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9 Posts
Discussion Starter #1
Good Morning Corral Crew,

I am too cooped up with COVID-19 and finally got around to posting this. I am currently in the middle of rebuilding (tip to tail) my 88' convertible that I drove in High School back in 2010-11. During that time I built a 331 for her and had it dyno tuned. The car ran great but something happened with the tune or a sensor and it started to run super rich. Cylinder walls got washed and eventually started to burn a lot of oil. I also suspected my block was not cleaned very well before the first build.

With new budgets, attitudes and an engineering degree later, I realized I made a few mistakes on the build but want to run it by the wizards to get their take on my next steps.

Reliability is big one for me
Drive to Work a few days a week from early Spring to late Fall
Cruise on Sundays
Run 3-5 Auto Cross Events in Great Lakes Region
Maximized my combo with above goals in mind

Engine Build per posted Dyno charts below:
Converted to Mass Air
Stock Bock
DSS 331 SX Rotating Assembly (-5 cc Flat top pistons)
Compression Ratio ~9.3-9.7:1 (unknown deck height)
Ford Racing Z304 cylinder heads, dual springs (non offset rocker style)
FRPP 1.6 Rockers
Trick Flow Stage 2 Cam
Edelbrock RPM II intake
70 mm Throttle Body
30 lb Summit Brand Injectors
Mac 1 3/4" Long tube headers
3" H-Pipe with Borla XR-1's dumped at rear axle (no cats)
Stock Clutch Fan
All Accessories Mounted
3.73 Gears w/T5 Trans

Mustang Dyno:
333 RWTQ

Modifications done or considering since:
TMoss Ported Lower RPM II to match 1262 port
Contour Electric Fans
A/C Delete
AFM Power Pipe
Multi Spark Ignition Box
Adding High Flow Cats (dont want to smell like exhaust everytime I run her) Any recommendations?
Cleaning Up Bowls and casting flaws in runners for Z304's
Valve Guide Align/Hone with performance valve job
Machine new to me roller block:
Bring Compression Ratio to 10:1 with gasket thickness and known deck clearance/height
Hone with Torque plates
Align hone Main Caps

Windage Tray
Under drive Pulley's (not alternator)
Custom Camshaft

Let me know your thoughts, reliability is huge for me. I want to build and enjoy for now. :)

My next build will be a dedicated SCCA or NASA mustang for Road Racing once I get my feet wet with Auto Cross.

Thanks guys!

134 Posts
Hmmm I would think you should be making more power with the Z304 heads. My 331 combo is very similar to yours, except 10:1 compression, and Edelbrock Performer heads with xe274hr cam. Mine makes almost the same Horsepower, and a good bit more torque than yours. I'm also running short tube headers with 30 pound injectors.

Am I wrong for thinking the Z304 heads should be making at least 70 more horsepower than my Performer heads?

315 Posts
I would try to figure out what's wrong with it before you spend any money on new motor, only to mess up new motor with same problem. Computer capacitor burnt, bad tune/chip, bad injectors, bad MAF, bad o2 sensor, etc. Then once you get it running correctly do compression check n leak down test to determine if motor needs rebuilt or refreshed.

412 Posts
I drove my 1990 vert in high school too. Bought it ‘01 and graduated ‘03. I still have it so I can relate and I like your story.

As far as the engine goes there’s a ton of different ways you can go. If you have a HP goal that may help others give you advice.

Tail pipes would help your exhaust smell issue. You can change the bumper to a 1993 Cobra and they’ll look really good.

I wish I would have added a real roll bar to mine when I had the interior ripped out. This would also open up seat belt options for you if yours ever wear out, look like crap, or whatever. Vert seatbelts are difficult to find in good shape.

If you need any vert specific parts let me know I’ve amassed quite the stockpile after 19 years of ownership.

4,262 Posts
Removing A/C from my '89 convertible is one of my biggest regrets. Even with the convertible, there are plenty of times I wish I still had A/C; I'd keep it if I were you.

7,332 Posts
Keep the AC.

Regarding cats I've got a lot of friends that swear by the magnaflow ones for both being very effective without killing HP. I think it was only a difference of 7hp on a 500rwhp terminator.

Formerly LSNotch
832 Posts
Bigger TB if you are to use a power pipe - how big is the maf?
Custom cam is a plus
Windage tray is good as the rpms go up

As long as the machining is done right and well balanced I don’t see why it won’t be reliable. If you beat the piss out of it with a tune on the ragged edge nothing will last. Lastly it seemed like it’s a strong runner. Good job!
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