At which point would anyone think it would be ok to jump up to 600 cfm for a 292. My motor is a mild build, re-done head, headers. I have a Offy 4 barrel intake arriving Monday and have been carb shopping. So far I have not seen a single 500 Edelbrock, plenty of 1406's though. Could have bought several today in Conroe. Should I just stop being cheap and buy a new one, or could the 600 work?
The 600 will work, it just won't be ideal for your situation. I'd be on the lookout for a 390 or 450 Holley for that motor myself, but I don't need to open up the Holley vs. Edelbrock debate. No matter what either the 500 or 600 is too much cfm for that motor in a mild street application. Buy the adjustment kit for that carb, you will need it. Devin
There was thread very recently that contained posts on how to calculate the CFM that would be useful for any given engine. As you would no doubt expect, it had to do with engine displacement and peak RPM. But it also took into consideration the volumetric efficiency (flow capacity) of the intake system and a few other variables. The upshot was, most rodders over carburet their engines. Your question is of interest to me as I too just bought a 4 barrel intake for a 292 inline. I think for street use, 4 pedals is pretty much on the mark. Ray
Thanks for the replies. Mr. Langdon over at Stovebolt recommended 500 cfm range Holley 390 or Edelbrock. I think I might save myself allot of headache just buying a 1404 Edelbrock. Holley's and I don't get along, just personal preference. Based on the CFM calculators I will be in my range. Holley's calculator told me to run anything from a 400 to 675 carb, lol. The other ones online all put me high 400 to low 500.
My 292 Y-block liked the 500 Holley vacuum secondary carb a lot. Prior to that a 600 double pumper drowned the poor thing when mashed upon. This engine had stock 57 iron intake and 57 distributor w/Protronix breakerless kit, that made an amazing difference and I do know how to set points.
There is a listing for new Edelbrock 500 cfms in the classifieds at the moment for $250 each. I bought one to swap out the 1406 on my 305 Chevy as it would flood too easily. I was going to run it up this weekend but battery was dead.
i'm using a 600 on my 292, but it has a ported head, mild cam, Clifford manifold and cast iron headers. it runs out real well and i'm happy with it.
I looked at the classifieds and only found one 500, looked kinda rough. Just ordered a new one with free air cleaner from Summit. Also ordered the bell crank kit for the throttle linkage. So now to play with it all this weekend and see how to hook up the throttle, lol, that will be fun. My Offy intake showed up today. Cannot wait to see the difference between all this and the crap Monojet. Thank you all again for the input. I spent a fair amount of time researching, I think it will all work out. Feel free to share any throttle hook up pics.
Rochester 4GC off a similar sized V8, like a 283 Chev, 303 olds, etc... a good rebuilder at the swapmeet runs around $20. With or without auto choke. Probably not much more to rebuild it yourself....
Mine was a 250 cu/in but had full cam and milled heads. It was also bored 60 over. I went through 4 different carbs be for I got a holley 390 with electric chock. It ran so much better with the holley. I had always heard bad things about Holleys but the 390 sure woke up my 250.
Not a 292 but a modified 261 ,different but sorta the same.I tried many 4 barrel carbs about 10 years ago.The Rochester 4G worked ok but was lean off idle requiring enlarging the idle restriction jets.Edelbrock 500 worked ok but had a bog when the secondaries opened.No amount of jetting changes or fiddling with the secondary air valve really cleared it up completely.The Holley 390 ran good with a change to #55 main primary main jets.For shits I bolted on a 600 Holley taken off a 350 Chevy,it ran as good as the 390. The secondaries on the 600 Holley never opened more than a 1/4 of the way with the stock secondary vacuum spring at full throttle on the road..A light spring made it run worse.All these tests were done on a Clifford water heated intake. A 292 might have different needs than the older 261.My opinion is to buy a Holley vacuum secondary 600 cfm,they are dirt cheap used and easy to rebuild.Tie wire the secondaries so they wont open. Then do test on just the primaries.When satisfied,untie the secondaries and see what happens.
Trucked up I ran a 390 holley and a 600 as well with the same basic results on my 292. Someone is not going to agree with this but I think that a tricked out 350 cfm holly 2 bbl would be a good choice as well. It would require an adapter plate for the 4 bbl intake. get one of the circle track units. New they only run about 290 bucks.
I'm running a 390 cfm on my 292. From what I've read, the 600 will be too much carb for a mild engine.
IMO, you bought too much carb. The 390 would have been ideal. 292 CI X max rpm 5000 / 3456 x .85VE = 359, so round up to 390. People buy too big carbs all the time because, as we all keep getting told (incorrectly), "bigger is better" (that's what she said). I just generalized VE above.
Not sure if this will help or not (b/c I used a Holley). For more pics/info click here One thing that I had to do with the Offy bellcrank kit was shorten the cable sheath and buy a new cable. The cable that came with it didn't slide through the sheath well, even with wd40 sprayed onto it. If you have the same problem, bring the kit to a bicycle shop and they should be able to hook you up for a couple of bucks.
That's a really nice Nova and thank you for the pics. That helps. I have the bell crank kit on the way, although they have it arriving Monday and the carb will be here Friday. I'm also thinking of going to the bone yard and pulling a factory gas pedal with cable set up and putting it in and either making my own brackets at the carb end or just getting one from the parts store as they are dime a dozen for Chevy set ups.
After some head scratching I am thinking of hooking the cable to the pivot arm where the linkage rod goes using a barrel fastener. Then I would hook up to the carb like the last 2 pics showing a cable on the carb.
I have the 500 Edelbrock and Offy bolted on and love it. Wow it's like a different motor. The 4 bbl really made her come to life. Thanks to all for the help. I did do some tweaking to my brackets for the cable after the pics were taken. We drove it up to the Hoedown and it did great.
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