Seemingly random 'will it fit' and 'how well does it work' kinds of questions...

JasonRP

Active Member
May 25, 2018
107
102
53
48
Annapolis
Folks,
I hope no one minds this seemingly random collection of questions. I've been searching forums and also watching YouTube, but, I have yet to find the answers to my specific questions. I'm probably an "oddball"- I like to keep things stock, and/or try to use Ford parts if not staying stock, keep a stock appearance. So, at minimum- maybe this thread will provide humor/entertainment value for dudes who long ago liberated themselves from the stock-ish/mostly Ford stuff requirement, and have parts that just work very well and hi-performance without stupid limitations! :) For those that are just gonna come back and say "Dude, use the search function", what's the point of having a forum if we can't talk about this stuff? We like to talk about this stuff, right? Besides- these are specific (and probably not the usual) use cases here.

If it matters, starting out with a '89 GT, stock EVERYTHING, T5 and 308 rear gears. Budget is I'd say moderate.. I'm a cheapskate at times, other times I'll pony up if I have to. Not trying to spend >1000-1500 at one time if I can help it. Would be MUCH happier in 500 dollar range, but over long haul, willing to spend $ to have the car right.

-=Here goes=-

GT40 heads:
-I know the Cobra ones have the thermactor crossover, and the Explorer ones don't. If you drill and tap the Explorer ones, will the thermactor system then perform as designed? Or is is basically a hole to hold the thermactor crossover tube to the head? (I know GT40P heads removed all thermactor provisions, but I am considering the GT40's)
-Will stock valve covers fit on GT40 heads?
-Will roller rockers work with stock valve covers? Either 1:6 or 1:7
-Anyone tried just the GT40 heads, with stock cam, stock intake, stock injectors? If so, did your driveabilty change much?
-What HP and Torque increase could be expected by this? (just the GT40 heads, without changing the cam or intake?)
-Stock injectors ok with just heads here? Or are they approaching duty cycle here too with just heads?

AFR or TFS "street" heads (with emissions control still avail)
-Since I don't have an '86 motor, but have an '89- is this just literally bolt on?
-Can you still use the stock valve covers?
-Do these work fine with stock cam? Any driveability problems?
-Anyone have problems with head gaskets, due to iron block and alum heads? I'm guessing no if cooling system is fine, but wanted to double check- I know stock is heavy, but iron:iron seems ideal for sealing...
-What HP and Torque increase could be expected by this? (just the AFR or TFS street heads, without changing the cam or intake?)

Cam:
-Ok, let's say I do just the GT40 heads as above, and then go with a not-extreme cam, say a TFS stage 1 (or maybe an F-cam).. If keeping stock intake, am I still able to benefit from the heads and cam?
-Anyone done this? What was your experience like?
-Will this push me to "bigger injectors absolutely required" territory if not already there from the heads?
-What if you're rebuilding a high-milage motor, and decide you want a stock cam (perhaps from 88 as I think by 89 they'd already softened it up a bit?).. Can these still be found in new condition? Or, do you have to have one custom ground?

Intake: (I know it's stupid, I've just always loved the look of the stocker- and it's what a lot of us all had back in the day)
-anyone ported a stock intake? Was the end result favorable if so?
-anyone had good result with increasing TB size, but keeping stock intake (assuming it can all bolt up?)

***Bottom line*** if the car is gonna run like a mis-matched herky-jerky nightmare because of just heads but not upgrade to a whole integrated system, I'll either stay stock or go with an integrated system. Just trying to maximize what I've already got, keep stock looks, and save some $$$ if possible.

============================
Clutch related:
-What's your flywheel replacement recommendation, if "performance" is not necessarily a driver, but quality/balance/smoothness (or at least as good as stock quality)?

============================

That's all I can think of for now, but I'm sure I'll have more random/odd combo questions

Looking forward to you all's knowledge!
Jason
 
  • Sponsors(?)


HemiRick

I'd be looking at jacking under the house
Jun 28, 2020
764
288
73
58
Memphis TN
The stock intake is the choke point or restriction....w the heads coming in right behind....to replace the heads and not at least goto the explorer intake would be waste of effort IMHO. GT40 heads also fall into this category why only get 30 more HP when you can 100 w a good head change?
 
