porting gt40's and RR Q's

viridionplague

New Member
Oct 8, 2007
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so im thinking about porting the gt40's in my 94 cobra along with getting a decent cam


first off is it worth porting the gt40's, also ive heard it is possable to get 1.94/160 valves???


second is that i hear the gt40's have 1.7 Roller rockers already?? would getting aftermarket RR's realy be worth anything? ? would getting a cam such as a TFS stage one cause clearance issues?

also if anyone has any cam recomendations it would be appreciated.

im putting a trick flow track heat intake, 1 inch spacer, and a 75 mm throttle body on at the same time. the intake is rated at 1500-6500 rpm.

im wondering if i would need new spring to accomodate the increased flow of ported heads and the intake, as well as the higher rpm??
 
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The heads are worth it if done well. Don't worry about getting a 1.94/1.60 valve, won't help you much on that head and it would be really close to the water jacket.

Do you already have the intake because for the rpm's you gave, a cobra can get the job done with some porting. Read up: http://www.tmossporting.com/tabid/3451/Default.aspx

Regarding the rockers, you don't need to buy aftermarket 1.7s, the stockers will work fine.
 
i already spent the money for the intake, this is what i got.

TFS track heat upper and lower
1 inch spacer
75 mm bbk throttle body
arp bolts and gaskets

got that stuff for just under 700 shipped.


plus i can sell the cobra intake and stuff and make some of that back.


the guy doing the porting builds race engines so he knows alot about porting and is good at what he does according to a few sources.

i plan on going with 1.90/1.60 valves, matching the intake ports to the manifold.

ill probably get the exhaust side gasket matched and try to get my exhaust manifold matched if it needs to be.

now just comes to cam selection???

any suggestions?????
 
those heads are good if properly ported. you will spend a good chunk of change getting them ported, good valve job etc. i think it would really only be worth it if you could port the heads yourself though. if your going through all of that to pay to have them ported, you would be better off just getting a set of aluminum heads. less weight on the front end and better port designs.
 
those heads are good if properly ported. you will spend a good chunk of change getting them ported, good valve job etc. i think it would really only be worth it if you could port the heads yourself though. if your going through all of that to pay to have them ported, you would be better off just getting a set of aluminum heads. less weight on the front end and better port designs.

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Its just not cost effective :nono:
to dump a bunch of money in an old OEM iron head :crazy:

Now ... Like was said ... if Y O U did all the labor .......

Maybe ... and I emphasize the word ... Maybe ;)

Your time is worth something :nice:
and
To properly port some old iron heads :eek:

Well ... Its gonna take you a more than just ... An hour or two :Word:

Grady
 
I'm going to have to agree but disagree at the same time with the above mentioned.

I spent some money on getting my heads done but this was only because I want to prove that the gt40's can go as fast as some aluminum headed combo. But in all fairness, the practical thing would've been to buy some aluminum heads and get more for the money.

As far as cam goes, custom is the way to, especially since you're porting. I went with Jay Allen @ www.camshaftinnovations.com and couldn't be happier with product and customer service.
 
I'm going to have to agree but disagree at the same time with the above mentioned.

I spent some money on getting my heads done but this was only because I want to prove that the gt40's can go as fast as some aluminum headed combo. But in all fairness, the practical thing would've been to buy some aluminum heads and get more for the money.

As far as cam goes, custom is the way to, especially since you're porting. I went with Jay Allen @ www.camshaftinnovations.com and couldn't be happier with product and customer service.

Nacho ... My Friend :D :cheers:

I don't know who it is you feel you have to prove that :shrug:
those GT40's you got can go just as fast ... OR EVEN ... faster ... :banana:
than a set of after market aluminum heads

but ................

It sure ain't me :nono:

I mean ... those guys who race in ... is it Pure Street ??? ... get WAY over
300 to the wheels with OEM stuff

but

is it cost effective ;)

Yes ... it is true ... thats an extreme comparison here :crazy:
but
I do think one needs to explore ALL the facts about what is involved

BEFORE ... choosing either oem iron or after market aluminum heads

I really do understand about wanting to prove a point :nice:
and
Doing it differently than ... the masses :Word:

as always ... I respect all methods to achieve successful results :cheers:

The peeps who get involved in these discussions :hail2:
its what makes this place the special place that it is :D

btw ... do you have any plans to dyno your combo

I would really ... really ... like to see what it can do :banana:

Grady
 
Yeah, I plan on taking it to the dyno, but my plans are pretty much on hold right now since I'm working in Maryland and my car is back home in Texas.

But I completely agree with what you are saying and to be honest it is NOT cost effective and I wouldn't do it again, but I just want my cruiser to be as fast as possible with the gt40 heads.

FWIW, I plan on it running 11's NA and I'll be shifting right @ 6400rpm with the Cobra intake and higher with the Downs Ford I have waiting to go on. I will let you guys know how it turns out but it will be a while.
 
***Bill & Ted voice***woahhh***end Bill & Ted voice***...

Didnt we just have this debate?

Yes gt40's can be ported, check out Thumper if you want a perf. port job and machine work as a very well priced package.

Tmoss is great for help and his site is very helpfull regarding intake choices/comparo.

Both are very helpfull and you can probably search for more information by searching under there names than you can even think about asking.

In the end have fun and enjoy the hobby. We run our cars, the cars do not run us.
 
i know that Tmoss and Thumper were mentioned... but anyone ever looked into or found any really good reads on self porting... best ways to go about it, what to port, smoothe enlarge.... basically a good PORTING FOR THE HOME DUMMY and then something more in depth about it like SELF PORT LIKE A PRO! .... haha i know thats a lil drastic, but that's what i'm looking for ... so speak up if you know.... please :)
 
I think Tmoss's webpage has info on how to do it yourself.

I know years ago some buddies and I got some detailed instructions for porting heads from powerheads website/std. abrasive's website. Ported a set of E7's and some chevy heads...they came out nice just took a ton of work and I think all of us were deaf for a few weeks when we were done.
 
Port them yourself. Some local porters will give you a rough idea of where you need to do it if you bring them the heads, and there's plenty of info online. When I bought some GT40s, I did my own porting and it worked out fine. My mistake was that I didn't get new valve guides. For about an hour the car ran like a bat out of hell untill the #1 cylinder died from being caked with oil. I still ran a 15.0@94 on 7 cylinders, haha!