Engine rebuild 99 GT

JohnyD05 · Nov 20, 2009

I had a spark plug come out of the PI heads on my motor. While the shop looked at it they told me I had low compression in 4 of the 8 cylinders. Presumably due to the rings going bad. (Had an issue running it a long time ago with low oil.. doh.)

I am going to be pulling the engine out and inspecting the cylinder walls. If they are in good shape can I just install new rings and put it all back togather. With Stock pistons and rods. Should I use new rod and main bearings and all new gaskets? I am hoping to get away from having the block machined at all.

I am looking at replacing the heads with the new Trick flow heads. Will the stock pistons/rods handle these new heads and a set of cams?

What are peoples thoughts on stroker/larger bore engine builds?

Just looking for some general input tips, tricks or any input. Am I crazy to re-use the stock bottom end assuming it is in ok shape. This will be my first engine rebuild.

RedDaemon · Nov 20, 2009

stock bottom end is good (reliably) up to about 425hp

Gearbanger 101 · Nov 20, 2009

If you're going to pull it apart, it only makes sense to inspect and replace the main and rod bearings along with the piston rings. Unless there was any damage done, a good honing of the cylinder walls just to gain a little friction for the rings isn't a bad idea. This would be a good time to replace your stock intake, with the one with the aluminum crossover if you haven’t already.

JohnyD05 · Nov 20, 2009

Gearbanger 101 said:
If you're going to pull it apart, it only makes sense to inspect and replace the main and rod bearings along with the piston rings. Unless there was any damage done, a good honing of the cylinder walls just to gain a little friction for the rings isn't a bad idea. This would be a good time to replace your stock intake, with the one with the aluminum crossover if you haven’t already.

I havn't replaced the stock intake. But I good idea I had not thought of.
Can I used stock sized bearings for rods and crank?

wmburns · Nov 20, 2009

What are your HP goals? Budget? How much work do you want to do yourself? How would you feel if after putting the motor back it, you had to take it back out again? Is this your DD or weekend toy?

IMO, all of these questions should be reviewed before deciding what is "best" for you.

If the engine has been run low on oil, I would have a hard time re-using anything without a complete going over.

What is the reason for reusing the stock bottom end without machining? Is it because of budget constraints? If so, you may put in a lot of work that may have to be re-done.

Explore the salvge yard route. You may find it cheaper to purchase a whole salvage yard motor than the cost of machining the old block. Try Car-Part.com--Used Auto Parts Market. Note, for a salvage motor you may find it cheaper to do the Windsor/Romeo swap. Low mileage 1999-2000 Mustang Windsors are hard to find.

If you lived in Texas, I could make a deal on a 2000 Mustang Windsor.

JohnyD05 · Nov 20, 2009

wmburns said:
What are your HP goals? Budget? How much work do you want to do yourself? How would you feel if after putting the motor back it, you had to take it back out again? Is this your DD or weekend toy?

IMO, all of these questions should be reviewed before deciding what is "best" for you.

If the engine has been run low on oil, I would have a hard time re-using anything without a complete going over.

What is the reason for reusing the stock bottom end without machining? Is it because of budget constraints? If so, you may put in a lot of work that may have to be re-done.

Explore the salvge yard route. You may find it cheaper to purchase a whole salvage yard motor than the cost of machining the old block. Try Car-Part.com--Used Auto Parts Market. Note, for a salvage motor you may find it cheaper to do the Windsor/Romeo swap. Low mileage 1999-2000 Mustang Windsors are hard to find.

If you lived in Texas, I could make a deal on a 2000 Mustang Windsor.

HP Goals are 320-350 rwhp with the trickflow heads, cams and intake. Hope this isn't a pipe dream. I can't do Long tubes because of mass emission laws.
The budget is what it takes to get the car back up and running. I want to do it as cheap as possible while upgrading as much as possible.

If I had to pull the motor back out it would suck, but It wouldnt kill me. This is a toy and isn't my main car.

I plan on taking everything apart and inspecting all of it. I didn't know if I really needed everything machined or not. What are the costs for basic machining?

I did look at some salvage motors and there are some semi decent deals. Not many that are the windsor build, I would prefer to not have to install a new flywheel and all.

I would like to do it all as cheap as possible. toss the head, cam and intake on top get it tuned and see what its got for power.

patman0911 · Nov 20, 2009

Run low on oil to the point that you've got bad compression would worry me if I was planning on making performance upgrades. I'd feel much more comfortable either rebuilding it or throwing a low-mile junkyard motor under those TFS heads, even if you have to swap a few parts around to make it work.

Gearbanger 101 · Nov 20, 2009

JohnyD05 said:
Can I used stock sized bearings for rods and crank?

