max lift on stock 85 ?

[emartin1071]

I remember years back some people would say you couldn't have more than .500 valve lift without modifying the pistons. I understand the 86 piston lacks the valve reliefs but the 85 should have them I believe. The reason I'm asking is i am trying to select a cam and it seems like a lot of people nowadays regard the ford letter cams as outdated and recommend something from Comp instead of which most seem to be over .500 lift. So does anybody know if the pistons need the reliefs enlarged to run over .500 lift ? Thanks

[Jerry peachuer]

It's also duration that will get you in trouble the valves stay open for a longer DURATION while the piston goes down in its bore and as its coming back up the valves are still open and the piston will chase it back up hopefully it never catches it

So it is possible to have more lift and less duration but everyone you speak with will say check piston to valve clearance
I know 3 cams e b and f that worked on factory head and factory block setup with sucess and it's really what your using the car for I would shoot for more torque rather than horsepower for street car and I would never buy a cam for the sound I would buy it for my application and I get what I get for sound these are my opinions of course not gospel and if you ask 10 people you'll get 10 different answers
Good luck im currently running the b cam in a 331 with a 410 it's a fun car

[liv2roc]

im running this one .512 lift on my stock 84 heads on a 91 block which is the same pistons as your 85.
http://www.compcams.com/Company/CC/c...csid=1045&sb=2
this is what it sounds like https://www.youtube.com/watch?v=wjgIihE0CQc

[FM2NOTCH]

this summer a friend had a 347 built with a X303 cam, edelbrock rpm heads, then we switched to a comp XE282HR that had more lift and duration than the X303, performance improvement was ZERO at the track

factory heads typically dont flow any better after .500 lift, and I've had to enlarge the intake valve reliefs slightly with shaved stock heads and stock 85 pistons at .520 lift.

need to add that the valves didn't hit the pistons, but the clearance was tighter than recommended, I believe the accepted clearance is .080 on the intake valve and .100 on the exhaust valve.

[bwguardian]

im running this one .512 lift on my stock 84 heads on a 91 block which is the same pistons as your 85.

Not quite, the 85 piston is a one year only slug being a true flat top with four valve reliefs. The piston you speak of is not a true flat top in that its center has a slight depression...I would have to say maybe worth about 4cc's or so...with four valve reliefs. They are close but not the same.

[bwguardian]

I run an E303 cam in my 85 GT with stock standard bore short block with no issues and love it. If staying carb and utilizing the car for a weekend toy I highly recommend it with better heads and intake manifold of course.

The depth of the valve reliefs in the 85 pistons...or many oem replacement types...are typically deep enough. Where you get in trouble is when larger than stock diameter valves are used...like 1.9+ intakes and 1.6+ exhaust...then the piston valve relief does not necessarily need to be cut deeper, but rather larger diameter.

Everything about the cam will make the difference wheather a piston kisses a valve. It is not only the lift and duration but also the point when the valves open and close.

If your 85 5.0 is still a standard bore short block, the pistons will be a true flat top design with four valve reliefs.

Also as mentioned above, any stock iron head along with some aftermarkets, are only going to be good for .500 lift...as a general rule.

[Ethyl Cat]

I remember years back some people would say you couldn't have more than .500 valve lift without modifying the pistons. I understand the 86 piston lacks the valve reliefs but the 85 should have them I believe. The reason I'm asking is i am trying to select a cam and it seems like a lot of people nowadays regard the ford letter cams as outdated and recommend something from Comp instead of which most seem to be over .500 lift. So does anybody know if the pistons need the reliefs enlarged to run over .500 lift ? Thanks

What are your intentions for the car?

Steve

[emartin1071]

A weekend fun car, maybe occasionally the strip. I'm looking to keep the budget fairly tight. The motor is all stock with around 40k original miles. I was planning to do a cam, heads, intake and carb while leaving the bottom end intact. Already has 86 up exhaust and 8.8 with 3.27. Emissions is not a concern. Thanks

[FM2NOTCH]

there is no rule of thumb, someone says this and that will work, but anytime you change heads along with a cam the piston to valve clearance should be verified unless you feel lucky. a few different ways to do it but the clay on top off the piston method seems like the simplest

[PaceFever79]

I'd go with a mild cam, people tend to over cam street engines (mainly for the sound). But all it does is kill your low end torque. If you're on a budget, the E303 cam will do just fine. Using the right heads, cam, intake, carb, EFI, etc, getting the package right is more important than using the biggest cam you can. I've seen lots of HCI 302s with E303 cam in the mid 12s. Why spend more money on special cams or run too big of a cam just to eek out another 10th of a second? It doesn't make sense.

[bwguardian]

A weekend fun car, maybe occasionally the strip. I'm looking to keep the budget fairly tight. The motor is all stock with around 40k original miles. I was planning to do a cam, heads, intake and carb while leaving the bottom end intact. Already has 86 up exhaust and 8.8 with 3.27. Emissions is not a concern. Thanks

You are starting out with essentially what I had to work with...in good shape stock short block, upgraded 8.8 with 3:27, and off road exhaust. I added E303 cam, GT40p heads, Ford Racing high rise dual plane intake, and then did some tweaking/tuning. There is no reason to get another carb as the stock 4180c is the way to go...it just needs a few tweaks...as you won't find much aftermarket that will perform as good.

[Ethyl Cat]

A weekend fun car, maybe occasionally the strip. I'm looking to keep the budget fairly tight. The motor is all stock with around 40k original miles. I was planning to do a cam, heads, intake and carb while leaving the bottom end intact. Already has 86 up exhaust and 8.8 with 3.27. Emissions is not a concern. Thanks

Heads can make a pretty big difference in cam selection as can rpm level.

