Swapping GT40P Heads on a Stock Low Compression 78 Fairmont, part 1
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- Опубликовано: 28 апр 2020
- This is the beginning episode to a series of videos swapping #GT40Pheads on the otherwise stock low compression 302 in my 1978 Ford Fairmont. Or what I like to call #projectLOWFAREmont the $4k budget build Futura. Before we begin the swap this episode we do a mild exhaust side port of the heads to make sure we get great flow out of the 69,000 original mile car. The goal is to see what difference simply swapping heads and upgrading exhaust will do for a car that came from the factory with 140hp.
Music in this episode -
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Love that I found this! I too have a ‘78 fairmont its a wagon and I am doing very similar things. So far I have 4.11 gears and tubular suspension. Weiand stealth intake, demon 625 vac sec carb, hei dizzy, and long tube headers. What are you doing for a cam?
Honestly...nothing for a cam. Stock. This will be it before I try selling it. It's a budget build at $4k total all in.
Grant if you needed to borrow a valve spring compressor, I got one and there is nothing that you can mess up as far as taking the springs off, because to ultimately increase flow, both sides need to be done. Just doing the Exhaust is only half the battle. Another thing to keep in mind and that is a common mistake is to only port the bottom side of the port, your real high velocity gases are going to be closer to the ceiling of the port rather than the bottom. Looks like you did a good job on cleaning up the ports, time to bust out the sanding drums and make 'em shine.
Thanks for the tips Jed. If I can't easily borrow a compressor at O'Reilley's I'll come get yours. I did clean out the top some. I don't feel like what I've done on the exhaust side is so aggressive that it's really going to hamper what happens on the intake side. I'm constricted all the way upstream so I'm not sure what good porting the intake side would even do in the first place. But maybe with some mentoring I could be talked into porting the intake side as well as the manifold.
@@Str8sixfan id be more than happy to help out in any way my friend, leave the intake ports with some texturing while make the exhaust side super slick. Just cleaning the casting up can improve flow by a ton
What about reversion and AR or Anti Reversion dams?
“bigger is better” was true and functioned well before there were lots of dynos around. The only way to get more power was to get more air through. Bigger and more carbs, bigger cams,port the hell out of the cast iron heads… you name it but they were sacrificing a broader power band for more peak power. The cup guys back then all spent much of the time “at” high rpm so 20hp at the top was measurable at the track, but that same engine would be a dog at the drag strip. (compared to the best motors of savy drag racers). The two rarely met and the in between was someone like Larry Widmer and Mr. Feuling who discovered that “bigger is not always better”.
Mr Fueling “learned” that “reversion” was not good, period, and any attempt to minimise it would result in a broader power band for a given engine. Whether or not it helped the car go faster or quicker was another issue,… did the car “need” the larger power band, back then they usually did. Not so much today, for lots of reasons.
The larger things got the worst the reversion. Reversion, which I have tried to clarify a definition of in other threads and my blog, is flow going the wrong way through the engine. If you make things bigger to allow more flow at the same delta P, then that also works the other way also, flow backwards through the engine is helped also, not good…
www.exhausting101.com/?p=68
Happy Motoring.
@@mostlymoparih5682 wow! what a wealth!
Thank you for this video. This is something i would like to do to my spare engine but have never done before. Just gives me that little extra confidence
First off, that comment tickles me because that's one of my objectives of my channel is to encourage people. What I also want to share is that since this video I've learned there's next to no advantage spending time when porting the exhaust port to do anything on the "floor" of the port. Spend your time knocking down any bad casting lips on the sides and ceiling only
@@Str8sixfan cool thanks for the tip. I want to do a build video series with this engine anyway and will give you a shout out and link to your vid when I do
Good shit, Buddy! 🤘
Means a lot J
Honestly, once I have a garage again, I'm gonna do some kind of project. You've inspired me
Dude that's awesome! That's one of my missions of my channel!
Great job Grant! I really enjoy your philosophy behind this build!
Thanks! Trying to make it relatable for those with skills like mine. Probably too early to take on an engine swap, as well as don't have the necessary means to do so. Also wanted the overall package to be nice rather than all performance. Thanks for stopping by Johnny, means a lot to me
Should make a big difference,great video
I'm hoping so. Make the car a little more fun!
Great job on part 1. Looking forward to the next part.
Wishing I was faster, I don't anticipate much getting done on Sunday.