As long as you were holding oil pressure throughout your normal operating temperature range, your crank is probably in decent shape, but you’ll not know for certain until you get it apart. When you have it apart visually inspect if for any excessive wear or scoring. Anything deep enough that catches your thumbnail in while running it across will likely mean that you probably need to have the crankshaft turned....in which case you would need a set of undersized bearings.

Assuming everything visually checks out with the crank shaft, you can check their clearance with some Plastigage. There should be approx 0.025-0.045mm clearance on the mains and 0.027-0.069mm on the rods according to some of the specs I found.

These specs are for a 4V Mach 1 engine, but the short blocks are virtually identical, as such the specs should essentially be the same as your 2V.

Mach 1 Technical Specifications

MACH 1 Engine Specifications Description Specification
GENERAL SPECIFICATIONS
Displacement 4.6L (4V) (281 CID) Aluminum Block.
Number of Cylinders 8
Bore and Stroke 90.2 x 90.0 mm (3.55 x 3.54 inch)
Firing Order 1-3-7-2-6-5-4-8
Oil Pressure (HOT 1500 RPM) 138-310 kPa
Drive Belt Tension a
Combustion Chamber Volume (cc) 52.6±0.5 cm c
Valve Seats
· Width-Intake
1.8-2.2 mm (0.071-0.086 inch)
· Width-Exhaust
1.8-2.2 mm (0.071-0.086 inch)
· Angle
45 degrees
· Runout (T.I.R.) Max
0.05 mm (0.002 inch)
Valve Arrangement (Front-to-Rear) c
· (Left Hand) Intake:
S-P-S-P-S-P-S-P
· Exhaust:
E-E-E-E-E-E-E-E
· (Right Hand) Intake:
P-S-P-S-P-S-P-S
· Exhaust: (C)
E-E-E-E-E-E-E-E
Valve Stem to Guide Clearance
· Intake
0.020-0.069 mm (0.00078-0.00272 inch)
· Exhaust
0.046-0.095 mm (0.0018-0.0037 inch)
Valve Head Diameter
· Intake
37 mm (1.46 inch)
· Exhaust
30 mm (1.18 inch)
· Gauge Diameters
35.0 and 28.0 mm (1.378-1.102 inch)
Valve Face Runout Limit 0.05 mm (0.002 inch)
Valve Face Angle 45.5 degrees
Valve Stem Diameter (Std)
· Intake
6.975-6.995 mm (0.2754-0.2746 inch)
· Exhaust
6.949-6.970 mm (0.2744-0.2736 inch)
Valve Springs
· Compression Pressure (N (Lb) @ Spec Length)

Intake
711.47 N @ 26.19 mm (159.9 Lb-Ft @ 1.031 inch)
· Exhaust
711.47 N @ 26.19 mm (159.9 Lb-Ft @ 1.031 inch)
· Free Length (Approximate)

Intake
42.16 mm (1.6598 inch)
· Exhaust
42.16 mm (1.6598 inch)
· Installed Pressure (N (Lb-Ft) @ Spec. Length)

· Intake
289.1 N @ 36.14 mm (64.99 Lb-Ft @ 1.4228 inch)
· Exhaust
289.1 N @ 36.14 mm (64.99 Lb-Ft @ 1.4228 inch)
· Service Limit
10% Pressure Loss @ 28.02 mm (1.103 inch)
Roller Follower
· Ratio
1.8:1
Hydraulic Lash Adjuster
· Diameter (Std)
16.000-15.988 mm (0.6299-0.6294 inch)
· Clearance to Bore
0.018-0.069 mm (0.000709-0.002717 inch)
· Service Limit
0.016 mm (1.0006299 inch)
· Hydraulic Leakdown Rated
5-25 seconds
· Collapsed Lash Adjuster Gap-Desired
0.80-1.20 mm (0.0315-0.0472 inch)
CAMSHAFT
Theoretical Valve Lift @ Zero Lash
· Intake (Primary)
10.0 mm (0.3937 inch)
· Intake (Secondary)
10.0 mm (0.3937 inch)
· Exhaust
10.0 mm (0.3937 inch)
End Play 0.025-0.165 mm (0.00098-0.00649 inch)
· Service Limit
0.190 mm (0.007480 inch)
Journal to Bearing Clearance 0.025-0.076 mm (0.00098-0.002992 inch)
· Service Limit
0.100 mm (0.003937 inch) MAX
Journal Diameter (All) 26.962-26.936 mm (1.0615-1.0605 inch)
Bearing Inside Diameter (All) 27.012-26.987 mm (1.0635-1.0625 inch)
Front Bearing Location e
CYLINDER BLOCK
· Head Gasket Face Flatness
0.15 mm (0.006 in) MAX overall
· Head Gasket Surface Finishb

