Grumbles

So I'm trading a MIG welder that's been sitting in my garage for a 350 out of an '83 suburban.

From what I've gathered just reading around, this will more than likely be a flat tappet 4 bolt main with smogger heads.

My plan remains the same: I don't intend to mess with it until my 305 dies. I'm going to drain it, shrink wrap it and wait for my mini mouse to grenade.

The guy who has the motor currently pulled it a couple years ago and says that it smoked on startup and stopped once warm, which makes me think either the valve stem seals are corroded or the rings may be leaking. I didn't bother to ask what color the smoke was so I can't be sure. My questions are primarily:

What casting codes should I be looking for?

How can I diagnose worn piston rings without disassembling the bottom end or having it running? (If I can get away with it, I would like to leave it together)

If the motor is in fact a flat tappet (very likely) what cam is recommended? I am looking to budget-build with either ported 416 heads or the factory castings and I'm only aiming for maybe a MAX of 300 hp.

I've heard the 305 head/350 motor combo referred to as the 'poor man's drag kit'. What kind of work will the 416 heads need to be viable? How much does it usually run a guy to get heads cut for bigger valves? ORRRR Should I use the smog heads (provided they aren't the accursed swirl-ports)?



Things I currently have:

600 CFM Edelbrock 1406

Aluminum Summit stage I intake

L98 cam (Doesn't matter because it's roller)

416 heads/heads the motor will come with

Valve springs for .550 max lift (on another set of swirlie heads atm)

As far as the car goes, I already have a set of shorties from Flowtech and a 2.5" system all the way back. I have the factory T5. I know this tranny is notoriously weak and will eventually give up behind a 350 even at the factory hp/tq rating. That's part of the reason I'm not looking to get too crazy.

Any and all input is welcome. Also, if anybody has a link to a comprehensive guide of some sort on camshaft selection, that would be amazing. I'm info hungry and would love to be able to say "that cam is too big!" or "that's gonna wheeze at 2.5k" and know what I'm talking about!

305sbc

iTrader: (3)

Well first I would lube every inch and hole of that engine before storing it.
PB-blaster on a lot of the bolts can help make it easier to disassemble later.

You can hook a battery up to the starter with the engine on the stand and the sparkplugs pulled out to do a compression test, but you have to make sure the stand is very secure or it will jump around.

Technically, I think 416's are also smog heads as they have the EGR ports in the center exhaust bowls. I weld those up before porting, and then backfill the holes with high-temp RTV and/or epoxy.
The 416's like most stock iron heads need a lot of work for performance. Most of the work will be in porting the bowl & seat area to match the larger valves. I always machine them for screw-in studs and guideplates so I can use non-aligning rockers. I also drill the pushrod holes out for clearance.
The guides are usually worn on used heads, so I refresh them with bronze inserts sized to fit the thinner stemmed LSX valves. Worn guides are what causes the smoke at startup. Worn or hardened seals will also cause this to a lesser extent.

I install 2.0"/1.55" valves into the 416's and deshroud the chambers to more closely match the 350's bore. I radius all the edges in the chambers. I also bias the chamber, seat, and port to follow the natural swirl of the factory head.

The main advantage of starting with the 416 castings or another 305 casting is the smaller chamber volume to start with. It allows more deshrouding and requires less milling to achieve a given compression ratio.
Before porting, the 416's don't flow any more than most other non-swirlport heads. If you can find some good used aftermarket aluminum heads on Ebay you could probably get by with much less work.

Your L98 camshaft will work in that block if you use retro-fit hydraulic roller lifters. It is good up to your 300 hp goal and will maintain good fuel mileage due to the relatively wide lobe separation and short intake duration. Ported heads work better the closer you can get to 0.500" valve lift. High ratio rocker arms will help there.

