Back Here After Years. Is It Worth Trying D00e Heads On My Stock 86? Need Experienced Opinions!

[Musktrangt]

HI I used to post on Stangnet all the time and I've learned a ridiculous amount about mustangs and engines here. Used to be my home whe i was a teen as I had no friends and just a 66 coupe to keep me buisy. I then had a 91 and got to know these foxes through and through. I've searched everywhere for hours and haven't found any definite answers to my question
I have an 86 gt. Bone stock. Needs paint, interior answer trim but everything works and runs good. Bone stock. I got a gt40 intake and 1970 351w heads I'm going to clean up and put good valvesprings and hardened valve seats in as well as mild porting. I want to keep STOCK cam. I know I got no reliefs in my pistons. I'm not interested in cutting pistons in or out of the car. I got a new 308 on the stand but I'm not even tempted to use it. I'm keeping stock shortblock. Boost later maby but I got to get these damn e6 heads and intake off of it. I know I'll need to clay it and check. HAS ANYONE SUCCESSFULLY USED THESE HEADS OR SIMILAR GT40 ON THIS ENGINE WITH STOCK CAM AND NO PISTON MODS? I need to now if it's even worth trying. It's all I got. I can't afford trickfow tw heads. I don't have a proper shop to install my other engine or rebuild right now. Just need a little better flowing 5.0 until I finish the rest of the car.

 

[CarMichael Angelo]

HI I used to post on Stangnet all the time and I've learned a ridiculous amount about mustangs and engines here. Used to be my home whe i was a teen as I had no friends and just a 66 coupe to keep me buisy. I then had a 91 and got to know these foxes through and through. I've searched everywhere for hours and haven't found any definite answers to my question
I have an 86 gt. Bone stock. Needs paint, interior answer trim but everything works and runs good. Bone stock. I got a gt40 intake and 1970 351w heads I'm going to clean up and put good valvesprings and hardened valve seats in as well as mild porting. I want to keep STOCK cam. I know I got no reliefs in my pistons. I'm not interested in cutting pistons in or out of the car. I got a new 308 on the stand but I'm not even tempted to use it. I'm keeping stock shortblock. Boost later maby but I got to get these damn e6 heads and intake off of it. I know I'll need to clay it and check. HAS ANYONE SUCCESSFULLY USED THESE HEADS OR SIMILAR GT40 ON THIS ENGINE WITH STOCK CAM AND NO PISTON MODS? I need to now if it's even worth trying. It's all I got. I can't afford trickfow tw heads. I don't have a proper shop to install my other engine or rebuild right now. Just need a little better flowing 5.0 until I finish the rest of the car.

A 351 w head will be little better than what you have. Cast w/ a therm actor bump in the exhaust ports, and stock w/ a 1.84(I), and like a 1.46 (e) set of valves, they are by no means worth the effort.
Now a set of GT 40, or Gt40p's as a stock alternative is a different ball game. You can read @hoopty5.0 's thread w/ regard to what he was able to accomplish with those.
I had a set of C9AE 351 w 4bbl heads on a 357. Bigger valves, ported as far as they could go. When swapped over to a cast iron set of unmolested world Sr. Heads, the car picked up almost a half second.

The best thing you can do with those dooe heads is give them to somebody that has a pick up so they can throw them back in the bed for traction in the snow.

 

[hoopty5.0]

Well, I can't prove that I've accomplished anything, yet. Hope to get some work done this weekend and get them flowed by the end of the month.

At any rate, I have $500 and 40+ hours in a set of P heads right now. I still get asked "Why?" and the simple answer is I wanted to learn the basics of porting. We will see what I learned here pretty soon.

 

[Musktrangt]

I'm going to port. I understand that an e7 is a 25 hp upgrade over my e6s. These heads suck. The 69 70 351w heads I understand are better than e7s. I'm not looking for alot of hp. I'm just looking for a better breathing engine until late I finish the rest of the car. I figured the heads and gt40 intake with the stock cam would be a good mild combo worth 50 hp with an electric fan, smog dlt, and exhaust. I NEED TO KNOW IF I'LL HAVE PV CLEARANCE ISSUES WITH THE STOCK 86 PISTONS TO SUM IT UP. I'm sure I'll see gains with this mild combo over the 86 heads and intake

 

[hoopty5.0]

I'm going to port. I understand that an e7 is a 25 hp upgrade over my e6s. These heads suck. The 69 70 351w heads I understand are better than e7s. I'm not looking for alot of hp. I'm just looking for a better breathing engine until late I finish the rest of the car. I figured the heads and gt40 intake with the stock cam would be a good mild combo worth 50 hp with an electric fan, smog dlt, and exhaust. I NEED TO KNOW IF I'LL HAVE PV CLEARANCE ISSUES WITH THE STOCK 86 PISTONS TO SUM IT UP. I'm sure I'll see gains with this mild combo over the 86 heads and intake

You shouldn't; people do it all the time. Go to a junk yard and rob some heads/intake off a V8 explorer. If you want to port, get on corral.net and read anything you can find on porting GT40 heads, there's a ton of info floating around over there but you have to dig for it.

