Best cast iron heads for 428 street build
 

I started another thread about possibly having to pull the RA III out of my '70 T/A for a rod/piston whap because I think the rebuild on that motor used flat-top pistons and with the #12 heads, I am getting a lot of pinging even though I only run 93-octane gas. Anyway, while that process starts to play out, I don't want to not have the T/A to drive this summer so was considering dropping in a 428 that's sitting under my bench that probably only hsa 10,000 miles on it since a rebuild back in 2002. That engine has 670 heads on it now, which I know is too high, so was thinking what would be the easiest and least expensive ways to keep the T/A on the road while the 400 gets massaged. I'm not really interested in going the aluminum head route, so was considering finding a set of larger -cc heads for the 428. Would the 6X-4 be a good choice? I see these come up on eBay from time to time and I know a lot of guys like these for the 455 builds. What about the 1970 #64 heads?

I would say that it depends on what pistons are in the 428. If it has factory 13cc dished pistons, it should be right at 10:1. I have actually had good luck with my 428's at near 10:1. I run 670 heads on one and it never pings on 91 octane. Another engine has 614 heads and runs good on 91 octane. I ran another one for years with 62 heads and when I had it back out of the car, the bearings all looked brand new and there were no signs of detonation. It ran on 91 octane as well. You would just need to be careful as to what camshaft you choose for the engine so it won't build a ton of cylinder pressure.

If you run the 6X4's and your engine has the factory style dished pistons, compression would be in the low-mid 8's. Obviously it would run good on pump gas but maybe not the best for performance.

What about a 7K3? Big valves, screw in studs, hardened seats,modest compression.
What is not to like?

Thanks John. I’m actually going to pull the heads off later today just to see what pistons I installed 20 yr ago. I’m guessing they were probably a standard 428 .030 forged piston. I certainly didn’t have any money back then for anything like a custom Ross or anything like that. I know it has early forged rods that were shot-permed because I couldn’t afford any aftermarket rods either. I think I ran a Lunati can but don’t remember the specs. Engine made good power in my 1967 GTO. Broke the trans. Broke the posi. Tore front sway bar out of frame. LOL. Funny thing is that I put that engine in the ‘67 back in 2002 when I took out the original 400 HO for a rebuild, and ran it until 2013 when the car was sent down to Barr’s for a frame-off. Now I’m looking to use it as a temporary service-replacement again, but would want it to be more streetable.


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I’ve got a brand new Crower 60423 HFT and Johnson lifters that I was going to swap into the RA III in my Judge before I traded that car for the T/A. I wonder if that would be a good cam in the 428. If I pull the 400 out of the T/A, which is becoming much more likely, then I would probably go the HRC route when it went back together.


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The semi closed chamber of the 670 heads are less likely to when the same compression is used as a open chamber head ,

Hi Steve
Are you saying the 670s are less likely to ping then, say, #12 heads?

Here are some quick photos of the partial tear down. Everything still looks really clean (so far).
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Just before the first cam lobes, you can see the a stamp that says
540
233
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On the back part of the cam it says F2
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Any idea what this means?


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You don't think that means .540 lift, .233 @ .050 do you?

So I did a little research and it appears that 540 233 is a camshaft core number. I have to pull the cam to read the codes that are stamped on the rear. Do I understand that correctly?

Correct, in answer to your ping question.
The 670s chambers do not burn as clean / complete as the later heads and this produces a small EGR effect which cools things down,

Appears its a factory cam?
The cam code would be on the front nose. If a later year cam could be on the rear. An aftermarket cam would be on the rear.


You do realize the 428 won't bolt in the 70 Firebird without putting some different frame mounts on? (and the engine mounts)


:confused:

Thanks John
I did not know about the frame mounts being different. Do I need the mounts for a 455.

I do t think it’s a factory can. I’m pretty sure it’s a Lunati. I vaguely remember ordering a Lunati kit when I was having engine built. I used to run a Lunati in another 428 I had in my bracket car and always thought that car ran well, but that car was 100% strip so I should’ve done more research at the time regarding a cam for the street.


