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#1
07-02-2012, 10:14 AM
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1st time on the dyno
I took the Firebird to Dynolab on Saturday and got some good numbers. Thanks to Jeff and Arthur, they did a great job. Surprising to me, the carb was dead on and showed extremely good A/F ratios. I think it was like 14.5 at cruise and 13 something at WOT, I can't remember exactly. The timing was a good bit off which I expected since I've been fighting it for a while. After taking 6 degrees out, Jeff was able to get the best numbers of the morning. It's at 32 degrees total. I have to say too that the cheap chinese HEI that lots of us were using is not accurate, it was adding almost 25 degrees mechanical advance when it should have only been 21. It's also right up against the firewall and is self adjusting itself (i.e. turning clockwise) as the engine torques and shakes and it rubs against the firewall. Rather than smashing in the firewall to make it fit, I'm going to a pro billet unit with external coil. I'm already running a 6AL box, and to be honest attribute a lot of my problems recently to the HEI design. Anyway, for a first dyno session I was very happy with the numbers. I don't know if the ambient temperature made a difference, but I will just mention that it was over 100F in Atlanta this weekend when the runs were made.
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#2
07-02-2012, 10:54 PM
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Deleted
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#3
07-02-2012, 10:57 PM
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Looks good
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#4
07-02-2012, 11:22 PM
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What are the lobe centers on your cam? It looks like you might pick up some hp if you retarded the cam, at the expense of some low end torque.
__________________
Rich The real democratic American idea is, not that every man shall be on a level with every other man, but that every man shall have liberty to be what God made him, without hindrance. Henry Ward Beecher "The problem with socialism is that you eventually run out of other people's money." Margaret Thatcher |
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#5
07-03-2012, 10:30 AM
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The cam is from Ace at PPR. I don't have the cam card in front of me but this is from his website. I think I remember seeing a handwritten note on the card from the PO that says it was installed at 108.
Tomahawk Hydraulic Cam 274/280 Dur@.050 224/232 Lift@1.5 480/485 LC 112 #TC-01-HF Overlap 56 While I appreciate the suggestion, I actually want to got he other way. Low end torque is what I want, not high end HP. I want the car to get moving from a stop faster, I don't care so much about top end. I'm not revving it to 6000 hardly ever, it's primarily street driven. |
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#6
07-03-2012, 10:32 AM
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Oh, and I also have 1.65 rockers, so the lift is higher than what's on the specs.
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#7
07-05-2012, 03:25 PM
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13.something is still lean. You'd be better getting it under 13.0
Do you have a manual transmission, or a really tight torque converter? Look into the www.davessmallbodyheis.com distributors too. Just like the MSD, except WAY cheaper, has vacuum advance, and Dave will curve it however you want it. Lee
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'73 T/A (clone). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 315rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'. '67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust |
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#8
07-05-2012, 04:55 PM
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Manual trans, TKO600.
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#9
07-05-2012, 07:35 PM
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It may be just me but it looks a little soft on the bottom TQ wise for that cam. The area under the curve for HP looks good.
Going back to the total on the dist. Kinda looks like when you got the total dialed in the start and all in might be slow. And yes, no engine likes hot air. Just like anything the cooler the denser and that makes more HP. Just taking a generic 400HP Pontiac and going from 66 to 100 degrees the puter says 30HP and 40TQ loss with just the temp change. 
__________________
72 GTO 400-M20 Lucy Blue 86 2+2 Black 09 G8 GT red 08 Torrent GXP (wife's) 09 G8 ST (UTE) black A pissed off fat house chimp on dope would be a lot more deadly. |
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#10
07-06-2012, 08:12 AM
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Thanks ufo. I know that the crappy HEI I had on there was an obstacle. I am actually putting on a billet MSD and blaster ss coil today. I'll have to experiment with their bushings and springs to get the curve right. To be honest though, I don't know what is "right". All I know is that the advance should start just after idle (~1200) and be all in by 3000 or so. As far as the rate of advance I don't know how to determine what's best. I'll try to write down some points along the advance curve with my dial back light and see what folks think.
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