Webers bogging on transition, how do I fix?

[john walker's workshop]

i think the timing could be advanced more and still be safe. that would help a lot. maybe go down one size on venturis next. like i said previously, don't drill the transition ports until all other attempts fail. it's hard to go back if it doesn't work. the jetting seems in the ballpark though. a larger air corrector makes the main jet pull less fuel at higher rpms, and vice versa, so you can fine tune the fuel flow without changing main jet size.

[cstreit]

John,

I'm sure you're right about the timing... I'm going to check it out this afternoon and I'll post where it is. Do you have a ballpark target?

I'll post the result of richening up the idle mixture too, but since it occurs at 3000 and 4000 RPM I'm thinking it is the mains... I may try the 180 a/c jets just for grins...

[john walker's workshop]

180 air correctors will make it run leaner on top end than 160s. is that where you want to go? timing on a street 3.0 with stock compression can be 35° total with no problems. on yours, with 10:1 comp, i wouldn't go that far. 30-32° to be safe. i think you're too lean when it bogs, especially with 46s and 40 venturis. what do the plugs look like? you have to put it thru it's paces for a while, then shut it down hot, to get a decent reading, which isn't like the old days, when we had gas that burned better, and left fewer dark deposits.

[cstreit]

John,

I forgot to mention that I'm running twin plug, which is why I've started running the timing slight less that what I've seen "normal" 3.0L motors run...

Lean was also my thought. I'll check the plugs after I'm able to get some real miles on it.

[TimT]

Chris are you using the DL90 to log advance vs rpm?

It sounds like all your your jetting and venturis are in the ballpark. Fine tuning is in order.

FWIW I had a transition problem on my car awhile back. I played with some different emulsion tubes and cured it.

I will have to look at my spares, or open the carbs to tell you what ended up using. Unfortunately my carbs are at my friends shop. He uses them as a benchmark if he gets a weber equiped car that have problems.. Ill try and get there soon and have a look at the carbs.


Im getting really close to having my car all back together and am jonesing to get on the track again

[cstreit]

Well I was trying to do that, but I can't seem to get the G-DARN car RUNNING!

I bought a brand new optima red-top battery and charged it fully, but I can't seem to get more than 30-60 seconds of cranking out of it before the starter can't turn the motor...

PLUS

I'm having problems getting the ignition to work. The company is mystified, I'm just getting so damn fustrated about the situation. Five months of building this motor and I'm going to start missing events because I can't start the car? AGH!!!!!!!!

[TimT]

WOW that sucks,

I hope electromotive is doing the right thing by you. We running elecromotive before the reuild? or is this a new problem?

[cstreit]

Yeah, I should say that they ARE taking care of me and are working with me to diagnose, no complaints there at all. The difficult bit for me, is that every time this happens (2nd time now...) It takes 1.5 weeks to send them the units, have them looked at, and get repalced. I'm 3 weeks off schedule now because of these problems. Grrr...

Haven't used the e-motive units before... It's such a simple setup, and so many people use them reliably, I just can't imagine what the problem is...

I'm actually quite impressed with their tech guys. THey have taken the time to talk with me to really learn the situation, offering suggestions, testing units, and trying to replicate my issue in their lab.

[jluetjen]

Are you still using a stock starter? Keep in mind that bumping the CR can significantly increase the work that the starter has to do. If you jump-start your car does it make a difference? If jumping it helps, then I'd suspect that something is draining your battary. But if jumping really doesn't help much I'd question your starter.

[jwetering]

Hey guys - My mechanic is about two weeks away from finishing my 3.0. It will have 120/104 cams, MSD, and weber 40IDA carbs. I hope to drive this bad boy on the street and I'm kinda doubtful that it will run smooth out of the box. I'm particularily concerned that the carbs will need some serious setting up. There was mention of a weber tuning guide:

I will email you a Weber tuning guide I got off Pelican. You probably have I, but if not it is a great reference.

Could someone email me a copy of that guide???? please??

my email is jwetering@shaw.ca

Also - just how racy are those 120/104 cams? I was under the impression that they're similar to S-cams.

Thanks

[RoninLB]

Originally posted by jwetering


Could someone email me a copy of that guide???? please??

Hey J.. sounds like a fun car.. cool

I don't have the tuning book.. but not for nothing.. the webers could be a long time in setting up the way you want it.. and a quick blast to JW's shop will probably reduce your weeks in tuning to 1/2 a day.. I do have a troubleshooting 3 pages on webers, if you want them.. so do a Webers in subject on a direct e-mail.. Roninlb@optonline.net .............Ron

[ttweed]

There's a 5-page guide for Weber adjusting at this site and there's support information for PMOs at their website

TT

[RoninLB]

Originally posted by ttweed
There's a 5-page guide for Weber adjusting at this site and there's support information for PMOs at their website

TT

I did the oil analysis a few times.. cool to compare different engine conditions info.. if you can keep the same routine going for 3k mi

[RPMClassic]

Chris -
How does the info below apply to your condition....

". Reducing Injection Quantity

We have found that race engines often need varying levels of injection quantity. Coming out of a turn, too much injection quantity can actually cause bogging. PMO has different float bowl check valves to adjust the injection quantity up or down. Rob King at S-Car-Go has cut the injection quantity down to almost nothing with excellent results. The normally installed float bowl check valves have a .5 mm side hole for bleed back. The larger the bleed back hole the less injection quantity. The valves come in increments of .1 mm up to 1 mm. We have 1.5 mm valves for people who want to almost eliminate injection quantity but still start the engine."

[cstreit]

Could be factor. As soon as I get the car running again I'm going to try their suggestion of exhaust first. I was told that the bogging was most likely caused by my exhaust not allowing the induction to work properly...

SOmething to the effect that my exhaust manifolds are too large and not extracting well, and therefore incoming air was restricted. ...and that this was particularly the case with a cam as overlapping as mine...