Holley carb questions

[IvaTiger]

The only modifications made to my tiger are an Edelbrock high rise manifold and a 4 barrel Holley carb.
The engine got a full rebuild to its original 260 and when it was put onto the engine break in stand we were having trouble with the secondaries working properly. The Holley did get a trick kit rebuild. Upon further investigation the carb is probably way too big being a 550 cfm but with a 57 jet instead of the original 62 jet.
Would this be a bad choice of a carb ? Considering my buddy who owned the car made this the carb choice probably 45000 miles ago The engine was full of carbon sludge , probably because it was running way too rich ?
I do have a Holley 465 cfm 4 barrel which I was thinking of rebuilding it would have also had a 57 jet but has a 62 jet in it. I live at 3000 feet
Should I switch to the 465 cfm carb and use the 57 or 62 jet ?
Or work with the 550 cfm ( don’t like that choice)
Model 4160
As I said freshly rebuilt 260 engine .030 oversized and a slightly modified RV cam
Both manual choke.
Spent all of its 56000 miles driving in New York
Thanks

 

[michael-king]

A 465 is a much better choice for the 260.. bear in mind that the 245hp full fat LAT 1 super induction motor was a 465 holley

 

[Austin Healer]

The only modifications made to my tiger are an Edelbrock high rise manifold and a 4 barrel Holley carb.
The engine got a full rebuild to its original 260 and when it was put onto the engine break in stand we were having trouble with the secondaries working properly. The Holley did get a trick kit rebuild. Upon further investigation the carb is probably way too big being a 550 cfm but with a 57 jet instead of the original 62 jet.
Would this be a bad choice of a carb ? Considering my buddy who owned the car made this the carb choice probably 45000 miles ago The engine was full of carbon sludge , probably because it was running way too rich ?
I do have a Holley 465 cfm 4 barrel which I was thinking of rebuilding it would have also had a 57 jet but has a 62 jet in it. I live at 3000 feet
Should I switch to the 465 cfm carb and use the 57 or 62 jet ?
Or work with the 550 cfm ( don’t like that choice)
Model 4160
As I said freshly rebuilt 260 engine .030 oversized and a slightly modified RV cam
Both manual choke.
Spent all of its 56000 miles driving in New York
Thanks

vacuum secondaries?? if they aren't working it's likely due to a torn rubber diaphragm...

 

[IvaTiger]

vacuum secondaries?? if they aren't working it's likely due to a torn rubber diaphragm...

I am not sure if it has vacuum secondaries and I am sure that we did not have a vacuum line hooked up to the thing on the side of the distributor

 

[Austin Healer]

The vacuum source is internal... It does not rely on a vacuum connection to the distributor. Look on the side of the carb. There will be a camber with 4 screws (the cover is horizontal and a metal casting about 2" roughly square) and a vertical rod connected to the secondary throttle shaft... if you have that, it's a vacuum secondary carb. Under the cap/cover is a spring and a diaphragm. The diaphragms are really thin and susceptible to tearing. The springs regulate how much vacuum is required to activate the secondaries. Holley sells a pack so you can tune this to suit your application.

I had the same issue with my carb... no secondary throttle shaft movement. sure enough, I removed the cover and the diaphragm was torn. when I replaced it, I put in a lighter spring. The springs are color coded. Unpainted is the base setting.

 

[IvaTiger]

The vacuum source is internal... It does not rely on a vacuum connection to the distributor. Look on the side of the carb. There will be a camber with 4 screws (the cover is horizontal and a metal casting about 2" roughly square) and a vertical rod connected to the secondary throttle shaft... if you have that, it's a vacuum secondary carb. Under the cap/cover is a spring and a diaphragm. The diaphragms are really thin and susceptible to tearing. The springs regulate how much vacuum is required to activate the secondaries. Holley sells a pack so you can tune this to suit your application.

I had the same issue with my carb... no secondary throttle shaft movement. sure enough, I removed the cover and the diaphragm was torn. when I replaced it, I put in a lighter spring. The springs are color coded. Unpainted is the base setting.

Okay. It does have the type of vacuum secondaries you mentioned and it was rebuilt with a new diaphragm when the rest of the carb was rebuilt. So maybe it requires a different spring like you mentioned.
What is the tube for that goes from the carb to the distributor purpose? It was not connected when the engine was being run in , I think it is to advance or retardant the spark and must use the vacuum from the carb ?
Thanks Sean

 

[Austin Healer]

The vac connection to the dizzy only deal with timing issues. Not the secondaries in the carbie... like I said, if the diaphragm is OK then you can deal with the springs to change the rate at which the secondaries engage. there are about 7 different choices you can make with the spring kit..

But, I'd double check the diaphragm... if it's damaged the secondaries will never engage

 

[spmdr]

My $.02

-There is minimal difference between those 2 carbs, flow wise. Ether, properly set up, should work well.

-A correctly functioning Vac secondary Holley carb will NOT allow the secondary
to open without a load on the engine.

