Thread: SBC Cylinder Head Info Request

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Hi All,
I've got a 1984 Camaro Z28 that I want to put a 350ci in.

I just purchased a semi complete engine that is in pieces.
The engine came with cylinder heads casting # is 3884520. I've searched the web and I've only been able to find limited information about these heads. They appear to be 283/327 heads with a 60cc chamber,and 172/150 valves, beyond that, there doesn't seem to be much other information floating around them.
The older gentleman that I bought the engine from claims that they are the heads that were on the engine when he had it installed in a '55 Chevy many moons ago.

I would like to make the 350 a 383 stroker and I'm in search of information about the heads to see if they are suitable for such a thing. Does anyone have any information about these heads that they would care to share? It would be much appreciated.

thanks

60cc chambers are going to build a lot of compression, so deep dished pistons are going to be required. 9.5 to 1 is going to be the absolute max that I would run with iron heads and I would probably shoot for less if you don't want to run 93 octane all the time.

The valve sizes are pretty small for a 350 in anything other than a truck that needs a lot of low end torque. They are going to be flow limited on a 350 and will probably run out of capacity around 4000 rpm (even quicker on a 383), so there's no need to run a big cam. It would be a waste.

If all you want is a very low performance engine that requires high octane gas just to move the car from point a to point b then they will work, but I would ditch them and get something better.

Always figure out what you want the engine to do before you buy anything no matter how "good" the deal. You would be better off with one of the cheaper GM crate motors than anything you could build with those heads. The $2000 L31 Vortec engine will easily make over 300 HP(probably closer to 350) and run for 100,000+ miles with no issues. Comes with a roller cam, so no cam/lifter issues. You could beat that price with junk yard parts, but if any real machine work is needed, you won't. Something to think about. Summit and Jegs sell these engines with free shipping all the time.

First, welcome to CHR! Glad you're here. NastyZ28 is about the best place to find SBC casting number info - Small Block Chevy Cylinder Head Indentification Looks like you're on target, and that the heads were an item '62-'67. With those small valves I'd ditch them for something better, ideally aluminum for better heat dissipation allowing a tad more compression.

Just a few days ago Glenn posted his suggested build for a 383, starting with a bare block. It's got a ton of good advice, if you're set on building your engine vs buying a complete package, link here -
Changing compression ona built motor

Those are the old "Power Pack" heads (neat sounding name, but pretty much obsolete). As mentioned they have relatively small runners and valves. A couple of other things that make them less than desirable are that they have no accessory bolt holes in the end of the heads which can make mounting accessories a challenge and they do not have hardened seats.

They could be opened up to 1.94 intakes, but trying to go out to 2.02s would likely put you into the water jackets.

I did a set of those heads about a year ago for an era correct 283 I was building. I went through then and with the machine work, new valves, hardened seats and opening them up to 1.94s etc, there were a lot cheaper alternatives out there. Even with the work I did on them I personally would not run them on anything bigger than a relatively stock 350.

Just my 2 cents.


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Thanks for the replies-exactly what I was looking for.
I bought the entire shooting match; 350 block (# 3970010), 327 heads, starter, alternator, THM 350 tranny, a Quadra Jet and a Holley 600 cfm, old Weiman single plane aluminum intake, along with an engine stand for $300 CDN- I was after the block and everything else was a bonus

I live in the Toronto area and it's really surprising how little there is available here-the next cheapest online 350 block (block only, no crank, rods or pistons) is $200.

This is my first foray into non-european, carb'd engine building/modifying and I'm looking forward to it. I bought an old '84 Z28 with a 305 (129,000 miles-starts, runs and moves), THM700 R4 and 3.73 rear end for $1000 last week. The driver's side floor pan is shot and it will also need some shoring up on the frame rails (yes, I know it's unibody) Everything else looks good though-the body is in great shape, as is all the weather stripping and glass. The interior is good with the exception of the carpeting-I've already torn it out and cut out the parts of the floor pans that need replacing. It's deemed a classic car in Ontario, so not emissions test necessary...

I have in mind a engine that will produce 300+hp, for which I've budgeted $2K CDN ( about $1400 US. I'm not adverse to buying new parts-I'll have to get a new crank, rods, pistons, bearings, cam, lifters, rods, maybe valve springs, rocker arms, intake and maybe a carb. I'll try and source as much quality used stuff as I can. There's an ad online in Buffalo for rebuilt , modernized (I'm assuming hardened valve seats?)with 1.94/150 valves for $300, so maybe I'll take a look at them... Meanwhile, I'll be sending the block I have to be cleaned up, rebored and squared.

Thanks for the advice, I need it

This tutorial concerning production L31 heads may interest you....
http://www.crankshaftcoalition.com/w..._cylinder_head
They are the best flowing iron production heads that Chevy ever produced.

In the final tally, I think you'll find that building a motor will cost about US$10.00 per horsepower.

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Great info. Thanks very much.

Originally Posted by techinspector1

......In the final tally, I think you'll find that building a motor will cost about US$10.00 per horsepower.

Depending on how crazy you get, I'd revise Tech's cost to read something like ".....about $10.00 per horsepower for a naturally aspirated, carb'd engine; pushing $13.00 per horsepower or more for an injected engine; and pushing $15.00 to $18.00 per horsepower if you get blower fever. Just my $0.02, hope you can prove it wrong.

Jegs sell a 290 hp 350ci crate motor for 1495.00, and you can usually get free shipping...

is the engine in the car fuel injected?
If it is-find a 400ci sm and add the vortec heads to it---

Originally Posted by jerry clayton

is the engine in the car fuel injected?
If it is-find a 400ci sm and add the vortec heads to it---

Read Post #5 - no mention of FI.

1984 Z28------means FI to me

also Post #5

The 84' Z28 that I have has a 305 with a carb. The 350/383 that I plan to build will also have one. I don't believe the Z28 got MPI/EFI until 87'.

I'd like to have a fuel injected engine, because I know more about them, but converting over would likely really exceed my budget.

that could be an option, but sadly, by the time I got the thing here (Canada) it's likely to be well in excess of $2K

I had a 86 Iroc with tunnel port and my brother had an 85 same way------- I believe that options in 84 also included that possibility (or maybe the twin tbi)

If car was originnaly Canada options might have varied.

so then next question-does your car have fuel pump on the front right lower corner of the block? What engine control module is in it?(chips are programable and can be changed out) Another item about that series of car is how high does the speedometer go? There where some that only went 85 mph ( are Canada in kilos?) and some as high as 150 IIRC.