[mrmark1957]

Timing I believe is at 16* BTDC. No issues with 87 Octane. I took the car to the track in October, running 16.1/16.2 sec at 87/88 mph. Wondering now if I put a 2802 cam in it if the stock 400 converter will be too tight with the weight of the '73.

[Jay S]

The pumping number sound like they are about where they should be.

You may not want to make a final decision on the cam until you pull the heads and see how far down the pistons are below the deck. The pistons you have can be up to .040” below the deck. I have an identical engine with the same piston, but the deck has be cut .025” and it still has .011” piston to deck height.

If the pistons are pretty high in the deck, .020” or less, you will have a decent quench, and I think you could run the 2801 with the 62s on 91 pump gas.

If the piston is further down in the deck than .030”, I would run the 068 regrind or the 2802 with the wider 115.5 and 114 LSA’s (versus the 112 on the 2801) to help get more heat away from the cylinders because the quench is bad.. With the 068 I think you could leave the logs and the 2” down pipes. The 068 seems to keep the power spread out better than the 2801. If you want more out of the 068 later 1.65 rockers work nice on it.

I like the 2802 in combos like what is described. But, if car is heavy running a highway gear like 3.23s, and the converter is stock, and it has a restrictive exhaust then I doubt you would see any for gains in performance with the 2802 at the race track. If you plan on some more mods down the road, like say more converter and a free flowing exh system, it is definitely the more powerful cam over the 2801 and 068. It will have some lope at low idle though.

[mrmark1957]

Jay, I am inagreement with everything you have mentioned. I will check the quench spec before I choose a cam. I believe it will be a wise move to upgrade the exhaust at this time, which will also help to get heat out of the cylinder. The cam in it is a Summit 2800 , which is similar to the OEM 067 grind. A cylinder head and exhaust upgrade alone might give me enough of an improvement without affecting driveability. I'm thinking of bolting the heads down with a couple pushrods and rocker arms on it and do a cold cranking compression test to see where the 13's put the psi at. I have a set of 3.08 gears I would like to use to make it a little more highway friendly.I'll take your advice and go step at a time.

[pontiacs-r-us]

MrMark,I’m following this post , as I’m in almost the same situation … please keep us posted as changes are made…. I have same (74) 400 @ around 8:1…. I have a set of 68’ 16’s ready , but cc @ only 67cc…I also worried about CR being too high? I was also considering similar cam choice, & have 2:93 rear gear…our only real difference is piston. I’m standard bore w/ stock pistons… I don’t want to highjack your post,but also very interested in opinions… Cliff has some interesting in-site on cam selection for high compression engines on pump gas,maybe he will chime in on your build? TY

[mrmark1957]

Pontiacs-r-us , don't worry about hi-jacking this thread. We are here to share information and experiences. The more people that chime in , the better. I'm trying to get back some of the lost efficiency of the smog heads.

[25stevem]

In terms of post #24 I get 10.09 to 1 compression.
This was figured with a Fel-pro head gasket.

.023” deck clearance.

6 CCs of piston notch volume.

1.5 CCs of top ring land volume.

[pontiacs-r-us]

Thank you Mark & Steve…I also came up w/ similar CR #…. This being a lil on high side for questionable pump gas sources is my worry (?)

[chiphead]

What's the typical deck height when a 400 gets the old TRW forgings? I'm in a similar boat. 69 400 with 62 heads. Stock rebuild in the 90s, except for forgings and an old crane 284 cam that's similar to the 2802. I'm swapping in a 2802 and wondering how it'll manage 93 octane? The unilite dizzy had a very slow curve installed. Not sure if that was on purpose or just the stock curve. From what I've read the 2802 should manage higher compression OK. I'd think it'd be too much cam in a lower comp 400.