Low compression 400 cam suggestion
 

I’m chasing down leaks in my stock ‘72 400 in my GTO and it looks like one of my head gaskets is leaking so I’m probably pulling the heads. At this point it makes sense to replace the original heads with a set of fresh 7K3’s that I happen to have and replace the camshaft and timing set while I’m there so I’m looking for a cam suggestion on a stock 400 lower end. The car is a ‘72 GTO four speed with 3.23 gears, typical weekend street cruiser.

I’d like to use parts that I already have for the cam swap and have a set of Crower cam saver lifters or Comp Evolution roller lifters so I can either go roller of HFT. I also have a nitraded Crower 60919 but that’s probably too big for this build and was originally going into my 455 build that’s in machine shop jail for at least the rest of this year. So looking for a suggestion on a cam, either roller or HFT that will work with my stock cast pistons and fresh stock rebuilt heads, can obviously change valve springs to match the cam choice.

When you say “fresh stock rebuilt” heads are they still using the original valves and valve springs ?

Have the valve guides been topped off to take positive valve seals.?

The stock installed height of the valve springs limits your valve lift to .460” to be on safe side of coil bind.

This means running a cam of no more then .306” lobe lift.

What I mean to say here is that running a roller lifter Cam with only a .460” lift at the valve is a wasteful expenditure.

I would not chance running a roller Cam with the stock two piece welded valves. I would want aftermarket one piece.

Also if you ARE or ever will run headers those 7K3 do not have the needed end exh bolt holes, so while the heads are still off you might want to drill and tap the needed holes to 3/8” fine thread and then use a stud .

You cant drill these holes when the heads are bolted on the block without removing the head bolt that’s behind where you need to drill & tap.

The set of rebuilt 7K3’s that I have are already drilled for the additional bolts , have the stock valves and already cut for positive seals. I have a set of stainless one piece valves that I can use but I’m more concerned with getting the car running for this season so I trying to stick with the parts that I have ready to use. Yes, the roller is a “waste” in essence due to the lift but I can also install one without fear of losing a lobe during break in.

All of the parts that I have are for my 455 build that’s has stalled due to my machinists having health issues currently so I if I can use them now to get the car out for this season I will. Essentially I need a cam for this motor since I’m going to tear it down to the heads to fix the leak and might as well put a fresh cam in while I’m there.

You did not mention if your high mileage stock springs were replaced.
You would want that with the 2801 cam.

That 2801 cam will work, but unless you mill the heads .055” your not going to get to recommend minimum 9 to 1 compression.
That much of cut off the heads would require the intake flange of the heads to get cut at least .035” so everything bolts and seals up nice.

If it where me I would go with the 2800 cam and maybe live with it being a tad on the small side, which with a street car always the better way to go, and besides if you find you want more power and can tolerate in effect a bigger cam you can always then swap over to 1.65 rockers.

This option would a be another point while you have the heads off to have valve springs that will allow .500” lift.

Used a 2801 in a 9.25:1 400 auto with 3.08 gears. Great cam for a heavy automatic with a 400 and even sounded good too.

I’ve seen Cliff recommend the Crower 60240 for lo-comp 400s. 2801 seems to be one of the most popular cams around

Another vote for the Summit 2800, same as the Edelbrock Performer cam that I used:

https://forums.maxperformanceinc.com...1&postcount=22

The Crower 60240 might be even better.

Here’s another vote for the 2800 cam. My brother rebuilt his ’78 W72 400 with 6X-4 heads from his Trans Am which is very similar to your ’71 400 with 96 heads. The 481988 block is 0.040” over with forged Icon flat top pistons & Eagle forged H-beam rods. The stock 6X-4 heads were resurfaced minimally to be trued and measured 92.5 cc’s in the chambers. The block was zero decked and had .040” quench, it calculated out to 8.75 to 1 static compression ratio. He used a Summit 2800 cam (204/214/112 @ .422”/.444” lift which is very close to the factory original 067 cam specs) that we had sitting on the shelf with new ‘stock’ style valve springs. It made 360.3 hp @ 5000 rpm (still climbing) and 456.1 lb-ft torque @ 3600 rpm on the dyno. With a little fine tuning (jetting and timing) it maxed out at 371.4 hp @ 5000 rpm and 460.3 lb-ft torque at 3600 rpm. It had D-port RA exhaust manifolds with 2.5” mandrel bent head-pipes for all pulls. You don’t need to over-cam these engines to make good power. The 2800 cam works well with compressions below 9.0 to 1, while the 2801 for higher compression ratios.

Dennis