gt40 heads
 

I just got my 88 gt running and was looking into some bolt ons for some extra power. My motor is bone stock and im running a set of hooker super comp headers (long tubes) off it. I found a set of gt40 heads off ebay for pretty cheap and was wondering if they would be worth the time.

http://cgi.ebay.com/ebaymotors/FORD-...QQcmdZViewItem


How much horsepower would they add and are they too terribly hard to install? Also would they work w/ the stock setup and would the hooker headers fit?

James

Re: gt40 heads
 

I dont have a lot of money to spend right now so those heads looked good but should i wait on working on the engine and maybe buy gears first. I have a 5 spd so i dont know what the best set up is gear wise. Any help would be appreciated. Gears first or go ahead and start engine work?

Thanks

James

Re: gt40 heads
 

Im not too sure about the heads, but gear wise i believe 3.80's or 4.10's are a good choice with a 5spd. There is a really good program which allows you to put in gear ratios of both your transmission and read end, then tells you what your RPM's are at certain speeds. Search on the net for it, I cant remember what the name is. (its on my other computer, when i head home i can tell u if i remember)

Re: gt40 heads
 

Those are GT-40P heads which are different from the regular GT-40 heads. Good heads but one of the differences is the spark plug angle which will require you to run a different set of headers.

Re: gt40 heads
 

I havent really thought about this much but my new hooker headers already are in contact w/ the wire boots. This is because the spark plugs are already angled. thats prolly a big problem as it will just burn the boot right off. What heads would work with this application. Which heads have a straight spark plug line instead of angled?

James

Re: gt40 heads
 

http://www.5speeds.com/rpm.htm There is the link to that RPM program. Its pretty cool. Good luck

Re: gt40 heads
 

It all depends on what you want to do with the car. If you are looking to get speed out of her, and the best bang for ur buck, throw in the 4.10's and you will still have decent street manners. If that is too much, at least put in a 3.73. I would gear it before I even messed with the heads.

When it comes to heads, I would save your money for a nice good set, unless the right deal came along.
Ryan

Re: gt40 heads
 

Prolly a dumb question but what is the big difference between 4.10's and 3.73's. Like if i get 4.10's what will my car do differently than a stock application. Also i think i am going to go w/ the gears first before the heads. Id rather get the smaller things done and then hit the engine all at once (new intake, heads, rockers, etc)..

Re: gt40 heads
 

The 4.10's are gonna give the car better acceleration, due to a better gearing ratio. The down side is they will top out at a lower top end speed. This use to be a major trade off in the day of 4 speeds, but with a 5 speed having that tall 5th gear, you loose very little top end.

Ryan

Re: gt40 heads
 

Awesome....the 4.10's seem like the way to go. And I believe I am going to do that first and tackle the engine all at once. Thanks for the help guys.

Also, how long does it take to install the 4.10's? Is it real complicated once you get into that differential? What other parts do I need to purchase besides the gears for this swap (gaskets, etc...)?

thanks

Re: gt40 heads
 

I personally wouldn’t tackle the gear change alone without some help. They are not supposed to be overly hard, but if you don’t get things shimmed right, they can end up failing.

There will be guys that speak up here, who know more on this then me.
Ryan

Re: gt40 heads
 

do yourself a favor and take it to a tranny shop and have a pro do the gear swap. The way it was explained to me a few years ago is that the older the diff. is the harder it is to swap in new gears and get them shimmed right. I do everything myself, but I wuldn't touch the gears. As for the heads, those GT40p heads are off the 5.0 exploders, and need special headders. Thoses hookers you have will mate up with just about most of the after market heads out there.

Re: gt40 heads
 

Yah...it seems taking it to the shop would be the best idea for the years. This is the first car that I have tried to work and therefore im learning the mechanical side as I go. Im sure i would mess something up real bad.

Re: gt40 heads
 

I agree about taking the car to to a shop to have the gears done. Even expereienced "shadetree" mechanics will usually leave the gears to the professionals, just to make sure they get shimmed correctly. You'll be very happy with the gears....best bang for your buck modification out there.

Don't rush in buying too many parts for your engine. It sounds like you ought to do a little more research and plan out your combo. If not, you'll end up with mismatched parts that don't perform like you want them too. Keep asking questions here....lots of knowledgable people are lurking around this place. Good luck.

Re: gt40 heads
 

I dont know why everyone is afraid of changing out gears. It is easy money if you buy Ford gears.

Re: gt40 heads
 

Well i see you live in Indianapolis as do I...so you can do mine if it will be cheaper for me :D

James

Re: gt40 heads
 

Because some individuals just dont need to be messing with gears :D no diss on anyone, But any doubts in your mind can screw ya up, i almost quit on mine numerous times
when i did mine..... :p with limited time and tools, they are not fms gears, but I succeeded, I just measured the backlash, rotated everything, and it would bind, finally I had my backlash set, tried using a new crush sleeve, but used my old one(not recomended) everything works fine, except now i hear a whine only when i take sharp left turns? sounds like an axle bearing, all in all I think most people need to leave the shimming of a new posi, to a shop, especially If you never done any kind of differential work, or seen one exposed.

Btw, gt-40 heads are alright (ported), just make sure you have some good springs on them.

Re: gt40 heads
 

If you don't have the correct pinion depth or backlash, gears will start making noise and/or will fail prematurely so it's critical they're installed right. Some people who just throw the shims back in may get lucky, but if you want them to last along time without noise it's just better to do it right