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  #166 (permalink)  
Old 06-16-2019, 04:38 PM
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Quote:
Originally Posted by ericnova72 View Post
You're running 7.9 Et and showing 3 tenths missing on the 60 foot....if you get the 60 ft down to where it should be, in the 1.5's area the better 60 will reward you with somewhere near a 4 tenths in the 1/8 mile.....now when you re at 7.5 ET and consistent, then you can start testing 2° timing changes and carb jetting for best MPH(Power).

By the way....the Cal-Tracs should be pushing the back of the car up, not squatting it.....if it squats then something is really wrong. You want separation of the body and suspension at the hit.....if body is rising, then the tires are being driven down......that pesky "equal and opposite reaction" thing from physics class.

When you have someone watch the launch or video it, they need to focus on the wheel lip to tire height relation ship at the center of the wheel well.....not the rear bumper.

Missing 2 tenths not 3. Asked my gal about the rear and she said it went down at the wheel well. No, that isn't good at all, I'm glad you mentioned it. I will try an adjustment there. Before ever going to the track I moved the pin that pushes on the spring to a different hole which made it easier to provide the lift, but gives less lift. A leverage thing.

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  #167 (permalink)  
Old 06-17-2019, 02:02 PM
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WOT vacuum

Tested the vacuum at wot between 5500 and 6k rpms. Old vac gauge read 3", brand new one measures 2". Both I'd consider cheap gauges even if the new one is a Bosch (Bosch makes a lot of crap these days). Good ones seem to start in the $275 range
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  #168 (permalink)  
Old 06-17-2019, 02:42 PM
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Quote:
Originally Posted by 55 Tony View Post
Missing 2 tenths not 3. Asked my gal about the rear and she said it went down at the wheel well. No, that isn't good at all, I'm glad you mentioned it. I will try an adjustment there. Before ever going to the track I moved the pin that pushes on the spring to a different hole which made it easier to provide the lift, but gives less lift. A leverage thing.
Reason I said 3 tenths missing from the 60 foot times is because on slicks it ought to be pulling times in the 1.5 second range....heck, my '72 Nova with 406 SC, solid cam, pump gas, 4.56 gear, 3400 stall can pull 1.6's on dirt circle track tires. Nothing more than poly leaf bushings, Comp Engineering slapper bars and cheap 50/50 non-gas shocks on the rear. 7.20's-7.30's in the 1/8th.

Right now your '55 is showing 340 HP flywheel based from ET, and 347 HP flywheel based off the MPH.
Something has you off 75HP+ from what the engine should have IMO.

I've forgotten, do you have a way to observe fuel pressure at WOT and in high gear??
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  #169 (permalink)  
Old 06-17-2019, 08:44 PM
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Can you tell us what RPM you leave at, what RPM you are shifting at and some idea of where on the track you are getting into high gear?
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  #170 (permalink)  
Old 06-18-2019, 07:00 AM
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What weight did you use for the calculation? I had weighed it at 3920lb with me in it. A little less now with the aluminum heads. I think the Nova was about 900lbs lighter.

No, I do not have an inside fuel gauge
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  #171 (permalink)  
Old 06-18-2019, 07:28 AM
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I can't say what rpm I'm leaving at, I just rev it up to about 2500, then floor it and let off the brakes. Not sure how high it goes.

Shifting at 6k - 6200.
Third gear, IDK. It's not real close to the finish, can't say what rpm it's at at the finish either. I'm too busy keeping it going straight.
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  #172 (permalink)  
Old 06-18-2019, 08:05 AM
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Assuming your convertor is flashing to 38-4000? The 2500 leave might be a bit much for the current setup. I would put air back in the slicks, probably around 14-15 psi, lower the starting RPM to 1500 and see what that does. I take the 6000-6200 shift point in 1st and 2nd is where the engine feels to be running out at?
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  #173 (permalink)  
Old 06-18-2019, 12:33 PM
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Quote:
Originally Posted by chasracer View Post
Assuming your convertor is flashing to 38-4000? The 2500 leave might be a bit much for the current setup. I would put air back in the slicks, probably around 14-15 psi, lower the starting RPM to 1500 and see what that does. I take the 6000-6200 shift point in 1st and 2nd is where the engine feels to be running out at?

Hmm, slower rpm. I'll try it. The first time I ever went with the Q-jet I was starting from an idle, but then I raised it up. Can't really say what the difference was then, I don't think the clock was working. hell, I'll try it from just off idle too... maybe it will hook? There is still some "tread" left on these, do you really think they could be down to the other rubber and still have some wear holes? At about 13-14psi I can feel safe the way it handles, was that a recommendation for traction or safety?
Oh, actually I think the engine wants to go faster, but I fear it flying apart.
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  #174 (permalink)  
Old 06-18-2019, 02:54 PM
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Actually the PSI is for all 3 - safety, traction and reaction time. A lot of people that drag race don't get the correlation between rear tire pressure and RT. While I know that's not something you're overly concerned about it will have some impact on how the car leaves. I would buzz the engine a bit harder at least on the 1-2 shift as you might find out that the current head/manifold package responds better at a higher RPM.