 

[Musktrangt]

You shouldn't; people do it all the time. Go to a junk yard and rob some heads/intake off a V8 explorer. If you want to port, get on corral.net and read anything you can find on porting GT40 heads, there's a ton of info floating around over there but you have to dig for it.

I got the intake. Every yard here is raped of potential mustang parts. I'm lucky to have the heads I have. I guess there's no market for the 69 351w 184 154 heads. I'll throw theme away and supercharge my stock engine. Not finding any gt40 heads around here

 

[Musktrangt]

You shouldn't; people do it all the time. Go to a junk yard and rob some heads/intake off a V8 explorer. If you want to port, get on corral.net and read anything you can find on porting GT40 heads, there's a ton of info floating around over there but you have to dig for it.

I mean everything I've read over years say these are the good heads with lots of potential. What's gives? I know gt40 heads have potential too but these heads are very similar and I've already got them. What has changed? Thought 69 70 351w heads were the cast iron ones to get.....

 

[hoopty5.0]

That's a Mike question. All I know about the 351 heads is they're small and run out of steam early.

 

[Musktrangt]

Ok hoopty5.0 I think I need to clarify. This isn't a huge power build. My question has to do with piston to valve clearance and will it be worth it to try to get these heads to PHYSICALLY fit on the one year 86 shortblock with no valve reliefs in the pistons. I know what the heads are and yes 351w heads aren't worth it UNLESS you get the ones I have. I don't care how much the heads flow compared to others. All the info I'm looking for is from people who know for a fact weather the valves will hit the pistons if I put these heads on. I don't care they aren't the best heads. There world's better than what I have. If you are not familiar with the 86 pistons and heads it ok but I need someone here who knows that one year engine

 

[CarMichael Angelo]

That's a Mike question. All I know about the 351 heads is they're small and run out of steam early.

I mean everything I've read over years say these are the good heads with lots of potential. What's gives? I know gt40 heads have potential too but these heads are very similar and I've already got them. What has changed? Thought 69 70 351w heads were the cast iron ones to get.....

All you have to do is look at a set of GT 40p's, and you'll see. A 351w head is weak. The exhaust port is tiny, restricted, and shaped poorly.
You can port the snot out of them, and they'll still be weak when compared to a set of GT 40 p's
( probably in unported form)
You've been told that 69-70 351 w heads are the head to get because the info is dated. GT 40 heads supersede anything you've heard about a 351w head being superior.
You don't have to worry about the fact that all of your yards are raped of donor mustangs, the heads come from a truck. Explorer is the donor source for the heads you want.

 

[CarMichael Angelo]

You keep asking about p to v clearance. The head swap isn't the biggest contributor unless you start increasing cam lift and duration. I'd seriously doubt that with a stock cam that the slightly bigger valve will be a factor

 

[Musktrangt]

All you have to do is look at a set of GT 40p's, and you'll see. A 351w head is weak. The exhaust port is tiny, restricted, and shaped poorly.
You can port the snot out of them, and they'll still be weak when compared to a set of GT 40 p's
( probably in unported form)
You've been told that 69-70 351 w heads are the head to get because the info is dated. GT 40 heads supersede anything you've heard about a 351w head being superior.
You don't have to worry about the fact that all of your yards are raped of donor mustangs, the heads come from a truck. Explorer is the donor source for the heads you want.

I understand. The question I have is will they work on my engine. I have these not gt40s. All the mountaineersame and explorers here have no topend on them. My question is can I use these on my 86 with no reliefs? What about 1.7rr since it's duration and timing that cause the issued with these enginges

 

[hoopty5.0]

@A5literMan has an '86, maybe he can comment.

 

[A5literMan]

You keep asking about p to v clearance. The head swap isn't the biggest contributor unless you start increasing cam lift and duration. I'd seriously doubt that with a stock cam that the slightly bigger valve will be a factor

"Shouldn't" be a problem. The 86 Pistons have no valve reliefs. They are more of a concern than the later Pistons. I agree with your advise.

Op..the only way you're truly going to know is to mock them up and check. Will the 351 heads be better than the e6's? Probably a slight increase in airflow. They still are a bad design. I highly recommend checking online sources to find some gt40's that are already done. Or better yet find some budget/used aluminums. I know you stated funds are short but if you really want a performance upgrade...this is a necessity.

 

[A5literMan]

@A5literMan has an '86, maybe he can comment.

