Inline dual four Holleys

[Jac Mac]

Backwards 'L' is channel that links to source for vacuum for dist vac advance unit.

[Michael C Henry]

No vacume advance in this rig, Mallory centrifigal advance, could they have just stuck a cap on the nipple.
Anybody have a brand of epoxy that isn't affected by gasoline to coat the notched area of a Nitrophil float?
Why would want to limit the spark advance? My engine idled faster with more advance at the same idle screw setting.

[StanJ]

Originally Posted by Michael C Henry

Anybody have a brand of epoxy that isn't affected by gasoline to coat the notched area of a Nitrophil float?

Miller-Stephenson #MS-907

[Michael C Henry]

We ( or I ) could use a nother forum for regular or irregular Carb tuning. I assembled the carbs with the parts Stan sent. As it turned out I started with Holley 1850 carbs. Primarys had #6.5 powervalves ,#65 jets and original fixed idle restrictions. Stan sent me two primary metering blocks prepaired for changable idle restrictions. He had installed .026" screw in idle restrictions and installed #5 powervalves. I transfered my #65 jets.

Vacume secondaries have QFT metering plates with changable jets and idle restricters and notched floats to clear the regular changeable secondary jets. The QFT secondary metering plates came with .038" idle restrictions. I changed to .032" restricters and left the #67 jets in. I just barely got it going and had to park the car for the upcoming home canning project. One circle of the neighborhood and the windsheild 's 2 inch crack at bottom went all the way to the top and started back down. I have yet to realy test and tune before I start the next goaround.

I'm expecting the engine throttle to be more crisp, but wonder with this cam shaft, intake manifold, and carb setup,I now have, It may never happen. The afore mentioned parts all seem to be parts intended for high RPM operation. I've had engines that when the throttle was cracked in neutral the engine was instantly at the RPM, not still climbing. But again those were single four barrels and dual plane intake manifolds. Now it seems to be acting like a built in form of traction control. I have a programable Mallory ignition and currently have the RPM limit set at 6000 RPM and without it I would probably get into real trouble. When driving the car accelereating in first and second gears, the engine is realy climbing quickly when the RPM limiter comes into play. I'm realy not into slipping the clutch and or burning tires( I would have to buy and replace all this myself.

[Jac Mac]

Micheal, I have my doubts that you will acheive that sort of throttle response with the setup as it is.
With your staged throttle linkage setup it tends to favour the #2/6 cyls as the front carb opens then around 1/3rd throttle the primaries of the rear carb above #4/8 cyls open and that rear accelerator pump toss's some extra fuel in at the rear of the manifold- meantime the front carb accelerator pump is just about all done. One end of the manifold has a carb that is now running on the main venturi's while the other is just getting off the idle circuit. Same thing will happen with the vac secondarys since the airflow thru the primaries triggers these- even though you have a balance pipe between the two vac cans the different airflow rates of the carbs will send the cans a false signal that doesnt relate to the actual airflow of each carb.

As Stan J has pointed out the 1850's are not really suited to this application and your 6000rpm limit is unlikely to utilise the 1200cfm you have available.

If it was mine I would ditch the progressive linkage for a 1 to 1 setup and use a cable throttle and a 'snail' cable drum on the carb so that the throttle opening was slow initially to give more 'feel' in the pedal etc for street use.

[Silverback51]

Originally Posted by Michael C Henry

We ( or I ) could use a nother forum for regular or irregular Carb tuning. I assembled the carbs with the parts Stan sent. As it turned out I started with Holley 1850 carbs. Primarys had #6.5 powervalves ,#65 jets and original fixed idle restrictions. Stan sent me two primary metering blocks prepaired for changable idle restrictions. He had installed .026" screw in idle restrictions and installed #5 powervalves. I transfered my #65 jets.

Vacume secondaries have QFT metering plates with changable jets and idle restricters and notched floats to clear the regular changeable secondary jets. The QFT secondary metering plates came with .038" idle restrictions. I changed to .032" restricters and left the #67 jets in. I just barely got it going and had to park the car for the upcoming home canning project. One circle of the neighborhood and the windsheild 's 2 inch crack at bottom went all the way to the top and started back down. I have yet to realy test and tune before I start the next goaround.

I'm expecting the engine throttle to be more crisp, but wonder with this cam shaft, intake manifold, and carb setup,I now have, It may never happen. The afore mentioned parts all seem to be parts intended for high RPM operation. I've had engines that when the throttle was cracked in neutral the engine was instantly at the RPM, not still climbing. But again those were single four barrels and dual plane intake manifolds. Now it seems to be acting like a built in form of traction control. I have a programable Mallory ignition and currently have the RPM limit set at 6000 RPM and without it I would probably get into real trouble. When driving the car accelereating in first and second gears, the engine is realy climbing quickly when the RPM limiter comes into play. I'm realy not into slipping the clutch and or burning tires( I would have to buy and replace all this myself.

I would suggest taking your car to Craig Blood at Blood Enterprises in Auburn. He worked wonders with my car, and I'm very happy with the results.


http://www.bloodenterprises.com/

[Michael C Henry]

Jac Mac
I'm unfamiliar with tha snail drum you mentioned . Do you have a picture, source or some more information?

[Jac Mac]

Originally Posted by Michael C Henry

Jac Mac
I'm unfamiliar with tha snail drum you mentioned . Do you have a picture, source or some more information?

Micheal , drawing attached should explain, they are common on the throttle body of many cars now, I know my 90 300zx has two of them, at idle throttle opening is slow due to the longer 'A' distance, while at around WOT the 'AA' is shorter & faster. Dotted line is throttle cable as it wraps around the 'drum'. In your case you would mount this drum on the center cross shaft and rearrange the links to each carb so that they open the primaries together.