Head opinion
 

So I’ve decided to hold off on building a 461 for my 57 chieftain and decide to build a nice street 400 for her. I’m saving the stroker for my next project (66 GTO)
I’m looking to build a 375-400 hp 450lbs torque 400. I’ve spect out a cam with Butler performance but haven’t figured out what pistons to go with yet because I have 2 different sets of heads to choose from.
I have a set of 1977 6X4 heads and a set of 1968 #62 heads. The 6X4 heads have 1.77 exhaust valves in it already, and the #62 still need hardened seats. I’m wanting to hit between 9.0-9.5 compression ratio. Which head is it easier to do that with, and which heads flow better?
Thanks for your opinions!

Here’s what I came up with.
I used both a .030” over motor and a .060” over 400.
Your target total CC volume to have an 9.5 compression are 97.79 for the .030” motor and 99.20 for the .060” motor.

Here’s the info / numbers I used .

Stock 6x4 chamber size = 89 CCs which now may be less or about the same due to the bigger 1,77” exh valve, but then again the valve job done on the 6X heads also sank the intake valve some.
Let’s call it a wash and use the stock 89 CC number.

I set deck height at 0

I used 3.35 CCs which is assuming two valve notch custom pistons instead of 4 valve notch pistons.

Head gasket volume 9.4 CCs

Ring land volume = 1.5 CCs


Using these numbers and a .030” over bore and the 6X heads your compression would be right at 9 to 1 because your total CC volume is 103.29, not the needed 97.79.

Using a .060” bore you would have a compression of 9.16 to 1, and once again your total CC volume is 103.29.

If you mill the 6X heads .042” you would end up with a 9.6 to 1 compression.



Assuming your #62 heads are 75 CCs then a .030” over 400 would have 10.3 to 1 compression.

Seeing as the 6X heads are set up for street gas those are the ones I would choose to run.
Both heads will make the same power and easily achieve 375 hp as long as HP manifolds are used.

Even with the small .406” lift of a factory 068 cam this 375 hp can be had, and headers bolted to the motor will make at least 15 hp more.

A aftermarket Cam with .500” lift or maybe even .525” lift will get you to 400 hp or better.

Steve the 6X-4s I pulled off a nasty junkyard(in the junkyard) 350 were about 94cc.

We’ve built several 400’s that are primarily for the street, but able to compete legally in the pure stock drags. The 3 that are shown are similar build-wise with forged rotating assemblies for safety, stock heads, mild HFT cams, and exhaust manifolds (both log & RA). As Steve25 suggested, the 6x4 and 62 heads flow equally (with a slight nod to the 6x4’s) and will achieve 375 hp/450 lb-ft torque easily. My choice would be for the 6x4’s to achieve a safe low to mid-9 static compression ratio as Steve calculated. A cam, like the Summit 2801, is a good choice for good torque and power for your relatively heavy ’57 Chieftain. You can see in the comparison that the cams were different specs, but fairly mild, the compression ration varied from 8.75 to 9.95, with log and RA exhaust manifolds; the power output between the three was very close. If you go with the 62 heads, I’d run a cam like the Summit 2802 to lower the cylinder pressure and dynamic compression a bit.

Dennis

Yeah Skip seeing as his heads have got some work done to them he should CC them.

A additional 4 CCs of volume would shave a 1/4 point off a 9 to 1 compression.

Thanks for the reply everyone! I will be going with the 6X4 heads. I will have them cc’d to see where I’m at, but what should my end goal be for cc on the heads? I was looking at summit racing for a set of pistons and found the speed pro forged pistons L2262F30. They are flat tops but are+6.7cc. Has anyone used them before, or what would you recommend?
Thanks again
Mike

Also here is the cam that butler recommended to me. I wanted to go with a roller cam
https://butlerperformance.com/i-3164...ory:1459685***

Those pistons have been used for over 4 decades and are a good stronger stock replacement, but off the shelf newer ones are (1) lighter so the motor gains rpm faster, (2) they use narrower rings for less friction which then frees up more HP..

Is there a set that you would recommend?
Thanks
Mike

Cc those 62s - they can be as large as 78cc.

I run a Summit 2802 in a 400 with 62 heads. Its a beast. If the 2801 made 385 HP, I must be cracking 400. Idles about 900 RPM making 14" of vacuum. It does want at least a 2500 stall converter and 3.25 or deeper gears.

A 9:1 400 with a 2801 would be a good mild combo. Why use a roller cam, that adds like $500 or more to a mild build?

The speedpro slugs with the lighter pins are fine for a mild engine with 75-90CC chambers. I assume they use the 1/16" ring pack? That's fine too. Go with a ductile iron top ring with moly coating, a reverse twist 2nd ring and a standard tension oil ring. That's the normal performance N/A ring pack.

