393W not running up to expectations - Ford Muscle Forums : Ford Muscle Cars Tech Forum
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post #1 of 43 (permalink) Old 10-11-2015, 04:59 PM Thread Starter
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393W not running up to expectations

I’m updating a way old post regarding an old 393W build post. After helping building it, putting it in the car, and taking it to the drag strip, we were a little disappointed. It only ran a best of 11.79 at 114 MPH. On paper, we thought it would at least run mid-to-low elevens. He is the set up;

• 393W; 850 Quick Fuel carb, Victor Jr & one-inch open spacer, .030 flat top 10.6 to 1 (cranking compression is 170 PSI), World Products Sr with moderate porting for the 2.02/1.60 valves, Lunati solid roller 253*/256* @ .050”, .621” in/ex on a 108* lobe separation +4*, 1 7/8” x 3 ½” headers with 18” collectors, deep oil pan modified with a windage screen, and a complete -8 AN fuel system & pump with a -10 AN pickup,
• The 351W it replaced used the same components as listed above and ran 12.09. Again, it too should have run quicker.
• ‘69 Cougar with roll bar and sub-frame connectors
• Car & driver 3300 lbs
• 4000’ish stall in a C-4 with a manual valve body
• 28 x 9 slicks
• 4.30 rear ratio
• Car launches well, pulls the tires off the ground, shifts at about 6300 and pulls through the traps at about 6200. This is a drag strip only car and I’m sure it has the potential to go faster. It has no hic-ups, surging or anything; it runs great! What are we missing?

Racing Cougars (the other Mustang) for three decades...
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post #2 of 43 (permalink) Old 10-12-2015, 09:08 PM
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Re: 393W not running up to expectations

Looks like a decent combo..Were the heads done by a reputable shop that knew what they were doing? What mph did the old 351 run? Were the heads ported on the 351 combo?


1968 mustang 408W Hybrid..Burns gas and rubber!
11.47@123.35 with a crappy 1.72 60ft.
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post #3 of 43 (permalink) Old 10-13-2015, 03:00 AM
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Re: 393W not running up to expectations

What was the 60' time?
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post #4 of 43 (permalink) Old 10-13-2015, 03:24 AM
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Re: 393W not running up to expectations

It does look like a nice combo that should run better. The work on the heads is a concern. Heads can make or break a build.

I feel that with that cam you are not spinning the motor high enough and are just barely getting into its power band.

Full incrementals of the run (and a video might be helpful.)

Dennis

65' Stang Street/Strip:



Dart 434W NA, G101A 4 Spd, 4:33 rear gear, on 93 octane pushing 3550lbs. 9.91@135.56
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post #5 of 43 (permalink) Old 10-13-2015, 04:56 AM
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Re: 393W not running up to expectations

If the heads were decently done the intake is the cork. i DOUBT IT FLOWS MUCH MORE THAN 190ISH cfm bolted to a good head.
Do those heads have a raised intake port location. Torker IIs are the wildest intake Edelbrock makes that retains the stock port location well almost. Have measured up a few that are off a bit but possibly just due to tolerance stack ups all gone to the extreme.
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post #6 of 43 (permalink) Old 10-13-2015, 05:15 AM
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Re: 393W not running up to expectations

Quote:
Originally Posted by turbo2256b View Post
If the heads were decently done the intake is the cork. i DOUBT IT FLOWS MUCH MORE THAN 190ISH cfm bolted to a good head.
Do those heads have a raised intake port location. Torker IIs are the wildest intake Edelbrock makes that retains the stock port location well almost. Have measured up a few that are off a bit but possibly just due to tolerance stack ups all gone to the extreme.
The Torker II intake is a low profile single plane intake that will not make the power the Victor JR will. And yes I have actually used that intake. It is not a good choice for drag racing unless hood clearance is a concern.
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post #7 of 43 (permalink) Old 10-13-2015, 06:13 AM
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Re: 393W not running up to expectations

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Originally Posted by turbo2256b View Post
If the heads were decently done the intake is the cork.
I respect your opinion but by experience shows that the stock 351w Vic Jr is not (yet) a cork on that motor, which is quite similar to my old 393w build. My race weight is a couple of hundred pounds more. I also used a smaller carb and smaller diameter headers.

First rendition of my 393w was Vic Jr, Pro Comp 210 heads, 10.5 compression and it ran 11.70's@117mph with 4.11 gears.

I then installed out of the box AFR 205 heads. Ran 11.20's@122mph with the same basic combo and 6600rpm shifts. That is why I would love to see a time slip.

I've also ran the same Vic Jr on my current 10.7 compression 428w and it has taken me well into the 10's with the same AFR heads, carb and headers. Gear has been swapped for a 4.33. Basically everything attached to the block was a cork-but it still performs adequately pushing the heavy turd.

This year I swapped out the Vic Jr on this motor for an out of the box Super Vic and there wasn't a noticeable difference in performance, even after tuning and trying a 1/2" spacer. Actually my best time is from last year with the Vic Jr.

We need to see more of what is going on during a run and his combo begs to be shifted higher, IMHO.