  • Like
Reactions: 3 users

TOOLOW91

If you're the village idiot what's that make me?
15 Year Member
Nov 29, 1999
7,653
7,595
234
S.I.NY
Folks,
I hope no one minds this seemingly random collection of questions. I've been searching forums and also watching YouTube, but, I have yet to find the answers to my specific questions. I'm probably an "oddball"- I like to keep things stock, and/or try to use Ford parts if not staying stock, keep a stock appearance. So, at minimum- maybe this thread will provide humor/entertainment value for dudes who long ago liberated themselves from the stock-ish/mostly Ford stuff requirement, and have parts that just work very well and hi-performance without stupid limitations! :) For those that are just gonna come back and say "Dude, use the search function", what's the point of having a forum if we can't talk about this stuff? We like to talk about this stuff, right? Besides- these are specific (and probably not the usual) use cases here.

If it matters, starting out with a '89 GT, stock EVERYTHING, T5 and 308 rear gears. Budget is I'd say moderate.. I'm a cheapskate at times, other times I'll pony up if I have to. Not trying to spend >1000-1500 at one time if I can help it. Would be MUCH happier in 500 dollar range, but over long haul, willing to spend $ to have the car right.

-=Here goes=-

GT40 heads:
-I know the Cobra ones have the thermactor crossover, and the Explorer ones don't. If you drill and tap the Explorer ones, will the thermactor system then perform as designed? Or is is basically a hole to hold the thermactor crossover tube to the head? (I know GT40P heads removed all thermactor provisions, but I am considering the GT40's)
-Will stock valve covers fit on GT40 heads?
-Will roller rockers work with stock valve covers? Either 1:6 or 1:7
-Anyone tried just the GT40 heads, with stock cam, stock intake, stock injectors? If so, did your driveabilty change much?
-What HP and Torque increase could be expected by this? (just the GT40 heads, without changing the cam or intake?)
-Stock injectors ok with just heads here? Or are they approaching duty cycle here too with just heads?

AFR or TFS "street" heads (with emissions control still avail)
-Since I don't have an '86 motor, but have an '89- is this just literally bolt on?
-Can you still use the stock valve covers?
-Do these work fine with stock cam? Any driveability problems?
-Anyone have problems with head gaskets, due to iron block and alum heads? I'm guessing no if cooling system is fine, but wanted to double check- I know stock is heavy, but iron:iron seems ideal for sealing...
-What HP and Torque increase could be expected by this? (just the AFR or TFS street heads, without changing the cam or intake?)

Cam:
-Ok, let's say I do just the GT40 heads as above, and then go with a not-extreme cam, say a TFS stage 1 (or maybe an F-cam).. If keeping stock intake, am I still able to benefit from the heads and cam?
-Anyone done this? What was your experience like?
-Will this push me to "bigger injectors absolutely required" territory if not already there from the heads?
-What if you're rebuilding a high-milage motor, and decide you want a stock cam (perhaps from 88 as I think by 89 they'd already softened it up a bit?).. Can these still be found in new condition? Or, do you have to have one custom ground?

Intake: (I know it's stupid, I've just always loved the look of the stocker- and it's what a lot of us all had back in the day)
-anyone ported a stock intake? Was the end result favorable if so?
-anyone had good result with increasing TB size, but keeping stock intake (assuming it can all bolt up?)

***Bottom line*** if the car is gonna run like a mis-matched herky-jerky nightmare because of just heads but not upgrade to a whole integrated system, I'll either stay stock or go with an integrated system. Just trying to maximize what I've already got, keep stock looks, and save some $$$ if possible.

============================
Clutch related:
-What's your flywheel replacement recommendation, if "performance" is not necessarily a driver, but quality/balance/smoothness (or at least as good as stock quality)?

============================

That's all I can think of for now, but I'm sure I'll have more random/odd combo questions

Looking forward to you all's knowledge!
Jason
gt40 stuff

I wouldn’t waste time making thermactor stuff fit gt40p heads , if you want to run gt40s just get 3 bar heads . Stock valve covers will fit with some aftermarket rockers if you clearenxe the inside . Stock stamped rockers are already 1.6 ratio . Gt40s could use stock rockers . You could use stock injectors with the head swap . Even H/C/I you would be fine for what you’re looking to do . More or less you’d want the bigger MAF sensor. Power is hard to say- maybe 25-35 hp esp if you’re keeping the Stock intake which is like sucking air through a straw into a garbage pale after a head swap . The straw is the restriction still.

Heads
Tfs 170 heads get my vote . 58cc chamber . Zero issues with head gasket stuff. You’re overthinking that one . 9333pt1 would be fine . Again hp is relative . If the intake dont flow enough air to take advantage of the head the gain is minimal .

Cam

The stock cam you can keep . Guys have been fast with them and you will have extremely good drivability still . Now would i leave it ? No

Out of what you mentioned I would not run a alphabet ever . I had a TFS1 and it was a decent cam and drove fine . To do a setup you speak of I would do a Anderson n41 cam .

