Tuning my 360 la motor

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Fatkatkev

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Bluff city TN
Hey guys had a question on some timing. I've got the motor running but just wondering what would be the best set up with these specs

Screenshot_20230214_233409_Samsung Notes.jpg
 
oH boy; that 292/.508 cam is a handful on the street. Mine was on a 108Lsa.I ran it in my 367 for a few months then chit-canned it.
the problem was that I saddled it with 3.55s, and was adamant not to run it with anything else.
It ran like a scalded dog with an A833 and 4.30s. but with 3.55s and a 2.66 low-gear in the manual trans, she was a one-gear deal finishing at 53mph=6200, and on the shift, the Rs dropped to 3800, Second gear finished at 65=5500 good numbers but all my performance-driving was at 40 mph or under, so that poor engine ran a lot of miles at 32=3750 in First gear..... And with 3.55s, 65=2900. I thought I could learn to drive 55(2500), but criminy that is slow.
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So then:
Which Lsa are you running?
What is the intended purpose?
Which trans? and
if an auto, what stall ?
What rear gears?
What heads?
What Induction?.
Headers installed?
and most of all;
What is your cranking cylinder pressure.
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For a dynomite combo, all of those have to be holding hands and pulling together, and the tune will vary quite a bit from one spectrum to another.
I know what tune I ran, but it is highly unlikely that my tune will work in your combo, unless you also are running alloy [email protected], and a high stall/or clutch.
and besides all that;
Wikipedia says that Bluff City is at ~4324 ft elevation, so that's gonna be a bit of a problem
 
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@AJ/FormS
Thats a create engine spec list which should have the 108 LSA.
It’s a good bracket cam. Lighten the car up a lot and it’ll be a good low 12 car no problem.
 
Oh that’s a problem!!!!!

What size tires?
 
That’s a problem. Look into 4.10’s at a minimum for gears.
 
Why 4.10s?
Because that cam power peaks around 5300 and with iron heads at 4300 ft elevation, that cam will have no bottom end, no matter what the crate-motor compression ratio is.
So then, to get off the line in a reasonable manner, without stalling or reving/sliping the clutch out, the 4.10s will help get you going.
You see;
as a streeter, you will be spending a lotta time in the speed zone of 25 to 35 mph. With 3.23s and 27s, this is;
In third; 1400>1970rpm
In Second:1930>2700
In First; 2675>3750
Do you see the problem?
The power doesn't even start until 4000 and with the modest cylinder pressure that you can typically run with iron heads, that engine is Not gonna be in a hurry to get going.
Listen,
I'm not pissing on your combo,
I'm telling you the truth.
At an Scr of 9.5, your pressure at 4350ft is expected to be a very modest 121psi. At 10.5 it is up to 141psi. At 11.5 it is predicted to make 160psi ..... finally a good number.
Now lets look what happens with 4.10s again from 25>35mph
In Third:1790>2500
In Second: 2450>3430
In First: 3400>4750 Here yago, this will power you thru the torque-peak, and should be lotsafun! Well it would be, if you have some decent pressure.
What's decent?
At 4350 ft elevation, I'd guess 155psi..... minimum. That would take an Scr of 11.2. and, At 4.02 x 3.58, that would take a maximum total chamber volume of; 72.3cc ...... you see the problem?
At the specs shown, the pistons are .037 down in the holes=7.7cc. add 5 for eyebrows, 8.6 for the .039 gasket, and this leaves only 51cc for the heads... Even if you mill the heads to 65cc and sub in an .028 gasket, yur total volume comes to 84.5cc which is an Scr of 9.38, which drives the pressure to just 127psi.
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so, since the engine is already assembled and installed, just drive it until you can't stand the 3.23s anymore. Don't do what I did , which was to try and force that cam to work with 3.55s
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As for the tune, here's a guess.
IMO that cam with 3.23s will not like much over 14 degrees initial timing; it will be just too hard to tune the idle-system to get rid of the low-rpm jumpiness. Your total timing will be about 34>36 degrees, but don't hurry it all in. That combo will like a Two-stage curve running about 28/30 at 2800/3000 rpm and then slowly bringing in the rest to be all-in, at say 3400/3600.
Don't forget to set the Transfer slots to about square to slightly taller than square. And the Vacuum advance is gonna take a bit of experimenting. My guess it is that it will like at least 20* for cruising with the 3.23s, but it might not like too much too early, on account of detonation.
I would run that beast on 87E10, on account of the lack of cylinder pressure; BUT, I wouldn't recommend that you start there. Play it safe and run a couple of tanks of best gas, until you get the low-speed timing worked out. My 367 liked some Idle-Air bypass with that. Mine liked one hole on the front side of each primary throttle blade, of no more than .078; It varies with cylinder pressure and timing, so start smaller and sneak up on it.
If you go too big, the idle-rpm will go up too high, at the previously mentioned T-slot exposure. With a clutch you can idle it up to 750/800, to help prevent stalling.
Now, I gotta tell you, when you get it set right, that cam will tick over at 550/600 in gear and pulling itself across the concrete parking lot. But mine required the timing to be pulled back to 5*BTDC, so as to lose the jumpiness caused by the very high cylinder pressure that I run.. The point is this: your car is a streeter, NOT a racecar, forget a locked out distributor. And forget that others run 20* at idle. Go ahead and try it for a week around town, and you'll see what I mean. Just so you know, I usually ran 12/14* with that cam.
The Important thing is to set the Transfer-slot exposure, then leave it there. Set the idle speed with timing. And set the idle-quality with Idle-Air bypass. When yur done, the mixture screws should be near to in the center of their working range. Make sure the WET fuel level is correct and stable; you can't tune if the fuel level is going up and down. My car ran a lil better with a 3/8s fuel supply hard-line.
Happy HotRodding.
 