And if you still have the tread holes, you still have usable rubber.
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  #175 (permalink)  
Old 06-18-2019, 04:34 PM
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Quote:
Originally Posted by 55 Tony View Post
What weight did you use for the calculation? I had weighed it at 3920lb with me in it. A little less now with the aluminum heads. I think the Nova was about 900lbs lighter.

No, I do not have an inside fuel gauge
I took a guess at your weight for the calc and figured it at 3600 lbs....I had no idea a '55 Chevy was that heavy, I thought I'd always heard they were as light as the '64-65 Chevelle.

My '72 Nova is all stock body panels, not lightened at all and with stock spare and bumper jack in the trunk is 3350 with aluminum wheels and intake manifold, and tube headers...3600 lbs with my fat butt in it. Title says 3083 lbs for vehicle weight, not even close...only way a stock one is that light is straight 6, Powerglide, rubber floor cover, radio delete type car.

If I re-do your power calc for 3850 lbs(alum heads drop 70) it gives 385-390 HP which still seems roughly 50HP below the minimum that I would expect from your combination.
390 Hp is stock 1970 LS-5 which was oval port, 214°@.050" dur .461" lift hydraulic cam and listed at 11.25:1 compression.....you've got more cam, better heads, better intake and carb, and headers - but less compression, and IMO the compression shouldn't impact the motor for that 50HP that seems missing.
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  #176 (permalink)  
Old 06-18-2019, 06:50 PM
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Quote:
Originally Posted by ericnova72 View Post
I took a guess at your weight for the calc and figured it at 3600 lbs....I had no idea a '55 Chevy was that heavy, I thought I'd always heard they were as light as the '64-65 Chevelle.

My '72 Nova is all stock body panels, not lightened at all and with stock spare and bumper jack in the trunk is 3350 with aluminum wheels and intake manifold, and tube headers...3600 lbs with my fat butt in it. Title says 3083 lbs for vehicle weight, not even close...only way a stock one is that light is straight 6, Powerglide, rubber floor cover, radio delete type car.

If I re-do your power calc for 3850 lbs(alum heads drop 70) it gives 385-390 HP which still seems roughly 50HP below the minimum that I would expect from your combination.
390 Hp is stock 1970 LS-5 which was oval port, 214°@.050" dur .461" lift hydraulic cam and listed at 11.25:1 compression.....you've got more cam, better heads, better intake and carb, and headers - but less compression, and IMO the compression shouldn't impact the motor for that 50HP that seems missing.
So where does that leave me? Fix my motor for me dang it! And I really feel I'm missing more than 50HP. Either that or those 781 heads really are as good as some people say!?!? With them I ran a 7.77, twice! That on the wallace racing calculator was 400-407HP.

I was emailing back and forth with Skipp White about it and all he could tell me is that my cam is too big for my compression (which it isn't according to comp) and that if I want 600HP on pump gas (which is way over my goal but wouldn't mind it ) then I should have bought his entire 496 rotating assembly! I don't know how an extra 40ci is going to give me another 200HP? (and getting the block zero decked). Maybe that is true? IDK? He kept saying that I never should have bought those heads for a little 454, but when I asked him why he advertises them for a 454 he would change the subject. Then I played along and told him when I'm ready to make it a 496 I'd let him pick out the parts I need. Suddenly he stopped replying. Sigh.

Twin turbo's won't fit so I guess I'll have to save up for a blower!
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  #177 (permalink)  
Old 06-18-2019, 07:58 PM
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I find it hard to believe the heads are too big....flow numbers are in line with both the AFR 265cc and 290cc Oval port offerings….and AFR says this for their 290cc "recommended for moderate street or street/strip big block chevy's with displacements up to 509", operating below 6500 RPM"
AFR's 300cc oval is a good bit better flowing, has 2.3" intake valve, and is recommended for aggressive street/strip or race BBC's up to 540"
The AFR 265cc is recommended for street/strip and towing up to 468" at or below 5200 rpm and is marketed as the ideal replacement instead of re-working stock oval port heads.

There's a fly or two in the ointment somewhere in your combination....we just have to find it.

Refresh me again on what your bottom end is..Crank, rods/rod bolts, pistons??
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  #178 (permalink)  
Old 06-18-2019, 08:12 PM
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I'm going to throw a monkey wrench in here.


This "dragstrip" is not a permanent installation is it? You had said something about the timing gear getting wet the other week. Any chance that the ET and MPH sensors might have been a touch closer to the starting line sensors on those 7.77 runs?


And I ask this because we tour multiple tracks in our area. It is not uncommon to run 6.00 on Saturday at one track, go 30 miles south to another and run 6.08 all day long on Sunday. We bracket race so it doesn't matter to us and we've probably raced 15+ different tracks over the last 10 years and varied times and mph are not unusual.
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  #179 (permalink)  
Old 06-18-2019, 11:47 PM
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Whoops, there is a typo I can't fix in my previous post....the AFR 265's are recommended by AFR up to 6200 RPM, not the 5200 that I typed.
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  #180 (permalink)  
Old 06-19-2019, 06:30 AM
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The bottom end is stock except for the pistons which are 25.7cc dome but in the hole ~ .020 Oh, it's .030 over. It hasn't been decked but it may have been trued a time or two, some of the numbers stamped on it are hard to read. The .020 in the hole is the best I could tell since the dome is above the wrist pins. The piston specs say "deck clearance .025".
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