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Discussion Starter · #1 ·
I know the subject of hat clocking has been covered many times , but..
I see Morris recomending hats set at 6 o'clock. However I see their videos and most of them show the hat at 4 or 7. Why is this?
 

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As with almost everything it comes down to the combo. Certain carbs and intakes are more sensitive to hat clocking than others. I have seen over 1 full point difference in A/F from bank to bank before with the hat clocked at 45 degrees. When we switched to a carb using a different booster style on the same motor it was less than .3 different. This was on a 1000hp BBC with a D1-SC.

On another engine the A/F on each bank was similar but the #6 plug was showing significant heat over the others on that side. Switching the hat to straight ahead brought the cylinder more in line with the others on that bank. This was on a 1300HP SBC with an F1-R

Short version: As long as you watch the plugs and tune to the hottest cylinder you will be fine but there is potential power and reliability left on the table by making the airflow into the motor better.
 

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C&S recommends 6 or 12 with their carb
 

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Running 3" of spacer . The 1" spacer is welded to the hat and the other is a 2" Procharger spacer . I've always had pretty good fuel distribution .



 

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I talked to Roger(C&S) he told me to add some jet to the opposite side where the hat inlet is for my application.

whats your application ?

If the theory is that more air on the outside radius will cause a lean issue on that side , that will all depend on how the vent tubes are getting pressure .

If the hat is at 6:00 then the secondaries will probably be richer , not leaner because the secondary vent tube and boosters will get a better signal .
 

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My hat is at 4:30 so I added jet to the 6-8 cylinders. Mine is a 496 with a d1sc so at most I get 12 lbs of boost. I have not tuned for each cylinder. It is a street car with 8-1 compression and I stay under 6k and the timing under full boost is around 30. You could be right, I just did what Roger told me. my afrs are 12 and under and I have the snow kit come on starting at 10 lbs of boost so I hope I am safe.
 

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I would imagine someone like Steve has done the actual testing to find the best locations, and some like me just turn the hat that best fits under the hood, lol
as Ryan said, diff combos react to diff clockings
 

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After reading the above problems with carbs with hats, would I be correct to assume that in an EFI combo neither clocking nor spacers need to be considered.

Has anyone tested a hat with and without the divider?

How much actual boost difference in the manifold?
 

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EFI has distribution issues as well depending on the elbow, usually not as pronounced since it doesn't affect fuel flow like happens to a carb. We have tested with and without dividers on both carb hats and elbows. Dividers can make a difference when done right but they also become a restriction at higher power/flow levels. There is no free lunch when it comes to forcing air to make a sharp 90 degree turn.
 

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Ryan, couple of questions since we are on the subject of hats, power and flow.

At what point does the divider become an issue? XV told me that the divider is actually better up to 1,100 or 1,200 but your opinion would be nice. Thinking about adding a smidge more boost...I'm at '6:00' and all that, albeit with small boost tubes.

Also, Steve told me when I was dynoing at your shop that at 1k I was 'at the limit' for my single inlet bowls...if I go from say 1k to 1,100 HP, do I need to upgrade? Also, at what point does my '950' CSU (750 LOL) carb become untenable?

This thread has me thinking...which is usually expensive! But if more boost is going cause too many issues...I'll stay where I'm at.
 

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Single needle and seats are typically good for 1100-1300hp depending how efficiently your motor makes power. As long as Kevin has the metering blocks setup and his BRPV system in it then you can go up to 1500hp pretty easily with the addition of dual needle and seat bowls. You best bet is to call kevin though and see what he says though.

For the hat, speaking in generalities (which usually gets me in trouble) the regular EV hats with or without the divider do well up to the 1000-1200 area and then the Pro Series hat starts making better power.
 

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How much actual boost difference in the manifold?


If your talking about the difference between hat and manifold pressure , it can be big on a carb .

At 26psi in the manifold I have 34psi in the hat .

Looking to get some of that back when going to EFI .



How much pressure loss is there on a 4150 throttle body or Dominator with EFI ?

And is there any loss at all with an elbow ?
 
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