badone07

I realize this is an F-Body, but the people here seem to have more experience with 305 heads on a 350 sbc.

I have a stock 1984 Chevy crew cab dually. It has 49k original miles. Just put on a new dual exhaust and new exhaust manifolds, when some bolts broke off, in the exhaust flange area. So I removed the heads. It is a 350 "m" code that has "624" heads on it. However, these "624" are 76cc chamber with 1.72/1.5 valves. I believe the motor is around 160hp and 260tq, with around 8.5-1 compression, if not less. Since I already have the new manifold and exhaust system, I have to use heads with the 7 bolt pattern, instead of the more common 6 bolt pattern. I have a set of 882's but they won't work with my exhaust. I also have a set of 376450 heads from a 79 c-10 305 4 barrel. These also have the 7 bolt exhaust flange and have 60cc chamber, with 1.84/1.5 valves.

As of now I'm undecided as to having the 624's redone while they are off and having larger intakes installed. Or using the 450's from the 305, without doing port work, etc. The 624's are prone to cracking and I have read just about everyplace, that they are junk. I'm not interested in putting headers on my car hauler, so I only plan on using heads with the 7 bolt exhaust flange.

It has a 4.10 or 4.56 rear, with the standard 4spd with granny gear tranny. I'm just replacing the timing chain and installing a Performer intake. My concerns would be primarily compression ratio (detonation) and excess heat, if I went with the 305 heads. Your help is much appreciated.

Air_Adam

Since you probably have dished pistons, look for #416 heads. They are very common as all 305 F-bodies except TBI and TPI engines, they can take 1.94/1.6 valves with some work, can flow pretty well with some porting, and are 58cc heads. take that 350 with dished pistons to around 9.5-10:1 CR.

badone07

I already have another 350 with a set of 416's on it. However, I used it in roundy-round racing with aviation fuel. It never gave me any problems. It has since been sitting for quite a few years, with about 50 miles on it. Since this truck's only function is to haul a SBC powered 70 Stang drag car, I decided to use the original 624's. This way no unforseen aggrevation later. Thanks for responding.

Vader

'416 heads have a 7-bolt exhaust flange. With 12cc dished pistons, your C/R is about 8.21:1, With '416 heads, that will go to about 9.3:1, where you should be able to use pump gas.

'624 heads make excellent wheel chocks. Just don't leave the valve in since you can pierce a tire. Need some? Are you sure you want those bolted on? Your fuel savings alone could be worth the trouble of installing valves.

badone07

but what started out as simple exhaust manifold swap, turned into a lot of aggrevation. I had a bunch of other things to do, which i needed my truck for. Like pick up the car I have in storage with the 305 headed 350. So I had to make the decision in haste and was pressed for time.

I've been reading up on a lot of the posts and will eventually do the set of 460's and 416's I have. I figured I would ask, to see if just bolting on of the 460's would've been a problem. Just too many other projects going on. I was concerned about the compression ratio. Thanks for spelling it out for me. Was reading too many conflicting opinions elsewhere. I definitely don't have a few weeks to invest in porting and having machine work done to them. Actually, I'd rather rebuild another 350 and have it ready to do a motor swap in the fall. This way I don't lose the service of my truck. With the height of the fenders, it's faster & easier to do a motor swap, than a head swap...for me anyway. I'll eventually unload the 624's when I pull the motor, this fall. Thanks.

Vader

If you can arrange it, that's usually the best way to go. Take your time building a spare. Budget your time and money as you like, and when it's ready, pull the swap. Since one has to come out and one has to go back (in either situation), having a prepped engine ready to install is a smart move.

badone07

Just as I anticipated, one of the POS '624's is cracked. The shop they are at, is backed up in work and I just received the phone call. Good thing I bought a set of '083's from a 87 H.O. Formula. They should be here in a couple of days. Knew I should've just thrown them away. Hopefully, I'll be able to get my truck back together sometime summer.

John

RB83L69

There was no HO motor in 87 in F bodies, only in Monte Carlo SS. Last year for it in these cars was 86. And 083s never came on the HO motors.

083s are just regular cast-iron L98 heads.

