253 high idle

[Aussie V8]

I'm just talking from personal experience and others I know, they're a good carb, just not on a Holden v8, there's always a flat spot somewhere.

That means the person who has fitted and tuned it hasn't done it properly or there is some underlying problem they haven't taken into account.

The top end will all be new once the quad goes on, it'll be jetted down with new rods and overhauled before putting it on, and by that stage I'll have a timing light. But I'll keep playing and see if I can get mate with one to get that timing right..

On a street 253 you will never use the full potential of a Quadrajet. At 750-800 CFM your secondary air valves will barely open at full throttle/max revs.

 

[kingswood country]

I'm just talking from personal experience and others I know, they're a good carb, just not on a Holden v8, there's always a flat spot somewhere.

You sound serious haha, a holley knows the difference between a Fraud, Holden or Chev???

I'm just talking from personal experience and others I know, they're a good carb, just not on a Holden v8, there's always a flat spot somewhere.

That means the person who has fitted and tuned it hasn't done it properly or there is some underlying problem they haven't taken into account.

All engines were new or good cond, and each were set up by those who seem to know what they're doing, they all say steer clear of the Holley and stick with the quady.

The top end will all be new once the quad goes on, it'll be jetted down with new rods and overhauled before putting it on, and by that stage I'll have a timing light. But I'll keep playing and see if I can get mate with one to get that timing right..

On a street 253 you will never use the full potential of a Quadrajet. At 750-800 CFM your secondary air valves will barely open at full throttle/max revs.

All engines were new or good cond, and each were set up by those who seem to know what they're doing, they all say steer clear of the Holley and stick with the quady

Wether it uses it's full potential on a 253 or not, I'm yet to hear of anyone preferring a Holley over a quady.

Every single person I've spoken to have said the same, the quady runs alot better than the Holley, they've all said the 253 was a rocket with a quady, and have better fuel economy to boot, hence my decision to change.

 

[jpetrou]

No need to be nasty ari666, only trying to help. Idle specs are from Holden factory manuals.

 

[Aussie V8]

All engines were new or good cond, and each were set up by those who seem to know what they're doing, they all say steer clear of the Holley and stick with the quady

Wether it uses it's full potential on a 253 or not, I'm yet to hear of anyone preferring a Holley over a quady.

Every single person I've spoken to have said the same, the quady runs alot better than the Holley, they've all said the 253 was a rocket with a quady, and have better fuel economy to boot, hence my decision to change.

Nearly everything you say here, as in a few other posts, tells me who ever set it up doesn't know how to set it up. A four barrel Holley of about 450 CFM will get much better economy than a Quad of 750 CFM. The reason being the Quad is really only using 2 barrels most of the time so the primary barrels are running out of the econony zone most of the time. It is the same with your current, if I remember correctly, 2 barrel. The size and number of barrels is all wrong for an engine this size.

If you put a 450 Holley on you will have 2 primaries which you can set up for economy driving and have the 2 secondaries when you need power. Size, not only of the entire carb but also the different sections of the carb, does matter. Understanding this helps to make better informed choices.

I'm not a fan of Holleys and I love the Rochestor but I wont put Holley down when there is no good reason for it. By all means fit a Quad, and I dare say you may get better economy and that will be because your current setup is not tuned properly either, but dont expect a 750+ CFM 4 barrel carby that is way oversized to the engine to give you better economy than a 450 CFM 4 barrel that is properly setup. It just doesn't happen that way.

 

[SL/ENUT]

Perhaps the OP get a Quaddy off a Blue 253. Simple fix there.

 

[kingswood country]

I've already got the quady sitting here, just needs to be rebuilt. So that'll go on, just waiting on the funds to do it all.

 

[kingswood country]

Well it's getting worse, and I'm 4 weeks away from the quady install at least,

So I'm going to throw a new needle and seat and float in the Holley, would the .110 needle be the right one? With out pulling it apart to find out. And is there a certain float to get or is it generic?


Sent from your god, for you to worship and give money

 

[ari666]

Change your power valve too. A simple backfire through the carb could easily pop the diaphram and leak fuel.

Generally when the float goes, youll have fuel coming out of places it shouldnt, and if you dont plan on keeping the holley, its a bit if a waste of cash. Better investment is to get the blue gasket rebuild kit and strip it down. The kit will come with a new 6.5 power valve, so its close to what you need with 15" (half idle vac)


Dinner time, bbl

 

[kingswood country]

Thanks ari, that's possibly half the problem there, it's done it a couple of times.

I pulled the needle and seat out, gave it a clean, put it back in and adjusted the float level.

Needle and seat work fine, there's nothing on the mating surfaces and it works freely, so ill be getting the fuel bowl gasket and a new float tomorrow with any luck so I can look inside, get a new power valve too,


Sent from your god, for you to worship and give money

 

[Aussie V8]

I believe the power valve suggestion was made in post 23.