My setup for what you speak of would be this . TFS 170 heads 58cc , Anderson N41 , Ported Explorer upper and lower if you are hung up on the stock look . It will drive great with the right rear gear (3.55/3.73) and have great street manners and run hard . This setup I’d do 24lb injectors / 75mm pro m mass air meter . Car would make every bit of 290-325 to the tire .

Clutch - Ford racing billet steel flywheel , centerforce dual friction clutch , Maximum MOTORSPORTS Clutch cable , quadrant and adjuster . Better then stock feel and will hold up
 
  • Like
Reactions: 1 user

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
31,906
13,194
234
Box behind Walmart
www.stangnet.com
The folks that initially came up with the thread I link below, had a little more in mind than just a place to brag about dyno charts and quarter-mile times.

Take a look through these timesheets and the associated engine combinations. I would hazard to guess that there is a combo in there for just about any power level you could want.

In the end, it's going to be about the sum of parts and how efficient they are [together] at producing the desired torque and power.


You really should study that thread a bit. It is a completely different approach to the pages of a magazine ad that promises X amount of HP per part added.

Some of my favorites used to be under-drive pullies and cold air intakes. :rolleyes:
 
  • Like
  • Useful
Reactions: 3 users

JasonRP

Active Member
May 25, 2018
107
102
53
48
Annapolis
I forgot to mention in the beginning- my use of this car is street/driving it. I'll probably never take this one to the track- I'd just get embarassed by some 19 year old kid in his mom's Camry! :D (Now- you guys with the full tilt Mustang's can and do blow those camry kids into the weeds! THANK YOU FOR THAT! Those camry bastards!) lol

Seriously- I love thinking about this stuff (and will consume the thread linked above too) As I said, I think my usage/wants are slightly different than most. I'd even go so far as to say, yes, they're possibly counter-intuitive and stupid. (but, it's fun to think about)..

And, I'm still heavily in the gathering data stage. The car currently has 249k miles- the stock engine is TIRED.. So, none of this stuff happens until the short block is refreshed. Then, who knows. Really appreciate the insight from everyone- love hearing of the combos you guys ran. BITD, I remember under-drive pullies, and of course headers/H-pipe/flowmasters.. Occasionally cams.. I don't remember heads and intakes (I'm talking ~1990-1995).. Maybe I just wasn't looking in the right places back then!
 

HemiRick

I'd be looking at jacking under the house
Jun 28, 2020
764
288
73
58
Memphis TN
unless the 249K shortblock is burning excessive oil or making bad sounds its fine to go some more.
 
  • Ah yes, I see.  I see.
  • Like
Reactions: 1 users

JasonRP

Active Member
May 25, 2018
107
102
53
48
Annapolis
@HemiRick Hey- great point! It seems to be running very well- starts right up, has good oil pressure (verified with oil pressure tester too, not just dash..) It doesn't burn oil or use oil as near as I can tell- I need to reseal the rear main, the oil pan sensor, and the valve covers- but even with those leaks, it's not using too much oil. I do think it would benefit from valve stem seals, and at this point I think it's earned a timing chain replacement.

@2Blue2 hope I didn't offend with my Camry comment! They're super nice cars- especially the sports one (XSE?) My comment was because, back in the day- when these came in the shop, management would warn us: "don't get squirrelly with them when you're getting them to pull into your bay- they have so much power, they'll get away from you!" Now- family cars all make more power (at least stock compared to stock.) I still love my GT- it's just funny how time has done that.
 

deathb4dismount

Crap, didn’t realize my crotch was in that picture
5 Year Member
Oct 6, 2011
1,015
510
154
THE BUCKET
Unless you find a set of GT40s that have been refreshed with new springs and valves for under 600. Don't even bother.

Trickflow 170s, stock cam, 1.7 rockers, and cobra style intake. You will need to go larger on the throttle body and MAF. Pro M makes a 75mm MAF for stock injectors and stock airbox. A stock replacement clutch will be fine for this setup, or upgrade to any of "stage 1" style clutches. I would stick with cast iron flywheel. Gear it to your preference (3.55-4.10s) You'll get a fun street car that pops at low rpms with great drivability.
 

KRUISR

5 Year Member
Apr 16, 2015
920
349
83
51
Go find an Explorer at a U-pull. Pay $80 for the pair of heads (pull the long block if its low mileage). Clean/de-carbon/degrease the heads, put new springs on (and valve seals while you are there). Don't worry about the thermactor ports, bolt on the cross-over tube if you want the stealthy stock look (it won't function though). Keep the stock cam and add 1.7 pedestal roller rockers (they will fit under stock valve covers), this will give a lift of .472 - almost a B-cam with the smooth idle and manners of the stock cam. Definitely grab the Explorer intakes, injectors and TB (65mm) when you grab the heads (together another $100 max at U-pull yard).

