Opinions on 390 build

[Brokenarrow]

I'm putting together a 390 for my '68 SWB. I'd like some opinions from the FE gurus. The short block came from a '69 Mercury Monterey.(C8AE) Fresh,Bored .030, crank turned .010 - .010. Heads are C1AE tall port from a '64 T-bird 390. Redone w/ new guides, seats, & springs. The pistons I have should give it about 9.6/1 comp. Factory cast-iron intake and 4100 - 1.12 carb from the same T-bird engine. Cam is .484/.510 lift, 204/214 duration with new Crane lifters. Exhaust ,Flowtech full-length headers, 2 1/2" Flowmasters. I've got all these parts, but haven't put it together yet. I'm not real sure about the cam. What do you guys think? Sound like she'll make some torque?

[My427stang]

That cam is a little mild, but it'll really run nice and pull hard down low.

I am concerned with your headers / head combo.

Take the header gasket you have and put it up against the headers, and then put it up against the heads. Some headers will seal to the early car heads, but most are made for the later truck style low exhaust port.

If the gasket matches both nicely, then you should be good, but it is possible that the C1AE heads will have ports that are lsightly higher than the headers (not the bolt holes, they'll be the same, the exhaust port itself will be higher when compared to the bolt holes)

If that is the case, you may need to elongate the top holes on the header flange and open the bottom ones all the way to the edge to allow the header to slide UP 1/4 inch.

You'll see what I mean when you compare the gasket, either it will match up perfectly, or the header port in relation to the bolt holes will be too low

[Brokenarrow]

Thanks for the heads-up. I didn't know there was a difference in the height of the exhaust ports. I'll check it out tomorrow. As for the cam, I want the power-band on the bottom end, I'm gonna drive this truck.

[My427stang]

Here is a pic, the calipers are set to the bottom of the port on the right (early 390 like your heads), and then laid over the truck head (what most truck headers are made for)

By the way, I ran the same cam in mine when I first built the 360, then the first iteration of the 390. Sorry if I made it sound negative at all, the truck ran GREAT.

[Brokenarrow]

I went out and looked, and you're right. The headers don't match the ports on the heads. I'm sure I can modify the headers to fit if I have to. But I wonder if the headers for, say a '64 Galaxy will work on the truck?

[My427stang]

I dont like that I am right brother, but I have run into it before.

I think you would be better off just slotting the bolt holes and moving the header up if there is room.

It sucks, especially after the cash in the heads. However I really think that a car header may cause more baloney, unless you went with a shorty of course, but even then who knows.

At least you know these headers fit the chassis.

Another option, if you dont have a lot of money in the heads, is to get a C8AE-H, C7AE-A, or D2TE-A casting and swap them, those heads of yours are relatively desirable and if you dont have too much money in them, you could selll to pay for the new head work

[Brokenarrow]

I only gave $200 for the complete Tbird engine, and the heads were already reworked. I also have the '69 engine (C8AE) complete with the heads and 4-barrel intake. The heads off it are fairly fresh ('bout 20K miles) But they have some broken exhaust bolts. Typical for a 390. Maybe I'll just get the C8 heads fixed. I'll think on it. Thanks guy

[fomocoguy]

Very good info here; I had no idea the ports were different between car and truck heads! Something to stash away in the archives.

[My427stang]

Just to clarify

Up to 1966, all the port locations are the same, truck or car.

There are some minor differences in C6 (1966) heads you need to watch for, but up to that they are all "high exhaust port" regardless of motor or use.

FE weirdos like me know part numbers, but a good rule of thumb is if you have a C6 head, just check to see what you have. Hawkrod has pointed out that 66 can go either way high or low.

67 up is where it sorta gets confusing.

Essentially they ALL change port location in 67 to the low style, passenger car and truck EXCEPT for C8OE-N which is the CJ head. The CJ head is basically just a pre 66 head with extra bolt holes in the exhaust and low riser valve. (There are nuances, but for argument's sake, its a return to the old style, nothing special)

So the issue is more of before and after 66 than truck versus car.

Now, on top of that, there is a very slight exhaust bolt pattern change for various heads, you may hear about.

That only is if the heads were in a unibody car, that one is not too important, because if your header PORT locations line up to your heads, it just means, at worst, having a couple holes drilled in each head.

Clear as mud?

[fomocoguy]

Just to clarify

Up to 1966, all the port locations are the same, truck or car.

There are some minor differences in C6 (1966) heads you need to watch for, but up to that they are all "high exhaust port" regardless of motor or use.

FE weirdos like me know part numbers, but a good rule of thumb is if you have a C6 head, just check to see what you have. Hawkrod has pointed out that 66 can go either way high or low.

67 up is where it sorta gets confusing.

Essentially they ALL change port location in 67 to the low style, passenger car and truck EXCEPT for C8OE-N which is the CJ head. The CJ head is basically just a pre 66 head with extra bolt holes in the exhaust and low riser valve. (There are nuances, but for argument's sake, its a return to the old style, nothing special)

So the issue is more of before and after 66 than truck versus car.

Now, on top of that, there is a very slight exhaust bolt pattern change for various heads, you may hear about.

That only is if the heads were in a unibody car, that one is not too important, because if your header PORT locations line up to your heads, it just means, at worst, having a couple holes drilled in each head.

Clear as mud?

So basically if you are going to use car heads and you want your truck headers to line up you should look for something post 1966. Got it!

[My427stang]

Post 66, but not 68-70 CJ. Which also means Edelbrock heads can be difficult because they use the CJ/early exhaust port.


Give that man a beer...

[kf6wxj]

I'm putting together a 390 for my '68 SWB. I'd like some opinions from the FE gurus. The short block came from a '69 Mercury Monterey.(C8AE) Fresh,Bored .030, crank turned .010 - .010. Heads are C1AE tall port from a '64 T-bird 390. Redone w/ new guides, seats, & springs. The pistons I have should give it about 9.6/1 comp. Factory cast-iron intake and 4100 - 1.12 carb from the same T-bird engine. Cam is .484/.510 lift, 204/214 duration with new Crane lifters. Exhaust ,Flowtech full-length headers, 2 1/2" Flowmasters. I've got all these parts, but haven't put it together yet. I'm not real sure about the cam. What do you guys think? Sound like she'll make some torque?

Your not going to go with an aluminum intake?? I love my performer and would never go back to stock. Bill

[390F100]

I have a Edelbrock Performer RPM Intake and I would never go back to stock. I would think about it, otherwise she should run like a champ...