Inliners International Forums General Discussion Hi Performance Open or 4-hole Center

I'm leaving stock class and headed for quicker and faster with my '65 Chev Nova wagon. By Spring, the particulars will be: .040 over 230 inliner; Schneider hydraulic cam .510 lift and I-224 and E-230 duration @ .050; lump-port head with 1.94 and 1.60 valves, mild porting, performance VJ, screw-in studs, about 11:1 compression, stiff springs and light retainers; Landon headers; 4:11 posi rear end with 24" tires; Powerglide with shift kit and 3,000 rpm stall converter. Car weighs 3,059 without the driver. Power band should be between 3000 and 6000 rpms. Here are my questions: I was given an Offy 4-barrel manifold and a Holley 390 cfm carb. The manifold doesn’t have an adapter and I have to buy one. Should the adapter be open center or 4-hole? Should I use a spacer? Should the spacer be open center or 4-hole? Or, will it even matter? The Offy manifold before the adapter is 4-hole. Thanks for your help.

1st: good luck, always like to see home-made projects go forward.
Light retainers, meaning titanium? or aluminum?
What cam LSA?
3,000 stall is whose rating? If it's based on a V8 with PG you'll have substantially less.
IMHO the manifold is small for that RPM range, which means an open spacer is probably faster. You can try 2 × 1" tall (if you have clearance). I'd remove the wall separating the secondary barrels, and blend the bottom of the bore cuts into the plenum interior, 3/8" radius or as big as you can.
Remember that your pump shot has to go up with a big spacer, possibly MJ also.
If octane is high, you want at least 15° initial spark lead (remainder in the curve, all in by 2,000 to be sure it's working when the converter flashes) before you do any idle adjustments to the carb. It's important that you not be above the idle circuit for staging, or the PV may open. You won't know the correct PV until your idle is sorted out, 2" below warm idle in gear is a good start (10" vacuum at idle, use a 8.0" PV). Remember, this determines only the timing, not how much fuel is added.
Because of the huge 1-2 RPM drop, you might find that the spark total that gives the best launch and 60 foot time is not as fast MPH as retarded by 2-3°. You can trick an electronic to retard in high gear with a solenoid on the shifter.

If your plain is keep the carb mounted 90deree on the offey you will need more then the stock plate because the throttle arm will hit the intake.If you make your own plate go at least 3/4-1in thick and you'll be fine.a 4 port will keep a stronger signal to the carb.The idea behind the 4port over the open was to make the carb was sitting lowwer on the intake which ment more low end , Where as the open was more designed for higher rpm. If your deside to go with the open plate by all means remove the 4port on the intake.

my2cents is remove the 4port anyway and blend it.

Panic: Some answers for you. The decision on type of retainer will be made by the person doing my headwork. I trust his advice, but not sure right now. The cam LSA for the Schneider 295H cam is 110 degrees. The stall speed on the converter is 3000 rpms for sure because it's now in the car and I can foot-brake it to 3000 before the tires break loose. Thanks and your advice is appreciated.

Twisted: Thanks for your comment. After reading, it raised another question for me. Your note says: "If your plan is to keep the carb mounted 90 degrees on the Offy..." I have an adapter now that places the carb bowls front to back. I did not plan to use it; rather plan was to place carb 90 degrees as you stated. What are the advantages and disadvantages of bowls front to back versus sideways on a car used primarily for drag racing?

The decision on type of retainer will be made by the person doing my headwork.
Titanium is $$$$$$$$$$$, aluminum has a bad rep due to chafing with long mileage. I use aluminum only on low pressure, high maintenance motors, and they're hard to find. Most people use quality steel replacements, no weight saving.
The stall speed on the converter is 3000 rpms for sure because it's now in the car and I can foot-brake it to 3000 before the tires break loose.
Not entirely reliable. If the motor is stock now, the stall will be less with the new cam, even with 11:1.
Stall is not where the tires lose traction, but when the brakes can't hold the car back or the engine speed doesn't go up. You may have more than 3,000 now.

I have ran the carbs both ways and have not had a issue. BUT if i was to make any change it would be to go with a center hung float. that makes for less float slush issue either holding the needle close or having it held open and flooding the motor. BUT with me leaveing the line NO less then 5000 rpm and pretty much pulling the front wheels off the ground I have not ran into either problem with running the carbs at 90degrees.Some also feel that running them 90degree has a better fuel distribution.
But again like i said In MY case I seen no difference either way.
So i would say mount it an test it and set it up which ever way works best for you.

Thanks. Given that I leave the line at about 2800 with a 4.11 gear, doesn't seem like I'll have any problems with float slosh.

i ran them line rpm with the 370s 456s and my 513s all with my muncie.

Consider having your manifold opened up and your carb spacer being one of the many 4 hole with swirl patterns for better distibution and atomization. I personally like the 1" HVH. Also consider a carburator isolator from Comp Cams. I believe they are no longer made but can be found. Great for 4 cylinders. The net says they have had some problems with them but I don't know personally of any.....IMO they work..................JD

Thanks for the advice!