DW

 

[IvaTiger]

Any thoughts or suggestions Holycat

 

[CLIFF_MK1]

Any thoughts or suggestions Holycat

Be sure and connect the vacumn line between the carb and the distributor as that contols the timing advance at slower speeds. https://www.catmbr.org/cat-forum/threads/carburetor-advice.3423/ is an excellent thread on this list which discusses both distributor/timing issues and carburetor issues . if the link doesn't work search carburetor advice to get to the link. Cliff

 

[HolyCat]

Any thoughts or suggestions Holycat

Tony,
I am probably not the best person to get carb suggestions from. I know my Tiger's carb runs very rich and I have not done anything about it. I feel my carb is oversized (500 cfm Holley on a 289 with a mild cam, headers, dual point dizzy. I have a smaller carb which I would like to fit, but have yet to do so. But it is not only the size of the carb, but as you know, the size of the jets and power valve.

There are a few articles about carburation in past Tiger Tales. As a member, you can check them out in the Tiger Tales Archives section of the CAT Member Area. Check out the July-August edition of 2018 and the November-December, 2019 edition.

 

[Max B]

I'm not a super carb guy, but, I don't think the 4150 had vacuum secondaries, it is a double pumper and has two metering valves and power valves if I recall correctly. The 4160 does have vacuum control secondaries, and only one power valve, metering block, and accelerator pump, plus only one fuel inlet. The Vacuum is better for a smooth transition and lower end power punch. The double pumper is more of a competition carb for higher speed power. I'm thinking the 416o/465 is what the LAT 1(?) kit came with. I think it to be a street/strip carb while the 4150/550/650/etc is more of a racing higher speed carb where all four barrels are used right off start. My 1 cents worth is you'll be happier with 4160 vacuum on 260 unless going all out. You need to tune accelerator pumps for smooth transition on secondary throttle opening or you possible may get a bog on secondary opening. I have both carbs, a LIST 1848-1 465 4160 just rebuilt and a LIST 4777 650 4150 just getting ready to rebuild.
Also, disconnected vacuum line could cause a bit of rich running because of low speed timing, but maybe vacuum leak could offset, don't know.
Like Austin Healer said the secondary diaphragm gets it vacuum source from the carb and check for leaking vacuum diaphragm. Sometimes, heavy handed screw driving can distort diaphragm surfaces causing leaks. Check for flatness on those as well as accelerator pump surfaces. Carburetors are not one place where if one firm turn is good, then two or three firm turns must be gooder.
As always, I'm old enough to finally realize I'm not always right, so happy and hopeful to be corrected if in error.

 

[at the beach]

The Tiger Tales article in the Nov/Dec 2019 issue is on point.
It reports on a 5,000 mile Tiger carb test of a 465 on a stock 289 involving altitudes from sea level to over 8,000 ft. using an air fuel meter accurate to a tenth. (not one's nose coupled with a "sensitive" fanny.)

It suggests that you may want to start your testing with 55 jets in a 465cfm Holley (which is a MUCH better choice to use on a 260, especially at your altitude).

(If you have criticisms of the TT article, feel free to address them to Holy Cat and not to the article's rather dogmatic and data driven author.)

Buck

 

[Austin Healer]

I'm not a super carb guy, but, I don't think the 4150 had vacuum secondaries, it is a double pumper and has two metering valves and power valves if I recall correctly. The 4160 does have vacuum control secondaries, and only one power valve, metering block, and accelerator pump, plus only one fuel inlet. The Vacuum is better for a smooth transition and lower end power punch. The double pumper is more of a competition carb for higher speed power. I'm thinking the 416o/465 is what the LAT 1(?) kit came with. I think it to be a street/strip carb while the 4150/550/650/etc is more of a racing higher speed carb where all four barrels are used right off start. My 1 cents worth is you'll be happier with 4160 vacuum on 260 unless going all out. You need to tune accelerator pumps for smooth transition on secondary throttle opening or you possible may get a bog on secondary opening. I have both carbs, a LIST 1848-1 465 4160 just rebuilt and a LIST 4777 650 4150 just getting ready to rebuild.
Also, disconnected vacuum line could cause a bit of rich running because of low speed timing, but maybe vacuum leak could offset, don't know.
Like Austin Healer said the secondary diaphragm gets it vacuum source from the carb and check for leaking vacuum diaphragm. Sometimes, heavy handed screw driving can distort diaphragm surfaces causing leaks. Check for flatness on those as well as accelerator pump surfaces. Carburetors are not one place where if one firm turn is good, then two or three firm turns must be gooder.
As always, I'm old enough to finally realize I'm not always right, so happy and hopeful to be corrected if in error.

another cause of a "bog" when the vacuum secondaries are opened can be caused by too light a spring for the vacuum diaphragm... Holley sells a kit with several different springs part # 20-13

the springs are color coded. originally the spring installed in my carb was plain (not colored) and the throttle opening spec. was 2240 rpm and would not fully open as full open spec was over 8000 RPM. I opted for a lighter spring (purple) which allows opening to start at 1900 rpm. Holley advises if there is a bog at secondary opening to use one step heavier diaphragm spring. Instantaneous bogging from off idle is caused usually caused by the accel pump.

I'm sure I'm running a little rich as well as I have a 600CFM carb on my 302 (289 hipo heads) but my plugs look normal and the car runs fine. I do not need to ever use the choke! Just remember, the leaner the mixture, the hotter the engine is going to run.