A question for the HEAD DOCTOR

[valley firearms]

Hello all,

I have been cruisng this site for a while but haven't posted yet. To introduce myself, my name is Mike, have 1968 coupe and I live in Alaska. Hello everyone!
There have been a lot of posts reguarding aluminum heads and I have been using the search engine to gather info. My problem is, I bought the car several years ago and don't know what pistons I have. I know the engine was rebuilt several thousand miles before I bought it. The miles are still low since I have been working on the car since and probably not have driven it more than 100 miles since the purchase. I'm sure the guy used standard flat top pistons. So, I don't know the C/R. A little background of what I have:

302 bored 40 over (307.65)
Holley Street Avenger 575
Edelbrock Performer
Pertronix Module
MSD 6A
Shorty headers
Comp Cams FS 280H-10 .512 lift 230 duration

This spring I will be installing a toploader 4 spreed w/hydraulic clutch.
I also plan on having a 9" built with 410 or lower gears . With that said, I have been pouring over information about aluminum heads. I have learned a lot in the last few days and I am glad I didn't go out and buy the biggest heads out there(like I wanted to several days ago). Just to give you the difference of my thoughts from several days ago, here is what I have learned. I was going to buy ProComp heads with 2.02 intake and 160 exhaust. I have read that the 2.02 valves with hit my pistons if they are not fly cut. But I have noticed some of these people advertising on e-bay say that there might be a problem with valve/piston clearance. Are they just trying to sell them by being vague? Now I am wanting the AFR with 190 / 160. I'm not sure about the intake runner size. A lot of heads are advertising 190cc. Is that the size/volume of the intake port? I figured with the 190 valves I'd be safe. Now there is the roller rockers. 1.6 or 1.7's? Will the 1.7's give me the piston slap I am trying to avoid? I'd like the 1.7 for more lift. Also there is the rail type rockers. Which is better, standard stud type or rail type. Is the rail type year specific? Can I use them? I have read they are non adjustable( only with shims). I am out to gain the most horsepower like every other guy so any help would be appreciated. If I have missed something please feel free to educate me. I want to buy the heads next week.

[valley firearms]

Head doctor, I just read your thread on selecting the right head. I think I'm overwhelmed now. Please excuse me while I choke myself. I hope I'm not left with hanging pictures of heads and throwing a dart.

[1979bruiser]

when you buy a set of aftermarket heads they are set up w/ studs and guideplates. you will no longer need shims as shims are for bolt down rockers only. i hope this helps.

[valley firearms]

I found the receipt from the engine builder. He listed the pistons as 1157 .040. I did a search for 1157 pistons and this is what came up.

http://www.kb-silvolite.com/spistons...tails&S_id=121

As you can see there are some cuts in the pistons. Would it be safe then to assume that one could use a 2.02 valve or 1.7 rocker if needed?

[1979bruiser]

i forget what the stock releifs look like but stock are similar and can only handle a 1.90 valve. does any one have a stock piston picture to compare?

[Dark Knight]

A couple things that I see..those KB's are a stock replacement piston, so sticking to a 1.90 intake would probably be best. The intake volume can be misleading, TW heads have the intake valve moved so runner cc will be different. With a performer intake I wouldnt go with to big of a cam, it will choke it at higher RPM. You might look at changing it to a stealth or performer rpm.

Rail type rockers are stud mount and were used to keep the rocker arms aliagned on the valve stem tip. They'll only work on valves that are designed for them with a longer stem. Pedestal mount is what they use in later 302's to keep the rocker straight, and yes, you can only use shims to adjust them. Regular stud mount rockers are what you want, the heads you get will have guide plates to keep things straight. Get a good roller tip rocker and you'll be fine.

You might go with less gear, or a T-5 conversion. 4.10's will suck of you do alot of freeway driving. Do they HAVE freeways up there?

Personally, I'd get eith AFR 165's or e'brock performers and the cam you have. I have the 165's and you can get them with a smaller combustion chamber so you wont lose to much compression.. but either one will make a bunch more HP than the stock heads. BTW is it an original 4v car?
I have a 68 coupe, but it's not really stock

[valley firearms]

Thanks for the input Dark Knight and bruiser. We don't have freeways up here, just a few highways (if that's what you want to call them). I am sure you are right about the pistons being stock replacements. I'm not sure if the car was originally a 4V. It does have the GT40P cast iron heads right now. It runs really good now but not good enough. I plan on swaping out the C4 for a top loader I purchased this last summer. I want to make a hydraulic clutch with the CNC slave and master cylinders. I was also contemplating using the hydraulic throw out bearing. I've heard pros and cons about those. Either way, I want a bad ass stang to cruise around in. I don't drive it much as I have been working on it for the last year. I bet I have less than 100 miles on it since I bought it year before last. Here is a link to my progress. I appreciate the input and really like this site.

http://www.putfile.com/valleyfirearms/images/16563

Thanks!
Mike.

[Dark Knight]

Those pics make me glad my 68 is an AZ car

[valley firearms]

word. But, when I'm done she'll be in great shape