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I have read and have been re-reading tons of forum, articles and anything else I could find on searches about increasing the HP in 68 289. My long term plan is full roller 331 with TW 11R's but just bought another home and moving in a month....so the big pause button got pressed...just as the movie was getting good.

With the 331 on pause I started my research on what I could do to my current engine. It's a 6000-7000 recent rebuild to stock spec low compression 289 from PO. It currently runs good, J-code intake and rebuilt autolite 4100. It doesn't burn oil, compression is around 145 and even within 5 on all cylinders. It's also the original block with a partial vin stamp.

I've been through the "mill heads, home port, new intake, install my new MAC headers and a cam designed to increase cylinder pressure numerous times in my head. No doubt it will add some ponies but it won't be what I want or usable on the 331. So money down the drain.

I am moving to Ohio so I will have some "winter project" time. Current plan is to send the dizzy to Dan and get it recurred, pull the heads and do a home port job, installed my headers and 2.5 exhaust and enjoy it while I save.

I will store the vin stamped engine and vin stamped c4...

It only took me 4-5 month to gain my senses.
 

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I am moving to Ohio so I will have some "winter project" time. Current plan is to send the dizzy to Dan and get it recurred, pull the heads and do a home port job, installed my headers and 2.5 exhaust and enjoy it while I save.
Add a C9OZ-C cam, 600 cfm carb, and Performer RPM or Cobra intake (stuff you'll need for the 331 anyway) and you'll be getting about 320 hp. At that point, you may decide to bag the 331 altogether, since that would be slightly more hp than a 65-67 GT 350 Shelby. (and MORE than a 68 GT 350).

A cam change is a Saturday project. Actually, since you'll have the heads off, it only adds a couple hours to the job. One hint- Replace the timing set when you do it.
 

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Discussion Starter #4 (Edited)
Add a C9OZ-C cam, 600 cfm carb, and Performer RPM or Cobra intake (stuff you'll need for the 331 anyway) and you'll be getting about 320 hp. At that point, you may decide to bag the 331 altogether, since that would be slightly more hp than a 65-67 GT 350 Shelby. (and MORE than a 68 GT 350).

A cam change is a Saturday project. Actually, since you'll have the heads off, it only adds a couple hours to the job. One hint- Replace the timing set when you do it.
Funny that you posted, actually that was exactly my plan from reading all your other post. Combo wise, my car is actually set up great for that combo. Car has a rebuilt C4 with 24-2600 stall and 3.40 gears with true-tac. The issue is the engine will be low compression (63-63cc heads) compared to the 54cc heads of a 65-66. Your referenced set-up is what drove my thinking to milling the heads etc. I just don't know how to pull all the math out of the cam numbers to calculate static/dynamic compression. I would go down that exact route you referenced with the comp cam 268h (same duration/lift is close) but with the tighter LSA I would loose vacuum for brake booster/c4 as compared to the C90Z-C cam at 113 LSA. A safe mill on the factory heads will only the bring CC's down to 58-59 without affecting intake etc. By rough math I would be in the low 8's compression wise with milling the heads. I even thought about finding a set of older 54-55cc heads but I would put 4-500 into them getting them runnable and at that point I would be 40% of TW 170 FAC heads.....and that drove my "came to my senses" post. I mean the 170's would work on a 331 but the 190 11r's would be ideal.

You are right though the carb and intake would carry over to the 331.

I even though about putting on the 190 11r's (56cc versions) on my stock block, intake carb, roller cam, linked lifters etc and then just swapping in a 331 when my short block got tired then I started to worry about all the factory hardware in the short block with all the new HP and RPM capability.
 

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Discussion Starter #6 (Edited)
"I've finally come to my senses"

Thought you were going to sell the car when I saw the title!
NEVER!!! 68 is my favorite year (it's a coupe) and i finally found a driver that was in my price point to fix/upgrade as I drive. The other cool factors for ME was the car was build in san Jose and the regional office is Los Angeles. That is where i was born and raised until I joined the military and moved away at 18. It's a factory A/C, P/S car. The PO owner was turning it into a GT. He found installed a date correct J-Code intake and Autolite 4100, installed some GT headlights and pop open gas cap. The interior is all redone as well. The paint was horrible! but it's now acceptable after I spent many many hours color sanding/buffing it out. Since it was a half way looking GT I added a dark blue ( wimbeldon white with two-tone blue interior) GT C-Stripe to the car. In my opinion it totally changed the look and I'm loving it.

Car is a great runner minus little stuff that i enjoy researching/fixing.
 

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Not in my opinion, but they're your dollars. I agree with 22GT, I personally like the sound and performance of the HiPo cams and the standard 289 stroke with higher compression and higher RPM. There is no rule that says you can't turn 5000-6000 RPM on the street. The HiPo build strategy permits that all day long. But that's just me.
 

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IMHO, home port your existing heads and call a cam grinder for a suggestion based on your specs. Getting a cam ground to increase dynamic cylinder pressure can make up somewhat for the lack of static compression. The only thing you want to be careful of is the potential for detonation due to the increased heat and large squish area.
 

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IMHO, home port your existing heads and call a cam grinder for a suggestion based on your specs. Getting a cam ground to increase dynamic cylinder pressure can make up somewhat for the lack of static compression. The only thing you want to be careful of is the potential for detonation due to the increased heat and large squish area.
for a hyd tappet....elgin? or someone of that sort?

I guess it will all unfold once I pull the heads off, i can then measure piston depth in the hole. Bore circumference etc. (who knows PO may have put non stock compression height pistons in there) I know from borescope that they have 4v reliefs and it looks like there is circular depression in the middle.
When I used the borescope the pistons tops were clean without a carbon build-up/stains. The walls still looked clean with cross hatching.

so if I pulled the whole engine and pistons/walls looked great, how much is it to to have machine shop install new APR rod bolts? That would give me assurance if i went with custom cam/port work on factory heads etc to rev it.
 
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