cam choices for stock gt40p head

stang-geoff · Oct 9, 2010

I just bought a set of gt40p heads today for my 86 mustang at a bargain! I'm wondering what cams are a good choice for the gt40p? Is it possible to keep the stock valvetrain and get something with better lift over stock? I know I have the flat top pistons and I'm going to get that addressed. There's someone local selling an 87+ block with piston for cheap so I might get that or do the valve relief notching on the flat tops. Anyways, any tips would great guys

gritchy5.0 · Oct 9, 2010

Have you done a MAF conversion yet? if not thats where you go next. Lumpy cams and SD dont mix. and if you are running a stock efi intake you will wanna replace that before the cam also. Just my 2cents.

stang-geoff · Oct 9, 2010

I was thinking of buying a quarterhorse unit from moates at the same time and reprogram the ecm.

RatStang · Oct 9, 2010

gritchy5.0 said:
Have you done a MAF conversion yet? if not thats where you go next. Lumpy cams and SD dont mix. and if you are running a stock efi intake you will wanna replace that before the cam also. Just my 2cents.

This is important.

stang-geoff said:
I was thinking of buying a quarterhorse unit from moates at the same time and reprogram the ecm.

Is quarterhorse compatible with the Speed Density EEC modules?

I doubt that it is (although I do not know, their website doesn't mention speed density computer specifically at all).

If you've not converted to a mass air system then you'll likely need to do that first before you can run a quarter horse, TwEECer or any of the other EEC programmers out there.

If it -IS- compatible with speed density then whoa! I could see there being a whole new following of speed density freaks cropping up in the Mustang world. SD capability for large cam and power adder fans... I'd think there'd be a good group of folks using their old mass air meters as ash trays. hehe

skunk21 · Oct 9, 2010

maf conversion, TFS stage 1, explorer, cobra or aftermarket intake.

Cobra1741 · Oct 9, 2010

maf conversion. tfs 1 cam. if not that one the comp xe270hr-12 would be a good cam as well.

stang-geoff · Oct 9, 2010

so all these cams will work just fine with the stock valve springs? With the tfs cam do I need to purchase new pushrods and what size do I need? Ooh, I forgot to mention I already have an explorer intake.

Biggest thing I'm worried about is the computer. It's probably going to be the most expensive thing to deal with. I'm having a tough time believing the quarterhorse chip wont work with speed density. I would think the market would be there for it especially with the f-series trucks. I'll do some research on this I guess.

UPDATE:
I'm looking at the moates site and it says it supports all eec-iv. It doesn't show any exceptions. Should I try contacting them and see if there will be any problems tuning an 86 GT EEC?

oh, I also notice that tfs stage1 cam will provide .510 lift. That will really work with the stock heads, if so that's pretty cool?

phutch11 · Oct 9, 2010

Stock cam with 1.7 rockers or custom cam.

Good luck...

clement · Oct 9, 2010

AFM N41 and holley systemax 2 and the correct springs.

Mustang5L5 · Oct 9, 2010

If the springs on the heads are stock, toss them and get some crane or tfs drop in replacements.

The stock 85-88 cam is a pretty good peice. Just add some 1.7s and call it a day unless you really want lope.

onefast89 · Oct 11, 2010

comp cams has a reccomendation page, you give em all your specs, and they size out a cam for you. could be an idea to think about. just to have a professional engine builders thoughts.

beyondspexj · Oct 12, 2010

dont forget about piston to valve clearance checks. rather be safe then sorry.

and let me know too if you find out the quarterhorse works with SD or not.

2000xp8 · Oct 12, 2010

Don't try any method of circumventing using the mass air system.
Buying tuning equipment to avoid using mass air is spending a dollar to save a nickel.
It makes zero sense.

If you change the cam you will need valve springs, maybe not today and maybe not tomorrow, but when you do, you will know it. Valve float is not particulary pleasing to the ear. I speak from experience.

Cobra1741 · Oct 12, 2010

yes u will need springs. afm n-41 is too big of a cam for those heads. id recommend the n-21 if your using 1.7 rr.

stang-geoff · Oct 14, 2010

So do you guys know how much lift it takes to max out airflow on gt40ps? I was trying to find specific numbers but I couldn't find anything. all the googling leads me to one site that's no longer up anymore. It sounds like I'm going to have to ditch stock valve springs also, so I guess I'll give that up. I think I'm decided on getting a cam and not the 1.7s now I just need to decide on the cam.

f8tlfiveo · Oct 15, 2010

I'm using stock cam and 1:7's.. Runs pretty good.. Noticeable difference from e7's.. Going to the track soon..

phutch11 · Oct 15, 2010

Before you buy an odd the shelf cam, make sure its SD compatible or plan on changing to MAF. And make sure its compatible with your 86 flat too pistons.

OR leave the stock cam, advance it 4 degrees and get some 1.7 RRs and go to town after checking the PV clearance.

Tmoss has an SD setup with a stock cam that he's made nearly 300rwhp with...with an SD computer.

It can be done.

I'd really do my homework on your SD and block issues befor spending a dime on a new cam.

Good luck...

Vinnietbird · Oct 15, 2010

skunk21 said:
maf conversion, TFS stage 1, explorer, cobra or aftermarket intake.

That's mine. complete GT-40P engine
Trick Flow Stage 1 cam
BBK shorty headers
Ported P heads with trick Flow springs
1.7 Crane Gold roller rockers
Explorer intake
Mass Air
65mm throttlebody

Sorry,for the '86 engine and flat tops,I had an E303 cam,ported E-7 heads,1.6 roller rockers,Explorer intake with a 65mm t-body,BBK headers,and the car ran strong.

85_SS_302_Coupe · Oct 15, 2010

Stage 1 is the magic cam for P heads. X303s work well also but a split pattern seems to work even better with these heads. PTV clearance is about duration, not lift. P heads and a Stage 1 have been proven to be a 12 second combo around here time and time again.

Mustang5L5 · Oct 15, 2010

Vinnietbird said:
That's mine. complete GT-40P engine
Trick Flow Stage 1 cam
BBK shorty headers
Ported P heads with trick Flow springs
1.7 Crane Gold roller rockers
Explorer intake
Mass Air
65mm throttlebody

That's the exact same combo I'm putting together. How's it run?

cam choices for stock gt40p head

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