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Old 06-15-2010, 12:28 AM
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385 fast burn questions

i have a somewhat stock 385 fast burn gm performance crate engine and some questions about it.
*what size carb is recommended for this engine?- i have a 725 street demon w/ electric choke and have been having some troubles gettin it runnin reliable and good.
*what are the best ways to get power out of this engine?- cam, rockers, etc.?
i would be happy with 450-500+hp (all engine no nos included in that)
right now it is runnin in my car (1969 camaro) but i want/need more power.
thanx for any help and advice. i figure this site would be a good one for getting advice from some people with knowledge and experience with this engine.
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Old 06-15-2010, 01:21 AM
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Quote:
Originally Posted by nossub
i have a somewhat stock 385 fast burn gm performance crate engine and some questions about it.
*what size carb is recommended for this engine?- i have a 725 street demon w/ electric choke and have been having some troubles gettin it runnin reliable and good.
*what are the best ways to get power out of this engine?- cam, rockers, etc.?
i would be happy with 450-500+hp (all engine no nos included in that)
right now it is runnin in my car (1969 camaro) but i want/need more power.
thanx for any help and advice. i figure this site would be a good one for getting advice from some people with knowledge and experience with this engine.
While the 725 should provide good performance in my opinion, this crate motor came from GM with a Holley 770 CFM carb.

So that you will get more contributions from board members, let me start off with the complete specs like you should have done when you first posted.

Fast Burn 385hp 350
ZZ4 short block with forged steel crank and PM rods.
Fast Burn 62cc aluminum heads
385 hp @5,600 rpm
385 ft/lbs torque @4,000 rpm
9.6:1 static compression ratio (suspect 14cc dished pistons to arrive at 9.6 with 62cc heads. GM says these heads were designed to be used with a flat-top piston )
Cast iron 4-bolt block, 4.000" bore
Forged steel crank, 3.480" stroke
Fast Burn, 62cc heads, 12464298
210 cc's intake port volume
Angle plugs, 14mm X 0.750" RC9YC
1.320" valve spring diameter
0.520" max lift
2.000" LT4 intake valves, 1.500" LT4 exhaust valves
208/221 camshaft duration @0.050" tappet lift
0.474"/0.510" valve lift
Aluminum dual-plane intake (Does not say, but looks like a high-rise in the photos of this motor).

Stock flow figures @28" water
0.100" 62 45
0.200" 129 85
0.300" 173 120
0.400 209 143
0.500" 230 157
0.600" 235 166

Despite the humongous intake port volume, these heads flow 18 CFM less than L31 heads @0.400" lift. Just goes to show you that runner volume ain't the whole story!!!!

Your motor needs heads, cam and 1 5/8" long-tube headers. It also needs a high-rise intake manifold. Like I said, in the photos, the manifold looks pretty tall, but I would be comparing it with another manifold such as a RPM or Stealth to make sure. I would stay with 64cc chambers on any aftermarket head I purchased if I wanted to re-use the pistons. Static compression ration would be 9.4:1.

Actually, I would sell the whole mess to someone and build a motor for myself from stratch.
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