Holley 470TA Tuning

Whatever came with the carb; never even paid attention, really. Other than changing jets and setting the choke idle, the carb has worked EXTREMELY well for me, so I didn't want to screw around with anything else.

 

first off; for drivability on the road you need to change the power valve. holley has it so it will only open at wot. still scratching head as to why. i would check your vacuum numbers at cruise and go four numbers below that for the power valve.

as for the secondary jets. if you look at what holley did with the 670 and 770 the jet spread is 21 and 25 respectively on them. that said why do the have an even spread on the 470. right now i'm at a 18 jet spread on mine and it may need more still, do not have it nailed down. 54-72

i've talked to holley about this carb and they really have been of no help.

as for the springs i've used the black through to short yellow. had no problems with secondary's opening with the black spring which is the stiffest .

i think it a good carb but holley needs to get there act together and have these things set up a little closer so one does not have to chase one tale quite so hard.


good luck

 

"I have just a touch of bog if you hit the throttle hard - always have had."


I do believe you'll have much better luck curing that type of bog with a change in the accelerator pump cam than anything else and possibly a discharge nozzle change.

i'm running a pink cam and a 25 nozzle.


good luck

 

Thanks, guys. Need to make another visit to the speed shop and order more parts.

EDIT - I'm reading the instructions and it indicates a .035 discharge nozzle and a 25 PV stock. You're saying you sized up to .037 on the nozzle? And how do the PV numbers correllate to vac? Are you saying I need to go from a 25 all the way down to the 7 or 9 range?

 

Thanks for the additional help, Warloch!

 

<Turns toward Falcon, CO and bows>

I was about to log on to say "Hey, Warloch, it didn't work." That would've been my 2nd mistake of the night:

I got some parts in today and went about changing the PV. Switched out to a 65 based on mentorship from Warloch and local conditions advice from speed shop. (Local shop actually recommended a 68, but couldn't find one, so settled on 65.) Tried to start the JEEP. Wouldn't start. Acted like flooding. Put pedal to floor and got it to run if I held my foot about 3/4. Putter putter putter with a billowing cloud of black smoke. Shut 'er down. Took the carb back apart. (I can just about do that blind folded now.) Went to swap back to stock PV when I noticed "One of these is not like the other." Oh, yeah, that little gasket. Probably important, eh? R) Put the gasket on the PV :smash: and started 'er up again. Blew soot for about 5 sec, then smoothed right out.

OMG that motor has come to life now. Night and day difference compared to when I first bolted on the Holley, and dare I say an improvement over the 2G. Maybe not so much on the street at low end, but definitely on the trail, and night and day at the top end; I can actually keep up with highway traffic!

The 470TA rocks! While it is not truly a "plug and play" operation like Holley advertises, it is not difficult, either. I am a very simple guy, and I'm here to tell you first hand if I can tune this carb, anybody can tune this carb. To me it is much easier than a 2G, and until now, I always thought 2G was as simple as it gets!

Also, much credit to wmunny; I am officially at 52 on the primaries and staying there.

Thanks, fellas!

 

Love the 4150 and 4160 Holleys. So easy to tune.

What are you flowing for CFM throught the 470TA? For some reason I have it in my head that 350CFM is about the max for a V6. Or are you running a small 8?:?

 

Ok, so what does the 225 flow at?

Don't have it here with me anymore, but used to have a formula that would take the CI and tell you how much max CFM through it would be, so you could choose the right size carb for the engine. At the time I was running a 425 big block Olds with a 2 bbl and wanted to go to a 4 bbl. A 450 to 570 was what was called for. This was from one of the local speed shops in Phoenix 10 or so years ago. Loper's, I think it was. :hurrican:

 

I did find this: http://www.4secondsflat.com/Carb_CFM_Calculator.html
This is the one I remember from before.