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Racerboy, we ran a 428 (+0.060 = 440) with '71 96 heads (94 cc chambers), iron intake/Q-jet and ran great on pump gas (must have been mid-8's static compression) with a stock 068 cam and factory valves springs, etc. The engine was in a '66 GTO convert with a TH400 and the original 3.55 10-bolt saf-t-track rear end. It ran 14.60's at 95 mph all day shifting at 4800 rpm (it was pretty tired at this point) on skinny snow tires! It was a ton of fun on the street!

Dennis

I had a set of 64s on one of my 428 builds,they were perfect for our calif piss gas.Tom

The engine only has the 2 bolt holes for the early style mounts.
(70 and up used the new 3 holes for mounting, total of 5 on the newer blocks)

It would require at least a set of adapter mounts for the engine.
Some companies make them, but not sure how good they are.

Or could use early frame mounts from 68/69 GTO then use the 68/69 engine mounts.

The adapters have a problem of raising the engine from the thickness of the metal adapters. Throws off alignment some I believe?
(never used them. did the early mounts for my car)

Or could use a front engine plate mount.

:)

Thanks John.
This may turn out to be more involved than I thought. Maybe I should find out just how long it would take to get new rods/pistons in the 400 block. Of course if I’m going that route, I wonder if I should just get one a stroker assembly.

Damn rabbit hole [emoji874]


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Since the build was done 20 years ago most likely the pistons are dished.

I had two different 428's in my car decades ago, one had #96's on it, the other 6X-4's. Both of those engines had dished pistons. In the first engine I ran a real 744 cam with high ratio rockers, in the second engine the HO Racing HC-01A.

The 744 cammed engine was "weak" below 3000rpm's and pretty much done by 5000rpm's. Not really impressive anyplace. The second one faired better, but both of those engines needed more compression for the cams I was using in them so I really wouldn't recommend going that direction unless you just want a decent running engine that will easily manage low octane fuel and move the car from point A to point B.......FWIW......

Could anyone comment on why you wouldn’t put a “larger” cam that bleeds off some of that compression enough to run 93? It would seem like a win win. The High compression would help keep it from having poor street manners?

Bigger cams are put in to make more HP!More HP comes from cyc pressure.Big cams bleed off compression at very low RPMs.Kind of hard to drive a engine that way.Its a crutch IMO.Tom

You are correct Tom S. #64 heads but one year only 455. rare.
you are correct Tom S. Big cams for ping control are somewhere between a crutch and a myth. BUT someone is going to jump in and say how well it worked for him.

Here’s my take for what it’s worth to anyone.

In terms of a pure street and limited strip motor of whatever displacement you care to make it under 440 cid , if it’s naturally aspirated and not making 175 psi of hot cranking compression then it’s not going to be much fun to drive below 3000 rpm even with something like 3.42 rear gears when where talking about cars of over 3600 lbs!

Street motor’s making under 160 psi rev like a 3 legged Dog unless your into non street friendly 4.11 gears!

Im not sure how big of cam your talking about but I have 3 engines running right at 175 pumping compression,in the 434 in range and 2 of them have OFs in them.No issue in lugging them at 1500 RPMs on the street with a stick shift trans and run great with 36 degree lead on our Calif 91 piss gas.2 of them are Dports with 2-4 tunnel rams and one is a RA V with big lazy ports which are supposed to suck at low RPMs.ANYONE in the So Cal area are always welcome to drive any of my cars.FWIW,Tom

I'm sort of on the fence here now. I have another ongoing thread regarding the Icon 14cc dish pistons. Turns out my RA III was rebuilt with low-budget 8-eyebrow pistons as well as an MPT-1 cam (smaller than an 068). There is no question I am going to pull the motor. The big question is what direction do I go. Do I simply drop in the 428 as-is (maybe with a cam change), This will obviously require some block adapters, as well as a cam change. Personally, i hate the idea of 670 heads on a '70 Trans Am, but that's just the ADD in me. But then really build a stout 400 (or maybe a stroker) out of the WS block? I reached out to Butler and they said I could build it up to 461 with the #12 heads, and they could cut a Ross piston with a deep enough dish to run pump gas. I have some concerns about stroking the original WS block, but they assured me that there was no risk to the block. I could also leave the 400 alone for now and build the 428 up and throw the #12 heads on that, but I still have the frame adapter issue, and would eventually have to rebuild the WS anyway,. Any suggestions are appreciated. I would really like to drive the Trans Am this summer, so I would hate to leave it out of service for too long.

