[dan2y]

Hey I'm new to here. Im mechanic guy and worked on some of domestic cars for most of time. But as for old mustang is kinda of new to me. I just had guy who owned 1970 mustang couple w/ original 302 v8, its great run but we want make t more power out of it. As we are looking for power from idle all the way to 5k rpm and high torque at low rpm, not interested in top speed. We want make it for daily driver with plenty of power we could have to hit gas on floors If we wants to.

A guy get the parts on the ordered now as well as spending the money in economy budget mode.

1)Edelbrock 600 cfm electric choke carb #1406
2)Edelbrock Performaner Intake Manifold #2121
3)Edelbrock cam & lifter kit #2122
4) few of things for upgrade to meet the modify level of above parts- such as fuel pump and thicker wirest, etc.

One question, The Edelbrock recommended the heads are pretty pricey as out of picture for economy budget mode. I think there is another way as alternative for heads performance....We could pull the original heads out for port/polish job and 3 angles jobs for better flow improvements and can handle with upgrade cams kit and carb. (cams kit specification use only stock ratio rocker arm). What do you guys think? Im up for open anything for any input about heads.

[paul289]

Stock heads are pretty restrictive. I'm running stock heads with a 262 degree cam and edelbrock intake and carb, mild porting, 1.94/1.60" valves, flat top pistons and an MSD ignition, and I'm pushing maybe 230 hp at the wheels. Go for some GT-40 heads, or some from a V8 Explorer from 97 or whenever they first came out. Also, I hear that Patriot makes a good set of heads that are really affordable. I think they're aluminum, too.

[The Greek]

A set of higher ratio 1.7:1 rocker arms will increase valve lift approx. .030". If there is no valve interference with the pistons, this is an option to increase flow. I'm using this ratio rockers to give me a .510 lift on my GT40 heads and stock 5.0 pistons with valve reliefs. No interference problem. The 1986 5.0 did not have valve reliefs on the pistons, the only year for this. FYI With those pistons you would have a problem.

The GT40 and GT40P cast iron heads can be found cheaply and have larger valves and better flow than the stock heads. These have the later design pedistal mounted rockers rather than the earlier stud mount. The use of a mechanical lifter cam is difficult with pedistal mounts and requires mods to the heads.

The GT40P heads flow better than the GT40s by a little bit, but it will require special headers to clear the repositioned spark plugs.

The port sizes on these heads are not too large and will be able to maintain flow velocity and the torque that you want. The only drawback is the 69cc combustion chamber size. It yeilded a 9.0:1 compression ratio on a stock pistoned 5.0 engine. This may or my not be what you want, but the deck can be shaved on the heads to increase the compression.

The key to torque is to stay conservative on the port sizing and you will have velocity. 302 cubic inches is a small displacement engine in the V8 world and this must be considered. A small port on a larger engine may be just right on a 302.

[dan2y]

Im assume that 1970 original 302 has valve reliefs on those piston, correct me if im wrong (we haven't pulling the heads out yet).

We are still dilemma about which we should go with stock heads with port polish job, make a better flow. Or go with gt40 heads. Is there anything required to specific modify when gt40 heads bolt on 302?

We are going to get edelbrock cam/lifter kit use only stock ratio rocker arm...If we go with gt40 heads, how can we solve the problem with the correct ratio rocker in the gt40 heads? By pull the original heads ratio rocker out and put it in gt40 heads?or gt40 heads is the same ratio rocker as original heads?

[The Greek]

The only things that you would need to put the GT40 heads on a 302 is a set of head bolt reducing washers. The head bolt holes are drilled for the 351's 1/2" bolts. ARP and maybe others sell special washers to fill the gap created by using the 302's smaller 7/16" bolts. The washers should be used to achieve an even clamping force on the heads. I've seen the washers omitted, but I don't recommend it.

You will need to plug the thermactor air pump inlet ports in the back of the heads.(GT40 only) Use a 5/8"-11x1" (Coarse Thread) Set Screw to plug them. (Available from any good hardware store) Use an Allen wrench to install them. Do not use a pipe plug it has the wrong threads. The ports must be plugged (One port per head) or else you will have an exhaust leak spitting out against the firewall. The port leads to each cylinder's exhaust port. GT40 heads don't have the restrictive thermactor humps in the exhaust ports like the regular production heads have. So you won't have to grind them out for better flow.

In 1978 Ford changed the rocker arm design to the pedistal mount arrangement. All 302/5.0s and 351Ws went to this and all of the stock rockers are stamped steel like you find on a Chevrolet. All of the earlier rockers were cast and mounted with a stud.

All of the factory pedistal mount rockers are the 1.6:1 ratio. The rockers are held in place with an odd shaped piece which is called a fulcrum. It acts as a bearing surface for the rocker to pivot on and as a pedistal to keep it from rotating. Instead of the rocker being held in place with a nut on a stud, it is held down with a 5/16" dia. bolt with a hex head on it. This bolt runs through the center of the rocker and fulcrum.

The 1970 pistons should have valve reliefs and there shouldn't be any interference problems unless the camshaft lift is too high. This needs to be checked out no matter which head you use.

E-bay is a place to look for the GT40 heads. Remember that GT40P heads have relocated spark plugs and header clearance may be a problem. You can try using the Accel "Shorty" spark plugs made for this purpose, but I can't say for sure that this would work. There are headers made to clear, though. The regular GT40s don't have this problem, but they don't flow as well.

The GT40 heads can also be found on 93-95 Mustang Cobras and 90s era Lightning pick ups and both the GT40 and GT40Ps can be found on Explorers. They're ID'd by:
GT40 Has 3 vertical ribs cast on the end and "GT" on lower corner and in rocker valley.
GT40P Has 4 vert. ribs cast on the end and "GTP" on lower corner and in rocker valley.

I think it would be cheaper to get the GT heads rather than have the stock heads reworked.