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730 Posts
Discussion Starter #1
I have been a lurker here for a while learning so much and figured it was time to post my build thread. My 1970 Mustang - stick car has gone through a few transitions over the years where it was a pure street/show car, then three years back it went to a 80% street, 20% drag when I dropped in a Ford Racing Boss 351W block bored/stroked to 460ci, and over this past winter it has seen another transformation to 90% drag, 10% street, bringing the SBF engine to 670HP NA.

Last year the best time was 11.2 sec at 125mph and I got the bug to go faster. So over the winter the engine seen some major work summarized below. So far this summer my best time has been 10.6 at 129 (and that was with 1.65 60's and not hooking up) then last month I blew the Liberty faceplated TKO600. I am now waiting on a Gforce G101a that I should have in a few weeks.

Over the winter here is what I did to bring the engine to 670HP from 550hp.
Started with the Ford Racing SBF 460 ci shortblock which is based on the 351W Boss block I had that which was already pretty strong with Mahle pistons, Scat crank with Forged H-beam connecting rods, and more and I focused on the top end.

Z304 heads were completely worked by Duane Busch with:
- Larger valves: intake valves from 2.02" to 2.10, and exhaust from 1.6 to 1.625" with Ferrea comp plus valves. Those are the max the heads can support.
- Went with PAC 1225 springs, topped off with Titanium retainers.
- To boost compression to just under 11:1, the heads were angle milled 1* (0" to .120") reducing the chamber size from 63cc to 54cc. Going with the larger valves did require opening the pockets up some, so we increased about 2cc from 52cc.
Duane also cleaned up my Vic Super intake.

The head work Duane did was great and resulted in a significant improvement:
- Original 2.02" intake valves flowed 272 cfm @.500, now they are 2.1" with 314 cfm @.500, .600" of 334cfm , and at .800 was 345cfm
- Original 1.6" exhaust valves flowed 212 cfm, now they are slightly bigger at 1.625" and flow [email protected] and at .800. 265cfm
Flow was done at 28 in Hg on a Superflow 600 flow bench.

- T&D Machine 1.7:1 shaft rockers
- Bullet cams did a custom solid roller grind with a gross valve lift of: .755 intake and .740 exhaust.
- Morel 5436 lifters and 3/8" x.120" wall thickness Smith Brothers pushrods
-AED 950HOM carburetor
- Hyatt Racing Services custom built slipper clutch

All of the work paid off. My goal was to hit 650hp with a stretch of 680hp. On the dyno the engine hit 670hp. That is a full 120hp more than when I first dynoed the engine. This is all on the same exact dyno that two years ago I got 550hp. PK Machine, Fitchburg MA did all of the dyno work and some of the other things that I could not do myself and I could not be happier with the work.

Before 550hp at 5500rpm and 561 lb-ft at 4400
Now 670hp at 6800rpm and 587 lb-ft at 5200

Not bad for a small block ford :)

Comparing the dyno results from 2 years ago old heads, cam, and intake, to show exactly what all of the recent modifications did. Blue/Green new HP and TQ, Black/Red older HP/TQ.

So more about the car:
Rear Suspension:
Calvert Split Mono-leafs, car is at stock height
Global West Del-A-Lum Shackles
Viking Crusader double adjustable shocks rear

Front Suspension:- Stock looking
Opentracker Racing Roller Components - Track LCA's, and Drag UCA's with Roller perches
Roller Idler Arm, all new performance tie rods and adjusters, and other linkage components
Street and Track Adjustable strut bars
Viking Crusader double adjustable shocks front

Shock towers have been reinforced on the inside and outside. Custom reinforcements on the inside tying the towers to the frame, and the common 45 degree plate welded on the outside.
Arning/Shelby 1" drop
Welded in subframe connectors along with other reinforcements

Rear is a Ford 9" with a Moser Detroit Eaton True-Trac, 31-Spline Axle, 3.70:1, this winter swapping to a 4:30 spool with 35 spline.

730 Posts
Discussion Starter #2
sorry this got posted a second time. My original post did not show up until now for some reason.

3,280 Posts
Man, I saw the title, and thought it was going to be a cool build to watch, and then I opened the thread and I'll be damned if I haven't already seen a complete build thread on the car. What a letdown! Lol ~ sportsroof69

730 Posts
Discussion Starter #6
Toofastcobra- Thanks
69fastback/Sportsroof69- you are everywhere :) But now you get to see it transition from my street car to what it is becoming. and yes it is staying a stick car.. LOL
Racerxmd- Duane did a great job on getting those heads to flow!

I was working on adjusting the slipper clutch as well as shocks/caltracs when the TKO went. Hopefully with the G101a I can pick up where i left off and get below 10.5 and get it to hook.

730 Posts
Discussion Starter #7
Here are some additional pictures:

Engine and heads:

Still has somewhat of a stock look.

Fabbed a scoop that looks similar to the stock shaker scoop. Needed to do this to fit the taller intake/spacer

After Duanes work:

Racerxmd here are all of the flow numbers for those heads after the work was done:

Intake Flow
done at 28 in Hg on a Superflow 600 flow bench
.300 lift 224 cfm
.400 270
.500 314
.600 334
.700 342
.800 345

Exhaust Flow
.300 lift 171 cfm
.400 206
.500. 233
.600. 249
.700. 261
.800. 265

Ford adverrtised Stock number right out of the box:
Lift Intake Flow Exhaust Flow
(in) (SCFM) (SCFM)
.050 31.1 26.4
.100 64.6 55.8
.150 103.0 84.6
.200 135.3 113.3
.250 167.0 146.8
.300 199.0 171.6
.350 227.2 190.2
.400 245.2 200.4
.450 259.8 207.2
.500 271.9 212.8
.550 277.3 218.1
Ford does not advertise anything else.

