Do I need to jet my Pict34-3 after upgrading to a 1641?

I just rebuilt my engine to replace some seals and decided to put in bigger pistons. I also went from Zoom Tubes to a Quiet Pack exhaust. Prior to the rebuild car was running great. No hesitation.

So now... Car idles great and revs fine. But.... Under a load from idle to about mid rpm it bogs or lacks power after about mid rpm it comes alive and runs great. I have the timing set to 28 degrees at 3000 rpms. The volume control screw is like 5 turns out it seems to run best here. I have 009 with the electronic ignition upgrade. There are no vacuum leaks. The carb was recently rebuilt. Should I rejet it and if so what size jets?

You changed displacement without rebuilding the bottom end?

60andslow wrote:You changed displacement without rebuilding the bottom end?

Long story but..... The engine was supposedly already rebuilt. The case needs to be replaced. We did not want to crack the case because it probably would not reseal again. its chewed up really bad on the bottom. But that has nothing to do with the said problem..

Sry i was just asking bc i have several known people who has done that and ended up slinging a rod bc the bottom end being worn in used to the old displacement.

60andslow wrote:Sry i was just asking bc i have several known people who has done that and ended up slinging a rod bc the bottom end being worn in used to the old displacement.

That would be my luck! This engine was mistake. Don't think the seller intentionally screwed me (at least I hope) but after opening it up it's not pretty! It look likes it had thrown a rod before and thru it thru the case. It was repaired but I found on the #1 cylinder the part the jug fits into has a small chunk busted out. I did not see the patch job when buying it it was under the tins. If it can manage to stay together until I can build a small block I will be happy. Unfortunately I paid 800 bucks and also gave the guy a 40hp longblock

But all that.... still doesn't answer the question do I need to jet it.

I wonder if timing might be part of the problem. When you set the timing, does it stop advancing at 3k? It should be revved until it stops advancing.

Hmmm. I will go check and give it a test drive. I was just looking around for a cheap SVDA Dist to try.

HeyRobi wrote:The volume control screw is like 5 turns out it seems to run best here.  

I'm not great with tuning carbs, but from what I've read, 5 full turns is way out of range.  Perhaps you have other carb issues that need to be addressed (though I'm not the person to tell you how to troubleshoot it, cause I don't know enough about them).

fluxcap wrote:

HeyRobi wrote:The volume control screw is like 5 turns out it seems to run best here.  

I'm not great with tuning carbs, but from what I've read, 5 full turns is way out of range.  Perhaps you have other carb issues that need to be addressed (though I'm not the person to tell you how to troubleshoot it, cause I don't know enough about them).

I agree I think it should between 2 and 3 that's why I'm thinking there is a jetting issue.

Check the plugs that tells the tale about jetting.

Greg wrote:I wonder if timing might be part of the problem. When you set the timing, does it stop advancing at 3k? It should be revved until it stops advancing.

Well that did not seem to change much, but after a quick run I turned the Volume Control another full turn and it actually ran better. I don't think its getting enough fuel.

wagtag wrote:Check the plugs that tells the tale about jetting.

I need to get some miles on it. They are perfect right now. But that was from my previous setup. I read you can look at the tailpipe and since it was new. I figured that would be good but it's still clean looking.

The 009 / 34 set up has an extensive history of not playing well together. Hesitation and falling flat on its face are common problems. Try that svda and report back.

X2. Anytime I had a 009 and 34 pict together, I always had that flat spot I could never get rid of.

X3 Flat spot , With the different pipes and displacement change hard to tell about jets without a plug read. Probably not but you feel a difference with the same carb distributor combination ... Might be time to recheck everything in the tune up ? The SVDA sure wouldn't hurt.

sounds like a 009 and 34/3 flat spot to me. svda could help but first id look down the carb and make sure it is squirting just as soon as the throttle arm moves. quite a few times ive seen carbs that had some slop in the accelerator pump linkage so they wouldn't squirt until the throttle moved a good bit.

OK, Update. I purchased a solex pict34 and rebuilt it. My problem is gone, well sorda. Now I'm having some other issues I can't adjust the idle at all using the bypass and the volume control I can screw all the way in and it doesn't really change much. I think both of those screws are allowing a vacuum leak. On the outside of them (the tubes that house the screws) its sweating. Would that indicate they are sucking in air. The car does run and runs much better. I just need to seal it up now or figure out whats causing the adjustments not to adjust! LOL

Sweating usually comes from lack of preheat, but if your adjustment screws arent making any changes, then sounds like some trash got in there. Blow your jets out again. Also, those rubber O rings in some of those kits are crap.

Well..... Things turned worse, carb was not running lean but too rich.  I changed the float check valve and several other parts, adjusted things took it off and on at least 10 times. Finally in desperation I took all the parts off the solex and put it in my old carb and wala it seems to run great! Unfortunately I can not say what the problem was, but it is fixed! I was thinking on the old carb the throttle assembly was leaking, I'm thinking now it may have just been the mounting gasket.

Glad you got it... When it goes wrong with a carb it can really test ones sanity.

wagtag wrote:Glad you got it... When it goes wrong with a carb it can really test ones sanity.

I do enjoy the hunt! Unfortunately the night before I did not sleep well trying to figure it all out in my head. My wife the next day reminded me it was supposed to be fun, lol. I was like "it is, dammit" lol.