Author Topic: Questions about restoring 428 scj engine  (Read 6840 times)

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Roberts Red GTA

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Questions about restoring 428 scj engine
« on: July 18, 2025, 08:28:49 AM »
Hello. Trying to decide on what to do with the 428 SCJ engine in the '69 Cobra.

Here is what I know:

Compression is good in all cylinders except #4 which is 150. I determined it is a leaky exhaust valve.

Leak down test revealed very good results with less than 10% loss at 80PSI on all except 4 which is about 15%

Main journals .010 cut. Plastic guage says .0015 clearance. Appearance is perfect smooth and polished.

Rod journals .020 cut. A little scratched but not excessive. Journal looks perfect. Plastic guage says .002 clearance.

Engine has been bored over .040. Has 2287P pistons.

Heads and intake are stock CJ.

The reason I dug into this is that I had no prior knowledge of the car before I bought it 2 weeks ago.

Had an intake manifold lead which leaked coolant into the oil. I checked the life on the hydraulic lifters as exactly factory CJ.

What would you do going forward? Want a dependable, good running car. More power is always good. Concerned about the .040 bore. Willing to put $ into this, but don't need a 550 HP engine. 4 Speed trans with 3:50 gears which I inted to change to 3.91.

Any thoughts are welcome.

frnkeore

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Re: Questions about restoring 428 scj engine
« Reply #1 on: July 18, 2025, 11:35:00 AM »
If your worried about the .040 over and have a leaking valve, pull both heads and get a sonic test done on the cylinders and get back to us on the results.

What heads are you using?

You can put in .001 oversize MB, I think the rods will be ok.
Frank

'60 Ford Starliner
Austin Healey Replica with 427 & 8.5 Cert

My427stang

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Re: Questions about restoring 428 scj engine
« Reply #2 on: July 18, 2025, 05:59:24 PM »
Hello. Trying to decide on what to do with the 428 SCJ engine in the '69 Cobra.

Here is what I know:

Compression is good in all cylinders except #4 which is 150. I determined it is a leaky exhaust valve.

Leak down test revealed very good results with less than 10% loss at 80PSI on all except 4 which is about 15%

Main journals .010 cut. Plastic guage says .0015 clearance. Appearance is perfect smooth and polished.

Rod journals .020 cut. A little scratched but not excessive. Journal looks perfect. Plastic gauge says .002 clearance.

Engine has been bored over .040. Has 2287P pistons.

Heads and intake are stock CJ.

The reason I dug into this is that I had no prior knowledge of the car before I bought it 2 weeks ago.

Had an intake manifold lead which leaked coolant into the oil. I checked the life on the hydraulic lifters as exactly factory CJ.

What would you do going forward? Want a dependable, good running car. More power is always good. Concerned about the .040 bore. Willing to put $ into this, but don't need a 550 HP engine. 4 Speed trans with 3:50 gears which I inted to change to 3.91.

Any thoughts are welcome.

There are a few of us who do concours or near concours builds for owners like you.  I would look up Anghels Restorations and look around to see how far you are from original.  If you are very close, nothing wrong with going that way, in fact, if you have all the CJ bits, especially things like fittings and PCV setup, carb, etc, you probably should restore it.  If you aren't, you get to choose to try go that way or go with a slight hot rod.

As far as what you see, it would be best to have the block checked for taper and square.  If it was recently rebuilt, has straight cylinders, likely a square deck, torque plate clean up, replace some push in oil plugs with NPT, and maybe get away with just a re-ring, but it depends what you find.  A c-scratch block is "usually" better than others, but should sonic check, then we can get pistons at even .005 larger and just torque plate hone to save cylinder wall.

The crank should be measured more accurately than Plastigauge, but depending on taper, runout and clearance likely reusable

As far as improving, a hydraulic roller cam is always good, adds about 1500 to the build as you build the heads too, best to do some work to the heads to get a good valve spring.  However, I really like NOT using aftermarket rockers on a milder one with stock valve covers.  End stands, hardened shafts, good hyd rockers keep things light, roomy and last forever.  FWIW last all-iron concours 428 hyd roller I did was 485 HP and pump gas / vacuum brakes, it had a little money in it, but won it's class in Lime Rock too, so it looked and acted very stock

https://www.youtube.com/watch?v=mtgO0UFeXIA

If staying flat tappet, if you can determine the cam now, some bluprinting to get things right, degreeing the cam, and a few other tricks can make them run well too. 

