stang_kllr

iTrader: (6)

I need some input on timing. I have a 383 ls1, 12.5-13.0CR, lunati forged RA, AI custom grind, .626/.626 270/278 (239/249@.050) 112 lsa, 2.3 Advances, AI ported/milled (58cc) 243s, super victor, holley hp 850 E85 carb, on E85.

so, to start off, I used to the preset #1 timing curve, and the car fired right up. idles/revs good. I was giving advice from 2 different people, both have been proven to know their stuff. anywho, I tried both the timing curves. 0*@0rpm, 5*@1k, 10*@2k, 15*@3k-redline. the other, 2*@0rpm, 7*@1k, 15*@2k, 19*@2400, 22*@3k-redline. both curves made my car run like junk. I re-programmed #1 curve and the engine runs good again. But on the start up of first rev, it pops, then revs great. not all the time. power valve? it has not backfired at all through the carb or headers. Can someone point me in the right direction on the timing I should be running? please. thanx!


Also, what micron rating are you guys running on your systems? and where are you mounting them? (before pump, after pump, after reg,)

ZONES89RS

iTrader: (25)

If it's cold, it will pop on a throttle stab usually if it is lean until the motor warms up. If winter, it will do it without a choke.

Tune it yourself. I would run 20* at 0 and 30* all in by 2000 across the board as a base tune.

TTur1996

The compression you have and those heads. IMO you should be running a 950 cfm carb. Unless you have a bad *** 850 that flows like a 950. I think you are leaving some on the table.

TTur1996

With E85 you should have a 100 micron before the pump and a 40 micron after.

3pedals

iTrader: (3)

try start your tuning with:
15* at 0rpm
30* @ 600 RPM strait across to redline or 8000.
you cant go wrong starting with this, those guys who leave the timing low through the low rpms are giving up a tremendous amount of throttle response

ZONES89RS

iTrader: (25)

Don't wanna say don't listen to those guys, but of it was gasoline I would have said 16* at 0 with that compression, but your running E85 so the burn rate is slower, so I say don't listen to them and run 20* at 0, lol.

Not that you'll notice much difference.

3pedals

iTrader: (3)

Ya Zone 15-20 @0 rpm is fine, but 0* @ zero Rpm will equal a harder starting engine

Pop N Wood

iTrader: (1)

Why 40 after? Most guides say 10 before the carb. I've never run E85

ZONES89RS

iTrader: (25)

I don't run a filter after the pump.

stang_kllr

iTrader: (6)

well I live in phoenix, and its about 100(+/-) when I start up, and I haven't had any problems before when starting on a "cold" engine until I did the timing change. I really haven't ran the car long enough to get it up to normal temp though, because I still have to plumb my fuel system. right now I just have a cup filled with e85 and wired up a stock 99 Camaro fuel pump to it for now. so it eats it up real quick. lol. I was hoping I didn't maybe mess up a PV in the carb?

ill have to give that timing a shot. It seems like it likes more timing. what do you recommend as for pulling timing on the bottle? I really don't know how to go about doing that as well.

Damn, I hope not lol. When I first posted my setup, I asked on here what carb, and an 850 was recommended since I don't have a lot of cubes. I want to squeeze out as much as I can out this motor without stressing it too much. So if I end up needing a 950, so be it. Heres the carb I have now. http://www.summitracing.com/parts/hl...44hb/overview/

ill give this a shot as well. if I run this as base, how much timing can I pull when I hit the step retard? I want to be as safe as I can. A few guys told me that they had to run 8* base timing just to be able to pull enough timing on the 350 shot.

I just hate not being able to use knock sensors



Thanks guys for all the feed back!!

TTur1996

Check out any good fuel pump site like Aeromotive or Magna Fuel. With gas you should have a 100 before and a 10 after. I run a A3000 Aeromotive. The 100 is a modular canister unit that attaches to the pump itself.

Pop N Wood

iTrader: (1)

Which is why I asked you about your earlier suggestion to run a 40 micron after the pump. 10 is what I have always read. Thought maybe there was something special about E85 that required a coarser filter.

VLS1

A little bit off topic, but surely the lobe ramp on your cam could not be this aggressive?

Especially if going by these numbers, the exhaust lobe is faster off the seat than the intake lobe??

I would assume you've misquoted the cam specs entirely.

stang_kllr

iTrader: (6)

TTur1996

Yes the 40 micron is for E85 only. And yes it is more coarse. Has less of a chance of gumming up do to the thicker fuel. Sorry my bad.

VLS1

Still doesn't seem right, unless they are listing @ .020" as their advertised duration.

Not to mention these cam specs are far from ideal for a carb intake regardless of the above.

stang_kllr

iTrader: (6)

I doubt it. I had the cam specd out from AI for me. i told them all my specs, and what i wanted out of the car. Although, this was specd for my previous setup, which was a Direct port FAST 90/NW 90. I already had the cam when i swapped top ends, but i contacted them and asked them if i needed to change my cam. they said as long as i am still on spray, it will work good. he said if i was going n/a then he would recommend something on a 109 lsa

VLS1

Hmmm, still think the advertised numbers must be somewhere in the @ .015" - .020" lift range.

If those numbers were at typical adv. spec of .006" lift, your valvetrain noise would be excessive, that's for sure. Would doubt it to be possible to run such an aggressive ramp rate with hyd roller, valvetrain life would be very short I'd imagine.

stang_kllr

iTrader: (6)

I didn't actually measure with a degree wheel but you make me want to. the cam is aggressive, but valvetrain noise is no where to be heard. 1. The engine is super loud with open headers, 2. I used a pushrod length checker, and with the lifter preload, 7.4 pushrods are a perfect fit. you can hear the motor here...

stang_kllr

iTrader: (6)

Also, what are you guys doing about vacuum for brakes? my carb doesn't have any vacuum ports. so my guess is I have to drill and tap the intake?