Carb or something else.
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Junior User
Joined: Sep 2009
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I'm not sure how my numbers ended up being off. I was shooting for 9.5 or less. The only thing I can figure now is that I miscalculated my deck height clearance. The motor is together and I can't easily measure that.
Hotshot
Joined: May 2003
Posts: 11,141
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From: south louisiana
It may just have too much advance in the ignition causing the poor hill climbing. His combo of that cam and too much compression and those small chambered C8 heads might not like 36 degrees of total timing. But it would be really simple to check, simply by pulling back on the timing and seeing how it does then. Don't be so ready to poo-poo something that you seem to not understand. 
Posting Guru
Joined: Jul 2003
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I have built many 390, 428, 427 engines and a few were used for daily drivers. Those worked very well with stock 1850 Holley 600 cfm carburetors. Very responsive. To extract the most hp out of his combination, a 735-780 cfm carb would work better, but the carb size is not causing his problems. There could be many possible problems, but most likely would be timing.
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Junior User
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I've heard various opinions on cfm. Most seem to say the 600 is planty big enough so I tend to believe that. I've heard guys say a 600 is small for even a 350 Chevy. It all depends on max rpms and I don't plan on ever taking it over 5000. My problem probably lies in the compression ratio and/or timing. They say most carb problems are actually timing issues.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
I've heard various opinions on cfm. Most seem to say the 600 is planty big enough so I tend to believe that. I've heard guys say a 600 is small for even a 350 Chevy. It all depends on max rpms and I don't plan on ever taking it over 5000. My problem probably lies in the compression ratio and/or timing. They say most carb problems are actually timing issues.
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Junior User
Joined: Sep 2009
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I backed it off to 6* and it didn't run much better but ran really hot so I parked it. I'll monkey with the timing at 12* and see about the vacuum advance, if I can't make any headway I guess I'll yank the motor out and measure everything again and see where I need to make adjustments. I don't really want to run 10.5 compression, but if that's the lowest I can get with my combo then I'll upgrade the camshaft.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
What octane fuel are you running in this ? Should be no less than 93 octane. I would also check to see that the balancer's outer ring hasn't slipped, giving you a false reading on the timing. Get #1 to TDC and see where the pointer is in relation to the balancer's timing marks.
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Junior User
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I'm running 93 and I checked the balancer a few weeks when I had the distributor out. I brought it to top dead center and the line and pointer were aligned.
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Post Fiend
Joined: Apr 2008
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From: Big Sky Country
Not to sound like a broken record but if I were you i'd try an adjustable vacuum canister, your motor is no longer stock but you're using a vacuum canister calibrated for a stock application.
Put a timing light on the motor with the vacuum advance line connected, you should see 14-16 degrees of vacuum advance (on top of your initial advance), if it's much less i'd consider an adj. vac. canister that can be "tuned" so you can get the vacuum advance dialed-in.
If you're running your Eddy carb "right outta the box" i'd also recommend fattening up the mixture a bit with a metering rod and/or jet change.
Put a timing light on the motor with the vacuum advance line connected, you should see 14-16 degrees of vacuum advance (on top of your initial advance), if it's much less i'd consider an adj. vac. canister that can be "tuned" so you can get the vacuum advance dialed-in.
If you're running your Eddy carb "right outta the box" i'd also recommend fattening up the mixture a bit with a metering rod and/or jet change.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Put a timing light on the motor with the vacuum advance line connected, you should see 14-16 degrees of vacuum advance (on top of your initial advance), if it's much less i'd consider an adj. vac. canister that can be "tuned" so you can get the vacuum advance dialed-in.
Post Fiend
Joined: Apr 2008
Posts: 8,261
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From: Big Sky Country
Good point, I neglected to mention that as i'm pretty sure the OP is sourcing a ported vacuum signal for his advance.
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Junior User
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The first thing I do will be check the vacuum advance. Like I said, I originally went into this with 9.5 to 1 compression planned, I must be missing something now when I calculated 10.5 to 1. So I'll check the vacuum. I did go a few steps richer with the jet and rod set I got but I'll mess with that some more also.
Now if i hook the vacuum to a manifold port, will that show me how much vacuum I'll pull with it hooked to the ported slot?
Thanks for the advice so far.
Now if i hook the vacuum to a manifold port, will that show me how much vacuum I'll pull with it hooked to the ported slot?
Thanks for the advice so far.