I need some advice. I have a 351w block casting number D4AE-6015-AA3. So far performance wise I am set on a Lunati voodoo camshaft. i need advice on heads. I really want to put gt40p heads on it. Yes I know I have to get the bolt holes bored out bigger. are they the cheapest best way to get horsepower head wise? Also where can I get a set of exhaust headers for them? Preferably long tube.

 

headers for that head are expensive and not many options. what vehicle is this motor planning to be in?

 

It's going in a 1977 f100. Ive searched for a while and you're right. There is barely any options for the headers for gt40p's. I'm thinking I should go with gt40 heads. Other than boring the bolt holes out, are gt40 heads a direct bolt on replacement like the gtp's?

 

Yes GT40s are a direct bolt on, there are no wacky head limitations with windsors unless you get some very early(60s) heads or intakes.

 

Good choice, basically a carbed version of a first gen Lightning

 

How's the block turning out?

 

So I have run into a problem with my local machine shop. They refuse to bore out bolt holes on heads. Has anyone or know anyone who has had head bolt holes bored out? There's a few other machine shops somewhat near me but I would like to know if anyone has ever had or know someone who has had gt40p head bolt holes bored out to fit a 351 before I call around and everyone tell me no because of some reason I don't know about.

 

I've done it. I thought it was a big deal but the mechanic that I was working for, we just got the right size bit and used a really big drill. I was concerned about the bit not centering in the hole but it did just fine. We set them on some plywood and drilled them out with a 1/2" bit. It sounds redneck but it worked out slick as a button.

 

You can't accept any more PM's either by the way

 

So i could "redneck" do it at my old high school with the drill they have there since I'm still good friends with my old agriculture teacher there. I have a drill press in my garage but it's tiny. No problems with the angled bolt holes? Did you use any special drill bit or just a regular steel drill bit and a lot of oil? And I fixed the PM problem lol sorry about that

 

Yeah I think just a point in the direction of the hole, it will center itself. Like I said, I was skeptical but the hole will only allow the bit to take off an even amount on the circumference, letting the bit guide you through the hole so to speak. I don't remember what kind of bit it was. I know they are 1/2" bolts but not exactly sure what size bit it would be. Maybe 33/64" or 17/32" I'm not sure but just as long as it cuts iron. Maybe some spray lubricant on it but nothing to allow it to want to cut crooked.

I'm surprised they aren't 351w size already.

Edit: P heads never came on a 351w, only 302's. I was thinking about the regular GT40's.

 

Ive heard of some people say that. They must have been talking about gt40's. Ive searched everywhere for a set of gt40p heads that came off of a 351. nowhere to be found and now i know why. gt40's must have been the only gt head on the 351's. but it doesn't make any sense as to why that machine shop refuses to drill out bolt holes. Perhaps ill take the heads to a machine shop in south Nashville. USA motor and machine. they've been in business for decades and know what they are doing but the machine shop closest to my house that refused to drill out the holes is a whole lot cheaper. Maybe the phrase "you get what you pay for" is trying to tell me something here. Next step is the first step. I have to get pistons. I gotta take the block to the shop 15 minutes away and get them to bore and hone my block, clean it, install cam bearings, press the old pistons off the rod and the new ones on. All for $290. Is that cheap or a lot compared to where yall live? They also charge $65 per head to clean it, reseat the valves and resurface the head.

 

That shop sounds a little on the cheap side. You're right, you do get what you pay for, but no one likes to pay through the nose of course. I would say, and this is what I would do, is you plan to use that shop, take into consideration of they have a torque plate for the hone job. If they do not, I would not use them. Some people may be thinking that's extreme but I would use that as a gauge for the quality control they have. Any really good shop would have a torque plate for one of the most common motors ever made.


I know some shops charge $40 just to mill. Believe me, it takes a fair amount of effort to use a machine level with the head on stands to make sure your runout from end to end is good.

 

I have drilled those bolt holes myself on my floor standing drill press, the holes are perpendicular to the head gasket surface so it's not at all hard to do once the head is positioned correctly, and cast iron is soft as far as metals go so it take no effort at all to drill them out.

 

I've have found that getting a reamer rather then a drill to enlarge holes works better.
If you do use a drill start with one of those "step drills" bits and make a shallow starter hole. The step for the 7/16 will center the bit so when the 1/2 inch part cuts it will be centered. One you go down about 3/16-1/4 inch you can switch over to a normal 1/2 dill and you know that the dill is centered.


Doing it on a drill press is the very least you can do to insure a straight square to the deck surface hole.