10-29-2012, 11:23 PM | #1 |
Drives: 10' 2SS/RS M6 SUPERCHRGED BUMBLEBEE Join Date: Jun 2009
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67 Camaro Mild 327 engine build help!!
I have a fresh built 327 small block in my 67 Camaro and need a little advanced help from people with good engine and carb knowledge...
Here are the specs on the 327 build.... 10:5:1 Compression running 91 octane Factory forged steel bottom end (Crank and Rods) .020 under on the crank bored .030 over 3.25 on the stroke 11:1 forged dome top pistons 2.7 dome cc Gap to fit Molly rings .016 on the deck clearance .039 felpro head gaskets So .055 total deck clearance High volume oil pump Comp cams flat tappet hydraulic 292h cam Cam specs http://www.compcams.com/Company/CC/c...x?csid=81&sb=2 64cc camel hump heads with 5 angle valve job 1.94int 1.6 exh SS valves 1.5 ratio full aluminum roller rockers High rise dual plane intake manifold Holley 670 street avenger dual feed carb Holley high volume fuel pump HEI billet distributor MSD plug wires Accel racing plugs gapped at .45 Electric fan Electric water pump 1 3/4 long tube headman headers 2.5" H Pipe dual exhaust 40 series Flowmasters Every bolt in and on the engine is ARP and torqued to spec Cam is broke in proper with 20mins at 2000rpms and 10mins changing RPMs between 1800 and 2300 Initial timing set at 12 degrees and timing is around 36 degrees with vacuum adv plugged in at 3000rpms I'm running a Borg Warner World Class 5-speed manual trans and a 12 bolt differential with 4:10 gears My question/problem being, is my carb to small for this build? Ive adjusted the hell out of my timing and this 670 carb and it is a pain to get it to idle cold and by itself. When it gets to temp it will run fine at 1000 rpms and pull 10 psi of vacuum which is good for this cam. If I turn the car off then back on I have to sometimes hold the throttle to the ground to get it to start then it will idle normal again. It also doesn't have the crisp throttle an engine like this should have when I rev it. When driving it doesn't quite have that spunk I expected it to have. There's no hesitation when driving so I don't know where my problem is...
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10-30-2012, 10:32 AM | #2 |
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It's actually a bit on the large side, how do the plugs look? Rich?
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10-30-2012, 11:01 AM | #3 |
Drives: 2012 45th Vert, 2011 4x4, 9sec Vega Join Date: Mar 2012
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Does this carb have a choke? Electric or Manual choke?
Very big cam too. Large overlap and not much displacement to make vacuum.
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10-30-2012, 11:05 AM | #4 |
Drives: 2012 45th Vert, 2011 4x4, 9sec Vega Join Date: Mar 2012
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Second read of the cam specs. Way too much cam. Street/strip my ass. 110 degree lobe separation and 292 duration is too much, especially for a 327. Had a cam like this in a 350 drag engine, wouldn't idle below 1300 and ran a 5500 stall convertor.
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10-30-2012, 12:38 PM | #5 |
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Wow, old school hella-cam.
I ran one back in the mid 80's in my 66 Chevy II 327, for 2 months before I scrapped it for a milder 268H. This was a bottom end dog, no matter what I threw at it for streetable gears or stalls. Bleed down lifters helped alot, cutting down the low rpm lift and improved vaccuum. Try moving up your initial timing, around to the 16° area. |
10-30-2012, 01:51 PM | #6 |
'69 Owned Since '79
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Needs smaller cam - Needs more ignition advance at idle to try to make up for huge cam. Careful carb setup would help. It is not about carb SIZE as much as it is the throttle stop setting/main jetting/float setting/acellerator pump setting/manifold vacuum at idle hooked up to the advance can (and fully deployed) that will help.
