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Discussion Starter #1
Ok, new to the site. But have found a ton of good information over the years here. My problem is this; car starts and ideals fine and even light cruise at a low high 13-14 afr. Tip into say going from 35 to 45 it jumps lean, like 15.5-16.2. The harder you roll into the throttle the higher and faster it goes lean. Stab the throttle and it goes way lean pegs the gauge and stays there, let out it comes right back down.

496
Electric fuel pump
Msd 6 plus
Distributor locked out at 36 degree have messed with it +&- 4 degrees
Head are reworked 781 castings bigger valves ported polished and milled a bit
10:1 compression
Mild hydraulic flat tapper cam
Carb Q series 950hp dp
Curently 82/90 jets worked up from 72/80 in 2 number increments
Power valve is currently a 5.0 had a 4.5 in it.
30cc diaphragms front rear pink cams with 33/35 nozzle.
11-12 vacuum at idle. I know my pv needs a little more tuning.

Jets sized seem to be getting rather big (4 over what it came from quick fuel with)

Any suggestions? Other than read the plugs, I’m not great at it hence the afr.
Keep jumping jets???
Has not blow black smoke at all yet. Would like to not get that far.
 

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Start by switching your power valve to a 6.5 or even a 7.5. What you are seeing is the lean transition between the primaries and secondaries.
 

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"Distributor locked out at 36 degree have messed with it +&- 4 degrees" Oh, yet another Top Fuel/Funny Car engine for the street. No hope to get the main jets sorted out to correct the WOT leanness. I'd also think the Idle Transfer Slots are also too far open, too, idle right up on the moon.
 

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Discussion Starter #4
Idle transfer slots .025 when I bolted the carb on and on had to give it less than an1/8 of a turn to idle at 950 rpm. If you think it’s a top fuel motor on the streets it is not and if you know so much about it enlighten me please. Thank you for the suggestion on the 6.5 pv I have one laying around I’ll try. I would think the main circuit take over at some point if it was only the primary-secondary transfer.
 

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Idle transfer slots .025 when I bolted the carb on and on had to give it less than an1/8 of a turn to idle at 950 rpm. If you think it’s a top fuel motor on the streets it is not and if you know so much about it enlighten me please. Thank you for the suggestion on the 6.5 pv I have one laying around I’ll try. I would think the main circuit take over at some point if it was only the primary-secondary transfer.



QCGbody== I suggest you search under the name of Dave Ray and prepare to be astounded, don't say I didn't warn you!!
 

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Discussion Starter #7
LeoP, thanks for the warning. Not sure what info/help I was suppose to pick up on from his comment.
 

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Why should I really care? I have fixed one heck of a lot more of these "locked out for the street" setups, it isn't funny. And, the next mess, "The DYNO tuning says to...(fill in the blank). But, you know more than anybody, that is why you are here telling us all about how great your Top Fuel/Funny Car set up engine for the street runs, aren't you.

Now, what compression ratio, what cam OVERALL duration (NOT .050), and what intake valve CLOSING degree, intake manifold, carb, SPARK PLUG GAPS, please?

BTW, I am an engine design engineer, worked for Holley in Pro-Stock carbs, Duntov in Chevy Skunk Works, and helped develop the large coil in cap HEI, still do that work for a major factory on their MotoGP World Championship bike engines, and used to race my very own AA/Fuel Altered drag car, big block Chevy, against all those Hemi's. Let me know when you wish to fire YOUR cannon at my position...again, sir, I'll be ready, you won't.


NOTE, since you seem to think it is lean on the top end, I will think you have already checked fuel pump delivery, pressure, and volume, fuel line(s), tank and tank venting (tank cap, or positive tank venting), and float levels, other factors in the fuel system. You have, haven't you?
 

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Why should I really care? I have fixed one heck of a lot more of these "locked out for the street" setups, it isn't funny. And, the next mess, "The DYNO tuning says to...(fill in the blank). But, you know more than anybody, that is why you are here telling us all about how great your Top Fuel/Funny Car set up engine for the street runs, aren't you.

Now, what compression ratio, what cam OVERALL duration (NOT .050), and what intake valve CLOSING degree, intake manifold, carb, SPARK PLUG GAPS, please?

BTW, I am an engine design engineer, worked for Holley in Pro-Stock carbs, Duntov in Chevy Skunk Works, and helped develop the large coil in cap HEI, still do that work for a major factory on their MotoGP World Championship bike engines, and used to race my very own AA/Fuel Altered drag car, big block Chevy, against all those Hemi's. Let me know when you wish to fire YOUR cannon at my position...again, sir, I'll be ready, you won't.


