I have a hesitation like no other down low on my Camaro. It is a 468 10.25 to 1 with a roller cam with a 108 lobe separation. It does have a Victor JR with a tricked out 800 cfm Holley double pumper, with a stock HEI with hi output coil... I just added Flowmaster Super 40's 3 in with turndowns... Yeah that was a good idea... Now you can hear me a mile coming down the road instead of a 1/2 mile... anyway...i forgot to mention it has a 400 with a 3500 10 in converter and a 3.90 gear. It has a hesitation at an off idle, and then it cleans out. I am running a 6.5 powervalve. I changed it and I added 76 primaries and 84 rears... it had 72's and 78's... it didn't seem to run very good, and it could also be in my timing, not sure where to time it... I think I have it at 34 degrees total advance @ 3200 rpm or somewhere like that... It burns your eyes like none other... Any suggestions would be greatly appreciated.

Is it locked out at 34* if not whats your initial set at and is it a vacuum advance or mechanical..

What vacuum do you have at idle.

What does your plugs look like.

Is your floats set correctly.

Fuel pressure.

accelerator pump correctly.

What is your mixture screws set at.

I'm guessing its a lean hesitation and eyes are burning from running lean.

Your combo sounds like it's built to schit and get!.....As for the off idle stumble, you will probably need to use a larger discharge nozzle and maybe a larger pump cam!....Also, make sure that the acc. pump arm is adjusted to .015" @ WOT!


If your eyes are burning, it's running too rich, lean it out a bit!

I kind of thought it might be lean as well... It's not squirting well... I had the screws anywhere from 1 turn to 4 turns... it doesn't much affect it. The timing is total timing, I have no idea where initial is at... I have no advance hooked up... I haven't checked the vacuum yet, because my buddy has my vacuum gauge.

Plugs are light tan and has just a tinge of black... The floats are dead on to when you flip them upside down they do not sink at all, just stay perfectly level... that is the way I was taught, and it had never giving me fits before, but this is alot more motor than I have ever had...

My accelerator pump may be giving me fits too... not sure... I went to O'Reilly's to get some electronics today, and seen that they have a 50cc accelerator pump for around 18 bucks. I didn't purchase it, and I know mine is kind of a stock one that they throw in their strip kits.... My power valve is a 6.5 and the spring on the old one I took out seemed to be completely worn out... this one was much stiffer, but it wasn't new.... The specs on the cam are:

294/302
254/260 @ .050
108 lobe sep on a 104 int centerline

The heads are stock 781's with 2.19/1.88 valves and bowl blended.
.629/.629 lift w/ 1.7 rockers
set at .31/.33 cold... I believe the specs are .028/.030 hot

Should I take the squirters out and see what I have... do you know what I should have? Thanks.

My squirters or discharge nozzles say 37 in the front and 31 in the back... does this help at all?

Jeremy the first thing you need to do is nail down the timing befor you screw with the carb anymore.

Vacuum at idle is key as well.

Then proceed with the carb.

Check this link out for ignition and carb settings.
http://www.4secondsflat.com/Technical_Information_for_Ignition_and_Carburetion .html

Jeremy the first thing you need to do is nail down the timing befor you screw with the carb anymore.

Vacuum at idle is key as well.

Then proceed with the carb.

Check this link out for ignition and carb settings.
http://www.4secondsflat.com/Technical_Information_for_Ignition_and_Carburetion .html
is there a good way to time these when you don't use a vacuum advance. I don't know if I am doing this right, but I run it up to whatever rpm it quits advancing at and lock it in at 34 degrees. Is this a correct way to do this?

That 50cc acc. pump for around 18 bones you're talking about is just the diaphragm, you'd still need the deeper housing, arm and all the hardware but you really don't need this as you're already running a double pumper!....The stock discharge nozzle is most likely a .031" you could try increasing it to .037"

cool. thanks for the info bird!

is there a good way to time these when you don't use a vacuum advance. I don't know if I am doing this right, but I run it up to whatever rpm it quits advancing at and lock it in at 34 degrees. Is this a correct way to do this? This will be a safe and good starting point until you can tell how much that motor wants for initial and total plus cruise...

Thanks Skeeter... I am just wondering if I am doing this procedure correctly? Is that how you time?

Jeremy check out that link i posted above when you have time.. It helped me along with the Team Camaro gang.

cool. thanks for the info bird!


You're Welcome!:thumbsup:....And now it's time to party on!.....I got some nice ice cold brews ready and a nice big fat doobie!.....Later!:beers:

Thanks Skeeter... I am just wondering if I am doing this procedure correctly? Is that how you time? Yes for total timing it is correct.. But there is more info needed about how your distributor is set up, vacuum advance, mechanical advance, or lock out.

Thanks. I went to the website and I don't see anything about timing on there at least for GM HEI's...

