Longtime lurker here, but first post. I usually find what I need without posting anything! I've been running a 283 in a 64 Chevy Bel Air that I've owned for 20 years. As far as I can tell it is original to the car. It ran pretty good with a Rochester 2GC since I rebuilt the motor and got it on the road again about 5 years ago. The only complaint was the idle not being very smooth, it would surge up and down in rpm. Not too noticeable, just enough to be annoying. It would do it sometimes at cruise too. I never did anything about it because I wanted to replace the carb anyway. Now I have replaced the intake with a 4 barrel cast iron from a 67 corvette and a Holley 4160. It idles better than ever, but falls flat on its face once I give it gas. It will rev up just fine in park, but in drive, just won't go. Stock timing spec is 4 degrees BTDC, but it doesn't want to idle there. I've got it at 15 right now. Vac advance is connected to ported. Air/Fuel screws are 2.5 turns out set by vacuum gauge. Idle is around 800 in park and 550-600 in D. It will move forward in D at idle, but once I hit the throttle, it dies. It seems like the floats are set right and the accelerator pump is squirting. Ignition system is all pretty new, worked well before the 4 barrel. Has points ignition and resistor wire was replaced by ballast resistor. Mechanical fuel pump. Powerglide trans. Not sure where to go from here. Any tips?
Maybe reinstall the 2 barrel Rochester with a rebuild kit? Some folks buy carburetors like the proverbial hillbilly buys shoes "the salesman said my size was 9, but 10's felt so good, I bought 11's" Jon.
I had the same problem with my ‘63. Found a vacuum leak at carb base gasket. Rebuilt the carb and runs fine. As for the Holley I would try a power valve with a softer spring. Sent from my iPhone using H.A.M.B.
The factory corvette setup uses 3 gaskets, one of which is metal. Consensus on the internet is that most run with only the bottom fiber and metal gasket, no top gasket. I'm running only the 2. How is your's setup? Im pulling about 20" vacuum. The carb has a 7.5 power valve, I think that is as high a number as it gets. By softer, do you mean a lower number designed for less vacuum?
Going back to what worked before would definitely solve the problem. Do you think 600cfm is too much for a 283? Part of my motivation was to put a 700r4 behind this and it's much easier to source the TV cable bracketry for a Holley than a 2 barrel Rochester. The only source I found cost more for the bracket than the whole carb/intake setup. Then of course I would also like to make a little more power than stock.
I think you have 2 problems. First you need to get your ignition sorted out before moving to the carb. When you advanced the idle timing you added 11 degrees to the initial timing. You also added 11 degrees to the total advance. Initial advance + mechanical advance should be about 34-36 degrees. Pretty much the golden rule for SBC ignition setup is 14-16 initial + 18-20 mechanical = 34-36 degrees total advance + 16-18 manifold vacuum advance = 48-52. Mechanical advance all in by about 3000 rpm. Then you can mess with the carb. My guess is the squirter needs opened up a little, but it could be a lot of things.
It was used, though didn't look it. Cleaned out all passages, and went through and replace all gaskets without digging into the main body.
Advance at idle with the vacuum advance disconnected is set at 15 BTDC. Is this not initial advance? Distributor mechanical advance is stock, and I measured the vacuum can giving 20 at the highest point. I will try and measure the all in value. Unless I am missing something here, I think the ignition system is set.
OK. So you have 15 initial + the mechanical advance. How much is the mechanical advance? It needs to be 19-21 to end up with 34-36 total. If it is then that's fine, but with your stock setting of 4 degrees, if that is the stock distributor, I would bet that it has a lot more mechanical advance than that. I always set the total timing, 34-36, (vac plugged) with the rpms above the all in. Then pretty much let the initial advance be what it is. Then add manifold vacuum advance for cooler idling and better mileage.
Here's my little plus++++..... Is the balancer/dampner original? It could have slipped (they do that when they get old) Make you a TDC finder/gauge and find TRUE TDC and mark it on your balancer( then glue on a timing tape...cheap). I like to use the lighter advance springs that come in a kit. Raise your revs (with the vacuum advance PLUGGED) to about 2500 RPM. Give the distrib. a twist until your timing reads 36*(as seen on the timing tape). bolt it down....Timing is set. If the problem still persists now you know its a carb issue (for sure). I'll bet its a vacuum leak around the base of carb! 6sally6
If the bracket is the prime mover for the 4-barrel, maybe you could find a 390 CFM Holley. On an other wise stock 283 that originally came with a two-barrel, I would not be surprised if your 0-60 times with the 600 Holley were SLOWER than with the original two-barrel, especially with an automatic. If you are looking for a bit more power than stock, returning to the two-barrel, and replacing the automatic with a three or four speed manual would give more rear wheel power than any carb on the automatic. Jon
Did the intake gasket fit the port opening in the heads,Mine did not it had a vacuum leak down inside the valley. My 327 intake ports were larger than the 283.
I only used a fiber gasket. I really don’t know about the numbers on the power valves, a buddy had a handful on the shelf and I took the one with the softest spring. Sent from my iPhone using H.A.M.B.
Standard 2v 283's have 12° mechanical advance in the distributor [which = 24° at the crank] The initial timing should be 8° at the crank to get 32° total advance. He is better off setting the advance curve to 14° in the distributor , than adding 4° initial timing [to get 36° total] He only needs 36° total at high RPM with little to no vacuum Personally, I think he should check there is no distributor issues and vacuum leaks and set it to factory specs And put the Rochester 2GC back on. 283's are quite crisp with a small carbs[a 600 Holley is overkill]
I appreciate all the input on timing. I double triple checked it and figure something would be up with the carb. I took it apart to check the power valve, went through and cleaned all the ports, and found the idle transfer ports had some plastic media in them, both sides. Put it back on, fired right, up and ran better than ever. I do need some more fine tuning, but problem solved.
ok first make sure the mechanical advance is operating properly. i have seen guys actually reverse the advance weights when they reinstall them. so make sure they move in the right direction. with the holley carb, the accelerator pump may need tuning here. some cars need a heavy, but short, shot of fuel to get going. others need less fuel over a longer period of time. the pump shooter may be too large for your stock engine. each of these shooters are numbered with the larger numbers giving more fuel initially. find your size, and try a shooter that is about three sizes smaller than what you have now. you should be able to pick them up at your local parts store, or you can get a tuning kit from holley here; https://www.summitracing.com/parts/hly-36-184 this kit has a number of parts you will need to tune the accelerator pump system on your holley.
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