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Discussion Starter #1
Well as you guys may remember I removed my 307 due to a backfiring condition, which appeared to be caused by a worn cam lobe. The 307 was on its last legs anyway (oil pressure at 20psi max hot), so I replaced it with a new GMPP 290hp 350 crate engine. Unfortunately, it looks like what was causing problems with the 307 is now attached to the 350. I was able to due the required 20 min break in at 2500 rpm, and it ran decently, but when I went to drive the car in gear I noticed it had absolutely no guts (bad hesitation, very little power) at all, much like what the 307 had been doing, with the exception of the backfiring through the carburetor. My initial timing is at 12*, and idle is fine in and out of gear, but I have only 15 in of vacuum with the idle circuit adjusted for highest vacuum. I'm not sure if that is normal for this engine or not. I transferred my edelbrock carb, summit hei distributor, and fuel pump to the new engine, so my bet is either I have a vacuum leak (which I couldn't find) or something is up with one of the three items above.:(
 

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did you rebuild the carb and set it up for the new motor?
 

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Is you distributor advancing? Also have you done the basic checks like fuel pressure and coil?
 

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Discussion Starter #4
yes my distributor is advancing, the carb theoretically shouldn't need to be rebuilt since it's only 2 years old, and has been used consistently since it was bought. I never messed with anything inside it because it worked very well on my 307 in its younger days. My younger brother has exactly the same carb on his 350, which is fairly similar to mine, and never changed anything either. Still, that's something I will look in to, but the problem seems eerily similar to what happened with my 307. Fuel pressure is apparently good, but the last time I had a fuel pump die it appeared to be OK as well, and I had similar issues, so I'm gonna replace it tomorrow. Its a cheapo mechanical one anyway. If that doesn't work I'll try my bro's carb, and see if anything changes, and if that still doesn't work I'll try my points distributor. What bothers me most now is the vacuum, I'm not sure it should only be 15" at a smooth idle.
 

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even carburetors used daily get old. Id do a complete overhaul on the carb.

also what other components off the 307 are you using on the 350?
 

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Found the problem. My fuel pump died. I'm wondering if it has something to do with it having a non return type regulator. Is it OK to use that type of regulator with mechanical pumps?
Yes, you should have no problems with using a regulator with no return. A piece of junk may have gotten into the pump and damaged the diaphragm. Once that happens, they need a rebuild or replaced. It would be a good time to put new fuel filters on too.

-Dan
 

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You said it was a cheapy pump. What type of pump are you using that needs a regulator?
 

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Discussion Starter #9 (Edited)
it is a cheapo autozone garden variety fuel pump. The problem is that they put out around 7 psi which is just enough to cause trouble on sharp turns and hard braking with an edelbrock carburetor. Edelbrock recommends the regulator be set at 5.5 psi. I'm now on my 3rd fuel pump in 10,000 miles, thats why I asked about the regulator.
 

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Quit getting them from twilightzone, got one from o'rielly's last month and it works great, i have an eddy too.
 

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Quit getting them from twilightzone, got one from o'rielly's last month and it works great, i have an eddy too.
stupid vatozone.

thank god they come with warranties. Im never going to have to pay 100 for a starter again!!! :devil:
 
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