You're Welcome!:thumbsup:....And now it's time to party on!.....I got some nice ice cold brews ready and a nice big fat doobie!.....Later!:beers: Ron how are thing growing :beers:...

Thanks. I went to the website and I don't see anything about timing on there at least for GM HEI's... Here you go http://www.4secondsflat.com/HEI.html

Well Skeeter... that may be where the problem lies. I have a vaccum advance, capped off, nothing else done... Just ran it up till it stopped advancing, locked it in at 34 degrees. Sounds too simple... Might have screwed it up..

Bad Bird... sounds good did you say big fat booby? lol

Ron how are thing growing :beers:...

Skipper....3 beautiful girls, 2 weeks into flowering, 3 weeks to go!:yes::hurray::beers:

Skipper....3 beautiful girls, 2 weeks into flowering, 3 weeks to go!:yes::hurray::beers: Cool triplets:beers::beers::beers:

Bad Bird... sounds good did you say big fat booby? lol My BBC i set the timing without the advance plugged in and set my total timing to 36* then my initial was at 22* with my custom distributor built from www.4secondsflat.com (http://www.4secondsflat.com) then i plugged in my vacuum advance which gives me 32* initial timing and 46* cruise and 36* WOT.

Well Skeeter... that may be where the problem lies. I have a vaccum advance, capped off, nothing else done... Just ran it up till it stopped advancing, locked it in at 34 degrees. Sounds too simple... Might have screwed it up.. Now plug in the vacuum advance to a ported vacuum source (constant vacuum at idle) and it will love you.. You will still need to adjust the carb after.

The only thing I can add is. AS soon as this matter is fixed you may need a neck brace. I 2x the party. Brian

Okay guys... Kind of confused here... I thought with a low vacuum signal... that you wouldn't want to run vacuum advance.... I don't know what the damn vacuum is yet... but I am guessing low...

Okay guys... Kind of confused here... I thought with a low vacuum signal... that you wouldn't want to run vacuum advance.... I don't know what the damn vacuum is yet... but I am guessing low... Good point if you have low vacuum then lock the distributor out at 34*.. But if you have 10" of vacuum in gear like i do with my 4-speed, then try the vacuum advance like i motioned above.

I purchased a new 800 DP for one of my 496 Camaros. Had the same hesitation. Changed both pump cams up'd them a size or perhaps two (can't remember) and she whistles dixie now.

The pump cams are color coded. If you want, I can go check the color for both the primaries and secondaries.

I believe that is where my timing is at.... I will check my vacuum tomorrow... I can't think it would be more than 10".

Straightline... any suggestions would be appreciated... This is the carb I ran on my mild 396, and it worked flawlessly... Of course 100 hp and 100 tq more, I have to do some adjustment. Just not sure where to start...

I appreciate everyone's comments... I am attending Good Guys next weekend and want to be in tip top shape!

You called it a tricked out 800 dp. Who tricked it out? I agree, get your timing set first. What heads? Some big blocks like 38-40 deg total. Too much pump shot will bog just like too little. Any smoke when you nail it?

Some guy tricked it out years ago.. It came off a 440 Mopar 600HP or so... roller cam, drag car that ran mid 6's in the 8th mile... The heads are stock 781's with 2.19/1.88 valves, bowl blended.

Smoke, just a touch... but not much when I nail it.

Jeremy,
Keep us posted and good luck. It will take some minor tweaking it sounds like your close.

I still have a stumble off idle when i release my clutch but i know its a lean stumble because i have an AFR meeter in the car. I have noticed that i could almost get reed of it by adjusting for more accelerator and 1/16 more fuel mixtures.

Jeremy,
Keep us posted and good luck. It will take some minor tweaking it sounds like your close.

I still have a stumble off idle when i release my clutch but i know its a lean stumble because i have an AFR meeter in the car. I have noticed that i could almost get reed of it by adjusting for more accelerator and 1/16 more fuel mixtures.
Skeeter. thanks for the encouragement. I do have a blown power valve. I was reading on Holley's website that if you have a carb built before 1992 that if you screw in the idle air adjustment screw all the way in... that the motor will die. I have tried it and it won't die. The power valve I threw in last night was one I had lying around, so it must have been bad. I will try a new one. I got my vacuum gauge, so I will let you know what I find out. Thanks again... for everyone's help..

With a loaner carb from my wife's car a 600 Edelbrock... everything is just fine. I wouldn't think that a smaller, stock carb would have performed that well, but it has never run that good... EVER... so my carb was way screwed up... I dinked with it all day, and it kept leaking. I never thought that running a stock 600 Edelbrock carb would make my car run so good.. It runs better than ever before... so much better, that it blew the belt off! lol So... I'm thinking possibly of running a 800 Edelbrock, and jetting and changing the metering rods. I have had good luck with them... but not sure if they are ideal for large roller camhafts... anyone else have any ideas on running one? Thanks.