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Performance from a mild 350. What is good enough?

Probably a bit different due to the manual, but I've got a small cam in mine (.454 max lift IIRC) and nowhere near what I'd consider ideal gearing for acceleration (works out to 12:1 final in "first") but I'm really impressed with mine on takeoff and crawling in low. FWIW it feels like it starts to choke right around 4K, but that's 65MPH in "second", and gets up to that speed plenty quick which IMO is acceptable. I should get out and time it 0-60MPH, at least that would be quantifiable.

I'm sure a large amount of the grunt comes from the long runners of the TPI (stock TPI numbers were pretty impressive compared to the truck engines up until 1996), but I also believe the Vortecs and long tube headers are a significant improvement over previous stock configurations, assuming a mild 350.

Most information indicates Vortec heads by themselves are worth ~25HP over a stock head on a stock motor. Obviously HP isn't the end all for a truck motor, and low end torque is fairly hard to quantify (most dyno numbers start at 2K), but the Vortecs should easily produce a significant amount of torque compared to older heads, especially on a mild ~350CID engine. The TBI heads are apparently pretty comparable to Vortecs when it comes to low end, so you'd expect that in a truck, TBI would seem fairly strong vs. older design heads. If you compare the 5.7L TBI truck engine numbers to the 1996+ Vortec 5.7L numbers, the difference works out to about 25HP, meaning if the cited +25HP number for the Vortecs is right, the induction system isn't the difference.

Very big changes in how it all runs with tune though...timing or fuel off a bit, and it's immediately noticeable. At least you are able to monitor what your setup is doing AFR-wise.
 
Mechanical and vacuum are two separate things. Vacuum does not affect your performance. Vacuum is just for idle and cruise. You would have to limit the advance weights for total mechanical.

You can have your distributor re curved. Check out 4secondsflat.com they have some good tuning information.
 
If you are running an HEI distributor, I think you can get springs and advance weight kits to tune it. From Jegs or Summit?
 
I'm almost running the same set-up: 355, RV cam, flat top pistons, except shortie edelbrock headers, dual plane RPM manifold and stock quadrajet, distributor and stock-ish torque converter w/ 700r4 with idle timing retarded at -2 degs. My gearing is worse 34" tires with 3.73 and I've "occasionally" (more like accidentally) broken the tires free on dry pavement. I was about to use the same intake as you but I read the air gaps start to work around 1500 rpm so I skipped it. However, my engine does fall on its face at 4k (a bit lean, stock fuel pump + could use a little more mech advance) but overall I'm happy with the torque and freeway gas mileage is the same as our Grand Cherokee. Upgrades for me will be better gearing and fuel injection
 
I have 383, Lunati cam [email protected]/ .447 lift/ 114 LSA. Full length headers, e-force 122 supercharger, MSD billet distributor, blaster 2 coil, edelbrock 800 cfm carb. Poweredex AFR. Devils own methanol/water injection.

TH400/Gear Vendors O/D, 35" tires, 4:10 gears.

Just ordered a new quick fuel Q750-B1 blower carb. Edelbrock sucks. Fuel/air metering is all over the place.
 
Alright so I changed a few things.. I double checked my timing again and set it to 14 drove it and it was decent, I got to thinking that is 14+25 which put me at 39 so that's prob to much and it didn't seem to rev out as easily.. Backed it off to 12 initial which puts me 37 total. It's better but not perfect, whatever I leave it there. I got some msd springs from a buddy and just put the blue or smallest springs in and there is a minor difference in feel, and seems happier under full throttle now as it comes up and on a little sooner.. Close to what I'd like but no cigar, I think what has to happen is, I'll have to get the full mechanical advance limited to 10-12 degrees, run 20-22 initial(yes it starts with that much) and run a vaccum advance with adjustable timing. When I set it to 22 it likes that a lot, very snappy with no load obviosly, I didn't drive it out of fear. But outa gear it seems happy with that much initial. I also need to mess with my low speed air bleeds and trim my main jet on the primary down because it's still really rich, 10:1 after it gets off the accel pump it comes up into the 11:1 and leans out from there to a nice 12:8-13-4 was what I was reading at 5-5500.

