was ~185. And it would be several years before I found FABO. And when I did, one of the first things I did when I got here was ask around what pressure other guys were running, still on pumpgas.. I was surprised to learn that with alloy heads, 185 wasn't even high. Well I sorta knew that, because by that time, I was running the 270/110 cam, and had tuned her also for 87E10. And I had had her apart several times for inspection. So what I discovered here on FABO, was that the upper limit for alloy and best pumpgas was about 200psi. I think only one fella responded at 205psi.
Last year, for the heck of it, I tested the 2.5liter 4-banger in my 2014 Orlando, and on the same gauge, it measured 220psi, and I run that on 87E10 as well. But of course that is a fabulous design; being a DI, VVT, injected and computer controlled timing marvel of engineering. Gee I hope it never breaks down,lol.
So having learned that stuff, I tend to preach it. And the biggest reason is that pressure makes power.
I know for a fact that my 367 shouldn't be making enough power to go 93mph in the Eighth at 3457 pounds, and with a 230 cam, and 930 ft elevation. Yet it does. And with a Hughes HE3037AL cam; that's 230/[email protected] on a 110LSA. That impressed the snot outta me when I got the timeslip, and even thinking about it today, 16 years later, still impresses me.
There is nothing magical about this build. It only has a couple of things going for it; the pressure is still close to 180psi (but now down to 10.95Scr), and the Quench is .033 ish. Oh and I run 1.6 rockers lol. That Hughes cam has advertised lifts of IIRC, .549/.571 with the 1.6s, which is no longer considered a big deal.
So yeah, I tend to preach this kindof combo.
I know alloy heads are pricey, and not everybody wants to or even can spend that dough. And some guys have, but only run 155/160 psi, so they have short-changed the principal purpose of the ALLOY heads, and so the power is not there, especially around town. And it is, IMO, a mistake to run them around town at low pressure, cuz the aluminum sucks the heat out of the chambers and so less energy goes into the production of power. And if you run them at 160 or 180*F, you will lose even more power.
In the end, for a streeter, running lo-compression, ALLOY heads are almost a complete waste of money.
But of course, the only way you will know this, is by swapping them onto an existing combo set up for iron heads.
If you are building from scratch, only the trapspeed will reveal the mistake.
And in all honesty, with a 65 mph speedlimit, your traction is the limiting factor; even a stout iron-headed 318 can, with the right combo, overpower the suspension and tires.
An overdrive transmission is a game-changer, because you can put second or third gear right where it needs to be, without worrying about the cruise-rpm. With an automatic, gearing a streeter properly is a bit of a challenge, cuz with a smallblock, you always run into the cruise-rpm wall.
So, I agree that putting it together as you found it, for performance, is rarely gonna work out. For a factory small block I doubt it ever will, unless your expectation is mediocre,lol.
And the final comment is this;
Think combo.
Once you change the operating characteristics of the engine, you gotta analyze every other part of the powertrain and especially the chassis; cuz everything is dependent on those tiny little patches of rubber,interfacing with the road. I my experience, the biggest baddest 15" street tires you can fit in your factory tubs, just can't handle even 275 hp, without a traction aid. By the time you hit 350hp, it's a challenge just keeping it on the road. By 430hp,(what it takes to go 93 in the Eighth at 3457 pounds) traction is a byword. It's like driving a new 1970 Swinger 340 on those E70-14 polyglass belted, worst tires in the world, that they came with. I remember it well. I couldn't hardly change lanes with the secondaries open, for fear of getting sideways or doing a 180 . Traffic was always an exercise in patience, for this 18 year old punk-driver.
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/6Duster
Active Member
160 @ 6 retarded
175 @ 0 straight up
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,874
- Reaction score
- 13,180
That new pressure is gonna do 4 things;
1) it will increase torque/power thru-out the rpm range; especially down low, and
2) increase your Part-Throttle response and torque at low throttle openings, and
3) the power peak will come down about 200 rpm or bit more.
4) with the Effective overlap restored, you should see an increase in power. That cam only has a small amount of overlap so you can't afford to give any away. Straight-up (110) to 108 is the window.
But, at very low rpm, the pressure will be pretty high. I think with the combination of 3.91s and 2800TC, it will be fine. But I know that with a clutch. you would need to take some Idle-Timing out of it, to smooth the drive-away. If you find that she's a lil jumpy from idle to stall, that's the first place I would go. With the 274 cam and alloy heads; I would try
12 to 14* Idle;(whatever gets the T-slot in a happy place.)
32* to 34 Power, and
I would use a two step curve with 28* at stall (2800IIRC),
and the rest whenever... maybe as late as 3600 on the street.
With alloy heads, My 367 is happy with 87E10 at those specs, and pressure as high as 185psi.
Note-1
I found the one-long loop spring that this will require in an old 318 distributor. But the I found all aftermarket springs were too fast on the first part of the curve. After I found a spring that got me into the ballpark, I ground a bunch of weight off the flyweights until I got what I thought the engine really liked.
Note-2
To make working on the D easier, I threw that horseshoe clip away, and drilled/tapped the top of the shaft for a tiny allen-socket screw, then cut a spacer so my screw didn't jam it all up. Now swapping springs only takes seconds after the cap is off. With the two-step timing-curve I strongly advise that you map your curve each time you change spring(s), to see what happens.
1) it will increase torque/power thru-out the rpm range; especially down low, and
2) increase your Part-Throttle response and torque at low throttle openings, and
3) the power peak will come down about 200 rpm or bit more.
4) with the Effective overlap restored, you should see an increase in power. That cam only has a small amount of overlap so you can't afford to give any away. Straight-up (110) to 108 is the window.
But, at very low rpm, the pressure will be pretty high. I think with the combination of 3.91s and 2800TC, it will be fine. But I know that with a clutch. you would need to take some Idle-Timing out of it, to smooth the drive-away. If you find that she's a lil jumpy from idle to stall, that's the first place I would go. With the 274 cam and alloy heads; I would try
12 to 14* Idle;(whatever gets the T-slot in a happy place.)
32* to 34 Power, and
I would use a two step curve with 28* at stall (2800IIRC),
and the rest whenever... maybe as late as 3600 on the street.
With alloy heads, My 367 is happy with 87E10 at those specs, and pressure as high as 185psi.
Note-1
I found the one-long loop spring that this will require in an old 318 distributor. But the I found all aftermarket springs were too fast on the first part of the curve. After I found a spring that got me into the ballpark, I ground a bunch of weight off the flyweights until I got what I thought the engine really liked.
Note-2
To make working on the D easier, I threw that horseshoe clip away, and drilled/tapped the top of the shaft for a tiny allen-socket screw, then cut a spacer so my screw didn't jam it all up. Now swapping springs only takes seconds after the cap is off. With the two-step timing-curve I strongly advise that you map your curve each time you change spring(s), to see what happens.
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