[Jay S]

6X-4 are better heads with a 400 for what was described, and have induction hardened exhaust seats which is much better for daily driving, use the Summit cam you already have and use the 6X heads, or could keep the stock 254 cam, either one you could run on 87 octane with the 6X heads. The 15s would require 93 octane.

[Squidward]

What heads are on your 350? 350 heads on a 400 usually give a little bump in compression from smog era setups (like 6x-8's), and should give a manageable compression when used in lieu of high compression 60's heads. Someone has already mentioned 6x-4's (350 heads) on your 400.

High compression 400 heads work nicely on a 350. Lower compression 350 heads work nice on a mild 400 build. I run #47's on a 400. I run #12's on a 350.

And for a daily driver with mild cam (2800), you won't really have to worry much about small valve heads. The 1.96/1.66 valves would be just fine.

1969 47's and 1970 11's seem to be out there still.

With your stated intention, a very fun daily driver would be easily achievable.

[dogwalkin]

The 350 i currently have in there has #17 heads as it happens to be a '68 as well so i don't know if they would be a good option.

[PONTIAC LARRY]

if its got #15 heads on the 68 400 290/340 HP I would not run less than a Summit 2801 or Blueprint 068 copy , either is a great daily driver do all performer in a 400 with some decent compression but have also ran very well in lower 8.8:1 400 too. the 68 265 HP B body engine had #14 heads the 15 is far more common as 290 hp 2 barrel Catalina/Executive and the base Bonneville 340 hp version in 68

[Jay S]

I agree with those things in the last post. The 2800 is not enough cam for the higher compression heads with a 400. You can run up to about 9.5 with a 2800, but it runs just as good at 9:1.. The 2801 and 068 are better choices above 9:1. The little 254 would very likely be as pump gas friendly as the 2800, the 254 is a very small anemic cam meant for a 2bbl, and won’t fill the cylinders like a cam designed for a 4bbl. Often times the very small cams meant for 2bbl engines can pump more compression but run equal or less octane fuel than some bigger cams because they are so small the engine doesn’t breath enough to make much HP, they cut off cylinder pressure making the entire power band lower.

[Jay S]

I prefer higher compression engines, but using the 2800 or a 254 in a 400, the 6X-4 would be my pick.

[dogwalkin]

I agree with you on enjoying the higher compression engines!! I'm just thinking daily driver and pump gas plus the best mpg(i know it's not gonna be great With a 50 plus year old v8) thanks for all the help and recommendations

[Joe-Touring]

I have a set of 17 heads that I was gonna use for a 400 build, but all the local machine shops quoted over $2000 to get em set up. The chambers measured out to ~83cc’s, about perfect for a 400.

I did a quick calculation for you for a stock 400, compression would be around 9.0:1. I think that would be great for your 2800 cam and you might even be able to run 87 octane.

6X-4 heads are also a popular choice, but you’d be down around 8.3:1 comp ratio.

If the 17’s are in good shape, and you don’t mind taking apart the 350, that’s where I’d go. I think that would be the most economical route. And it’ll give you a good recipe. The smaller 1.96/1.66 valves will help with port velocity/torque down low.