According to AFR, who published results from an "independent" dyno tester, an otherwise stock 5.0 with AFR 165 heads/Comp XE266 cam/roller rockers makes 403HP at 5800 and 370 or so torque at some lower RPM with a carburetor.  That's at the flywheel on an engine dyno so with closed exh and in the car you could prolly expect 300, 325 or so on the ground. 
This is the setup I have except mine is injected and has not been tuned to get what it's capable of.  I can say that even with the stock EEC-IV setup it feels pretty good...now that TKO suggested I go back to the stock MAF.  I had a Cobra MAF on it and it felt kind of dead.  Switched back to the stock Fox MAF and......holy crap, what a difference.  Now I'm working up to tuning the ECM and getting it right.

 

Agree with TKO about the boring. Sure.....'probably-be-OK' with a hone & ring job butt you don't wanna "make-that-trip" back into the engine because of a ring that didn't seat and start getting blow-by. Be a great time to get some pistons with 10:1-11:1compression too.
BE SURE......and rotate those pistons on the rods. Have the notch face the REAR of the engine. Free HP.....zero draw back!
Heads are where the power will come from so......'how-fast-do-you-wanna-buy'!!?  AFR's brag about big numbers (HP & torque) butt.........for the $$$ they SHOULD perform.  Never tried Skip White heads butt I have "heard" a lot of guys that wuz real happy with his stuff! (I did buy an alternator from him.....life-time guarantee AND it was chrome plated AND best price around!)
Camshaft(My flavorite subject).........A/T with a stock convertor....can't use A LOT of overlap. I WOULD get something with a "generous amount" of lift( 560-570ish) butt...not so much it will beat your rockers/springs to death.
  SBF can tolerate a lot more duration AND a tighter LSA than "Shivel-laz" and other GM stuff. An LSA of 110* will let the cam 'come on' pretty early and be finished by 6 grand or so. WAG on duration about 220* or less.
When you install the cam BE SURE and degree it. Get a timing set so you can advance the cam timing a few degrees MORE than what is already ground into the cam. This will move the  torque peak LOWER.....meaning more low end grunt. With an A/T you need all you can get.
Doubtful you will be wringing-it -out to 7 grand too often so why not move the torque LOWER where you can use it! 55-6 grand area.
Money spent on a good/adjustable MSD ignition box would be well spent. You've heard me preach about ignition timing, well....this will make it more adjustable and EZ'er to do it.
I like headers over mani's butt ........your call. 600 CFM  Edelbroke carb and Performer RPM intake(or Wiend) will work flawlessly.
6sal6

Last edited by 6sally6 (12/16/2019 7:42 PM)

As the saying goes: fast, cheap, durable; pick any two.  Here's the issues with the GT40P heads:

1.) Used heads can be cracked.  Unfortunately its not uncommon.  I've heard estimates as high as 3 out of 5.  Having them Magnafluxed to check for cracks is an absolute must. 

2.) Stock springs are not going to work with a high performance cam shaft.  Max lift is like 4.88 I believe. $

3.) Exhaust valve rotators cause early coil bind, so just changing springs isn't going to solve the lift problem.  You'll need to swap exhaust valves while you are there to allow for a taller installed height to tolerate high lift without coil bind. $$

4.) To go through all that and not do a valve job, seals, possibly guides depending on wear, check the decks, and possibly mill the decks flat would be foolish.  And this bill just keeps on climbing. $$$

5.) GT40Ps also use the nonadjustable pedestal mount rocker arms that are more expensive and weaker (5/16" bolt vs. a 3/8" stud) than conventional roller rockers.  With the kind of spring pressures you'll be running vs. stock I would consider this a liability at best if not a time bomb. $$$$

6.) The ports in the heads are decent as is, but you're still dealing with 20+ year old technology.  These are also truck heads, so the idea is low end torque, area under the curve, and done reving at 5,000-5,500.  They don't support a lot of high lift flow as cast.  So to hit even 350HP they need to be ported.  Problem is, these aren't 50 year old casting where its hard to screw them up with an at home port job.  You have to know the heads and where to grind or you'll make them worse.  Its not just a simple "don't touch the port floors" deal, so now its getting farmed out and $$$$$

In the end you'll have the cost of a set of Edelbrocks in the GT40Ps trying to reach your goal and they still won't flow as well and they'll still be 50lbs heavier.  FWIW 50lbs by itself is worth a 0.050 reduction in ET at the strip.  Its the equivalent of 5HP, and maybe more because the weight off the front end aids weight transfer and improves the hook. 

Also, aluminum heads tolerate another point of compression than iron.  In a carb engine you could get 9-9.5:1 with iron heads, not great for your performance goal on a small engine.  Aluminum heads puts that at 10-10.5:1, making the goal a lot more realistic. 