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I ran very close to that cam in a 340 30 over legit 11 to 1 comp 243@50 108 lsa in@106 507 lift adv specs 300/507 general kinetics . Ran it both 727 and 4sp 3.23s both setups 26.99 tall tire
4.30s would have been nice i used spray instead of gears it trapped in 2nd with the 727 mid 12s. It was stoopid fast on the hi-way. I loved that cam. It was soft below 4k without the spray with the 727 it sounded wicked. I say if you are not racing a 3 gear 6500 rpm ride will be alot of fun with a 4spd
 
Veeeeeeeeeeeery poor choice for 3.23 gears + street use.

Timing.
To keep yourself sane from the rough idle, it will need a LOT of initial timing. I am not going to waste time typing out the procedure, so try this & report back for more info.

Engine idling with factory timing [ about 8-12* ], turn dist slowly CCW to advance the timing. Idle will get smoother & rpm willl increase. Stop when you have the highest rpm & check what the timing is. Do not be surprised if it is 40+*.
 
Good starting point, Advance the timing till the starter bucks and/or there is slight detonation, then reduce 1 to 2 degrees.
 
Great information guys thank yall so much. I'll see how it goes and report back. May end up having to change those gears like yall say. And here's what I've been fooling with for 2anh half years

20230310_152730.jpg


20230310_152806.jpg


20230310_152746.jpg
 
What heads and head gaskets? Spec shows pistons are 0.037 in the hole at TDC. Do you know the piston CC? Carb and Intake? What distributor?

Until we know more and based on what you have, as stated it would be a dog. You have a very nice looking car, be a shame not to drive it just because of the cam.
 
I don’t know cams, but everyone’s “street-able” tolerance is very different. As long as the parts match well (seems you need more gear) you might find it “street-able” you might hate it. I find my car pretty street-able, but I could be weird. With the low first gear 904 and 4:10’s first gear knocks the tire off and rpm’s SO fast you just have to walk it through 1st. 2nd still knocks the tire off but it is controllable. I would drive it anywhere, but I don’t mind clicking it into neutral when stopped. Mileage? Never cared, rpm? 65 mph ish at 3300-3400 rpm. I don’t hold up traffic. Fuel? It will run on pump gas, but it sucks to do it. Egg under the throttle is the only way to do it. 12.2 to 1. It does NOT like very hot days and hills! Still not a deal breaker for me……maybe I am weird?
 
that cam ran great on the street for me.

i was running the mp 360 short block with eddy heads.

the key to it on the street was the proper converter (i had an automatic) and atleast 3.91 gears. my car ran a best of 12.17 with that combo. may have been able to go a little faster but i didnt care too much about the track. it was a street car
 
