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 Post Posted: Wed Jan 30, 2008 7:27 am 
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I have been looking for 2  circuit blocks for my hp8896 where are they on ebay Ken???  Can you just order new ones??

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 Post Posted: Wed Jan 30, 2008 10:26 am 
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Yeah Barry, you can order those from Summit new if you want, or, check on a guy called "BPTcarbs" on fleabay.  Here is a link to his fleabay store.  
http://stores.ebay.com/Bolduc-Performance-Technologies

He will match up a pair of them for yas for about $25 each or probably $50 or less a pair.  I'd get some for an 850 up 4150 if they're available.  

The ones I used, which have the two center mainwell plugs recessed are good ones to use.  

Slowpoke bought two new alky 2 circuit Dominator blocks from Summit for $65 each plus shipping so that's probably near the going rate for new ones.  I looked last weekend and they (Summit) have a pretty good selection listed but they are special order.

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 Post Posted: Wed Jan 30, 2008 2:21 pm 
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Tuner, thanks for the links, I read through all the threads and whilst I've got a better understanding of why the problem exists, my brains a little fried from trying to follow the threads and I'm still no clearer where or what to drill.

If I'm honest I think it's all a bit beyond me at the moment. I don't have the testing opportunities nor the data logger to track my changes.  

Would the 2 circuit billet metering block be an off the shelf alternative of the converson and allow me to actually flow whatever jet I put in there ?.

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 Post Posted: Wed Jan 30, 2008 4:06 pm 
 
If you mean, “off the shelf” as in “plug and play, no.  You must measure and make the various passages and itty-bitty orifices the correct sizes.  You can use stock or billet blocks, whatever you can get easiest but you must drill the angle channels to .160”and be sure the booster pins are at least that size.  The t-slot jet must be added to control the low throttle opening mixture.  This ain’t hard, if you can drill and tap a hole you’re in clover.  If you re-read things a few times it may become clearer.  There’s lots fewer moves here than in a game of chess or poker.

No matter what, when you get the carb configured with the 2-circuit blocks and T-slot jet you will have to fine tune it to your engine by experimenting with different sizes of the little itty-bitty holes but at least it can be tuned to run to your satisfaction.

In ideal conditions, on the dyno or a cool day at the track, the 3-circuit block cannot be jetted rich enough to reduce engine power and usually can’t be jetted rich enough to reach maximum power.  In less than ideal conditions, such as a hot day when a little vapor can form in the fuel, the mixture is compromised in a chaotic and totally random manner and the same jetting can run much leaner than it will under ideal conditions.  If the flow path is large enough the vapor passes through un-noticed.

If you can’t jet it rich enough to slow it down, how do you know it’s rich enough to go as fast as it can?


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 Post Posted: Wed Jan 30, 2008 5:04 pm 
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Tuner wrote:
If you mean, “off the shelf” as in “plug and play, no.  You must measure and make the various passages and itty-bitty orifices the correct sizes.  You can use stock or billet blocks, whatever you can get easiest but you must drill the angle channels to .160”and be sure the booster pins are at least that size.  The t-slot jet must be added to control the low throttle opening mixture.  This ain’t hard, if you can drill and tap a hole you’re in clover.  If you re-read things a few times it may become clearer.  There’s lots fewer moves here than in a game of chess or poker.

No matter what, when you get the carb configured with the 2-circuit blocks and T-slot jet you will have to fine tune it to your engine by experimenting with different sizes of the little itty-bitty holes but at least it can be tuned to run to your satisfaction.

In ideal conditions, on the dyno or a cool day at the track, the 3-circuit block cannot be jetted rich enough to reduce engine power and usually can’t be jetted rich enough to reach maximum power.  In less than ideal conditions, such as a hot day when a little vapor can form in the fuel, the mixture is compromised in a chaotic and totally random manner and the same jetting can run much leaner than it will under ideal conditions.  If the flow path is large enough the vapor passes through un-noticed.

If you can’t jet it rich enough to slow it down, how do you know it’s rich enough to go as fast as it can?


Is this like deja vu all over again?  O:)   =;  =;


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 Post Posted: Wed Jan 30, 2008 6:17 pm 
 
I think so.


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 Post Posted: Thu Jan 31, 2008 7:39 am 
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sorry if this is old gorund, appreciate repeating and educating the next person who comes along with the same issue is tedious, but I guess it proves your theory if the issue with 3 circuit 4500's is constant and far reaching the world over !.

I'm prepared to do the conversion espcially since I got the narked reply from Holley ! but I found it hard to dicipher from the conversations / threads what the actual actions required to do the conversion were. I'm not as familiar with the different metering blocks as you guys but if it's a case of drilling a few holes and tapping out. I should be able to do it.  I have a friend with a lathe and mill who can assist me, but I need a full understanding to direct him.

So I guess the first step is getting 2 850 DP 2 circuit metering blocks. Do these hava Pt No or with the BLP ones suffice ?.  Do you have any photos annotated with where you drilled and to what size ?

Thanks for all your help so far.

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 Post Posted: Thu Jan 31, 2008 2:51 pm 
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Quote:
sorry if this is old gorund, appreciate repeating and educating the next person who comes along with the same issue is tedious, but I guess it proves your theory if the issue with 3 circuit 4500's is constant and far reaching the world over !.


No not old ground LOL!
I just went through this 2 months ago that's all. I'll chime in when I get a spare min.