IMO the only reason to use a factory style iron head is a very tight budget or racing class rules requiring them. 

AFR heads cost about $1,600.  I paid just over that for the 180 Renegades on the 331 I'm building for my '89 GT.  Edelbrocks are more like $1,200.  Summit's site often lists this as the cost for a single head, but there's always been two in the box. 

Bullet Bob wrote:

According to AFR, who published results from an "independent" dyno tester, an otherwise stock 5.0 with AFR 165 heads/Comp XE266 cam/roller rockers makes 403HP at 5800 and 370 or so torque at some lower RPM with a carburetor.  That's at the flywheel on an engine dyno so with closed exh and in the car you could prolly expect 300, 325 or so on the ground. 
This is the setup I have except mine is injected and has not been tuned to get what it's capable of.  I can say that even with the stock EEC-IV setup it feels pretty good...now that TKO suggested I go back to the stock MAF.  I had a Cobra MAF on it and it felt kind of dead.  Switched back to the stock Fox MAF and......holy crap, what a difference.  Now I'm working up to tuning the ECM and getting it right.

 

I am seeing edelbrock or AFR heads may be the way to go.. but keeping it carb-ed... I had a chance to put fuel injectiion with a lot I bought.. I am not ready for the computer stuff while it may be easier in the long run.. I am still stuck on TV pressures and carb needles :D
 

A popular misconception is that seeing crosshatch in the bore means the bore has no wear.  A freshly honed cylinder has almost no visible crosshatch.  The crosshatch is where very tiny slivers of metal have actually been ripped out of the cylinder walls, allowing you to see the lines.  Honing a cylinder is like sharpening a knife.  On a microscopic level there are tiny "fingers" of metal that are created by the process.  On a knife, when you apply a butchers steel you aren't sharpening the blade; you are smacking those fingers back towards the center of the cutting edge, restoring the sharpness.  The final step in the honing process does the same thing, and this is why you don't typically see much if any crosshatch in a freshly honed bore.  I've had plenty of engines that had weak compression, burned oil, etc. that still had crosshatch in the cylinders, in fact I don't think I've ever seen one that was smooth, excepting one that was fresh from the machine shop.

Cost wise, my last machine shop bill for a bore and hone was $200.  I paid $213 to have the block hot tanked, cleaned, brass freeze plugs installed, and all critical dimensions checked, including the line bore.  Balancing added another $200, but this was starting with an unbalanced rotating assembly for the stroker (I would check the balance even with all stock parts).  I paid $100 to have the rings file fit, saving me hours.  I then paid $40 for them to polish the crank.  It was new, but the finish wasn't great in their estimation so another $40 to have it right wasn't even worth thinking about. 

On the headers, don't use JBAs.  They hit the box.  I have heard FPA headers clear without issue.  Wish I'd known that before...

On the heads, you need a tiny combustion chamber, because the swept area in the cylinder is so small.  I would suggest about 58ccs, this will get you right about 10:1 with a head gasket of 0.020" compressed thickness and zero deck height (this can be checked at mock up, but SBFs typically are right close to zero deck without machining). 

The AFR 165 Renegade fills the bill, #1402 has the exhaust crossover, #1399 doesn't.  I prefer the crossover for a street engine; it helps with warm up.  Current pricing on Summit is $1,640.91

Edelbrock has an E-CNC head that has a 59cc chamber, 185cc intake port, and bigger valves.  Would be better suited for a slightly larger engine IMO, as a port that big tend to be a bit lazy on a smaller displacement engine.  Edelbrock No. 79259 for $1,099.50.  BUT, IMO their 60229 heads are a better match with 170cc intake port, 1.90/1.60 valves, and 60cc chambers, but you're looking at $1,459.00 for a set, and at that price I'd just buy the AFRs.  The biggest issue with Edelbrock is they have splatter focus now.  They're building heads for everything from AMCs to Chevy Duramax engines.  I don't think each head gets the same amount of attention so they tend to just keep using what has worked.  Nothing against them, they are a workhorse head.  I have a set that's been on two different engines and was always happy with them, but the cost disparity for SBC heads between Edelbrock and AFR was also over $500 at the time, and this was over 20 years ago when $500 was worth like twice what it is today. 

Another viable options would be TFS.  They have a decent head in #51410004M58.  Its a 170cc intake runner, 2.02/1.60 valve head with a 58cc chamber.  Cost is $1,320 for the pair.  TFS has been making SBF heads since the early days of the 5.0.  They typically perform well, though IMO the technology is a bit dated.  They were initially based on an old Brownfield head design used on short dirt ovals.  They use Chevy sized valves to save cost, but IMO those valves are a bit too big on a bore this small and actually hurt flow because the mixture has to get around a larger valve head and into a tight space between the edge of the valve and the cylinder wall.  Hey, they'll work, and should allow you to hit your power goal, but again, I'd gladly spend the extra $320.91 for the AFRs. 