At New England Dragway

38 Posts
Cool Build! Pretty good flow numbers out of those heads. Very similar numbers to my CNC'd "Big Block" heads . . LOL
My first car was a 1970 Boss 302 then a 1970 428 SCJ Mach 1. Love those '70 Mustangs

730 Posts
Discussion Starter #14
Thanks for the feedback folks. It is a blast to drive and can't wait to get the new trans in.

408GTA- I am running Ford Powertrain (FPA) headers that they built for me. Initially I had a hydraulic clutch with an external slave and they fit very well with only minor dimpling, and quality was good. This past winter I went back to a Z-bar setup for better adjust-ability, and they required some significant mods to fit the Z-bar. If you look at the full engine pic at start of the thread, you can see the primer on the headers where I had to cut, reshape, and weld the pipes. Since I was cutting them up, the areas that I had to dimple, such as at the idler arm, steering box, and shock towers, I made up for the dimple by adding pipe in that area to make the pipe oval versus round to maintain the cross section area. As a side note, the headers are a full 1 3/4" pipes, and really should be 1 7/8", but there is no room with the shock towers in place. Bullet cams took that into consideration when spec'ing the cam. With the header mods I can pretty easily slip them in place from the underside when on a lift.

133 Posts
Damn, im in a similar boat. 67 with a 408 and tea hiports, hyd clutch and i need 1 7/8" at least, ive been worried about getting stuck at 1 3/4". gonna try accufab and see what they say, fpa will be my next call. was considering the hedman 85004, but never seen them on a car. thanks so much for that info. im actually setting up my external slave this weekend on a toploader... should be fun. gorgeous car man, ill be following the build closely.

730 Posts
Discussion Starter #18
The order for a new Gforce G101a transmission was placed last month and now waiting on the delivery which will probably be 2 more weeks. Since this transmission is a different size than the TKO600, Gforce shipped me an empty case a few weeks back so I could do any fabbing/mods needed in advance.

Things impacted from the different case size were:
1. Transmission cross brace needed to be modified to work with the new mounting location and mount type. As it turns out the cross brace bar was directly under the mount bolts, so I had to slide the slide the cross brace back, and flip the horizontal mount plate from the back to the front.

This is with the TKO before the brace is modified:

Here you can see the mount plate flipped held by the clamps and the cross bar is moved rearward. Nothing has been tack welded yet.

These modifications will allow me to use the same bracket if I ever decide to stick the TKO back in. This mount is stronger and has much more clearance than the stock one, so I should be okay with linkage clearance where as the G101a has external linkage- At least I hope so. There is also another plate that goes under the horizontal plate for additional reinforcement that the mount bolts will go through acting as a washer.

2. The Gforce G101a is a good 2" shorter than the TKO, so I had to move my driveshaft loop forward, to meet the NHRA rules of 6" from universal centerline. I had it right at the 6" so I could remove the TKO without removing the loop. Now it was too far back, so I had to modify my mounting points. Just one of those little things that take time. I have only had my loop even looked at 2 times in the past 3 years by tech inspectors, so it was unlikely this would be caught, but rather not chance it.

3. The shorter transmission, plus a different tail shaft required a new driveshaft. Having the empty case allowed me to do the mock-up and measure for the new driveshaft. I was very happy with my Dennys Driveshaft (chrome moly) that they built a few years ago, so I ordered this one from them. That was ordered and should be here before the trans.

4. With everything taken apart I wanted to work on improving the clutch geometry. With the slipper clutch, the recommended TOB clearance to fingers (pedal up) min .25", optimum .375" and also have the air gap between flywheel/disc (release) at 0.075". With adjusting the linkage I was only able to get just about 0.25 clearance (so at the minimum), and 0.070 gap at one end or .3" with .050" gap at the other end. To increase travel, I lowered the clutch pedal upper rod mounting point which should give the upper rod about 0.6" more travel and with the Z-bar ratio move the fork about 0.2" more and by the time that gets to the TOB, something even less. Some of the additional travel was limited to the lower portion of the Z-bar hitting the headers, so the lower Z-bar tab was modified for additional clearance (forgot to take a pic)

The washer shows where the original hole was located.

I built a jig using an input shaft to more easily measure the TOB airgap and see if my mods did help. This let me adjust all of the linkage while my wife pushed the clutch so I could optimize the travel. The input shaft/TOB retainer sleeve is pinned to that cross board and centered in the scattershield bore. I could then use dial calipers to accurately measure the TOB gap to the fingers as I adjusted the Disc/flywheel gap. I did this before the linkage mods were done as a baseline.
It appears that I now have .065" air gap, with 0.34" TOB/fingers gap. If I increase the airgap to 0.075" the TOB/Fingers gap drops to .28, so definitely have more margin than before. I will remeasure once the trans is installed.

The G101a case is larger where it bolts to the scattershield and it now blocks the clutch adjustment, so another hole had to be made 1" higher. The original one is behind the trans front face.

and with the "domino effect" my damper alignment marks used to align the clutch adjusters with the scattershield hole, based upon the timing pointer had to be redone. Old ones have since been removed.

Now just waiting for the goodies to arrive and hoping to be back at the track the beginning of Sept.

Over the winter the rear end will be upgraded.

5,130 Posts
most things turn into a domino effect lol...its cool they let you borrow a case for mock up
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