I would guess you want to stay below 6K rpm, but did you have an idea on what heads you wanted? I would recommend staying below 180cc runners max and 1.94 int valve max. I would also try to get near 10:1 compression if any level pump gas is ok with you.

Stick or automatic?

Steve

[emartin1071]

Guys thanks for all the good info, bwguardian I like what your saying and am leaning towards that kind of combo : E cam, GT40 heads (would like to keep stock headers to keep that originality) and the idea of improving the stock 4180. What ford racing intake did you use? Also the car is stock 5 speed.

[FM2NOTCH]

I think the latest ford racing intake is a weiand, the older ford motorsports intake was a edelbrock performer rpm, thats what I use. I would consider headers, the stockers are a little restrictive with stock heads and aren't going to help with gt40 heads.

[bwguardian]

Guys thanks for all the good info, bwguardian I like what your saying and am leaning towards that kind of combo : E cam, GT40 heads (would like to keep stock headers to keep that originality) and the idea of improving the stock 4180. What ford racing intake did you use? Also the car is stock 5 speed.

I used this intake
http://www.cjponyparts.com/289-302-d...-/p/M9424F302/
I also utilized these Ford Racing Performance Products stainless steel headers
http://www.cjponyparts.com/289-302-d...-/p/M9424F302/
These headers were redesigned from the earlier Ford Racing units to have the ability to fit the GT40p heads. They also look like the factory stock stainless steel headers. The only thing they will be missing for the 1985 year model is the heat riser but that can be transferred over from the stock units to these. Other than being a little larger they look like the 1986 and up factory stock stainless steel headers.

[Ethyl Cat]

Guys thanks for all the good info, bwguardian I like what your saying and am leaning towards that kind of combo : E cam, GT40 heads (would like to keep stock headers to keep that originality) and the idea of improving the stock 4180. What ford racing intake did you use? Also the car is stock 5 speed.

Now one can get away with a little more cam with a stick than an automatic, but realize that you are decreasing the compression of your engine with that head swap and increasing duration of the camshaft by 16 degrees seat to seat and 10 degrees @.050. These two actions oppose each other in the quest for the correct combination.

You might not feel it as a loss as the head swap would improve power over the original combination, but an E cam might leave a little on the table.

I agree that a well sorted stock carb would be a good choice for you.

Steve

[emartin1071]

How would I lose compression? I thought the gt40 chambers were smaller than the stock 85 heads, I thought the 85s were like 67-70cc.

[bwguardian]

The combustion chambers on my GT40p heads wound up at 59cc's after all was said and done. If they come off again I may mill them a bit more for a little more squeeze.

[Ethyl Cat]

The combustion chambers on my GT40p heads wound up at 59cc's after all was said and done. If they come off again I may mill them a bit more for a little more squeeze.

ACK! My spreadsheet is wrong. I was under the impression that those early heads were smaller. Sorry.

Thanks for posting that BW, I will make the necessary corrections.

I still say that an E leaves power on the table.

Steve

[Ourobos]

this summer a friend had a 347 built with a X303 cam, edelbrock rpm heads, then we switched to a comp XE282HR that had more lift and duration than the X303, performance improvement was ZERO at the track

factory heads typically dont flow any better after .500 lift, and I've had to enlarge the intake valve reliefs slightly with shaved stock heads and stock 85 pistons at .520 lift.

need to add that the valves didn't hit the pistons, but the clearance was tighter than recommended, I believe the accepted clearance is .080 on the intake valve and .100 on the exhaust valve.

I ran the same Comp cam with a set of 2.02" trick flow heads, had over .120" clearance to the pistons with a 1.7 rocker - .604" lift.. Honestly it's the duration that really determines PTV clearance BTW.

[bwguardian]

Here is a picture I took for original spark plug wire location routing. You can see in looking at this that the FRPP stainless headers look original without taking a closer glance.

[bwguardian]

ACK! My spreadsheet is wrong. I was under the impression that those early heads were smaller. Sorry.

Thanks for posting that BW, I will make the necessary corrections.

I still say that an E leaves power on the table.

Steve

No problem Steve. Though I agree the E303 might leave a small amount of power on the table, it is a match for my intended use. It is a weekend car that bust off with an explosion, sounds good, and pulls on past 6,000 rpm's...plus I would not hesitate to get in it and make a road trip...Steve

[8ballEinstein]

Here is a picture I took for original spark plug wire location routing. You can see in looking at this that the FRPP stainless headers look original without taking a closer glance.

Yes they do. I took it one step further by welding the heat riser connection to the FRPP headers. If anyone decides to do this, make sure there's enough room to remove the spark plugs without having to yank the header out of the way.

[emartin1071]

I like the way they look, 8ball any pics of yours with the risers welded on? Does anybody know if MAC headers work with the P heads.

[bwguardian]

I like the way they look, 8ball any pics of yours with the risers welded on? Does anybody know if MAC headers work with the P heads.

Funny you mention the MAC headers. Those were what I originally put on the power plant when I installed it. Yes they will work with Chebby style 90* spark plug boots...as long as you don't plan on removing the plugs without pulling the header. I knew that the FRPP headers were in the plan so not a big deal for me. What I absolutely did not like about the MAC units is how difficult they were to install on the engine...and I had it on an engine stand...given there is no header flange and had to be forced to line up with the exhaust port attachment bolts.