Oh and I have an 89 motor
86 shortblock was long gone by the time I purchased the car. I found a different longblock and overhauled it instead.

I have read and seen a few 86 stock shortblock builds. The Pistons are a problem with cam/head changes. They actually aren't a bad design of using a proper setup. They actually have a slight bump in compression over the later designs. They are forged and have less dish/lack of reliefs.

 

[Musktrangt]

Oh and I have an 89 motor
86 shortblock was long gone by the time I purchased the car. I found a different longblock and overhauled it instead.

I have read and seen a few 86 stock shortblock builds. The Pistons are a problem with cam/head changes. They actually aren't a bad design of using a proper setup. They actually have a slight bump in compression over the later designs. They are forged and have less dish/lack of reliefs.

Yeah this is why I want to use the stock short block and add a vortech later. Just need a lil boost in power to hold me over until late I restore the body and interior

 

[A5literMan]

Does the current motor run ok? If so, I'd recommend just saving some more cash for the future mods. Concentrate on the other issues you may have. Also start by building up the suspension,BRAKES!(man these 86 brakes suck),rearend,chassis,fuel system/MAF-ecu upgrades,and any other odds and ends. All these systems need to be upgraded before adding any additional power. They were barely adequate(or not even in some areas) from the factory. You'll enjoy the car more and have a safer vehicle. Just my .02

 

[Noobz347]

Yeah this is why I want to use the stock short block and add a vortech later. Just need a lil boost in power to hold me over until late I restore the body and interior

Let me start by answering the question that you've started with:

I do not know for sure if your 351 heads will cause a problem or not. Never tried those specifically but you have the heads. Clay it up and measure it. Use your old head gaskets to make the measurement.

86 heads are junk because of the swirl port / heart shaped design that shrouds the spark plug and already tiny valves. When you start talking about boost, the differences between stock 86 heads and e7 heads, is really non-existent. The bottle neck at that point would be the upper and lower plenum along with the tiny little throttle body.

Of course E7 heads can go a little further through porting (slightly) but E6 heads really just require un-shrouding. Trouble is, it's a LOT of unshrouding. If you have a die grinder lying around, just reshape the ports and chambers on the heads and toss it back together. You will also discover that the stock 86 CAM responds very well to boost.


My vote considering your plan to rebuild later? Clay up the 351 heads and see where you're at. Compare the ports and remaining material on those heads versus your E6 heads. If the valves etc. are the same size, clean up the E6s and boost the crap out of it until you're ready to rebuild.

I think Mike mentioned that without more lift, you really wont gain anything. That's true but you do actually get a little more lift when swapping to something like an E5 or E7 head. If your 351 heads look anything like those then you will get a benefit from boosting it because the exhaust valves are so much more functional.. Below you can see all the shrouding on an E6. you can also see that you really do gain lift because the valves are not sunk as far into the casting.

Now.... I would also replace every soft part on that motor before boosting, up to but not including rotating assembly bearings if oil pressure is still good.

Do not put money into either of those heads tho.

 

[Musktrangt]

Let me start by answering the question that you've started with:

I do not know for sure if your 351 heads will cause a problem or not. Never tried those specifically but you have the heads. Clay it up and measure it. Use your old head gaskets to make the measurement.

86 heads are junk because of the swirl port / heart shaped design that shrouds the spark plug and already tiny valves. When you start talking about boost, the differences between stock 86 heads and e7 heads, is really non-existent. The bottle neck at that point would be the upper and lower plenum along with the tiny little throttle body.

Of course E7 heads can go a little further through porting (slightly) but E6 heads really just require un-shrouding. Trouble is, it's a LOT of unshrouding. If you have a die grinder lying around, just reshape the ports and chambers on the heads and toss it back together. You will also discover that the stock 86 CAM responds very well to boost.


My vote considering your plan to rebuild later? Clay up the 351 heads and see where you're at. Compare the ports and remaining material on those heads versus your E6 heads. If the valves etc. are the same size, clean up the E6s and boost the crap out of it until you're ready to rebuild.

I think Mike mentioned that without more lift, you really wont gain anything. That's true but you do actually get a little more lift when swapping to something like an E5 or E7 head. If your 351 heads look anything like those then you will get a benefit from boosting it because the exhaust valves are so much more functional.. Below you can see all the shrouding on an E6. you can also see that you really do gain lift because the valves are not sunk as far into the casting.

Now.... I would also replace every soft part on that motor before boosting, up to but not including rotating assembly bearings if oil pressure is still good.

Do not put money into either of those heads tho.

Thanks alot. My 351w heads have 1.84 intake and 1.54 exhaust and flow alot more than the E6 based on numbers I've seen.

 

[Musktrangt]

Thanks guys. So do you guys think using the gt40 intake and adding a throttle body will be sufficient for a lil boost or should I also be doing the heads