I am a turbo Buick guy so I am somewhat lost when it comes to carbs so I have a few questions about a car I recently bought. I bought a 67 Firebird with a 327 Chevy motor in it. The motor is a 65 275 horse 327 that has been rebuilt with a little better cam, Weiand dual plane intake and headers so I figure the motor is around 300 flywheel HP max. The car has a Holley 3310 750 vacuum secondary carb which I think is a little big. The car seems to load up at idle a little when in stop and go type of traffic and seems to be a little sluggish. Does that sound like the carb is oversized or maybe the carb just needs some work or adjustments. Any help would be greatly appreciated. Thanks
Tuning should take care of it; the 3310 is a pretty good all-around carb, even for your small block. Sure, you might get a tad more throttle response from a spreadbore or smaller squarebore, but you're not exactly off the deep end with that one. One thing in particular to check is the condition of the power valve. Don't discount the ignition advance curve, either. Might be worth looking into. Devon
That's great to hear and thanks for the quick response. I will check the power valve and make sure it is OK. Any other changes you would recommend for the carb? The car has a HEI distributor of unkown origins in it. I was thinking of buying one of the HEI tune up kits which has a high performance coil, module and wieghts and springs for a more aggressive advance--would that be advisable? Thanks again!
The best guide for mapping your advance curve is Larry's thread here: http://www.v8buick.com/showthread.php?t=63475 Just because it's a bit tailored for a big block Buick doesn't matter, the principles apply to your engine too. At the end of the day, the right jetting & advance curve for your application will depend on experimenting with drivability and track performance; it really depends on what you're trying to do with the car. In general I try to run the primary side of the carb lean, making up for it with the secondaries. The kicker is that you need to avoid detonation which can be influenced with both jetting & timing. Trying one change at a time is the best, but of course slowest, way to get there in the end. Devon
Check your intake vacuum and then see what power valve you have, it might be loading up from the power valve being wrong in the carb.
here are 3 pdfs from the corvette forum. these were done by lars who rebuilt my L79 dist. hope i did this right good luck jim
my opinion is that carb is way too big for that engine. i think it will be happier with a 600 or even a 500. you will have alot better throttle response and probly get better mpg too......
The 327 can handel that carb just fine.... most likely needs refreshing,,, if the carb is the problem.... most of the time the carb is not the problem, the problem is engine electrical needing a good tune up... set the basic timing, inspect the plugs, wires, dist cap and rotor, ck the vac advance diaphragm, and clean and lube the mechanical advance in the dist... Then.... start on the carb,,,, the jets most likely are just fine....make sure all the external adjustments are right .... then clean it internally, if needed and put in another kit....ending up with the external adjustment just like holley says to do them and it will run its best.....
there is a lot of things you can adjust on a 3310,the first thing you should do is put it back to stock,most likely someone changed set up from stock in the past or the diaphram is shot,start over check jet size,72 primary,76 secoundary,squirter size31,consider putting on quick change kit for vacume spring,what spring is in there now? just putting it back to stock should fix it if you have a carb problem
Yep, One of the best kept speed secrets is to set a carb up just like holley says to do....:Brow: Holley wants thier carbs to do well too... so they research the best ways to get milage and performance.... about the only way you can do better is by fine tuning for your individual application.:Brow:
