Holley metering block questions

[Mr. Fink]

Hello,

New to the forum, but have been lurking for sometime reading up on the carb posts. I have a few metering block questions that I hope someone can help me with. I have came across what appears to be a Holley 1000 HP carb. I wanted to use the carb on the street in a milder 489 BBC—10:1, 781 heads with big valves, roller 240 @.050.

I have purchased a set of cast metering blocks that have been modified for adjustable bleeds. I had planned on taking a pin gauge and set the block up as the factory blocks were as a base/start. Now to the questions I have. The blocks and idle tube (that goes into well) came separate. How do I install the tube? Press in until flush, or will it bottom out? Does it take any type of sealer? Which way should the top hole in the tube face or does that matter? The long tube drop tube should not have any holes in it correct?

I may not have used the correct terms in describing what I have. I am familiar with rebuilding and basic tuning, but this will be my first time going as in depth in carb with this carb.

Any help or guidance is appreciated.

[PRH]

The only metering blocks Ive seen with press in idle tubes are for 3 circuit carbs...... which a normal Holley HP1000 is not.

[Mr. Fink]

I’m sorry, I should have mentioned the blocks have been converted from 3 circuit to 2 circuit. They are BLP blocks. So not just in someone’s garage.

[PRH]

On the 3 circuit carbs that I have R&R’d the idle tubes on, I just use a tiny amount of red loctite around the top lip of “spool” when reinstalling.

Frankly, it seems like it would have just been easier to buy some tunable billet 2 circuit blocks.

[Alaskaracer]

As stated, you need two circuit blocks, and appear to have three circuit blocks. The feed tube that fits into the main well is a restriction on flow and can create issues. Many of the aftermarket three circuit carbs now use a divorced idle feed circuit that eliminates that problem. Save your frustration and get the proper ones for that carb....

[Walter R. Malik]

As stated, you need two circuit blocks, and appear to have three circuit blocks. The feed tube that fits into the main well is a restriction on flow and can create issues. Many of the aftermarket three circuit carbs now use a divorced idle feed circuit that eliminates that problem. Save your frustration and get the proper ones for that carb....

SOME 2 circuit blocks have idle tube restrictions pressed into the IDLE WELL but, certainly not the 1,000 cfm carb.

[BillK]

Personally I would try the carb the way it is before you start screwing with things. You might be surprised at how well it runs the way it is.

[i82much]

Personally I would try the carb the way it is before you start screwing with things. You might be surprised at how well it runs the way it is.

wait ... are you saying that you shouldn’t start fixing stuff before you know that it doesn’t work? that’s crazy talk! dogs and cats, living together ... MASS HYSTERIA!!!!

[BOOT]

BLP actually has a deal on 2-circuit blocks atm if you don't mind clear anodized. Bought some myself and made a quick vid for my subs https://youtu.be/z-NswrrlCBM

[Mr. Fink]

Thanks for the suggestions so far. Would the blocks I have be any different than the BLP billet blocks? BLP did the conversion from 3 circuit to 2 circuit.

[Mr. Fink]

Personally I would try the carb the way it is before you start screwing with things. You might be surprised at how well it runs the way it is.

wait ... are you saying that you shouldn’t start fixing stuff before you know that it doesn’t work? that’s crazy talk! dogs and cats, living together ... MASS HYSTERIA!!!!

I have been known to complicate things before….

[WolfWengler]

If they are BLP blocks, why would you not address your questions to BLP?
Me? I use 2 circuit BLP blocks

[Mr. Fink]

I will call back on Monday. I was just curious and to have something to do over the weekend.

[Mr. Fink]

Just a follow up, closure to my questions in case someone else in the future has these questions. I followed up with BLP this morning. The Holley cast blocks they sell and convert from 3 circuit to 2 circuit are fine for my HP carb. The idle tube is pressed in with the hole at the top of the tube pointing towards the idle restriction in the block. The idle tube has no other holes, except at the top as mentioned.

Ansley

[1980RS]

I had a 1000hp and the metering blocks were not much different than my 4781 850 Holley's were. I do have one 850 that was tricked out by Fuel Curve Engineering (anyone remember them?) from way back in the late 70's and the metering blocks it has have 3 circuits and a intermediate tube just above the throttle blades and does it work good, so good in fact that it hung right with the 1000hp on the dyno and works super good at the track. Have not used it in a while but I think I will give it another try.