Casting #3998983. Please let me know if you have any info on them.
Thanks
Mike

www.mortec.com (http://www.mortec.com)

Don't know that #; but 3998993 is a real familiar one.

It is pretty much the ultimate dung. There are 2 versions that have had that casting #; one was an early 70s smogger 2-barrel motor, the other is that "Goodwrench 350" phone company van replacement motor you can buy for next to nothing at the dealer, that's basically the cheeeepest most basic possible thing that will push a disabled fleet vehicle around after the field crews tear up the OE motor. The later ones usually have "Hecho En Mexico" cast into them.

I don't know what info you're looking for, but about all I can give you, is that whichever version they are, they mostly belong in the trash.

I was looking at buying these heads from a guy around here. This is what he told me:

Ported 2.02 heads I think they are 74cc
The # on the heads look to be 3998983.
Double spring.
3/8 screw in studs and guideplates.
I ran them on my 67 camaro with a small journal 327 and 75hp NOS with a 537 lift cam and the car went 11.20s
The heads have been ported with manley 2.02 valves.The only reason I am geting rid of them is I have the Dart pro1 aluminum heads.
for $400.

If the numbers really are 3998993 would they be ok if they are ported w/ 2.02's. Let me know what you think. I want a set of heads for my 350 nothing too radical. Just need to run some low 13's or so.

There's a lot of 461s and later stuff from the 60s which work well massaged. But you'll have about the same in those as aftermarket ones so unless you're a numbers guy looking for correct heads but with a kick then I'd use what you have. I've got a set of 461's with "stuff" done to them but I'm putting them on a 327/350 and taking off the older ones to play with them too. Unless you know that combo works then I would spend my money on known combos with proven bench flows.

I guess you're wanting to sell the others?

Originally posted by RB69SS396Conv:

It is pretty much the ultimate dung.

I don't know what info you're looking for, but about all I can give you, is that whichever version they are, they mostly belong in the trash. That's not necessarly true. I have a set on one of my 350's. It's making close to 275-300 horse flywheel. I won't say they're the best head out there but unlike their cousin the 882 they're not as prone to cracking.

Yes the 993's have 75-76 cc chambers.

I have 882s on mine, they're what we had handy for a fast rebuild

My dad spent quite a bit of time on the porting and they seem to be working very well for a performance daily driver

It's making close to 275-300 horse flywheel I'm getting that out of a 305, that almost passes CA emissions. It would if the SLP headers supported the EFE valve. It did in fact pass CA emissions with Edelbrock TES on it.

It has 186 heads.

I don't believe those numbers are any indication of adequacy, let alone superiority. Considering how cheap stock head cores are, it's wise not to spend a dime on inferior smogger ones. If anybody is going to work up a set, it pays to start with the best you can get; because the core is the least part of the cost. I'd rather have $600 worth of head work tied up in $200 worth of 186s or 041s or something, than $600 worth of head work tied up in a bunch of those others that I got for free, and still run slow.

I would not under any circumstances advise someone to use inferior head casting cores; even if they're "free", they "already have them", or whatever. There's too much to gain for too little money and effort, in getting good ones to start out with.

List your 305's combo.

Flat-top Speed-Pro hypers; 186 heads; Comp XR264HR cam; ZZ4 intake; SLP 1¾ headers; stock carb, dist, air cleaner, exhaust, cat, all emissions devices (except EFE) installed and operating. It was built while I lived in Carlsbad, to pass "enhanced" emissions there.

It put 237 HP to the rear wheels at a Mustang club's Dyno Day event in about August. That's around 290 at the crank, as installed in the chassis. No DD2000 or any of that.

Power lives in the heads. Do that part right, power will follow. Do it wrong, all hope is lost.

So I guess there is hope for that old LM1 in the Chevelle? Say how much power could we get if I threw a set of 186's or something on the old LM1? It's bone stock right now.

Hard to say exactly how much difference they'd make; but it would be an improvement, for sure.

The cam in that motor (929) isn't known for being a real ground-pounding fire-breather either. Obviously, in a situation where you're trying to get as much material as possible to flow through a valve that's only open part-time, there's 2 ways to do it; either increase the flow rate (make the passages less restrictive) by smoothing or enlarging them or open the valve farther, or hold the valve open longer. No rocket science there. That cam doesn't do much of either one. Better heads allow a more aggressive cam to do its job.

Well it look's like we've strayed off what I was questioning, but oh well. Do you all think these heads would work decently on my 350? I have a rebuilt 350 bored .040 over 2 bolt somewhere around 9.5:1. Comp cams xtreme 252H, stock 76cc heads with I think 1.90 intake valves, eldlebrock performer intake, holey 750dp. I was hoping on finding a set of used heads to slap on her, do a cam swap, and install a bigger stall something around 2600. I want to run some low 13's for now. Untill I build my blown small block combo. With the current setup I have ran 14.1. Should I buy these heads for $400 or wait untill I find something else? I can't really afford a set of new heads right now. I need your help. I'll look at my current casting numbers tomorrow if that helps.

Thanks

Oops it the comp cams XE256H.

Do you all think these heads would work decently on my 350? Personally I don't. Not worth the cost of the gaskets, just to get yourself a disappointment. Basically, those are exactly the same as "stock 76cc heads with 1.94" intake valves", since that's what they are. Stock 76cc heads with 1.94" intake valves (the usuall stock 350 size). I doubt you'd notice any difference by swapping to them unless whatever is on there now, is broken somehow.

There might be worse castings than the 993, maybe; can't think offhand of what they could possibly be; they couldn't be very much worse though. But, go ahead and post what you've got.

Sorry about the diversion..... wasn't my idea.