Glad to hear you've got a good excuse to rid the face of the planet of one more set of 624s.

badone07

Thanks RB83L69. I was more concerned with the casting numbers, than what the seller claimed they came out of. Probably more of a selling ploy on his part. The bottom end on my 350 is fine. I just had the oil puffs on start up with the 624's, before the attempted exhaust manifold swaps. Since this taking longer than it should had, I'll probably through a cam in and new chain set. I was looking at putting in something similar to the Edelbrock performer Dur@50 204/214, adv. dur@ 270/280, lift @420/443, 112 center lobe. I'll have to now modify the center intake bolt holes, buy aligning washers for the Performer intake and get new valve covers. I'll throw the Rochester Quadrajet back on, with the heat choke tube. Along with the added compression, this should all wake it up.

I have a couple of questions though, if anyone can answer... I was planning on new springs anyway, but would the stock roller springs perform with the cam? Did the 14101083's come with guides machined for positive seals? Do they use self-aligning rocker arms? Providing they are within specs and do not have to be replaced. I just want to get everything together prior to dropping them off at the machine shop.

John

RB83L69

There's no such thing as "stock roller springs"; among the things that the factory's roller system porked the pooch on, is that they merely transferred their same lame profiles onto a roller blank and considered their job done. So, no, the stock springs on those heads are the same garbage as any others, not suitable for any further use.

There are positive seals available to fit them, from Fel-Pro among others.

Generally they do come set up for self-aligning rockers, but a few sets have surfaced around here with the old-style narrow slots; so you'll need to look at them and see what you've got.

badone07

Thanks again RB83L69, I figured as much. Just wanted to make sure. Guess I'll just have to wait until they get here and disassemble them, before I gather up anything else. I had seen some viton positive seal sets being sold in eBay, so I was going to get them now, but wasn't sure on the guide o.d.'s for these heads. I was curious if I would need guide plates or not. Or just pin the stock studs. Another thing I'll have to wait for. Well, I can get the springs now. A set of .550 lift, stock diameter springs should do the trick. Definitely not a performance motor here, but don't want any problems later. At least until I pickup my spare motor, that I have sitting in storage.

Thanks again,
John

badone07

Now one of the 083's are cracked. Didn't bother having the machine shop check the other one. Probably time to stop dealing with other people's junk and just buy new castings. Pulled motor and it's on the stand, presently reaming ridges. Still no heads $170 later.

Vader

Wow! Sorry for your experience. Have you scoured the wrecking yards and machine shops in your area? Many times machine shops seem to "collect" parts (like heads) that people never pick up. I've found decent factory heads for reasonable prices that way, many times with cleaning and Magnaflux already done, among other work. Just a possibility.

badone07

Thanks for the suggestion. Guess I'll try that Vader. The machine shop suggested that I would have a better chance of finding heads not cracked if I looked for casting numbers 14071114, 10110810, 14102191 and 14102193. Which are accordingly, swirl port heads, which I've been trying to avoid. Especially after reading the numerous threads here about them. They said they should be fine for my application. They made a suggestion of who to call for them, but I can't stand the wrecking yard they suggested nor their ridiculous prices, so the search continues. I just won't be buying a set not magged or pressure tested, after being removed from a block anymore(plus shipping). Truck's been sitting for like a month, since my initial post.

RB83L69

Watch the classifieds on this site; they show up frequently.

badone07

Thanks RB. I didn't realize there was one, since I found these forums through a search engine that came to the message boards. I'll be picking up the 4 POS heads tomorrow morning to see where they were cracked.

Had a little time tonight, so disassembled the rest of the short block. Only good thing so far is that the bottom end looks new. Crank has been cut 10/10 and the X rods were reconditioned. The cylinders look good and had a very, very small ridge. Not even a broken ring, which I was expecting to find a couple. Looks like I'll get away with a boil, mag and hone. Throw in a new oil pump, moly rings and full set of bearings. Haven't decided if I'll replace the cast dished pistons yet. I'll mic up the bore first.

Hopefully, I'll come across a decent set of heads, before the short block is assembled. Besides Dyno Don, has anyone else fooled with a set of swirl ports? Just trying to keep my options open.