Gap the plugs at .035". Big gaps are needed for lean, emissions-type mixtures. You do not need that big of a gap. Not going to fix anything but might help. -Mark. |
10-30-2012, 02:20 PM | #7 |
No Tags/Habitual Violator
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I'm no expert, but..
1) 670 cfm shouldn't cause these issues. Bad carb setup maybe. 2) cam spec says "Very Rough Idle". That says to me it's gonna stall easily and needs 3500 rpm to smooth out. 3) need to verify you have functional Vacuum Advance timing. This will turn any street motor in to a dog if not setup properly. So before swapping carbs or cams I would go over the vacuum advance setup. |
10-30-2012, 05:53 PM | #8 |
Drives: 10' 2SS/RS M6 SUPERCHRGED BUMBLEBEE Join Date: Jun 2009
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Thanks guys for the input I've been reading on this cam being a bit too big. The carb seem tuned to the best I can get it all my engine math says a 670 should be fine. This carb is also a vacuum secondary if that changes anything.
I'm gunna try to curve the distributor with some lighter springs and see if that helps. I've also read about the bleed down lifters too but if I go that route I mine as well change the cam. I also might have to change my vacuum can on the distributor to accept a lower vacuum at idle to stop the eratic idle and the stumble it sometime does when the engine idles also. If anyone has any other ideas or input please let me know. If not I'm gunna try swapping cam soon. I want some good off the line power with a nice 2000 to 5500 rpm power curve so please shoot me some good roller cams with some good off line power with that power curve
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Ordered Bumblebee 10/15/2008Part of the Family 6/11/2009 #11423
My Bumblebee to Superbee build story...http://www.camaro5.com/forums/showthread.php?t=105163 Superbee's 536hp Dyno Run...http://www.youtube.com/watch?v=AE7wePluPAc |
10-30-2012, 06:01 PM | #9 |
Drives: 10' 2SS/RS M6 SUPERCHRGED BUMBLEBEE Join Date: Jun 2009
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It's has an electric choke
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Ordered Bumblebee 10/15/2008Part of the Family 6/11/2009 #11423
My Bumblebee to Superbee build story...http://www.camaro5.com/forums/showthread.php?t=105163 Superbee's 536hp Dyno Run...http://www.youtube.com/watch?v=AE7wePluPAc |
10-30-2012, 06:03 PM | #10 |
Drives: 10' 2SS/RS M6 SUPERCHRGED BUMBLEBEE Join Date: Jun 2009
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Plugs look clean!
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Ordered Bumblebee 10/15/2008Part of the Family 6/11/2009 #11423
My Bumblebee to Superbee build story...http://www.camaro5.com/forums/showthread.php?t=105163 Superbee's 536hp Dyno Run...http://www.youtube.com/watch?v=AE7wePluPAc |
10-31-2012, 04:36 AM | #11 |
'69 Owned Since '79
Drives: '69 Z/28 LeMans Blue w/White Join Date: Oct 2008
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Crane F-278-2 Solid Lifter cam is worth a look. I have it in my 302 and our engines are very simmilar in spec except you have .25" more stroke. Nice little buzz bomb.
-Mark. |
10-31-2012, 08:26 AM | #12 |
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Your cam may be out of spec or not properly degreed.
It may help to shift the peak rpms down and marginally help low end torque by advancing this cam a few degrees. Double check PTV if you do this. Last edited by Southern Comfort; 10-31-2012 at 09:17 AM. |
10-31-2012, 10:53 AM | #13 |
Drives: 2012 45th Vert, 2011 4x4, 9sec Vega Join Date: Mar 2012
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Verify that it is operating correctly then. You've got too much cam but the hard warm starts could be the choke not releasing all the way when hot.
If you are going roller then get something around 270 duration with more lift. .530 to .550 lift.
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10-31-2012, 12:22 PM | #14 |
Senior Camaro Fanatic
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Drill a 1/16" hole in each of the front butterflies. Old School cam, Old school fix
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mild 327 build 67 camaro |
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