Don’t let the use of a motor mount adapter be part of your decisions it’s basically a non issues.

Here’s a way around that anyway!

Thanks Steve!

Just to be transparent, this is for a 1970 Trans Am (not sure of weight) with an M-20 and 3.55 12-bolt posi.

Thanks Cliff. Is there any way to tell if these are dished or not without taking off the heads? Maybe I should get one of those inexpensive borescope cameras. If it turns out they are dished, would it be possible to put in a decent cam and tun it as is with the 670s? I haven't run this engine for about 7 years, but when I did run it, I don't recall it pinging on 94 octane, but it had too much lump in it to really drive it on street. I definitely went with too big a cam, I just don't recall what it was, other than I think it was a Lunati. I distinctly remember it being more than an 041 cam. I guess I'd have to pull it for a final determination. I have a Crower 60423 kit sitting on the shelf. I was originally thinking of putting that in the 400 until I found out about the low-budget pistons in that motor. How do you think that cam would work in a 428 +.030 and 670 heads?

I guess that leaves me to wonder the point of the Wallace dcr calculator. I’m kinda surprised by the response.

I recently got a cheap bore scope and it works great and find useful

DCR can help BUT the old GIGO comes into play.

Let look at a Pontiac 455 ci engine. It will have 175 psi cranking compression / 7.3:1 DCR

So how can I get there

8.5:1 / IVC 56 ABDC

9.5:1 / IVC 71 ABDC

10.5:1 / IVC 81 ABDC

11.5:1 / IVC 88 ABDC

12.5:1 / IVC 94 ABDC

Do you think because they all have the same DCR they will run the same?

Stan

I was under the impression for octane requirement, yes. ??

What scope did you get? I did a Google search and found ones from $50 up to $500!


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I took the oil pan, balancer and timing cover off of the 428. I’ve never pulled a cam before so I want to make sure I do the next steps right. Not sure if this is right order, but here goes:
1. Loosen all the rocker arms and then remove the pushrods and lifters. It’s important to keep these in order, correct? How do you manage that?

2. Remove timing chain/fuel pump eccentric.

There is no distributor in engine so I think that’s it. How do you actually get the cam out? Don’t you have to be super careful not to scratch the cam bearings?

My progress today:
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I would find a set of heads in the 90-100cc range, put the 60243 crower in the 428 and drive it, get the T/A back on the road. Look for 64 off of a 455, or off of a 400 or 350 look for 96, 7K3, 4C,4x or 6x. As long as the head has screw in studs I would not even care if it had 1.96 intake valves instead of 2.11s.


I would not do a bigger cam to try nurse the 670s along on your 428. I don’t think you will not be happy with it. The big cam becomes a crutch once the heads do not supply enough air/fuel for the engine for the desired rpms. 670s do not flow great in stock form at higher lifts, irc they are done at about .4”. With a big enough cam and no airflow to match, at some point the engine will loose cylinder pressure and spreading what cylinder pressure it has over more RPMs, making less power over a wider rpm range. Go to big on the cam and it can run like crap and won’t be fun to drive.

DCR is a guideline and a starting point. But you absolutely can not use it in totally different engine combo’s and expect to to tell you every little thing going on in the engine. Using the Wallace calculator for guidance the user needs watch the V/P index as well as the DCR numbers. Plus you must have to have an idea what the profile is going to do, intensity and actual numbers that are consistent to use it consistently. I use DCR and the V/P a lot, but is is one design criteria among many.