Dennis

65' Stang Street/Strip:



Dart 434W NA, G101A 4 Spd, 4:33 rear gear, on 93 octane pushing 3550lbs. 9.91@135.56

Last edited by dennis111; 10-13-2015 at 06:26 AM.
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post #8 of 43 (permalink) Old 10-13-2015, 07:14 AM
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Re: 393W not running up to expectations

Excuse me I meant a VrJr. As for a Senior as far as I KNOW THEY are a raised port configuration (never had a chance to measure one up) not a stock port location. Heads up on flow testing both the TorqerII AND the VrJr they both flowed about the same. I flow tested them both on ported DOOE heads flowing 235 CFM at .500 lift and a Canfield head flowing 320 CFM at .500 lift.
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post #9 of 43 (permalink) Old 10-13-2015, 08:43 AM
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Re: 393W not running up to expectations

Turbo if the vic jr intake was such a cork there wouldn't be much point in running aftermarket heads. As has been established by many an out of the box vic jr works just fine. I just ran 123mph with mine on the weekend.

Like Dennis said a timeslip might help narrow down where the problem is but your mph is definitely low. I would expect your mph to be somewhere in the high teens or around 120 mph. I don't have any experience with those heads but doing a quick google there seems to be a bit of a love/hate relationship with them. There are some pretty quick cars running them though but usually with some work done to them.


1968 mustang 408W Hybrid..Burns gas and rubber!
11.47@123.35 with a crappy 1.72 60ft.

Last edited by frdnut; 10-13-2015 at 08:49 AM.
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post #10 of 43 (permalink) Old 10-13-2015, 01:33 PM
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Re: 393W not running up to expectations

Quote:
Originally Posted by k718cougar View Post
The 351W it replaced used the same components as listed above and ran 12.09. Again, it too should have run quicker. What are we missing?
A set of these . . intake 315 exhaust 235 @ .650 with only 195 cc runners with small diameter valve springs

Air Flow Research

or these

intake 321 exhaust 227 @ .600 with a 205 cc runner with small diameter valve springs

Trick Flow® Twisted Wedge® 11R 205 Cylinder Heads for Small Block Ford TFS-52616601-C03 - TrickFlow.com


In stock form, the Windsor Seniors flow around in 240 ex 150 . . I know yours have had some work done but just how much? . . In addition to the intake flow, the exhaust flow on those heads kinda sucks and has a poor ratio to the intake of around 66% . . The AFR's have an ex to in ratio of around 74 and the Trick flows are around 70% . . I think a custom cam would work better than that Lunati with those heads . . I would give Chris Straub a call [don't email] and see what he says . . He is one of the top cam grinders in the Country.

http://www.straubtechnologies.com/

I know this doesn't directly answer your question buy it's all I got for now.

Last edited by barnett468; 10-13-2015 at 02:06 PM.
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post #11 of 43 (permalink) Old 10-13-2015, 05:41 PM Thread Starter
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Re: 393W not running up to expectations

The heads were not "worked" but cleaned up and the exhaust was polished to a mirror finish. These heads when on the 351W went 12.09 @ 109, but did rev higher (6700). Again, everything was the same with the exception of the CID.

60' - 1.683
330 - 4.833
1/8 - 7.497
1/8 MPH - 91.59
1000' - 9.817
1/4 - 11.790
MPH - 114

On the return trip home from the track, I realized I forgot to bring a vacuum gauge to check top-end vacuum pull.

It runs well, it seems like it doesn't have the pull that it should.

Racing Cougars (the other Mustang) for three decades...
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post #12 of 43 (permalink) Old 10-13-2015, 08:18 PM
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Re: 393W not running up to expectations

Here is a timeslip from last year for my combo. My car is a 4 speed manual so it is a little slower than a comparable combo with a good working auto trans (at least with me shifting). It is very similar for the first half but my combo is much faster (mph) through the second half. I am running vic jr cylinder heads and a camshaft with similar intake duration but more exhaust duration,lift and a wider lobe separation. I run a 4.11 gear with 26 inch tall tires. Is it possible that you are running out of fuel on the top end?
60ft......1.68
330......4.88
1/8th....7.50
mph.....93.8
1000....9.73
1/4......11.59
MPh.....120.32


1968 mustang 408W Hybrid..Burns gas and rubber!
11.47@123.35 with a crappy 1.72 60ft.
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post #13 of 43 (permalink) Old 10-14-2015, 06:01 AM
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Re: 393W not running up to expectations

I don't doubt that the MPH would be a little lower in a auto vs stick car. Maybe in the order of 2-3mph?

Fuel is a good place to look--hook up a pressure gauge and see what its doing when the motor is pulling. Might make sure the throttle blades open all the way when the pedal is pushed (verify.) Mess with the timing a couple of degrees each way at the track to see how the motor responds. Perhaps the converter is not up to snuff and is robbing more power than it should?

But then again, it could just be that the motor is not capable of making more steam. Although the heads may have been fine for the 351w, for the the big block bore of the 393w they are not adequate to increase performance to the levels that you are looking for. Big block cubes need to be properly fed in order to perform.

Dennis

65' Stang Street/Strip:



Dart 434W NA, G101A 4 Spd, 4:33 rear gear, on 93 octane pushing 3550lbs. 9.91@135.56
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post #14 of 43 (permalink) Old 10-14-2015, 06:07 AM
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Re: 393W not running up to expectations

Your 1/8 mile time is equivalent to a 12.0 quarter mile. This seems to indicate that you have more issues in the first half of the track than at the top end.

1966 Falcon, 347 stroker and C-4
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post #15 of 43 (permalink) Old 10-14-2015, 08:04 AM
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Re: 393W not running up to expectations

Change the heads and let it breathe
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