[63 Pontiac]

So I'm thinking about freshening up the 400 in my Catalina which has the factory 2 brl. I don't think it needs a full rebuild but I would change over to a 4brl and a mild cam. It has the #15 heads and stock log manifolds with single exhaust now. Do I keep the 15s or go with different heads? Also intend to go with front disc brakes. I have a '72 cast iron intake and a '76 qjet. Will go with dual exhaust also.

1968 Cat, th400, 2.xx gears. Intended use is a daily driver and cruise-ins.

[tom s]

If your going to just drive it just put a 4 bbl setup on it.Tom

[63 Pontiac]

What about using the 068 cam, still keep the 15s?

[25stevem]

I would have a issue with using the 068 cam without at least 3.23 gears.
.
Also the stock jetting of a 76 carb and even 067 cam will not play nice together with duel exh.

For sure plan on re-jetting that carb!

The 15 heads are fine for what you want to do, but they should get new springs and valve stem O-rings while your at it.

[63 Pontiac]

Originally Posted by 25stevem

I would have a issue with using the 068 cam without at least 3.23 gears.
.
Also the stock jetting of a 76 carb and even 067 cam will not play nice together with duel exh.

For sure plan on re-jetting that carb!

The 15 heads are fine for what you want to do, but they should get new springs and valve stem O-rings while your at it.

So what cam makes sense assuming fresh 15s and a properly jetted qjet?

[tom s]

What makes sense is what’s in it!Not broke don’t fix it!Tom

[25stevem]

Here’s how you need to look at .
The only time pre 1970 and during 1970 that the factory used the 068 cam was in motors that had a true 9.5 compression.

After 1970 and into the low compression era the only time the factory used the 068 cam was in the 71 and 72 455 HO motors with a true 9 to 1 compression .

Even the 067 cam was only used up to 1976.

You should convert those heads over to screw in rockers studs and then run the 067 cam with 1.65 rockers which will add 3 to 4 more degrees over the nose without effecting the idle plus provide close to .450” lift, or run a aftermarket cam with close to the same specs.

[63 Pontiac]

Going by the Wallace racing info, compression for the YC 400 is shown as 10.5 but that may be just the advertised number?
Anyways, appreciate the advice. This is likely a late 2023 project so I'm in the info gathering stage right now.

[hurryinhoosier62]

Originally Posted by 63 Pontiac

Going by the Wallace racing info, compression for the YC 400 is shown as 10.5 but that may be just the advertised number?
Anyways, appreciate the advice. This is likely a late 2023 project so I'm in the info gathering stage right now.

Nearly all of Pontiac’s compression ratios in the 1960s were overstated by .5-.75 of a point. I agree with Tom; add a 4BBL intake and a properly rebuilt and tuned Q-jet and drive it.

[b-man]

6X-4 heads, mill them about .025” or .030 to bump the compression to about 8.5:1. These heads play very nicely with the ‘72 iron intake, the exhaust crossover mates up as it should without messing around with gaskets and block off plates.

Factory 066 cam, perfect for a low compression 400 tugging a big boat with 2-something gears. The same cam was used in the 7.6:1 400 along with a TH350 and 2.41 gears in the 1976 T/A. You know chances are good that your current cam which is likely the original has a couple of badly worn lobes so definitely change it out.

You could likely drive it on 87 octane regular, daily driver heaven.

You’re welcome.

[63 Pontiac]

Thanks Bart!

[Goatracer1]

There is no reason to change heads if yours are in good condition. You don't even need screw in studs. The 066 cam is inexpensive and will work very well in your situation. The factory used them in everything. They must have known something. Big heads are only going to give you more top end power. It doesn't sound like you plan on building a high revving engine. Be realistic and keep it simple.

[25stevem]

My statement of installing 7/16” screw in studs was in conjunction with my suggestion of adding 1.65 rockers to a factory cam.

If that’s not done you WILL be snapping off the tops of the stock pressed in studs sooner or later.

BTDT not once but on two different motors with the same cam.

Some lessons come hard, but I was lucky, as both times I was only broke down for less then two hours and it was day time thank God!