In the end, think hard what you want the car to be, then find someone who can help you find the target.  Welcome to the forum


« Last Edit: July 18, 2025, 06:01:07 PM by My427stang »
---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

oldiron.fe

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Re: Questions about restoring 428 scj engine
« Reply #3 on: July 18, 2025, 06:36:27 PM »
    x2 -my427- but add has seen some use how hard always ????- mag crank store the rods  -- i know they are used over many builds-- i have been running fe iron for 60 years now --orgional rods    may be ok - at min. check the web about 1-1/2 inch below pin some rods you may damn near see through-- over all the years a friend had a new factory side oiler short block --rod broke at about       first time at around 3500 rpm  almost no material in web- i had 390 do the same thing 2500/3000 on interstate same thing rod just no good also they have a life cycle-- store for a numbers guy but    do not possibly destroy a lot of good parts/work on a bad rod-- if you dont have a egg on the footfeed - use deeper front sump pan or accumlator or extra qt. at min and windage screen not flat tray   type-- good times w/fe-- john-oldiron
66' Fairlanes 427 (08/26/67- present)
66/67' Fairlanes
70' Mustang Fastback
66' Dually

jayb

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Re: Questions about restoring 428 scj engine
« Reply #4 on: July 18, 2025, 10:41:14 PM »
.040 over isn't a concern in my opinion, a good 428 block will handle .060 over despite what you may have read on the internet.  Your leakdown checks don't sound too bad either, and it won't lose a lot of power with a leaky exhaust valve.  You could run it as-is for a while if you didn't want to go through a major teardown.  Standard hot rod stuff, intake, carb, headers and cam will pick you up a lot. 

By the way, my 69 Cobra has a .060 over 427 block, made up to 675 HP as a 492" stroker years ago when I did all my intake testing, and still runs fine today at the 600 HP level.  It has a Performer RPM intake, FPA headers, a Holley 1000 HP carb, and a pretty stout solid roller cam.  If you went with a hydraulic roller cam and maybe a 750 double pumper carb, you could easily get to 500+ HP.

In short, my advice is run it; don't tear it down unless you have to.
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

Phil Brown

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Re: Questions about restoring 428 scj engine
« Reply #5 on: July 19, 2025, 10:18:20 AM »
Pull the heads and get the valves touched up to fix #4 then drive the wheels off of it and enjoy it

6667fan

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Re: Questions about restoring 428 scj engine
« Reply #6 on: July 19, 2025, 02:36:41 PM »
We, (I), need pics of machine. Is it a Formal Roof or FB?
You are in the right place being on this forum.
JB


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482 cid 636/619.
Tunnel Wedge, Survival EMC CNC heads, Lykins Custom Hydraulic Roller, Ram adjustable clutch, Jerico 4-spd, Strange third member with Detroit Locker, 35 spline axles, 4.86
10.55@125.74 1.46 60’

Roberts Red GTA

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Re: Questions about restoring 428 scj engine
« Reply #7 on: July 19, 2025, 07:55:16 PM »
Here are some photos. I don't have photos of the cylinders yet, but they have the 2287P pistons .040 over. I mic'd the bore and came up with .006 cylinder to piston. I know plastic gauge isn't real reliable, but the rods were .020 larger with .0025 clearance. The crank is .010 under with .0015 clearance.

Add'l it looks like the CJ heads have hardened seats? When I removed a valve there was no evidence of any port work.

Here are some photos I have.

Roberts Red GTA

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Re: Questions about restoring 428 scj engine
« Reply #8 on: July 19, 2025, 08:00:23 PM »
more photos

Roberts Red GTA

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Re: Questions about restoring 428 scj engine
« Reply #9 on: July 21, 2025, 10:21:54 AM »
The '69 Cobra.

rockhouse66

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Re: Questions about restoring 428 scj engine
« Reply #10 on: July 21, 2025, 06:49:14 PM »
I had a red formal roof Torino GT CJ car.  Love the look and ride quality was excellent too.  I would rebuild the heads and carry on for now.
Jim

Roberts Red GTA

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Re: Questions about restoring 428 scj engine
« Reply #11 on: July 22, 2025, 08:13:10 AM »
Thanks. I have come to the decision to replace the rod bearings. Crankshaft looks excellent. A little tight at .0015 clearance. Still thinking of the edelbrock heads for weight savings and detonation concerns. The camshaft is stock CJ and the dial indicator says it is exactly to specs on lobe lift. At .040 on the bore and the good leakdown results before removing the heads, I will leave the engine in and just deal with the top end.

