hi all,I am having afew problems tuning the 350 chev in my boat and this looks to be the perfect place for some info...after all, the chev is all american iron and specs are hard to find here in new zealand.
Engine specs are:
comp ratio approx 9.2:1
world products torquer heads
94 octane fuel
weiand intake
600 vac sec holley
hei dizzy
.470" lift cam (all cam specs unknown,came with block)
Vac advance is connected to the fitting on the primary metering block on the carb,

After a full rebuild and installing a HEI dizzy, I took it out on the water today to tune the carb and timing..
The following are the timing results,
6 deg ATDC at 1000rpm(idle) vac disconnected,
17 deg ATDC at 1000rpm with vac connected,
32 deg ATDC with throttle wide open.
It runs ok but when you puch the throttle from idle it back fires through the carb and dies, if you throttle up slowly it gets up and goes ok..
Also i have noticed that with the throttle wide open while planning the secondaries on the carb are hardly open, if at all..
Any help would be greatly appreciated...

I would add more timing, at least 10 static at 800 rpms. The lower rpms assures that the mechanical weights are not playing a part in the measurement. 1000rpms is borderline depending on the weight sets in the distributor.

Then report back and we'll see how the carb behaves. If the secondaries are not completely open there is a problem and the vacuum actuator will have to be recalibrated for less vacuum.

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STEVE JACK
SOUTHEASTERN GOODGUYS REP

8 to 10 degrees BEFORE top dead center.
Total advance - around 36 degrees.
If retarded like you set it, you would have hard starting, rough idle, lack of power. Perhaps coughing at mid to high rpm's.
David

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Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Chev 350 Can-Am Vintage Racer

hi all,I took the HEI apart today and found that the mech advance was too much and I havn't got the springs or weights to adjust it so I borrowed a friends HEI and it made all the difference..
12 deg BTDC at 800rpm (vac disconnected)
32 deg BTDC at 800rpm (vac connected)
34 deg BTDC all in at 3000rpm and above...
Unfortunatly the vac advance is one of those smog units that is advancing 20deg at idle..
I have ordered a crower adjustable vac can from jegs so it will probably be 2 weeks away before it gets to new zealand..
I am aiming for around
10-12 deg at idle
32 deg total (all in at 2800)
approx 20-22 with the vac connectd at idle)
Am i on the right track??
This message board is proving invaluable and your advice is greatly appreciated.
I have learned much just by reading the old messages...
ps..now that the timing is close,the secondaries on the carb are coming in but way too late..I think a slightly weaker spring should sort that out, I just wanted to get the timing done before I started carb fine tuning..

Get 36 to 38 degrees total above 2500- 3000 without vaccum advance connected. 12 degrees at idle with no vac is good if there is no starter kick back.
Then plug in the vac advance, and tailor for no pinging.
Those HEI advance units are not easy to get right!
There are some good specifications from Ignitionman in the engine and drivetrain section archives. Just ignore the B.S.
David

------------------
Check my web page for First Gen Camaro suspension info:
David's Motorsports page (http://ourworld.compuserve.com/homepages/David_Pozzi/)
First Gen Suspension Page (http://ourworld.compuserve.com/homepages/David_Pozzi/first_gen_suspension.htm)
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Chev 350 Can-Am Vintage Racer