• 1 Vote(s) - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Cylinder head porting
Hey guys! I've decided to break down the 40 year old original 302 and my first mod is to take care of the cylinder heads. I don't have enough money to buy a good new set of AFR heads so I'm leaning towards having the original heads ported, polished, new springs, and freeze plugs. How much HP do you think the porting will get me? As always guys, thanks for the advice!
It depends on the rest of the engine work. If you use a mild cam and smallish intake, carb and exhaust probably not much. It all depends on your intent. Cleaning up the valve bowl and a good valve job can increase low lift flow, hogging out the ports will help high lift / high rpm flow.

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
No need to pay someone to do a head job!



[Image: 25yvyp3.jpg]
For what it is worth....

My pony car experience is:

73 Mustang Fastback, 351 2V Automatic. New until stolen, 1985
70 XR7 Convertible, 351 4V Top Loader, 1977-1980
73 Mustang Convertible 302 650 Holley, Hedman Headers, Weiand Intake Manifold, HIPO Heads(whatever that means).

Based on my experience(built by previous owner, run into the ground by me) I would not bother with the 302. New heads sometimes mean new exhaust, new manifold because the ports don't always line up. Sure, there are ways to get power out of it, but it is probably a lot easier to just step up to a 351 for an extra 50hp.

Be patient, find a cheap 351 block(W or C) and build it with 2v Cleveland heads. There are LOTS of guys here, droptop73 in particular, who can tell you exactly how to extract power for the street from this setup. Probably for a lot less dough.

If you do a search of partslist on the forum, you will see I am compiling a list of every single piece needed to build an engine. Copy to a spreadsheet and compute the costs....if you dare!!!

Good luck...

[Image: 11jmcuc.png]
351C Bold Manners, Brash Attitude
Favorite Teams: Michigan Wolverines and Whoever Is Playing Ohio State.

When I drive past a herd of cows, the cows MOO at me
I also rebuilt the 302 in my 71, and used the original cylinder heads too.

I did all I possibly could at the machine shop to improve performance:
* ported in bowl area
* street competition valve job
* enlarged valve seats
* oversized stainless steel intake and exaust valves, (the AFR heads are using 2.05" and 1.6" - mine were a little bit smaller)
* machine for srew in studs (for adjustable valves)

I thought the expense was acceptable at the time.

I also finished out the block with a good hardware, e.g., nice pistons and push rods.

I wanted a car that performed well and could still drive to college, so I used a Crane 260 duration cam ~ .440 lift and a Holley 600.

1971 Mustang
Grabber Lime with black deluxe interior
302 engine with C-4 transmission and 9" rear end with 3.50 gears
Before the '72, my dad had a '71 that he built the 302. I'm not sure of the cost, but I know parts for the 302W are cheap and his '71 was a BEAST even with the "little" 302.

All I did was burnouts in that thing.


[Image: 25yvyp3.jpg]
I ported some E7 heads, gave em a valve job and installed them onto my 85 GT. Gained .4 seconds in the 1/4 mile and three mph. That's on a much lighter car. You may see a 10/20 h/p improvement tops but don't expect it to be anything comparable to a set of aftermarket AFR's or the like.

If you need anything to the heads other than a valve job, start adding up h/p gains per dollar spent and those aftermarket heads start looking better and better.

Black 1985 GT
Yellow 1973 Mustang Mach 1
Black 2012 5.0 GT, 6-speed, Brembo brakes, 3.73's
Wimbledon White 1966 F-100 Shortbed Styleside, 390ci, Tremec 3550, FiTech EFI
for the coast of SBF heads, you are better off paying 1000 for aftermarket heads.

now with big blocks, you can come out infront with ported iron cuz of the cost of bbf aftermarket heads. i got fully all out porting and bigger valves on my heads for less than the cost of new heads by 25%.

i think people usually pay 1000ish for head porting which is about the cost of aftermarket assembled heas.
If you can't afford aluminum, I'd yank a set of GT40's off of an Explorer.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
You can get these http://www.edelbrock.com/automotive_new/...reet.shtml for less than it would cost to (professionally) port, replace valves, guides, springs, retainers, keepers, and the valve job. You would need to buy studs, guide plates, hardened pushrods, head bolt bushings, and rocker arms. None of this is cheap. Before you do anything you need to decide what the end product is supposed to be and figure out if it is attainable given time and money constraints. If you decide to buy heads you need to do a lot of research to make sure they are a good fit to the other components and the end product goal. There are dozens of SBF heads available, not all will meet your needs (port volume, chamber volume, valve size, springs). Have a complete and realistic plan before you buy the first part. Chuck
Share Thread:  

Possibly Related Threads...
Thread Author Replies Views Last Post
  Best hydraulic clutch master cylinder solution?? GonHuntin 21 398 08-16-2018, 12:20 PM
Last Post: GonHuntin
  Head and Exhaust Confusion digithead 14 605 04-20-2018, 07:47 AM
Last Post: Hemikiller
  What should be done to a 351 CJ head? scgamecock 10 1,097 01-23-2018, 08:29 AM
Last Post: Ron Tanzi
  351c head number location??? scgamecock 3 363 12-17-2017, 07:22 PM
Last Post: Stanglover
  Over tightened head bolts. What now? EvilPuppetMaster 14 1,588 10-06-2017, 12:10 PM
Last Post: will e
  Intake manifold porting Heardatbeat 7 881 08-06-2017, 03:17 AM
Last Post: Heardatbeat
  Open vs Closed chamber head Omie01 8 1,143 07-19-2017, 05:42 AM
Last Post: c9zx
  Big Block into a 6 Cylinder Convertible - Rear Swap? red73mustang 6 808 06-15-2017, 09:09 PM
Last Post: turtle5353

Users browsing this thread: 1 Guest(s)