NOTE, since you seem to think it is lean on the top end, I will think you have already checked fuel pump delivery, pressure, and volume, fuel line(s), tank and tank venting (tank cap, or positive tank venting), and float levels, other factors in the fuel system. You have, haven't you?
There is no need to quote you on this but I just want to say thank you for being a part of this forum. You are valued and respected person here. You saw those folks take up for you. I myself may have given you some bs in the past and i'm sorry if I did. But I hope you can continue giving good advise here even if the folks that won't take it please remember I still do.
 

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Discussion Starter #11
Look Dave, you don’t have to care at all. Never asked you to, simply asked if the jet sizes were out of the question or I should look somewhere else. Also not sure what you have against my setup, iv gathered you don’t like a locked out distributor. Congrats on the coil in cap distributor and the extensive resume. I also never claimed to know it all, clearly I’m here asking for help and advice. My dad died in the middle of this build and just recently decided to take a stab at it alone now. I have a part number for the cam and the closest thing to cam card I can find. 10:1 compression same as stated in original post. .035 plug gap. Floats are 1/3 up the sight glass 6.5 psi fuel pressure, vented cell. -8 fuel line cell to carb. I’m sure I missed something you asked or commented about in your post. If you don’t care, don’t reply. That being said thanks to the folks who have offered help and info. Honestly I felt pretty good about joining this site and looking for some guidance so far all you have implied is that I’m wrong wrong wrong. So thank you Dave, you have helped so much! I can’t thank you enough!
 

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Please, remind me when another topic like this one comes up, so I can go fix someone else's setup to work correctly.

You just aren't worth attempting to help, you never needed help with it in the first place, did you.
 

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Discussion Starter #13
Clearly I do not have it figured out. That’s why I asked for help/recommendations in the fist place. I have only listed what I have done and what I know for sure. If something I have shared is so out of wake and off the spectrum let me know, if not and it’s close and on the right track let me know. Just looking for some guidance here is all. Yet another post from you with no suggestion or real information. I did not seek you out specifically. After 50plus year in the industry maybe tech team is where you don’t wanna be anymore. I never asked for dyno numbers or a full blown tune to throw in my car.

Sorry if I have wasted your precious time with a post and a question that you chose comment on but offer little to no valuable content. Thanks for all your help, hope your small body hei distributor catches on one of these days, might even slap one in my car. Have a good day Dave
 

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Thank you 77 cruiser I will check out the link you posted.

"...check fuel pump delivery, pressure, and volume, fuel line(s), tank and tank venting (tank cap, or positive tank venting), and float levels, other factors in the fuel system..."

"...Start by switching your power valve to a 6.5 or even a 7.5..."

Have you checked these items?
Are you sure your gauge is accurate?
Are you getting a good pump shot on both the primary and secondary side?
Have you verified your timing marks are accurate?
What are the specs on your cam?

No carb expert here but it sure does seem like something is inhibiting fuel flow through the jets. Even with a bad accelerator pump shot, the carb should recover once fuel starts flowing. While there is disagreement over locked out timing versus mechanical advanced timing, to me, at WOT with your timing "all in" it shouldn't matter a hill of beans how you have it set up. Good luck and please post back what you find out.

-Kevin
 

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Discussion Starter #17
Thank you Kevin, attached is what I have for a cam spec. I will recheck my fuel system up to the carb and I might try bumping the pressure a bit, -8 line from cell to the bowls. Squirter nozzles are 33 front 35 rear I do have a 37,42 and 45.
As for the gauge, it has maybe caused me some confusion with a bad o2 sensor originally. It’s an AEM and It should be all good now, really pretty easy trouble shoot. I will keep trying, thanks again.
 

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Did you make sure there is NO slack in the accelerator pump linkages? You can also try larger nozzles if you haven’t done so already.
 

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Discussion Starter #19
Yep I check pumper linkage every time I take the bowls off. Jumped jets up and it didn’t peg the gauge, so that’s good. Still on the leaner side but much closer. Also tried a 6.5 pv and it was a little rich during my short cruise. Went back to a 5.0 for the time being, I’ll grab a 5.5 and a 6.0 as the 5.0 is just slightly lean when cruising from say 35 up to 45.
 

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There are usually different size needle and seats, your fuel supply to the carb could be very good but if you can't get it through the needle and seat, the engine would go lean at WOT. However lesser throttle settings, less demand, the N & S should be adequate. If the carb goes lean as you lightly advance the throttle you may need some air bleed changes.
 
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