Brent Lykins mentioned that a cam change could net more hp. I would be willing to do roller hydraulic, etc.

Not sure yet here. With a .040 bore and old style forged pistons, don't know how durable the lower end would be making another 100 HP as I am also looking at headers instead of the CJ exhaust manifold.

Not sure. But I definitely want nicer drivability.

frnkeore

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Re: Questions about restoring 428 scj engine
« Reply #12 on: July 22, 2025, 11:55:32 AM »
It's always a slippery slop when modifying a engine but, a few quick things you could do is change out the intake, heads and water pump, for aluminum. That will net you at least 120 lb less weight and give you enough hp to be very noticeable with the header change. Head bolts will need to be replaced,  too.

I wouldn't worry about the pistons. Those old, forged pistons are very tough. Those are the things I would do, in the car, with good compression but, if it's out, just open your wallet and do a complete rebuild, including honing, decking, modern pistons and a roller cam.
Frank

'60 Ford Starliner
Austin Healey Replica with 427 & 8.5 Cert

My427stang

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Re: Questions about restoring 428 scj engine
« Reply #13 on: July 22, 2025, 12:55:09 PM »
Thanks. I have come to the decision to replace the rod bearings. Crankshaft looks excellent. A little tight at .0015 clearance. Still thinking of the edelbrock heads for weight savings and detonation concerns. The camshaft is stock CJ and the dial indicator says it is exactly to specs on lobe lift. At .040 on the bore and the good leakdown results before removing the heads, I will leave the engine in and just deal with the top end.

Brent Lykins mentioned that a cam change could net more hp. I would be willing to do roller hydraulic, etc.

Not sure yet here. With a .040 bore and old style forged pistons, don't know how durable the lower end would be making another 100 HP as I am also looking at headers instead of the CJ exhaust manifold.

Not sure. But I definitely want nicer drivability.

If talking to Brent, he will steer you right, but I'll throw my opinion based on what I would do if you wandered into the shop. 

1 - Headers and a modern exhaust with crossover, be sure to use ceramic coated headers in a unibody to control heat
2 - Recurve the distributor based on what you end up with for parts
3 - I'd not bother with Edelbrocks, they save weight but don't perform much better than a CJ head.  You could do a modern multi-angle job and 11/32 valve on what you have and do better (minus the weight savings).  I also do not consider an Edelbrock being any better for detonation for a properly tuned car with the right parts.  TFS with a small modern chamber, maybe, but would have to look close at valve clearance
4 - I'd absolutely go with a custom hyd roller, it will be your biggest gain beyond the headers.
5 - The CJ intake works well, but really heavy.  I like a Performer RPM intake unless it's a shaker or Ram Air car, then you need to look at carb position.

A CJ with a modern cam, built to match use, and a nice vacuum secondary, CJ or aftermarket, will be a strong runner and if done well, extremely drivable.

As far as your clearances, bearing manufacturers vary noticeably, I tend to see FM 125M the loosest, but you could also try a King or Clevite (I use Clevite the most due to consistency).  Don't be afraid to deburr the bearing either.  I'd really like to see you at .0025-.003, especially on a used block and crank.
« Last Edit: July 22, 2025, 12:57:01 PM by My427stang »
---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

Roberts Red GTA

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Re: Questions about restoring 428 scj engine
« Reply #14 on: July 22, 2025, 02:08:03 PM »
First of all, thanks to all for the replies!

My goal is 450 or so HP. More better, but not at the cost of drivability.

What roller cam/lifters? The long term goal is power brakes and 3.91 alxe ratio. The car has a 4 speed transmission.

I have a set of Hooker supercomps ceramic on my '66 gta. And, though difficult to get in there, seal excellent. The negative is how low they hang. I understand FPAs are better at tucked under. Dougs? I would love a sugg here.

The valves look good. I removed the exhaust valve to inspect. Looks completely stock. Old of course.

The RPM intake for sure. Thinking of a 780 VS Holley.

The car still has the stock distributor. Amazing.