@@Str8sixfan slow and steady wins the race
I port heads for fun and profit. In the future, when you port stock iron heads on a mild engine, *do not* gasket match the ports, that will only slow down the velocity and make the car feel a bit lazy because they are too large. Port and match only the long turn radius, (top of the port) to the gasket or header contour, and leave the short turn radius (bottom) alone - do not touch it. This one tip is 10 horse and 10 ft/lb of torque.
Appreciate the feedback. This may have been the only way to learn. Luckily I didn't go true gasket match, but could have left the floor alone. Next time. Really appreciate the advice. This is exactly what my first project car and series of videos is supposed to do for me! Help me learn for when I build a car for keeps.
thumbs up shared
Thank you so much Drew! The share is almost better than any like or comment.
Woooooooosssh !!!!
Looks good, thanks for the shoutout! Get that thing breathing.
This pandemic world in which we live in, every one can use some good exhaling!
@@Str8sixfan HAHA indeed
Also! Summit racing has a knock off the the weiand stealth dual plane. Which is the best sbf dual plane you can buy. It’s about $150 brand new
Hey, good pointer!
Flat tapped cam 150-180$ it’s gonna make such an improvement and your already in the engine 🤔
I didn't have to take the timing set/timing cover off this way. Or remove the radiator to get cams in and out. Pretty happy with how it turned out. I'll let the next owner pic their own cam! Thanks for watching
I could be wrong since i dont know alot about fords. But i heard there was an aluminum intake in 82 that was 2 barrel for an h.o. they were slightly taller i believe maybe something to look into
OK, I'll give that a shot. I know of 4bbl HO manifolds for sure.
@@Str8sixfan i have been looking more into it and apparently it was a one year only from the looks of it. in 82 it had a 369 cfm 2 barrel, then in 83 a 600 cfm 4 barrel. of course if you can find one cheap because i get the budget carbs are not to cheap, you can find them cheap sometimes but not always. maybe a phonolic spacer under the 2 barrel will help
The GT40p heads do have an exhaust valve and port size problem. You can just put an angle on the port exit on that side and no need to make it too much bigger but these direly need full on exhaust port polishing because any cam over .500 it starts to lose cfm because it simply cannot scavenge due to the small valve.
well said. Thanks for watching
That's a really good deal for a really good set of heads and it looks like you've got just enough left in the budget for a timing keyway kit plus shipping too!
Over the years I've seen a bunch of people throw awesome sounding cammed up engines together that can barely turn a tire over. If your nice heads, cam and intake don't match each other well then they will often run worse or barely better than stock. Unfortunately the stock broomstick cam isn't even close to optimized for the stock heads, much less the GT40 heads.
I know what's done is done but having a tech help you pick an ideal off the shelf cam based on the engines compression ratio, the stock intakes peak RPM and the cars gearing would have been cheaper than the finished heads, much easier to install and much more rewarding in both the performance and sound departments. Advancing the stock cam with a 60 dollar keyway kit will do almost as good as a mild cam by getting you closer to the air speed and cylinder pressure you are gonna need to see a real gain from adding more port.
Keep in mind by adding so much port on an otherwise mild combo you are actually going against the logic of velocity that Uncle Tony is trying to teach us about by purposely putting smaller 318 2 barrel heads and a purposely restrictive intake on his current 360 high torque daily driver build. (This is the same intake I showed for my Olds 260 build in one of my last vids by the way)
289 heads with smaller combustion chambers for even more compression and smaller ports for velocity would have actually been a better pick for a low compression engine with the stock cam but hindsight is 20/20.
I'm not trying to beat you down or sound like a know-it-all here, I just want to make sure you understand how important it is for an engines cam, heads and intake to all work together. Efurd's comments about the garden hose and velocity are pretty much spot on.
Your hose just got bigger so now you need to increase speed and pressure.
There's a chance these heads alone with no other accompanying upgrades might actually make the car slower but I'm sincerely hoping that won't be the case. A cam that works properly with these heads and the stock intake would make this one mean little combo but I understand that's not in the budget. Speaking of budget though, I was just researching these heads to give myself an idea of what your compression would be when I found out that the GT40P heads come with very weak stock valve springs. So weak they can't even handle a stock .444 lift 5.0 H.O. cam so that adds a lot of money and hassle to any potential future cam swap plans.
At this point advancing the stock cam is looking like a really good idea. Probably one of your best options if you want it to have good throttle response and still meet the budget.
