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Old 05-20-17, 07:28PM   #16
rexs73gto
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Keith, I know there hard to come by now but have you ever thought of using the OFFY duel quad intake that was designed for the use of 2 Q-Jets. I have seen a few on ebay in the recent past for in the price range of $ 300.00 +-. You may consider to run them in a progressive linkage so they work the way they were designed. I don't know of anyone that has ever used one but it would look different then all the rest. Now just a little input for you. I am at present running a 400 + .60 over with round port E-heads & round port exhaust manifolds. Now for the part I usually get hit on. I run a Crane Blueprint RA IV cam with 1.65 roller tip rockers, a Performer RPM intake, & right now with this engine I have the old TRW forged pistons with the 4 valve reliefs in them & stock rods that have been shot peened & buffed. The best part is the carb. I have tricked out myself an 800 cfm Q-jet. I use the Pertronix ign. with the flame thrower coil. My 73 GTO is a 4 spd. an M-22 with 3:73 rear gears. The engine dyno'ed at 487 hp. & 5300. It's not a rocket but I can shift this set up at 5800 all day long. I have tried a couple of times a bit higher 5900-6300, but it doesn't make any difference in the times. Shifting at 5800 or right around there depending on how good my tach reads I can turn a low of 12.91 & a high of 12.96. It has gone slower when i don't pay enough attention to the lights , but then I just kick myself. I only go to the track about 3-4 times a year, but if your looking for that real kick in the pants feeling this set up for me really does it. I don't know how fast your trying to go but this works for me. It not real good on the hwy. for top end but you can run 65-70 & not hurt it. Gas mileage is way down at that speed but I don't pay much attention to that as i don't take it out of town to much or farther then 40-50 miles away. I know a lot of guys turn their nose's up at the RA IV cam but I like it. I've used this cam in several engine over the years for myself & others. Let me know what you think. I know a lot has to do with my E-heads but........
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Old 05-20-17, 07:39PM   #17
tjs44
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Guys,I have been running 2-4s on the street since 1963!Nothing has been easier or better than a pair of 625 REAL AFBs.3012s are good,2984 are good and the best are the factory 421 SD dual AFBs.Even better is a pair of 750s with the factory SD AFBs but close second are the mopar max wedge carbs.Dont try to discover america,use what you will know works without a lot of testing.Holley can be made to run but there is SOooo much info out there on jetting and such what will be pretty much dead on.JMHO,Tom
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Old 05-08-18, 12:01AM   #18
keith
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Hey Tom .. you still there? Looks like my crank is done at Scat end of month .. will be sent to Paul for balance/cryo. Need to get my intake setup done and am needing basic linkage to start with. Want quality no bull hardware, was hoping to use all Offy stuff but looks like their available setups are for sideways carbs. ?? They had specific 4360 intake adaptors which I have but not a linkage specific to that setup. Do you have any recommendations for linkage since you are a Pontiac DQ guy? Have pictures on computer of my adaptors carbs and intake mounted but cant seem to get transferred here yet. I have water neck that works and my Old Mallory distributor looks like will fit. Am not using AFB's as I had 4360's available and just got a third, now I have 2 with exact same numbers .. both those are complete and work well. Will try intake on my enduro car once I have it set. 4360 dyno results are impressive in Holley Urich/Fisher book pg. 68 for a smaller cfm carb ... more bottom torque, higher mid peak than either 2GC or Q-jet although in between and top slightly less in some areas. X2 on a DQ should do ok .. there is no secondary air valve on smaller secondaries and they open sooner than Q-jet maybe they'll be bog-gone good
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Old 05-08-18, 07:29PM   #19
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Just noticed Edelbrock 600 Performer carb I have is a late Carter AFB basically. Does not fit my Offy intake without adaptor as my intake was for 2 small bolt pattern early Carter AFB's. Eddy will bolt to my 4360 adaptor but throttle plates don't match up. If I could find 2 small bolt pattern AFB's in good condition to rebuild I would be interested. Havent rebuilt an AFB so would be interesting anyways. Excuse to get a good AFB book. Really makes sense to start with the carbs manifold was designed for anyways.

? Anyone have laying around and like to sell?

?? Does the smaller bolt pattern relate to CFM capacity as in small 500cfm larger 630cfm ??
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Old 05-16-18, 03:43PM   #20
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Didn't find bolt pattern addressed in Carter book but found following information in case anyone interested ..

WCFB Carter CFM rated at 385 cfm .. doesn't look adequate for my needs, not sure AFB's made in small bolt pattern, Carter models have the following flow ratings,

AFB early (square-bore) 450 to 625 cfm
AFB late (square-bore) 400, 500, 625, 750 cfm
AVS (square-bore) ? same as AFB late?
Thermo-quad (spread-bore) ? up to 800cfm
Edelbrock Performer AFB (square-bore) 500,600,750,800
Edelbrock Thunder AVS (square bore) 500,650,800

Found 4G(4-jet) Rochester CFM's were 486,553 and 692 (online) .. couldn't verify small bolt pattern exists on these either, ebay seller said his 4-jets were not ??

Offenhauser tech maintains 4360's a good carb choice, will just start with those

Next question is .. ignition. Choices appear to be fix up my old Mallory 4lobe dual point, possibly retrofit with Pertronix electronic ignition, or get the small no-name distributor offering on ebay, since factory HEI is out the window with dual quad ... The Mallory does not have vacuum advance only centrifugal, not sure it is possible to change this or how overall advance is limited/regulated with this distributor. Or what the Pertronix upgrade does affecting this. Does anyone have numbers on it? I know I want street response and drivability with DQ and am thinking vacuum advance will be necessary.
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Old 05-16-18, 05:08PM   #21
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Don't worry about vacuum advance. You don't need it. Set you mechanical advance to be all in by 3000 RPM.
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Old 05-16-18, 06:48PM   #22
keith
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Would actually prefer to retrofit my old Mallory. Bought in Kailua HI in 1978 .. one of my first high perf purchases with Crane Gold rockers and Holley 780 I still have ... wish I had kept the Street Dominator manifold. I will probably do the Pertronix conversion, need to figure out whether I can couple that with a MSD 6T and High output coil ... might still have the Mallory coil, I preferred its squarish form to the Accel supercoil though I will still use Accel yellow jacket plugs once Paul freezes em for me. I don't know if any shops still have distributor machines that can monitor output at various rpm and allow for setup and adjustment. Would like to have a paper printout of distributor performance/advance to 8000rpm tho I will never turn that high. Good to not be close to edge with ignition I figure. Anybody in our circle that does the distributor jig? maybe Pertronix does this?? Will find out.
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