Just as example. A RA 4 cam has duration of about 292* @.006” tappet. It has 231* @.050. That is a difference of 61*. The intake is shutting at around the upper 70s. I just did a solid lifter cam in a mopar that has closer to 20* change in intensity from .006 to .050”. Totally different valve lift curves.

Thanks Jay. If you had to choose between a 6X-4, 96, or 64, which would you go with? The 64 seems like the most expensive since it is a one-year only head, so not sure that makes the most sense, though i'm sure I could sell them if I decided to once I got the 400 finished.

Got the heads off. Like Cliff said, these pistons have a round dish in the middle. They have part no. L2257 030. I think the 030 means .030 over, right?

I can’t seem to get the crank sprocket to slide forward at all to remove the timing chain. The cam sprocket slides but not the crank Is there a trick to this?
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The pistons have some carbon on top. Do I have to get rid of that (and how)? Also I don’t think it is at zero-deck. It looks like when it is at TDC the piston is still a little below the deck.


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Here is the #1 piston at TDC.


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6x-4 is my first pick, best of the induction hardened seats, and the easiest to find. The 64s are rated at 87cc, but most of them run 91-93 cc, almost the same as a 6x-4. Also for some odd reason the 64s had a little bit smaller intake port and do not flow quite as much as the other D ports stock. I wouldn’t be picky though, any of those 90-100 heads would be fine to get you buy until the RA 3 is finished. Even a 6x-8 would be fine, a little lower on compression (101-103cc give or take) actually probably my 2nd pick is a 6x-8. Won’t miss the compression as much with the 428. The 96 and 7k3 often run 98cc, not much different than the 6x-8.

428 looks promising. IMO, looks clean, not enough carbon to worry about. Should be able to lightly pry the crank sprocket forward with a small pry bar lightly prying and tapping on the end of the crank with a rubber mallet while you pry..

I got the crank sprocket to move and removed the timing chain and then carefully pulled the cam. The reading on the back says:
COMP CAMS 2
51-224-4 911
Z0274 (I think)


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Thanks Jay. There are a number of 6X-4 heads on eBay right now. Here are what my 670 heads look like. Not sure if this is good or bad.

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This is what Summit has listed under the COMP CAMS 51-224-4.

How does this compare with the Crower 60423?


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For your scenario I'd look at a Summit 2802, inexpensive but looks that it will be out of stock for some time.
https://www.summitracing.com/parts/sum-2802

Before you get too far into this engine and picking parts to lower compression/dampen detonation: If your pic in post 39 actually shows the piston at TDC, unless an optical illusion, the piston looks way down in the cylinder. Like .040-.060 down. You need to get an accurate measurement so you can calculate your compression ratio accurately. Not sure why they would be that low unless they had to cut the heck out of the rods to recondition them or the block is extremely tall for some reason.

Thanks. Is that something I can figure out or do I have to take it to a machine shop?


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Just for the record, this isn’t the engine I was having the detonation issues. That is the 400 RA III in my ‘70 TA. This engine was in my ‘67 GTO, until I started a frame-off on that back in 2013. I don’t recall this engine pinging back then, but I do recall it having a pretty lumpy idle.


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I had forgotten how big the dish is on those pistons, I think I over estimated the compression. You are probably ahead to swap to the 60243 and stay with the 670s. The dish should measure 2.3” in diameter and .126” deep, about 8.5cc. I don’t have the total cc’s with the valve releifs and the dish. Pistons mfg specs are not listed in any of my older books. Guessing the compression is in the upper 9s though.

I think the bevels on the piston perimeter give an optical illusion that it is down lower in deck. Should be about .015-020” down.

60243 should idle a little bit smoother than the xe274. Power wise there isn’t much difference, but I think the 60243 would have slightly more hp. The 60243 power band is a little broader and is more friendly for higher compression, lower compression the xe274 is better. IMO With the compression it is at with the 670 heads, I would rather run the crower. On the street the XE274 would likely feel like it is meaner, it builds more compression and has a strong mid range. If you swapped to a lower compression head I would leave it in there, as is I would swap the cams.

Thanks Jay. Do I have to change valve springs if I go with the 62043 cam?


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