[Jay S]

With the 6x-8s and an off the shelf cam I would either look for the summit 2800 or the Howard’s cam I shot a screen shot of in one of the earlier posts. I would have suggested that Lunati 256 if it were available, but I know it will be impossible to find. Better shot finding the Howard’s, but I think it is a long shot also. So IMHO… Best cam that is available off the self at the moment is the 2800. Would work good degreed in at 108 ICL. If it was my engine I would have a shop cut .040-.050” off the 6x-8s to get the compression up a little, I think it would be close to that 160 cranking pressure that was mentioned.

[steve25]

With only a cut of .040” the intake flange should get cut also so the intake manifold bolts up and plays nice!

Once your paying for both of those machine milling jobs removing a cut of that amount, a custom small dome piston is within the money ball park, and plus your not then jerking around with the need for different length push rods to get the geometry back while having adjustment range left in your lifters!

[Jay S]

FWIW, we usually find that after a valve job seats the valves in a little further, and swapping in a higher lift cam that uses a smaller base circle the stock pushrods are closer to the correct length with some taken off the heads.

I have some .005” over 400 domes on the shelf. The last set of 400 pistons I bought were IC890 Icons. They gain some compression over a stock 2262 speed pro or a cast piston, don’t quite get the SCR as high as a dome though, and the min size is probably .030” over on the ic890s. For the money they are nice pistons.

Barnett performance might be a good shop to check out for cams, I think they are in Alabama. I have bought parts from them that they stocked that were hard to find otherwise. Would be worth looking into, I would rather run this cam than a 2800 summit.

https://barnettperformance.com/6014....p&VIP=02019002

[455abody]

I chose the 6x-4 for my mild 400 build a few years back and was happy with the outcome. Had a little clean up done in the ports. Brian

[67Fbird]

Originally Posted by Dragncar

Find some 13s or 62s, 6X4s. 64 heads work great on 400s too.
13s and 62s are not 72 cc like the manuals say. More like 77. They will get you 9.4-9.6 CR if they have not been milled.

true story there...both sets i have are in the 76 cc area. Had my (now dead) set decked to bring into 74 after I did some chamber work 30 yrs ago.

[noalibi]

Originally Posted by Dragncar

Find some 13s or 62s, 6X4s. 64 heads work great on 400s too.
13s and 62s are not 72 cc like the manuals say. More like 77. They will get you 9.4-9.6 CR if they have not been milled.

Thanks for the advice, I found a pair of 62’s. The 6X-8,s had one crack and the 4x-4s were both cracked. The 4X-4s were in a running car with not known issues, go figure. Now I just need to match a cam for the 62’s.

[1968GTO421]

Originally Posted by Jay S

Barnett performance might be a good shop to check out for cams, I think they are in Alabama. I have bought parts from them that they stocked that were hard to find otherwise. Would be worth looking into, I would rather run this cam than a 2800 summit.

https://barnettperformance.com/6014....p&VIP=02019002

Last time I visited Barnett's shop they were in Atlanta, GA. Very nice folks, good recommendation Jay.

[Baron Von Zeppelin]

Originally Posted by noalibi

I found a pair of 62’s.

Things just took another turn for the better .
It hurts to see smog-era parts under the hood of a 66 GTO

[67Fbird]

Originally Posted by grivera

62 heads are not hard to find complete and ready to bolt on

Complete yes....ready to bolt on...unlikely. There is no way I am bolting on a set of heads with 50 yr old valves. Just went threw this. Actually am using some #62's on my 455 build ONLY because I MUST buy pistons....so -18cc dish it is. #62's on my old 400 (trw slugs -7 cc reliefs) netted a 10.2:1 compression as they were .028 in the hole (trw's way of lower the compression for you on OLD high compression motors) Yeah i didn't know they needed to be zero decked to help with squish and detonation ...this was almost 30 yrs ago..

[padgett]

+1 on 6Xs for street - have all the manifold bolts and hardened seats.

[noalibi]

OK, need more advice. the 62 heads were a no go, but i got a pair of 16 (72cc) heads so i need more direction. Just a recap, 1974-400 bored .030, will be running Holley Sniper EFI, 3.42 gears, 400 Trans, and cast factory manifolds. I'm trying to build a torquey streetable mild performer that will run on pump gas without detonation, and maintain cooling in Louisiana summers. My questions are.... intake (thinking Torker II), cam, and piston choice? What compression etc....?

[steve25]

The T2 is not worth running two reasons in a motor built like yours and in a car like yours.
1) your not running enough Cam to make the needed great port velocity thru that intake that translates into a torquey street motor.

2) they add enough height to the carb such that you you have to jump thru hoops to fit a good air cleaner that will not end up being a restriction!

If you have a factory iron intake from 68 and up without a EGR valve then that will work great!
If not that then to save some weight get your hands on a performer.
They also work great with stock heads and will pull hard to 5400 rpm with a 406 cid motor.


Which year 16s did you get?

I would shoot for a 9.2 to a 9.5 compression ratio.

[noalibi]

Originally Posted by steve25

The T2 is not worth running two reasons in a motor built like yours and in a car like yours.
1) your not running enough Cam to make the needed great port velocity thru that intake that translates into a torquey street motor.

2) they add enough height to the carb such that you you have to jump thru hoops to fit a good air cleaner that will not end up being a restriction!

If you have a factory iron intake from 68 and up without a EGR valve then that will work great!
If not that then to save some weight get your hands on a performer.
They also work great with stock heads and will pull hard to 5400 rpm with a 406 cid motor.


Which year 16s did you get?

I would shoot for a 9.2 to a 9.5 compression ratio.

i never stated a certain cam size, was looking for suggestions to optimize this build. i don't anticipate having an issue with intake clearance (GTO area is cavernous). don't have a usable intake so a edelbrock must be spec'd. thanks for the CR suggestion.