Engine New Cam or Different Rockers?

93CalypsoConvert

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Nov 26, 2020
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I got the GT40p heads. They look great and there doesn't seem to be any issues. Added bonus: The heads already have upgraded valve springs. Upon further inspection, I actually have a roller cam/lifters. I find it interesting that the previous owner told me it was flat tappet, considering he, well, owned the thing.
 
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Wayne Waldrep

Before I post a pic, do you have one of yours?
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Great thread to read! :D
Looking forward to hearing your thoughts and results as you do this project.
 

Potomus Pete

Gretchen Whitmer is eating at me
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I wish somebody could put the 1.7 rocker kit part numbers that we could use on stud mount stock set up. Some say 1.7 adds decent small hp's, and on Corral they say no extra at all.
 

Wayne Waldrep

Before I post a pic, do you have one of yours?
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This applies to mild hp efforts....
Y'all know how I feel about mild hp gains on a fox body. Whether you have 200 or 325, you are still way below every current performance car and equal to or below half the normal cars....like a Sentra or Accord. Most family sized SUVs can outrun you. So what does that mean? Make your car enjoyable to drive and dependable. Forget hp cause you won't have enough. Put your money in good brakes, nice suspension, nice seats, paint (I need that!), good looking wheels and tires, a good audio system. Make people see your car and say "damn, look at that old Fox body!"
These are just my thoughts. I have nothing against tinkering with engines. I've been doing it for a long time. Just don't concentrate on more hp at the expense of everything else. Again.....what does even 75 more hp honestly get you? An Acura SUV only outruns you by 2 lengths instead of 6? :jester:
 
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Mustang5L5

Put lubricant all over the balls
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E7533399-D950-4DD8-8EE1-614D6533A7EF.jpeg
 
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7991LXnSHO

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This applies to mild hp efforts....
Y'all know how I feel about mild hp gains on a fox body. Whether you have 200 or 325, you are still way below every current performance car and equal to or below half the normal cars....like a Sentra or Accord. Most family sized SUVs can outrun you. So what does that mean? Make your car enjoyable to drive and dependable. Forget hp cause you won't have enough. Put your money in good brakes, nice suspension, nice seats, paint (I need that!), good looking wheels and tires, a good audio system. Make people see your car and say "damn, look at that old Fox body!"
These are just my thoughts. I have nothing against tinkering with engines. I've been doing it for a long time. Just don't concentrate on more hp at the expense of everything else. Again.....what does even 75 more hp honestly get you? An Acura SUV only outruns you by 2 lengths instead of 6? :jester:
That's just depressing, Morgan Freeman Meme or not.
 
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Wayne Waldrep

Before I post a pic, do you have one of yours?
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That's just depressing, Morgan Freeman Meme or not.
Lol... Well, it took me longer than most to give up my all out street racing mentally where I wanted every last bit of hp. But in those days, we could complete. I see my car now as a cool old mustang that used to be fast. I don't need more than that now. I don't want to break it just to win a race. Don't care to risk my life just to beat a loud mouth. So cool cruiser is fine with me now.
Now if the op wants to keep rolling with his mods I'll be happy to read about it!
 
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93CalypsoConvert

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Update: Got the heads on. Lapped the valves, cleaned mating surfaces, and installed. Took a while but got everything put back together. I screwed up the firing order and thought something major was wrong. whoops. There is a noticeable increase in power and everything is running well. New headers are still on the way... still have the bad stock ones for now. I'll post another update with the part number if I can get those to fit without plug clearance issues.
Engine.jpg
 
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Potomus Pete

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How noticeable. Would you do it again , and how is the power all the way through the throttle. You have to remember the GT 40 heads have become the topic of conversation on many Mustang forums. I would love to do it, but of coarse I have read so much that aluminum aftermarket is the way to go.
 

93CalypsoConvert

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How noticeable. Would you do it again , and how is the power all the way through the throttle. You have to remember the GT 40 heads have become the topic of conversation on many Mustang forums. I would love to do it, but of coarse I have read so much that aluminum aftermarket is the way to go.
I don't know how to describe it very well, but its enough of a difference to warrant a "holy crap" the first few times I dipped into it. You don't have to push the throttle near as hard to get the same result as before. Difference is present in the whole rpm range, but I think upper end is still choked from exhaust... I'll let you know once my headers get here (and if they fit, of course). I would do it again. I considered aluminum too, but as far as cheap power goes, I think 40s are the way to go. Total cost of the project was about $500.
 
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Monkeybutt2000

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I hope you went long tubes because there's really no difference in shorty headers. There's nothing wrong with the gt40 setup,I went 12.80's with the stuff. And as far as an Acura suv outrunning your Mustang,unless you're a terrible driver it's not gonna happen. Looked it up,the newest one runs a 14.2, that was the exact time I ran on my very first pass in my old 87' LX. Just sayin'....
 
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General karthief

wonder how much it would cost to ship you a pair
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Long tubes with gt40p heads will pose a problem with a couple spark plugs, shorty headers work better and I think there is still some made to fit the P's. You really will not lose much, just a little bottom end torque.
I should say 'may' cause issues, I had that setup and was looking for ways around the burnt plug boots when things went south (that's not racist to say yet is it?) with that engine.
 
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Potomus Pete

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He better read up because there are issues even with shorties. Certain brands don't work with the GT's. I have read a lot about GT's because I want some. They make sense for cost , and weekend cruisers. I like the way you can use standard rockers. Plus I like iron on iron to save on major head gasket issues.
 

General karthief

wonder how much it would cost to ship you a pair
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He better read up because there are issues even with shorties. Certain brands don't work with the GT's. I have read a lot about GT's because I want some. They make sense for cost , and weekend cruisers. I like the way you can use standard rockers. Plus I like iron on iron to save on major head gasket issues.
It's not the GT40 3 bar heads, the issue is with the P's 4 bar heads spark plug angle.
aluminum heads do not have head gasket issues, they have installer issues.
 
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Potomus Pete

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And I would be the installer that would have the head gasket issues...I have never done one, and I fear the head gasket. I would think with the GT heads you don't need tall valve covers. Another plus.
 

93CalypsoConvert

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Installed the headers. I can confirm the Speedmaster 746-PCE316.1002 will fit GT40p heads without clearance issues. I have 45 degree plug boots, but I think normal ones would fit too. Might touch the header though. The only piece I had to remove to make them fit was the dipstick.
Headers1.jpg

The driver side was a little more crowded, but the plugs were pretty much in the same spots.
Headers2.jpg

I haven't had a chance to see if there is a difference in power yet. Sounds better idling.
 
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