[McQ]

Need an opinion on a tuning mistake.

Test ran 1 month ago. 2 carbs both hole shotted very well.

Shortly after truck made a funny idling noise kind like pre-detonation.

Checked a bunch of stuff, set the timing back a couple degrees and went on.

The truck stumbled out of the hole terrible the next day with the first carb athe race. 1000 aed 4150. Lost 2 and out.

just thought I'd bump my timing back up today. Turns out I'm running 24 advanced total!! My dial is really small on my light and I must have set it for 24 rather than 34.

So my question is. I have no place to go test right now. That carb has never stumbled before. Was the lack of advance possibly causing it to stumble?

I an thinking of running the same class in two days with no testing again?

I have never ran that little of advance and have no idea if it can effect your hole shots referencing stumbling.

Thanks

Jeffro

 

[fordman59]

Sure it can! I think ya got it figured out already.

 

[crittersf1]

OH YEAH!!!

 

[800+BBF]

YES SIR THAT WILL MAKE IT RUN LIKE CRAP! CAN YOU LOCK IT OUT? I KNOW YOU RUN A VACUUM CLASS BUT DO THE RULES SAY THE DISTUBITOR HAS TO BE VACUUM ADVANCED?

 

[rklessdriver]

It will make it lazy and if the load is high enough on the engine I figure it could feel like a stumble.... but more or less it will feel kinda like it's laying down. Really low timing will cause it spit back when throttle is applied... I don't think 24* is low enough to cause this kind of problem but in a heavy truck, pulling 4wd ect it might...

If it continues with the timing set up to 34* - I would look at your carb's pump shot. Espc the secondaries.
Will

 

[575ciBronco]

Yup these big blocks (especially iron heads) love a lot of timing! I'm sure you will be fine if you set it back up to 34.

Derrick

 

[fordpower]

24 is pretty lazy for ur setup Jeff. 34 would put it back in the ballpark although you may benefit from more timing. If you don't mind posting what kind of heads are you using???? Open or closed chambered heads?, it does make a differance. I was having alot of trouble getting my timing dead-on and did an EXTENSIVE search here on the website. After reviewing all the options I set it and went out and won my class next race and have never looked back.

 

[McQ]

Thanks guys for all the help. I understand the lazy-ness that retarded timing can bring. but.....

This may not be lazy. it is "pop......blugh....wait..wait. sputter..then it's 100%.

In drag racing time it's an eternity but in real time it's probably about a 3/4's to a WHOLE SECOND .

I'm scared to drive 2 hours to hear the death chant come out of the 4150.

Thanks again for all your help..You guys are awesome!!!

Also how many ponies on a 600 HP engine do you think 10 degrees and headers leaking bad enough to put your fingers in up be the head flange could rob!! I'm stoked about this weekend! I think I'm picking up a tenth or so!!





Jeffro