I was going to go roller because I’ve been told that the flat tappet cams have a tendency to get whipped out due to the quality of oil and lifters these days. Is it not worth going roller cam?
I have 3.23 gears in the back right now and was trying to stay with a stock stall converter. I also was going to get forged rods for it, instead of getting new rod bolts and line honing, or is it ok to stay with factory rods?
Thanks Mike

I was looking at the comp cam XE274 Flat tappet cam, it only calls for a 2000 stall, I can live with that. Would those match up with the 6X4’s? Thanks

Ponchomike57,

I had a CC XE274 (230/236/110 @ .490”/,490”) in a ’71 455HO that was completely stock with 8.4 to 1 compression and it was a ‘turd’, especially with the M22/3.31 combo. We swapped it out for a Summit 2801 (214/224/112 @ .444”/.466”). The 2801 was easier, hence quieter, on the valvetrain, idled better and made a ton more off-idle to mid-range torque. The 2801 has longer ramps that help stabilize the valvetrain and not shock it like the XE cams fast opening ramps. That cam in a slightly higher compression 400 wouldn’t be my first choice. I like the 2801 with the 6X4 heads and the 2802 with the #62 heads. Both would run well with RA exhaust manifolds. Forged rods are a great improvement and the Eagle 5140 I-beam rods would be more than adequate for your needs (and a bit cheaper than the H-beams). The 400’s we build usually run the off-the-shelf Icon flat tops (6 cc reliefs or the 14 cc dish). They have the 1/16”/1/16”/3/16” std. ring pack.

We have a 455HO (again all factory stock) with the 2802 cam and it made 430 hp and 535 lb.ft torque through the factory RA exhaust manifolds with 8.6 to 1 compression. It's a monster.

Dennis

Aftermarket rods are worth the money for the reliability they provide.

I also ran a XE274 in a 8.8:1 400. Idle quality was choppy, had noisy valvetrain with the fast ramps. Needs a lot of spring for what it is. Had good midrange power, sounded good. It would pull hard 2500-5000. I had a 3000 stall and 3.90s, which really helped. Consistent 13 flats at 103MPH. It liked a small shot of nitrous. Eventually it ate a lobe. Could have been a lot of spring pressure and idling at the dragstrip, along with me changing oil types and overreving it. That's all hard on the valvetrain.

This 9.8 compression 400 with summit 2802, same converter, 3.25 gears feels much stronger everywhere in comparison. The tuning is more challenging with the higher compression. Gotta be on my game to make it live.

The crazy thing is, both motors pumped about 160 PSI on a compression test. What a difference intake closing point makes!

One of my favorite 400's I ever built was a 400 with 62 heads and a 2802 Summit camshaft. It idled with a slight loap and ran fine on 91 octane fuel. The car had a 4 speed and 3:55 rear gears and it had plenty of bottom end torque to turn the rear tires into smoke through a couple of gears from a roll. I have no clue what the hp/torque numbers looked like. It was nothing special at all as far as parts and was built on the cheap. I used .030 TRW flat top pistons, stock rods and bolts, stock 62 heads with only a valve job, seals and new springs and a tripower. I did not 0 deck the block and I would estimate that my compression was in the 9.5-9.75:1 range. I even ran the stock style points distributor. It was a good running and reliable engine.

John-- Do you remember how much total timing your combo liked? Mine seems to like 32-34 above 3300 RPM on 93 octane. Any more and I get pepper on the plugs.

Slight lope is right, its a rolling idle where you can hear the pulses but not a complete chop. It idles "heavy", like its barely able to contain its desire to rip. With enough tuning, the throttle response is pretty good, even with a DP carb. The wide LSA helps tame the idle and manage the pump gas.

Sorry, but I don't recall what I had the timing set at on that engine. I sold that car and engine back around 2011.

I think I’m going to run with the 2801 cam. I want to stick with a stock stall (1800). I’ve calculated with 3.23 gears and 29.1” tires (255/70/15) at 55mph I should be at 2152 rpm. I live on Vancouver island Canada and most of our highways are 50-55mph with an exception to one stretch that’s 68mph (110kph). I talked to my machine shop guy and asked about connecting rods. He said if you can get a set for forged for $500-$600 Canadian do it. After buying rod bolts and getting cast rods resized it’s not worth it. I’m picking up the Eagle 5140 I beam rods, they are $550 here.
Do you think it’s worth 1.65 to rockers with the 2801 cam? I do like the lift of the 2802 cam but don’t want the 2500 stall. Only thing I need to figure out is a set of lifters. Trying to find a good set with hardened bottoms preferably not made in china!
I asked butler performance what would be a good flat tappet cam and they recommended there version of the 2801

I think you'll be very happy with the 2801 with the 6X4 heads. If you want to use 1.65 rocker arms, you need to open up the pushrod holes in the head to allow them to fit, otherwise, they may (most likely will) contact the head and not allow the pushrod ball to sit in the rocker arm cup properly. Personally, I don't think your combo will benefit much from 1.65's. Yes, you may get a few more hp, but the juice ain't worth the squeeze in my opinion...and it'll reduce your low end torque a little. Get some Icon pistons too and you'll have a great foundation to add more power in the future.

Dennis