Camshaft key might be a great investment. Certainly scares me at my skill level however. Good news is my stock cam can't be compared to a 5.0 H.O. cam I wouldn't think. I figure the 1978 camshaft is so crappy that I should be fine on the stock springs. I'll have to go look through my Chilton's manual and see if there's a number for cam lift. I know you're trying to help and I don't take any of your comments as less than that Impact's (you've been around long enough for me to know that). I understand I'm taking a risk, and there's a lesson to learn at the end of it. I can't imagine that I'm going to end up slower. At the very least the bump in compression has to help, right?
@@Str8sixfan I was just getting ready to tell you that advancing the stock cam is a very basic task but after doing some more research on that subject for this specific combo I've come to a startling conclusion. According to a few Mustang forums I was just browsing, installing GT40P heads on a 5.0 with no valve relief cuts in the pistons will almost certainly result in piston to valve clearance issues. Luckily you can check this by properly mocking up head installation with clay or silly putty in the cylinders. If they do clear then you can disassemble the head and measure the depressed putty for proper clearance. I read that seventies 302's had dished pistons for lower compression with valve relief cuts too so they work fine there but I can't find a solid answer on whether or not the 1978 5.0 pistons had any dish or relief cuts. Basically what I've gathered so far after a couple hours of research is that if you pull the heads and see you don't have relief cuts then you will need to make some relief cuts with a special tool or swap pistons or ditch the heads. If you DO have relief cuts then there's a chance it will work but it's an expensive thing to gamble on. If this was my motor and it does have relief cuts I would still clay test it first. Here's some VERY important info on the subject. www.stangnet.com/mustang-forums/threads/cobra-gt40-heads-cam-options.856372/
www.stangnet.com/mustang-forums/threads/gt40-p-heads-with-flat-top-pistons.764282/
www.corral.net/threads/flat-top-pistons-and-gt40-heads.763533/
www.fordmuscleforums.com/threads/gt40p-heads-with-flat-top-pistons.490062/
www.corral.net/threads/302-piston-identification.2370202/
www.stangnet.com/mustang-forums/threads/foxbody-came-with-these-pistons.892747/
This last one is a decent how-to-vid for clearance testing small block Fords.
ruclips.net/video/tjs61-TCZYw/видео.html
I like it. Doing anything with the bottom end?
Rolling the dice
When I hear never cut the floor? I kind of laugh. Why? You can knock of the rough cast but nothing more. The short side radius is a place to learn something. There is more power in the valve bowl area then any where in the port. There is a book I suggest because every pro has a input in it. As a few Pro's has told me. "It's not the best book but it's a damn good start." The book is called "Engine Airflow" by Harold Bette's and another book to get is "Engine Airflow" by John Baechtel. Trust me those two books will change your way of thinking in porting cylinder heads and intakes.
appreciate this! I'm glad I did what I did (even if some people think it was wrong), because regardless it helped me learn so much in doing so!
Good video! Did you mention Rick's garage or Red's garage? Thanks a lot!
I did not. Not sure why
Love the video. Are you using headers? If so which ones?
BBKs...Look for my video titled "GT40P Head Swap is One Carburetor Away from Completion" There's some up close views of them
Curious how. Does it run being low compression I have 85 cougar I am doing thinking I am doing a cam and gt40 p heads with a carb
unfortunately I suck at getting things done quickly. If you watch my next upload tomorrow, you'll see I'm still struggling with start up issues. I wish I already had this answer for you!!! It's killing me not being able to drive it. If you can find normal GT40 heads (non P) I'd recommend that so you don't have to deal with the spark plug clearance issues.
Your stock compression ratio being 8.4:1, these heads should give you a decent boost in compression and is one of the best flowing factory heads Ford made.
Looking through old literature I could of sworn it was more like 8.1:1 stock. But regardless for sure looking at increasing it!
Anyone ever told you that you look just like an alpaca?
No. Have not. Curious what people have told you what you look like too. This could be a fun, irrelevant conversation.
These are bolt down rockers with 1.7 ratios right?
Stock is 1.6, I really want to do 1.7s, but running out of budget
Never cut the floor on an exhaust runner....just lost ponies there.
This has been the biggest lesson I've learned since this episode went up. You can probably scroll through the comments and see you're not the first to recommend! But that's exactly what this project was designed to do! Help me learn the lessons now, so when I build for keeps I have a better shot of doing those things right then! Thanks for watching Newb!
@@Str8sixfan Research is free , don't sell the project short it looks to be a clean car.
Not worth the effort ,grinding the bottom of an exhaust port, , spend your money on a good valve job and port work in that area 1 inch before and after the valve is every.thing
you're not the first to respond about the time I spent on the floor. I've certainly learned quite a bit since posting this video. Totally makes sense