QUINN FORBES said:
I have the same crate but pulled the cam for a 268/280.
Beauty Duster!
:popcorn:
Click to expand...
A 268/280/106 Solid-lifter flatty, together with an Scr of say 10.2;
this would make a huge difference in Cylinder pressure at 4350 ft elevation.
And, at an Lsa of 106, the Overlap would still be significant enough (62*) to make her a ripper after the torque peak. The Wallace predicts 161psi. With iron open-chamber heads, this is about as high as you want to go, to be free from detonation.
And with such a cam, OP can keep the 3.23s. Still no where close to ideal, but it's hard to argue with 65=2600(with 27s). The clutch will make the 3.23s bearable.
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When I pulled the 292/292/108 out of my 11.3Scr alloy-headed 367, I opted for a similar Hydraulic cam; 270/276/110. The pressure rose to over 190psi, and overlap was still 53*.. That was my favorite combo ever.
Sure it nosed over early, but with 3.55s, this wasn't noticeable until over 70mph, and the car still went 12.9@106 @3650 pounds, on 245/60-14 street tires, on the only timed run it ever made.
I was very sad when the cam started dropping lobes.
Plus, you know, she ticked over at 500 rpm, just by rolling the timing out....... and leaving the stinking transfers alone.
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You know, Ima thinking our hot-rods should have a choke-type cable hooked to the distributor, so that the timing could be varied from the driver's seat, in the range of say ....... 15 degrees, lol. just like an old John-Deere tractor. I think I'd like to install mine on the side of the shifter.
I'd set mine to get from 6* advance to 9* retard, from a baseline of 14*.. giving an idle-timing range of 5 to 20 degrees. Hyup that should do it. I think the device should be infinitely adjustable over that range, but steps of two or three degrees would be fine also; and it needs a simple lock on the outboard side of the rack to keep it from slipping, and a robust positive anchor on the inboard side, so that it will stay put on the shifter. Ima thinkin aluminum body/steel lever.
If someone was to to whip one up, I'd be willing to review it for you. I'll even provide a napkin drawing..... we'll make mucho-dinero. I already have a brand new cable.................. lol.
 
AJ/FormS said:
A 268/280/106 Solid-lifter flatty, together with an Scr of say 10.2;
this would make a huge difference in Cylinder pressure at 4350 ft elevation.
And, at an Lsa of 106, the Overlap would still be significant enough (62*) to make her a ripper after the torque peak. The Wallace predicts 161psi. With iron open-chamber heads, this is about as high as you want to go, to be free from detonation.
And with such a cam, OP can keep the 3.23s. Still no where close to ideal, but it's hard to argue with 65=2600(with 27s)

When I pulled the 292/292/108 out of my 11.3Scr alloy-headed 367, I opted for a similar Hydraulic cam; 270/276/110. The pressure rose to over 190psi, and overlap was still 53*.. That was my favorite combo ever. Sure it nosed over early, but with 3.55s, this wasn't noticeable until over 70mph, and the car still went 12.9@106 @3650 pounds, on 245/60-14 street tires, on the only timed run it ever made. I was very sad when the cam started dropping lobes.
Plus, you know, she ticked over at 500 rpm, just by rolling the timing out....... and leaving the stinking transfers alone.
-------------------------------
You know, Ima thinking our hot-rods should have a choke-type cable hooked to the distributor, so that the timing could be varied from the driver's seat, in the range of say ....... 15 degrees, lol. just like an old John-Deere tractor. I think I'd like to install mine on the side of the shifter.
I'd set mine to get from 6* advance to 9* retard, from a baseline of 14*.. giving an idle-range of 5 to 20 degrees. Hyup that should do it. I think the device should be infinitely adjustable over that range, but steps of two or three degrees would be fine also; and it needs a simple lock on the outboard side of the rack to keep it from slipping, and a robust positive anchor on the inboard side, so that it will stay put. Ima thinkin aluminum body/steel lever.
If someone was to to whip one up, I'd be willing to review it for you. I'll even provide a napkin drawing..... we'll make mucho-dinero. I already have a brand new cable.................. lol.
Click to expand...
Dash adjustable timing MSD 8680 with a MSD6AL box, 15 degrees adjustment available
 
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