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 Post Posted: Thu Jan 31, 2008 4:29 pm 
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I would also like to do this mod but like Phil kind of clueless of where these holes are and where to drill them O:) ..Ken have any pics =;

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 Post Posted: Thu Jan 31, 2008 5:11 pm 
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Like most of you, I was the same way.  Didn't know jack about where all those holes went nor what they actually did.  I found some pics that identified the holes and stuff, that and I did take my carb apart and look at EVERY hole in it to kinda familiarized myself with as much of it as I could.  I also have an old Mopar Direct Connection manual that details this stuff pretty good.

It ain't rocket science especially since I found a tuneup that was an excellent starting point.  Only problem I've seen with it is it's a little rich with the jets that were suggested.  When I finished it, I bolted it on the engine, started up and set the idle then floats, then idle again and that was it.  If you're running an electric pump then you can likely skip the first idle adjustment.  

I found that the carb community uses some abbreviations for different things. Here are a few:.

PV=power valve
MJ=main jet
PMJ=primary main jet
SMJ=secondary main jet
IJ=idle jet
TSJ=T slot jet, which probably isn't in your carb now, or is too large if it is
PVCR=power valve channel restrictor
MAB=main air bleed, sometimes referred to as high speed air bleed
IAB=idle air bleed, and btw, when you do this 2 circuit mod, the present intermediate air bleed becomes the idle air bleed and there will be NOTHING in the outboard holes.  The new IAB holes will likely need to be drilled and tapped to 10-32 or in Phil's case, something in metric close to that OD.

You will need to find some brass set screws in 10-32, 8-32 and 6-32.  These can be bought form McMaster Carr online and they're cheap.  Taps and drills can be bought from them also.  These will pretty much cover anything you need.  There are some small holes that will need to be gaged.  To do this you need either some small drills, ie, 60 to 80 number drills and or a welding torch tip cleaner and a way to measure them.  I've used that more than anything else.  You'll also need a pin vise to hold those small drills.

There will be one air bleed that opens up into the cross well that is called a "kill bleed" that pretty much has to be in the primary side block and the secondary doesn't matter one way or the other.  There will also lileky be several air bleed holes in the metering blocks and if the tuneup you use is like mine, all but one of those needs to be filled with lead.  Get some fishing line split shot to use to plug those along with and piece of coat hanger to tap it in with.

All these mods can be un-done.  Just make sure to map out all the holes and write that down before you start drilling so you can put'em back if you want.  

My Dominator is an old style L8896 with standard boosters so I don't know how much different the newer HP versions will be but I'd almost bet that everything in the idle circuit would be pretty much the same.

I got to run some more wire.  More later!

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 Post Posted: Mon Feb 04, 2008 6:26 am 
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pulled my carb at the weekend, to familarise myself with all the holes.

I think I see what the restriction is. I pulled the main jet and behind it theres a tube pointing downwards. Is this the restriction ?

In anticipation of doing the conversion, I worked on getting the throttle blades closed fully. The primaries close fully now, however I discovered that the actual soft progressive linkage that the carb came with, at the closed position on the primaries actually holds the secondaries open enough to expose the TS enough to the point you would normally set up for ie, TS appears square. I can close the blades fully with the linkage detached. Anybody ever come across this ?.  Should I go to 1-1 ratio ?

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 Post Posted: Mon Feb 04, 2008 8:48 am 
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Quote:
I think I see what the restriction is. I pulled the main jet and behind it theres a tube pointing downwards. Is this the restriction ?


Yep that's the idle tubes on a 3 circuit.


I bought the pin gauges off Ebay.
.061 thru .250

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.011 thru .060
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 Post Posted: Mon Feb 04, 2008 8:53 am 
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Here's a few on Ebay

http://search.ebay.com/search/search.dl ... +pin+gauge

If that link doesn't work search for "m1 plug pin gauge"

Here's a set of M-0 gauges but the picture shows M-3

http://cgi.ebay.com/M0-PLUG-PIN-GAGE-GA ... dZViewItem


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 Post Posted: Mon Feb 04, 2008 10:45 am 
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Scott, I take it the pin gauges are for measuring the small emulsion holes in which, the new block or old 3 circuit. ?

Still a little fuzzy on whats required in the conversion, would you be able to sum up what you actually did ?

Thanks
Phil

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 Post Posted: Mon Feb 04, 2008 10:47 am 
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PSweeney wrote:
pulled my carb at the weekend, to familarise myself with all the holes.

I think I see what the restriction is. I pulled the main jet and behind it theres a tube pointing downwards. Is this the restriction ?


Yup, that's it!

PSweeney wrote:
In anticipation of doing the conversion, I worked on getting the throttle blades closed fully. The primaries close fully now, however I discovered that the actual soft progressive linkage that the carb came with, at the closed position on the primaries actually holds the secondaries open enough to expose the TS enough to the point you would normally set up for ie, TS appears square. I can close the blades fully with the linkage detached. Anybody ever come across this ?.  Should I go to 1-1 ratio ?


Hummm, don't remember having that problem with mine?  If you go to the 1 to 1 linkage you will somewhat defeat the primary side PV as on 1 to 1 you're opening the secondaries at the same time and you can't run a power valve in the rear!  There has to be a way to make the secondarys close. Justmake sure that you put some blue locktite on that screw that holds the linkage on the shaft.  They have been known to come loose and really hork up stuff!

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