These head have received some good reviews and the price isn't to bad.    https://lmr.com/item/SVE-6049A-K/SVE-Mustang-Performance-Aluminum-Cylinder-Heads-79-95

The SVE heads do have good reviews, but I've never seen anything on them dyno wise.  The factory E7TE heads were so restrictive that it isn't a tall order to make a better flowing head.  Looking at their flow numbers you see the issue; they have a weak exhaust port.  Here's the figures for the AFRs as a comparison:

https://www.airflowresearch.com/165cc-sbf-street-cylinder-head/

Now, you can use a dual pattern cam to crutch a weak exhaust port, but to me this clearly shows the difference between AFR and pretty much everyone else.  The AFRs have an excellent I/E relationship.  You can crutch the port, but as they say TNSTAAFL.  To do it you either need more lift, more duration,or both.  More lift you risk running the valve into the piston, more duration you get more overlap and a worse idle.

Power wise you'll likely hit close to the numbers you'd make with the AFRs, maybe 15 less HP and a slightly lower torque curve, but peak power isn't everything, even in racing.  The AFRs will produce a better running engine across the board. 

Now, what's it worth to you?  Over $600 is hard to ignore, but I've purchased some SVE items for my '89 GT, and the price is always very attractive.  The quality isn't terrible, considering the cost, but its by no means first rate.  Looking at these heads they look like a copy of the Edelbrock heads.  I know I harp on this, but one thing I really respect about Edelbrock is they make their heads 100% in the US.  The SVE heads I'm sure are made in China, and either they figured out how to skirt Edelbrock's patent(s) with minor design changes, or they are just able to avoid legal entanglements due to international law not protecting intellectual property stolen by the Chinese.  I'm a big believer in buy American and Americans work, so I'll gladly pay more for a company's products who invests in America.

11:1 is too high for a pump gas carbed engine.  10:1-10.5:1 is about the most I'd go.  You can get away with a little more if the cam and converter are right, but I don't think the compromises are worth it.

Its great these budget friendly heads are out there, but I see the same kinds of features that put me off the cheaper Edelbrock heads, TFS heads, and SVE heads.  190cc intake port is WAY too big for a street 302.  The exhaust port is weak.  The valves are too big. 

I'm also about 2000% sure these heads are at least cast in China. 

In the end peak power will be good, but these heads on a 302 are going to be less than stellar everywhere else.  I'd have fewer misgivings on a higher winding stroker or 351. 
 

The old valve and runners too big, plus too much comp for today's pump gas.story is why the cleveland 4v heads (cast iron) work so well. There is way,s to tune around it without costing big $. I,m sure a 302 alum. headed with flat tops would also work, and why is it so dang cold down here near the Gulf.
Well it hasn't snowed yet...

50vert wrote:

Rich ... you can come ta Mammoth if you're feelin homesick

Somehow, I can't see myself or Bonnie letting me drag this thing up your snow cover hills
 

Bullet Bob wrote:

Triton wrote:

Bullet Bob, do you have a link for the AFR build?

Went to AFR website yesterday trying to find a link to that Dyno test but they don't seem to be showing any dyno results now.  I saw that info nearly five years ago when I bought mine.

BB

I found one where they built a 371 HP 302 that only had like 7.5:1 compression using the AFR 165s.  This was a carb engine.  Obviously the compression ratio was not ideal, but it gives you an idea of how those 165s could fairly easily make 400HP.

I saw another test where all things equal they swapped a set of GT40X heads for a set of AFR 165s and it picked up almost 50HP and 50lbs/ft at the rear wheels.  The GT40X heads were off road use (non-emissions) versions of the GT40 design. 

The interesting thing is that if you look at port volume and flowbench numbers other heads are often close to the AFRs, but the AFRs make more power because the shape of the ports matter just as much as how much air you can force through them.  Interestingly the cross section of the AFRs, like the valve sizes, are typically smaller than their competitors. 
 

My 400+HP 351 Windsor I used to have only dyno's at 302HP at the rear wheels.  Unless you go with an unrealistic compression ratio and 6sally6 style camshaft, I think you are better off shooting for 250hp at the wheels so you can have a car that will idle and act with good manners when you actually get in and drive it. 

From experience, if you want a car you can comfortably drive on a trip, you will be much happier with more low end torque, snappy acceleration and a smooth idle.  Oh, and 20+ mpg rather than 10-12.  Or stick a coyote in there and have the best of both worlds.  I prefer to keep it simple with old school dependability and simplicity.