I'm a C&L MAF guy, so I would suggest a 73mm with correct flow tube for 19s. Keep stock air box and intake tube (adds to stealth) and add a K&N panel filter.

Headers and exhaust is up to you, but aftermarket ones will help a bit.

Definitely get some gears - 3.27 min, 3.55/3.73 probably better.

Engine.jpg

Sooo...

Heads - $80 + springs $150-200
Intakes, injectors and TB - $100
1.7 roller rockers - $100-150 (used)
73mm MAF - $100-150 (used)

Do the install yourself and these parts should get you 50-70hp combined and cost $550 - 700. Not bad for used iron "junk". I didn't include for head gaskets and any other seals or gaskets but they will be needed with any change.

Enjoy, have fun and let us know how it goes.
 
Last edited:
  • Like
  • Agree
Reactions: 2 users

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
5,365
1,722
194
Kearney, NE
You (or a pro) can port the stock intake to flow about as well as a stock Explorer intake. But when Tmoss can port a lower Explorer to flow much better, and you can open the throat to match a bigger EGR and TB, I would not do it unless someone had a ported stock one ready to go.
(Let me know if you are interested, and I’ll see if my extra ported stock one is in the right box after we moved.)
 

mikestang63

SN Certified Technician
Aug 27, 2012
10,595
7,401
204
In the garage
There are hundreds of recipes to make power on these cars. It comes down to how much do you want to spend. My advice would be to save up and do it the way you want to the first time. We have all been down the road of GT40 iron heads , etc. and then later ended up going with a good aftermarket set of heads- AFR, TFS.
 

Monkeybutt2000

Advanced Member
Aug 11, 2019
620
409
73
50
Lafayette,IN
Don't discount the GT40 stuff, the Factory Stock cars were running low 12's 20+yrs ago with this stuff. I went 12.80s with a stock cam and speed density, Car ran hard and was tough to beat. And you can do this WAY cheap if you depending how crafty you are.
 
  • Like
Reactions: 1 user

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,294
6,880
203
polk county florida
Wow, some good opinions here, some, kinda good, but ? Takes some planning, first, an engine with that many miles likely needs a refresh, I agree with the explorer engine/parts but swapping to a 4:10 gear without proper planning you might find that all your power will have a small window of use. You'll start out in first gear and before you realize it you're bouncing off the rev limiter, this is why you need a plan.
Look at what the factory does for example, the truck 5.0 uses a different cam and intake, the perceived torque curve matches the cam/intake, same with the pedestrian 5.0 and the 5.0 HO.
Just the thoughts of a mad man.
 

JasonRP

Active Member
May 25, 2018
107
102
53
48
Annapolis
I've considered what everyone has said, and decided: Lots of Nitrous! :banana: (kidding! I kid i kid...)
I've still got to review more of the Guess my HP thread. I'm drinking it in- and starting to look for an Explorer intake set. Seems like most options can use that at least.
 
  • Like
Reactions: 1 user

Wayne Waldrep

Before I post a pic, do you have one of yours?
15 Year Member
Apr 14, 2003
1,154
623
143
55
Cuba, AL
Wish we had u-pull wrecking yards here. We have wrecking yards and even ones that allow you to walk out and get your own stuff. What we don't have.... Drivetrain. Every one of them near me has a huge engine room and a huge transmission room. They all have employees that pull every single engine and transmission before the cars are allowed on the actual lot. And you cannot remove any part from the engine. Complete sale only.
 

JasonRP

Active Member
May 25, 2018
107
102
53
48
Annapolis
New Question: Where do you get/can you get those rubber caps that go on the stock front brake calipers, that cover the ends of where the slide pins go on the inboard side of the calipers?
 

85GTStangGuy

New Member
May 19, 2021
1
0
1
Florida
New Question: Where do you get/can you get those rubber caps that go on the stock front brake calipers, that cover the ends of where the slide pins go on the inboard side of the calipers?
Are these what you mean?


or these?

 

2000xp8

SN Certified Technician
Aug 8, 2003
7,210
1,240
194
NJ
If you like ford parts, find a set of used X heads.
Should cost $500-$700.

Honestly, your range of options is too deep. You list basically the worst set of heads to add and then the best.
Personally if you offered me gt40 iron heads for free, i'd pass. Too little for too much work.
 
  • Like
Reactions: 1 user