Main Bearing Bore Diameter 72.400-72.424 mm (2.8504-2.8513 inch)
CRANKSHAFT
Main Bearing Journal Diameter 67.481-67.505 mm (2.6567269-2.6576718 inch)
Connecting Rod Journal
· Diameter
52.983-53.003 mm (2.085941-2.086728 inch)
Crankshaft Free End Play 0.130-0.301 mm (0.005118-0.011850 inch)
Crankshaft Runout to Rear Face of Block 0.050 mm (0.01969 inch) MAX
Connecting Rod Bearings
Clearance to Crankshaft
· Desired
0.027-0.069 mm (0.0010629-0.0027165 inch)
· Allowable
0.027-0.069 mm (0.0010629-0.0027165 inch)
Bearing Wall Thickness (Std)f 1.920-1.928 mm (0.075591-0.075905 inch)
Main Bearings
Clearance to Crankshaft
· Desired
0.025-0.045 mm (0.00098-0.00177 inch)
· Allowable
0.025-0.050 mm (0.00098-0.00197 inch)
Bearing Wall Thickness (Std) f 2.451 mm (0.0965 inch)
Connecting Rod
· Pin Bore Diameter
22.012-22.024 mm (0.86661-0.86708 inch)
· Crankshaft Bearing Bore Diameter
56.866-56.886 mm (2.23881-2.23960 inch)
· Length (Center-to-Center)
150.7 mm (5.933 inch)
Alignment (Bore-To-Bore Max. Diff.)g
· Twist
0.050 per 25 mm (0.00197 per 0.9843 inch)
· Bend
0.038 per 25 mm (0.00150 per 0.9843 inch)
Side Clearance (Assembled to Crank)
· Standard
0.15-0.45 mm (0.00591-0.01772 inch)
· Service Limit
0.50 mm (0.01969 inch) MAX
CYLINDER BORE AND PISTON
Cylinder Bore
Diameterh
· Surface Finish (RMS)
0.2-0.6 Microns
· Out-of-Round Limit
0.015 mm
· Out-of-Round Service Limit
0.020 mm
· Taper Service Limit
0.006 mm
Piston
· Diameteri
.028 mm (.0010 inch)
· Coded Red 1
90.167-90.188 mm (3.299-3.5505 inch)
· Coded Blue 2
90.180-90.195 mm (3.5504-3.5510 inch)
· Coded Yellow 3
90.198-90.208 mm
Coated Piston-to-Bore Clearance -0.010/+0.026 mm (-0.0003937/+0.0010236 inch)
Pin Bore Diameter 21.9985-22.0025 mm (0.866081-0.866238 inch)
Ring Groove Width
· Compression (Top)
1.230-1.250 mm (0.484-0.0492 inch)
· Compression (Bottom)
1.520-1.540 mm (0.05984-0.06062 inch)
· Oil Ring
3.030-3.055mm
Piston Pin
· Length
61.601-62.030 mm (2.42523-2.44212 inch)
· Diameter
22.0005-22.0030 mm (0.8661596-0.8662581 inch)
Pin to Piston Fitj -0.0045/+0.002 mm (-0.000177/+0.0000787 inch)
Pin to Rod Clearance
· Standard
0.004-0.0175 mm (0.000157-0.00689 inch)
· Service Limit
0.035 mm (0.001378 inch)
Oil Ring 1.15 mm (0.04528 inch) MAX
· Side Clearance
.075-.1000 mm (.0030-.0040 inch)
· Compression (Top)
0.0090-0.0235 mm (0.000354-0.000925 inch)
· Compression (Bottom)
0.030-0.080 mm (0.00118-0.00315 inch)
· Oil Ring
Snug Fit
Ring Gapk
· Compression (Top)
.150-.300 mm (.006-0.0018 inch)
· Compression (Bottom)
0.300-0.550 mm (0.0018-0.0022 inch)
· Oil Ring (Steel Rail)
0.15-0.66 mm (0.00591-0.02598 inch)
Piston Rings
· Ring Gap

· Compression (Top)
1.00 mm (0.03937 inch) MAX
· Compression (Bottom)
1.00 mm (0.03937 inch) MAX
· Service Limit
1.15 mm (0.04528 inch) MAX

JohnyD05 · Nov 21, 2009

Thanks all for the help. I will post here when the motor comes out over thanksgiving. Maybe some pics too. This will def be a learning experience hopefully it runs when I put it all back together!!!

Is there anyone on stangnet who has put the TF heads on a stock shortblock. Any Idea what kind of power they made?

Engine rebuild 99 GT

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