Club Cobra - 302 HO Build Pre-planning

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302 HO Build Pre-planning

Bonjour, ça va? (That's French for "yo, what up dog?")

I may have taken some liberties with my translation.

This seems to be the place where real Ford engine experts hang out, so I thought I'd post this up and get intelligent feedback.

Planning out a build to go in my 1987 Mustang LX (5-speed).

Bottom end: .030 302,
Pistons: Trick Flow
Piston Head Volume: +2.00cc
Crankshaft: Steel, 3.00" stroke

Heads: Twisted Wedge 11R 170CC runners/53CC chambers
Rockers: Crower's shaft-mount
Cam: Trick Flow HR-236/359-2S1-10
Lift @ valve: 0.542 int./0.563 exh.
Dur @.050: 224° int./232° exh.
Lobe Separation: 112°

Intake option 1: Holley Systemax
Intake option 2: Speedmaster ITB

Exhaust option: BBK Long Tube

Oil Pan: AVIAID Road Racing

Engine Management: Pro-M

Use: Mostly spirited driving. I want strong, but I'm not going racing. I do like higher revving engines--don't know why.

Chassis Info: Maximum Motorsports torque arm, Bilstein HD shocks & struts, Cobra brakes, etc.

Differential: 3.73:1

Any thoughts? Real thoughts, I mean. Am I way off on cam?

Previous versions of twisted wedge cylinder heads required specific pistons to fit the non-stock valve angles. Be sure and check on the new versions.

53cc combustion chambers are kinda small, depending on the type of pistons you plan to use. Be sure and calculate static and dynamic compression.

Jasper is a pretty good rebuilder for stock replacement engines. Not so much for high performance stuff. Be sure and check deck height on ALL cylinders.

Quote:

Originally Posted by bobcowan (Post 1511118)

All good info.

Pistons should be factory style flat tops, which, if I did the calculations correctly, should net me a static compression of 10.5:1.

I've personally not had good luck with them. Received a service truck with a new jasper engine twenty five years ago. Lasted 5k mi. spun mains. Bought a Suburban with a 3k mile SBC and the lifters failed after 13k miles.

My FIA has a 351 and I personally put together my current engine after the third engine from them that failed. Granted, they were ran really hard. 9k miles and i built the fourth engine myself. When this one lets go, Its on me.

Quote:

Originally Posted by incoming (Post 1511121)

The good news is, I'm wrong. I read the info the guy put in the ad when I bought the car. It's a "50K mile 1990 engine, NOT a Jasper or other rebuild."

Doh!

Quote:

Originally Posted by WordMan (Post 1511122)

The good news is, I'm wrong. I read the info the guy put in the ad when I bought the car. It's a "50K mile 1990 engine, NOT a Jasper or other rebuild."

Doh!

Quote:

Originally Posted by incoming (Post 1511121)

Quote:

Originally Posted by bobcowan (Post 1511118)

Okay, I need to stop being cheap with the bottom end when I'm willing to spend the money on the top. Instead of using the short block in the car, I'll build a new short block.

I changed the specs in my OP, but here it is again:

Bottom end: .030 302,
Pistons: Trick Flow
Piston Head Volume: +2.00cc
Crankshaft: Steel, 3.00" stroke

Compression calculation with the deck clearance set to .006" is 10.63:1 with 53cc heads and 10.25 with 56cc heads (assuming a .060 head gasket).

If you use a .060 head gasket, that gives you a quench area of .066. That's way too much. Should be much closer to .040. You need a gasket closer to .035'ish.

Be sure to calculate dynamic compression with the big cam you're planning on. Keep that around 8.0 or so.

Quote:

Originally Posted by bobcowan (Post 1511129)

All the head gaskets I can find list .050 as compressed thickness. Never mind... found them.