289 with gt-40s

[gbarber]

I have a '66 289 that I am trying to put gt-40 heads onto. The problem I have is that the coolant ports on the upper part of the 289 block don't line up with the newer style heads. Can this be fixed? Will it cause major cooling issues with the heads?

 

[12sec67]

they can be fixed, but you also have one other problem.... you'll be losing a lot of compression!

 

[gbarber]

I know I can mill them, but not enough to get where I think it should be. The problem is that it was going to cost $450 to get to D00E's that were on the car when I bought it up to par. A friend gave me these gt-40's for $300. The gt40's only have 10K miles on them, and I'm pretty much out of cash.

 

[GaPonyFarm]

I know I can mill them, but not enough to get where I think it should be. The problem is that it was going to cost $450 to get to D00E's that were on the car when I bought it up to par. A friend gave me these gt-40's for $300. The gt40's only have 10K miles on them, and I'm pretty much out of cash.

Sometimes its cheaper, to spend more up front. This is one of those cases. Maybe a machine shop will make a trade with you... they're more likely to be able to sell the GT40's. You should also be able to get some 302 heads from a boneyard and have them reworked.

Unfortunately, its only been about a month since I gave away a set of C6OE-M heads that had been sitting under my bench for about 3 years...

 

[Edbert]

Even the 302 heads will lower your compression compared to 289 heads. What you really need are some domed pistons. They are not THAT expensive, the problem is they require major surgery to install.

 

[allcarfan]

sell the GT40s for $400 on ebay or someplace else online. Then take your 289 heads and have them ported.

Shane

 

[Edbert]

sell the GT40s for $400 on ebay or someplace else online. Then take your 289 heads and have them ported.

A modest port job on the 289 heads and retro-fitting some chevy 327/350 valves in there and they'll flow about the same as the GT40s. That way you wont have to rebuild the reciprocating assembly. Or you could get some stock 351W heads and use an ARP stud kit since the head bolts were larger, but they might lower your compression too unless you can find the early 351 heads.

 

[GaPonyFarm]

Chebby parts??? God is going to get you for that!

 

['69Stang]

I think you should keep those GT-40 heads vs. the stock heads. Getting the coolant holes lined up should be an easy and cheap fix for a machine shop. I know going from stock 302 heads to the GT-40’s made a huge difference on my old 302. I guess you could keep your old 289 heads and have them ported to get to the GT-40 level, but figure spending at east $400-$500. Really, you may just want to spend $1000 on a set of good aluminum heads like Twisted Wedges or Brodix or Edelbrocks and be done with it.


However, for the money, the GT-40’s are good for a small-block Ford. I would get the heads milled so that you get the chambers down to 52-54cc’s so that there isn’t a big drop in compression.

 

[allcarfan]

[QUOTE='69Stang]I think you should keep those GT-40 heads vs. the stock heads. Getting the coolant holes lined up should be an easy and cheap fix for a machine shop. I know going from stock 302 heads to the GT-40’s made a huge difference on my old 302. I guess you could keep your old 289 heads and have them ported to get to the GT-40 level, but figure spending at east $400-$500. Really, you may just want to spend $1000 on a set of good aluminum heads like Twisted Wedges or Brodix or Edelbrocks and be done with it.


However, for the money, the GT-40’s are good for a small-block Ford. I would get the heads milled so that you get the chambers down to 52-54cc’s so that there isn’t a big drop in compression.[/QUOTE]

and I'm pretty much out of cash.

 

[gbarber]

Okay, thanks to everyone for the advise. What I have decided is to keep the gt-40's, and fix the water flow problem. M&M head service is drilling three new holes per head and milling them .030". This should take them down to near 60.5cc. I realize that compression will effect power, but dropping compression by 1 ratio point will only drop horsepower by 3%. I am not going to drop compression that much. I think that the increased air flow will outweigh the drop in compression. I'm only increasing the chamber size by 1.5cc. The 302 D00E heads that were on the car measured close to 59cc. So the way I figure it going from the 59cc heads to the 60.5cc (gt-40 heads) will take my compression from 8.3:1 to 8.2:1. (The block is bored .040 over) That's nothing. Even if I had some 54cc 289 heads, that would only take it from 8.7:1 to 8.2:1. That's 1.5% compression horsepower. I still have better heads than what I had.

