xpndbl3

iTrader: (5)

850 dp
34 total timing at 3k
16-18 initial, plus whatever from the vacuum cam
at idle out of gear when warm it's 1500-1600, and 900 in gear

When first starting the motor though, I have to rev it for 2-3 minutes to keep it running then I can put it in gear without 2 footing it. I'd really like to be able to just fire it up wait 15-30 seconds and pull it off the trailer. I checked the floats and they're adjusted, 7psi off the regulator, idle mixture screws are set for best vacuum, although the idle speed screw is probably 2 turns out, so the transfer slots might be open too much, I haven't pulled the carb off to adjust the secondary throttle opening, but didn't think either way it would matter on a cold engine for this issue. Any thoughts on how other race cars with much larger cams can start them up and drive off the trailer almost right away, or start them and drive them to the staging lanes and shut them off and not have a problem. Is it all linked to the idle speed screw being open too far possibly? Is 900-1000 in gear an acceptable idle speed for a 106 lsa cam?

five7kid

iTrader: (14)

Mostly they do it by running too rich.

It doesn't sound to me like you've got a problem. With no choke, you should expect to have to warm it up some. I need about 3 minutes before I take off for the track. Once I'm there, it isn't a problem since the engine never fully cools off.

xpndbl3

iTrader: (5)

alright, that's just what i figured. how do they set their cars up to run that rich so they fire up and drive instantly? I have to rev mine almost constantly or else it wants to die out on me. Do they just turn their idle mixture screws out a few turns more ? Just trying to think of a track only solution for it.

91CamaroRS305

iTrader: (2)

I can attest to the revving issue

Steve try bumping up your timing to 36 and your fuel pressure to 8 psi. I run mine around 7.5 and my engine, well atleast sounds, a lot more tamer than yours. Most the guys I know run their timing at 36 or 38, and the guys who spray run closer to 40 (my buddy ran it at 44 i think on a 377 with a 300 hit).

Plus the guys let their cars warm up in the pits, or they use the block and oil warmers before they fire up. Try jetting your carb some more, always go richer and work your way back from there.....com'n I thought YOU were the race car guru on the Northwest Indiana board, thats why I called you

xpndbl3

iTrader: (5)

i have heads that do not require that much timing due to their superior combustion chambers. Furthermore, I watched 15-20 cars this weekend fire up really radical 383s and 388s and just blip the throttle open 2 times and pull off the open trailer. As for the guru comment, I've yet to take a car to the track that I couldn't get to run faster than the owner of each vehicle, I think I'm at 7 cars tuned this summer so far all running faster than before, but even some of them can fire up and go.

xpndbl3

iTrader: (5)

opened the secondary screw a little more, still not open to the point of seeing the idle slots in the bore, but now the motor runs even worse. Should I open the secondarys until I can see a "square" shape out of the transfer slots, then back off the primaries? Because right now it seems to want even more primary, and the slot is already too far exposed. Also I'm running a PCV valve, since I heard that could help as a secondary air draw all the time.

mw66nova

iTrader: (13)

hmm...my dad's car is like that...10.2:1 c/r, big solid lifter cam on a 106lsa and dart iron eagle heads (200cc)...getting it to fire up the first time of the day is a chore...but once it's lit, it's alright. eh...car runs 11.8's with a power glide @ 3300lbs...i figure it's running alright...

xpndbl3

iTrader: (5)

yea i know, i'm thinking about opening the secondaries more possibly, but really looking for some better ideas on this. I am going to have to get quieter mufflers because the neighbors seem to like calling the cops on me, and i'm just revving the motor to keep it running to pull out of the garage and shutting it off even--takes 2-3 minutes to get it to idle enough in gear to pull it out, but today it ran like crap after opening the secondaries just a little off being completely closed. I'm kinda lost what to do with it, I can't see driving this in stop and go traffic until it's solved.

xpndbl3

iTrader: (5)

opened the secondaries up until the slots made a square shape. not sure what else to do, still needs more throttle opening to idle high enough in gear, have to two foot it and it's embarassing at a car show to not just idle around in gear, instead constantly having to stab the pedal. any thoughts?

Sonix

iTrader: (1)

just out of curiosity, why can't you run a choke? no provision on that carb?

how big is that cam? I didn't think it was huge, 1600RPM idle and 900RPM idle in gear sounds quite excessive... What's the deal? What is the timing at idle, with vacuum can hooked up? (manifold vac right?)

xpndbl3

iTrader: (5)

no choke provision on this carb. the cam is 242/246 .520/.540 on a 106 LSA. comp said that the 106 lsa would require 1000-1100 in gear, compared to a 112 or 114 lsa which could idle much lower, and wherever the RPMs fell due to how "loose" the stall is will determine how much the motor is pulled down at idle compared to in park. which for my stall it seemed to be 1600 out of gear and 1100 in gear, but that is with the primaries open way past the transition slots.

yallwatchthis

I am running a 13.5:1 355 and I have a small carburetor (650cfm) now, my carb is hand built on the flow bench and here are my base settings:
110 octane
32 deg locked timing
throttle blades on primaries and secondaries equally adjusted to expose about .020" transfer slot
idle mixture screws are 1.25 turns out
.068" maxjets f/r
enrichment cicuit is blocked on secondaries with jet extensions, and 6.5" power valve in the primaries

this probably won't work on your set up as your carb is a little larger than mine, reallistically by about approximately 100 cfm....try it and see, but the motor will tell you what it likes...listen to it and look at your instruments later, vacuum, EGT, timing is all irrelevant to performance in the aspect of what "everybody elses motor" is doing. Your engine will performa different than mine, just as your next engine will perform different than your current one. No two are the same. good luck with it and try going back to 1T on IMS and throttle closed completely, adjust primaries up to acheive idle and then taylor it to suit your prefference with you IMS(idle mixture screws).

mw66nova

iTrader: (13)

what is the base timing set at?

xpndbl3

iTrader: (5)

base timing is 18 plus 13-15 off the vacuum can.

xpndbl3

iTrader: (5)

i created a post on the drag racing board since this one didn't offer many suggestions, but i'll bump this up one more time to see what I can get for answers.

rjt76

try your timing locked at 34-36. I just did this to mine and I am very happy with the results. I gained 3 inches of vacuum in drive at idle 800rpm. total is now 14"
I have been playing with the mixtures screws alot and mine are set to 1/2 in rear 3/4 front this seems to give the best all around idle for me and the 50 mph cruise in 4th locked up is no longer choppy. going 1/4 of a turn makes alot of difference itleast it does with my setup. keep playing you will get it..

xpndbl3

iTrader: (5)

just locked out my timing and the motor runs much much better. still need to adjust the mixture screws more to get a lower rpm idle possibly but for now it's 1000 in gear and i'm happy with not having to two foot the car anymore. thanks again for the suggestions guys.

91CamaroRS305

iTrader: (2)

ever thought of drilling some really small holes in the butterflies on the carb steve?? just a thought, not sure how you feel on that

xpndbl3

iTrader: (5)

already drilled holes in the butterflies and now i have the mixture screws out 2.75 turns or so, when really the timing probably just needed to be locked out from the beginning instead of 18 initial, 34 total like I had it. Now I kinda regret drilling the holes, since the mixture screws are so far out