As far as my combo I wanted something that has a really broad spread of power, I know I'll pick a decent sized cam like my 72 had 218-226 on a 112 and that made power all the way to redline. For now it is decent and I just need to make more Lowe end tq.. Worst case I'll pop the heads off and measure everything and go from there cause I have no idea what the quench is or gasket, or cam because my dad built this in 94.
 
I'm no expert, but sounds like you are head in the right direction.

Crane Cams makes a limiter plate that you can install on your vacuum advance canister to set the amount you would like from it. I did it because having the supercharger I am very wary of detonation even at cruise. I have it restricted to 10 degrees vacuum.

I found a vacuum advance canister that pulls all 15* advance by 8"HG. It is an Echlin VC 1810. My engine does not make much vacuum at idle. Cross referenced it at Advance auto and got it there. About 9 dollars I think.
 
Sounds like you are still really rich as well.

If you get your timing to 22, you should be able to set your idle screws so that you are reading 14.5:1. No more smelly idle.

12:1 would probably be a good goal for full throttle.

13:1 partial throttle

14:1 cruise
 
So in an effort to reduce timing with a stop I managed to lock the timing out.. Well I experimented with it and omg all I can say is it's much better.. I ran with my vaccum advance also and no pinging. So at 36 degrees it still starts easy enough I don't need an ignition off switch either. I am happy! Now all left to do is trim some fuel..
 
You said earlier that you vacuum can only gave you 5 degrees of advance. I'm no expert, but that is not the norm I don't think. Most standard cans give 15 degrees. With your advanced locked at 36, add 5 and you are only at 41. I think you are still safe there. If you here no ping at cruise. Might read you plugs later to check for detonation.
 
Right the advance can is for an hd truck and it's the only can that provides so little advance.
 
Well then that gives you room to play. I don't think you are going to get detonation at cruise with 41* total advance. I'm at 44 now myself.

I bet it gets up and moves locked out at 36* !!!

Might not like long pulls in the hills.

Probably need to figure out how to modify your curve. I don't know anything about grinding on the timing plate.
 
Correct this was more of an experiment just to see how it feels. Ill make a video this weekend so you can see what its like. It is very happy, but it doesnt seem to change much after the 20 degree mark. Im going to try to limit the advance like we talked about and set the initial high and go from there.
 
Once my new carb comes in, I'm going to try 2 more degrees advance. 26 initial, 36 total. We'll see.......
 
Quick Fuel Q750-B1. It is a carb for a roots style blower which I have. No choke and mechanical secondaries, so we'll see.
 
You could always put a programmable MSD box on it, will give you the curve back, and/or start retard, and you can add vacuum advance too with a MAP sensor if you want.

http://www.summitracing.com/parts/msd-6530

Or install an ignition cutoff switch for emergencies. If it ever won't turn over when it's hot, just flip the ignition off, start the motor turning over and then turn the ignition switch back on. It also serves as an antitheft device if the switch is hidden (leave the ignition off). My regal is locked at 38, but my truck I still use both curves. I did eventually add a digital 6+ with start retard, but still have the timing locked at 38 other than cranking on the 388 in the regal.

With that said, since you are making 16" of vacuum, I would set it up right with the proper stops and vacuum advance, or the MSD box. A spring kit is like $10, and you can flip the center piece to reduce mechanical travel. I have found the adjustable vacuum cans unreliable and when you adjust them they still aren't all in at low enough vacuum sometimes. I used the std one from a 83 305 truck and then weld in a tack and file it back until it gives me what I need. With a hand pump and guage you can play with the vacuum advance setup without creating a vacuum leak.
 
Aww man I didn't know flipping the plate would reduce total advance, I ended up with a light spring and a heavy one which reduced my advance to 12 degrees, that's close enough and it now runs like a raped ape! I have some go pro to prove my point. Now if I could ge t off my lazy....
 
You still have full advance my friend. Springs only determine the rate of change. How fast it comes in. You still need a mechanical stop to limit total advance. Do you have a digital timng light or a timing tape on you harmonic damper to see total? On the MSD, a light blue and light silver give you something like total advance by 3000 rpm.

New carb supposedly showing up today. Hopefully there won't be too much tuning to do.
 
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