 

['69Stang]

I think you should mill those heads to get 54cc's. That's what I did with my 302 and GT-40's and I ran a big cam - 230/235 duration @ .050, .510/.515 lift. No piston to valve issues at all. I fyou have 8.3:1 compression now, with 54cc's you should have 9.0:1. Believe me, you want more compression. BTW, what intake and cam are planning on running?

 

[gbarber]

My machine shop guy was concerned about intake issues by milling the heads enough to get 54cc's. Did you have 64cc gt-40's? I just went with what he told me.
I have an Edelbrock performer intake and Edelbrock 1405 carb 600 cfm. I have a Summit SUM-3601 cam-218 and 228 @ .050, 114 separation.

 

[gbarber]

'69Stang,
I guess what I should have asked you was did you also have the intake surface milled on your heads? The machine shop told me I might run into intake alignment and sealing problems if I had too much taken off the deck. They would have to take material off the intake surface to match the deck if I took too much off.

 

[golf4283]

I have some 289 heads that I just took off of my 302. I can sell them to you if you want to. PM me if u want them. They will be cheap.

 

['69Stang]

'69Stang,
I guess what I should have asked you was did you also have the intake surface milled on your heads? The machine shop told me I might run into intake alignment and sealing problems if I had too much taken off the deck. They would have to take material off the intake surface to match the deck if I took too much off.

Yes I did. They had to mill the intake to make up for the drop in the cylinder head height. But, it was like $50.

 

[LMan]

So the way I figure it going from the 59cc heads to the 60.5cc (gt-40 heads) will take my compression from 8.3:1 to 8.2:1. (The block is bored .040 over) That's nothing. Even if I had some 54cc 289 heads, that would only take it from 8.7:1 to 8.2:1. That's 1.5% compression horsepower. I still have better heads than what I had.

8:1 compression? This is N/A? I dont get this at all. Thats mid-70s smog-motor compression

Unless you are going to run a power adder, you need at least 9.5-1 or 10-1. Less than that leaves damn near all your potential power gain on the table.

 

['69Stang]

8:1 compression? This is N/A? I dont get this at all. Thats mid-70s smog-motor compression

Unless you are going to run a power adder, you need at least 9.5-1 or 10-1. Less than that leaves damn near all your potential power gain on the table.

Agreed, the compression numbers look lower than normal.

gbarber: are you sure those are the right compression numbers? Do you know what kind of pistons you have? Those numbers would be the result of dished pistons. Flat-tops would result in considerably higher compression numbers. Also, I thought the original 289 heads had small combustion chambers, like 53cc's.....

 

[gbarber]

Okay, here is what happened. I had used some numbers I had got from an article in MM&FF reguarding compression and its effects on horsepower. I really had no way of accurately measuring the cc's of the pistons that were in the engine, so I used the numbers the article had used on its example car. The piston in that car had a .030 dish and eyebrows. Using those numbers I came up with 8.2:1. However, it gets worse. Now please realize I knew very little about engine building when I started this project, and my goal was to learn by doing it. When I order the rebuild kit for my engine, I told the dealer that I was rebuilding a stock 289. I really didn't care that much about the performance. He assumed I had a set of original 289 heads. The pistons that the kit came with are dished. 12CC's WORTH OF DISH. I guess I learned what dished pistons are. Anyway, I measure the cc's below the deck using a piece of plexiglass and some atf. This showed that there was actually 18cc's total. Plus 9.87cc for the head gasket and I figured head cumbustion chamber being milled to 59cc. This ended up at 7.9:1. I don't understand the choice of pistons that came with the kit. Even 53cc heads that would be a 8.1:1 ratio. My Hayne's book said it should be 9.3:1.

Anyways, what I have done is bite the bullet and order some domed pistons. I called the machine shop and stopped the milling. With the 64cc heads the new compression ratio will be 9.6:1. The machine shop is drilling new water holes. So now all I have to do is pull my oil pan off and pull 8 dished pistons out of my short block. It's only a $300 mistake. At least you guys helped me find it before I had the engine back in the car. That really would have sucked. Thanks