very lazy off idle after head swap

ok some of know already i swapped my tpi to a carbed 350 stats i know on the engine are its 60 over and the deck has been cut so that when the piston is at tdc it is at the very top of the cylinder ithink they call it zero deck hight any how it also has a good sized cam but i dont know how big
and the heads are now a set of factory 305 ho heads 64cc fitted with 1.94/1.5 valves with lots of port work
http://www.automotiveforums.com/vbulletin/showthread.php?t=949675
this thread has a pretty good vid of it idleing ok now you know what i got here is my problem befor i swaped the heads from a dead stop the car would spin the tires till i got out of it now its very lazy just barely get a chirp (same tires btw) dosent seem right the car is definatly faster over all but this lazynes dosnt seem right and it also means i wasted money on slicks
any advice would be apreciated

what is your timing set at? what size power valve and accelerator pump nozzle is in the carb?

well that's a problem in its self i don't know what the timing is no marker i advanced it till it cranked hard hot and backed it off a hair
the carb is a q jet :frown: that worked great before the heads i got a holley but it needs rebuilt and i got layed of so it will have to wait

i think your problem lies within carb tuning and timing. square those 2 away first then see how it responds.

ok heres what i got the more i advance the timing the better the car gets but now the car cranks hard when hot

ok, well back your timing off a little bit like you had it before.

now let's think about this, you changed heads so now you have different flow characteristics and compression ratio. you need to tune your carb to compensate for that. whether it be jetting up or down, different power valve and/or accelerator pump nozzle.

do you know how to tune a carb by reading spark plugs?

yes but not a quadrajet Ive read up on it but it seems like a lot more work rater than just rebuilding and using my Holley that i know how to tune

then get that holley rebuilt and put on. i don't know how to tune a quadrajet either.

ok i did it the holley is on and sucks spent 8 hours and about 100 bucks changed jets accelerator pump nozzles and so on and so forth with the aid of holleys web site and the old fart (dad old school race guy) the car just falls on its face off idle some times it will die as soon as i touch the gas ive tryed up and down several numbers on the primarey nozzles different cams for the pump just about any thing and every thing:banghead: im going backto my QUADRAJET befor i pull my hair out and wast any more money

you got the bowls at the proper level? sounds like you're not getting enuff fuel. how much fuel pressure are you running?

For timing try this. Get a vacuum gauge and warm up the engine. With the car in park/neutral Check the vacuum reading. Start moving the distributor to get it as close to 20" HG at idle.
The carb is either over or under fueling the engine. (I hate Holleys BTW) If it is a vacuum secondary carb, make sure the butterfly over the secondaries isn't set too loose and causing the secondaries to open too fast.
Setting up a Q jet is pretty easy and once set it stays rock solid...The holley you have wouldn't be a 780 would it?

ok the floats are set fine and 6psi for fuel pressure

Morley (http://www.automotiveforums.com/vbulletin/member.php?u=205225) the holley is a 650 and i cant use a vac gauge to set timing with my cam the car makes little to no vac at idle and the q jet is set pretty good just dosent seem to perform well at hi rpms

you can still use a vac gauge to do the timing, just advance it until you get your highest vacuum reading. 6psi is too low, bump it up to 8psi. You could be draining the bowls faster than the pump can fill them. do you have the specs on the cam? you might also have too much cam for you application.

yeah the timing cant be set that way to big of a cam little to no vacuum at idle

and i figured out the holley it has a needle valve under the accelerator pump nozzle i shortened it and now it work perfectly could be jetted up a bit i think but it is way better than the q jet its still pulling after 5500 (my old shift point)
o and 6 psi for fuel pressure its a 660 vacuum secondaries

and on a side note it is still kinda lazy off idle

yeah the timing cant be set that way to big of a cam little to no vacuum at idle

and i figured out the holley it has a needle valve under the accelerator pump nozzle i shortened it and now it work perfectly could be jetted up a bit i think but it is way better than the q jet its still pulling after 5500 (my old shift point)
o and 6 psi for fuel pressure its a 660 vacuum secondaries

and on a side note it is still kinda lazy off idle

Try running the RPM's up to 1100-1500 and see what kind of vacuum you can get that way.

Try adding a higher octane fuel. A 64 CC chamber on a 350 yields compression over 10:1. This will "detonate". Retarding the timing is a "patch", not a "fix". Your timing being held "back" so far to avoid the "ping" is one of the main reasons it's "lazy". Detonation "rattling" the rings is another.

Get a bolt-on timing pointer from a performance parts outlet. Find "true" TDC (several methods work) and install the pointer. "Shooting in the dark" is NOT the way to hit the "target".

Jim

Try adding a higher octane fuel. A 64 CC chamber on a 350 yields compression over 10:1. This will "detonate". Retarding the timing is a "patch", not a "fix". Your timing being held "back" so far to avoid the "ping" is one of the main reasons it's "lazy". Detonation "rattling" the rings is another.

Get a bolt-on timing pointer from a performance parts outlet. Find "true" TDC (several methods work) and install the pointer. "Shooting in the dark" is NOT the way to hit the "target".

Jim


yeah 11:1 plus with zero deck and flat tops im running premium and haven't got the knocks yet but just hard crank when hot but you are absolutely right i will get the pointer and try 115 race gas :sly: 5.75 a gallon wont be able to use it a lot but i want to see what this car has ill be posting more videos soon probably wont get it to the track for a while tho
:shakehead
sorry no punctuation:twak:

aaaaaaaa :banghead::banghead::banghead::banghead::banghead: this carburator is driving me nuts :cya:went for a little cruse today (about 1.5 hours one way) i got in traffic at the end of the first half and the d$%^ thing kept wanting to die when i accelerated from idle :angryfire it was fine when i left the house i dont get it


just a little info the accelerator pump nozzle is a 35 power valve is blocked 74 jets and number one on the accelerator pump cam idle in gear is about 500 to 600 (big cam no converter)


other wise the thing performed awsome got a straight a way and punched it got up to 140 like nothing HELP befor i go insane :bloated:

what do you mean by the power valve is blocked? 74 jets sound kinda high. I could be wrong tho.

what do you mean by the power valve is blocked? 74 jets sound kinda high. I could be wrong tho.



it means what it says the power valve is blocked offf http://store.summitracing.com/partdetail.asp?autofilter=1&part=HLY-26-36&N=700+115&autoview=sku never have to replace it again and for the jets the car still seems to be a little lean at high speed/rpm so im not sure as of yet im gonna try number 2 on the accelerator pump cam (FYI its the red cam with 3 positions) i still dont understand how it was fine then an hour later it acts up

well i started the car this afternoon and it was fine i didn't change a thing WHAT THE HELL is the deal with this carb

that power valve plug is for racing use. I think you should install a functioning power valve. and if you're lean up top, then you need to jet up on the secondaries,

http://store.summitracing.com/partdetail.asp?autofilter=1&part=HLY-0-80457S&N=700+4294925239+400178+4294919007+115&autoview=sku


this is the carb i have i only payed 40$ for it there are no secondary jets

i know sucky carb but i dont have 400$ to spend on a carb

well if that's the case that's your problem. you cheaped out on the wrong thing. I would start watching craigslist, ebay, and other classified areas for a different carb.

ok my dad said i can just get a secondary metering block that takes jets and get a longer transfer tube in fact he has all that so im gonna try that and see what else i can screw with