oldfogey47

OK, I recently bought two sets of heads. A pair of "late" 243's and a set of 853's.

Q1: Is there any difference in "late" 243's vs. earlier 243's? Is one set more desirable than another?

Q2: Both sets were advertised as: "just clean them up and bolt them on". The funny thing is, they both look like you could actually do that! The question is, how do you tell? If I could do that... then great!
I'm a rookie in the LS world, so I don't know. I've always dealt with SBC & BBC steel heads.

There, that's a good start, for now.

Thanks...

G Atsma

243's are 243's. COMPLETELY interchangeable. Along with 799's, which are identical to 243's in function.

ss.slp.ls1

iTrader: (36)

I haven't heard of any differences existing between 243 castings. As for your second question, are you asking how can you tell if you can just bolt them on? Well besides a visual inspection, you could get them tested by a machine shop to see if the values seal and if the heads are completely flat.

A.R. Shale Targa

iTrader: (2)

At this point it would be a great idea to replace the valve seal
Also the earlier 243 heads with yellow springs are from the LS6 engines
which have lighter valves and they are .0236" longer as well to make up for the reduced base circle diameter of the higher lift camshaft

ss.slp.ls1

iTrader: (36)

Oh, duh, yes there are differences. I was only thinking about the casting themselves, not the valvetrain components.

G Atsma

Yep, I was in casting-think mode too. Good job A.R.S.T.!

oldfogey47

I appreciate the input. It really helps.
I'll be taking the heads to the machine shop today or tomorrow. I've spoken to my machinist there and he says LS heads seldom need a lot of work to get them going.
That said, I pulled the springs off yesterday and I think the 243 heads aren't going to need anything except a cleanup and new springs!

The 853 heads may need a bit more help, but I don't know.

Anyway, I'd like to put a spring kit on the 243's as they will be used before the 852's. After searching through similar threads, I think the PAC 1218 kit looks like it would work well for me.
I don't know which cam I'm going to use, but I don't plan a lift over .600, and the engine. eventually, will see 99% street use, and I'm not searching for huge HP numbers. What do you think?

Gotta go... Thanks

A.R. Shale Targa

iTrader: (2)

Would need to know a bunch more info about your vehicle/combination
weight/trans/gearing/converter/other mods/exhaust/etc.
AND intended use

HappySalesman

iTrader: (3)

The 243s, an LS6 intake, full exhaust and a mild cam would net you something like 350-370rwhp? (I'm kind of guessing here. But I'm thinking sub 400 without a donkey dick cam lol)

I would have the machine shop lap the valves in if they aren't already. Otherwise as long as it's not warped or cracked you should be fine.

A.R. Shale Targa

iTrader: (2)

Was some Seattle fella a while back.....boosted383....IIRC; had a documented bolt-ons F-body with single pattern 224/224 cam (off brand) and fancy valve job 243s that put down 440 RWHP w/LS6 intake....STD and open cutouts
through the exhaust and SAE it was like 415....still very strong for such a docile combination

oldfogey47

OK, I'm looking at either a '98 - '00 S-10 pickup or a Camaro, of some(?) year. Weight would be the avg. weight for the particular vehicle, except the S-10 would be a couple hundred lbs. more, with headers & full exhaust.
If I use an automatic, probably a 4L60e and 3,000-3,200 stall, with around a 3.90:1 rear gear. Again, about 99% street car.

I'm currently looking at a '95 and a '98 Camaro. The '98 is a little more attractive, as it is a V8/Auto and will already have some of the computer related gear I will need, right? (he is asking $3500.00, right on blue book value).

Question1: didn't the '98 Camaro come with the 5.7 Aluminum motor? I won't be using that motor, but I've read good & bad about the Aluminum block. This one has about 133,000 miles on it. Is it "usable" or worth anything to sell?

The '95 is a nice car with the TPI 350 sbc and a 5speed trans. Its a bit cheaper, but I have to do all of whatever is necessary, computer-wise (same for the S-10 option).

So.... what da ya think? Would that PAC-1218 Valve Spring set work ?

Thanks again for the patience.

ss.slp.ls1

iTrader: (36)

Yes the '98 has an aluminum LS1 5.7L engine. At 133k I think the engine is definitely usable if you want to upgrade it (heads/cam/etc). The engine can still fetch a pretty penny.

The '95 should have an iron LT1 5.7L engine, not a TPI. I've had both engines and both are good platforms for making power. The LS1 will make a little more due to the better head flow, but I like the low end torque that comes from the LT1. If you are not keeping either engine and plan to swap out to a different GenIII or GenIV engine, then the '98 car will make for a more simple swap. However it won't be that hard to rewire the '95 if you get a new PCM and wire harness with the new engine.

Those springs are good up to .600" lift so keep that in mind with your cam selection.

stp001

If you are going to invest money into the 243 heads to get springs and possibly a valve job, I would suggest that you sell the 243 heads and take your 853 heads and send them off to Lloyd Elliot for his LE1 port job. It comes with new .650 lift springs, valve job, milled to your specs, and I almost forgot.....over 300 cfm flow numbers. I think that costs about $850. If you sell your #243's for $300, you get ported heads for just a couple hundred dollars more than stock heads with good springs.