Grumbles

considering I don't have many of the tools necessary to do some of the work you suggest for the heads (porting isn't an issue, but turning down the studs/brass valve guides/machined pushrod guides/cut valve seats is machine shop stuff) do you think it would be financially wiser to attempt to work the 416's or find a decent CC 350 head. I am looking to use factory iron castings because they can usually be found on the cheap, but I don't really know what's out there that isn't Vortec and thusly requires a new manifold.

Do you have any cast suggestions? I'm really looking to keep the heads portion of this motor in the $300 range. Aluminum isn't ruled out mind you, I just have my doubts that aluminum castings can be found for under $600 a pair (and that's shady Ebay brands).

camaronewbie

When I had them, I ported/polished the 416's myself at home with a $40 electric Die Grinder and $20 worth of carbide cutters. Then I paid the machine shop $300 for cutting for one size larger valve, install of new valves and stem seals and a 3angle valve job. I used 1.95 intake valves, stock 1.50 ex valves - the new Manley valves for intake side were $85 I think - but this was 5 years ago.

Grumbles

UPDATE:

I may be in fact getting a motor from a '92-'93 chevy truck. This is of course pre-vortec, but I was wondering if the factory heads on this motor might be better, and whether or not it may be a roller assembly.

Thanks in advance :]

InfernalVortex

iTrader: (4)

The 193 heads on a 93 350 truck arent much better. Theyre not really good performance heads. Those wont be 4-bolt mains or roller blocks either. I'd stick with the old one unless you want a 1 pc RMS which can be very, very beneficial if you want to swap to a T56 or something later. But you can get 2 pc conversion flywheels too so thats nto a huge deal.

Also the TBI truck motors arent machined for roller lifters even though they're casted for them, this means they have REALLy tall lifter bores which makes finding retrofit roller lifters a bit more difficult. I know of some that are supposed to fit and I'll be trying them eventually. But just keep that in mind.

Tall lifter bores that interfere with some retro-roller linkbars:

Grumbles

I don't mind using flat tappet. They're a bit less forgiving than roller but I like the noise they make.

What are the specs on #193 heads? If the block is cast but not machined for Roller, will it have the necessary posts for the spider bolts, and if so can't they then simply be tapped?

What's the difference between 1pc and 2pc rear main seals? Is my 1988 305 a 1pc or 2pc?

So many questions so little time!!

305sbc

iTrader: (3)

With a die grinder and a drill you can trim down the guide tops and open up the pushrod holes. If you're going with a mild cam and not installing guideplate then you can skip the boss machining and drilling the pushrod holes. Trimming the guide tops lower is to increase clearance for more valve lift. Machining the O.D. of the guide-top is to fit positive valve seals.

On the cheap you can skip the guide-top O.D. machining and just use thin umbrella seals, though I never do this.

I suggested BRONZE guide inserts. It's really an inexpensive and great way to recon the guides. Have you read the information at the two links (LSX valve conversion) links in my sig?

Aluminum heads - yeah cheap Ebay deals can end up needing some work, but it's usually no worse than the work needed when starting with used iron castings. Aftermarket aluminum have good ports already, generally have deshrouded chambers of a small size, have seats installed for the larger valves, and come machined for screw-in studs and guideplates already.

For performance you don't want to use the TBI swirlport heads. They are for towing and fuel mileage.

If porting yourself, then there isn't much difference between starting with 305 or 350 heads since the ports are generally the same volume and shape.
$300 is really too low of a budget for heads unless you already have them and do most of the work yourself. You might squeak by with $300 of machining cost for cutting the seats, a valvejob, light resurface, guide recon, and cleaning. That's pushing it though.

All truck TBI blocks don't come with the raised lifter bores. I've run across at least 3 so far with short lifter bores. If you have raised bores, then it's very easy to just use factory GM roller lifters. Drilling & tapping some shallow holes for the spider is very easy. The last set of GM roller lifters with brackets and spiders I got from Ebay was only about $60.
If you have the short lifter bores then you would use the retro-fit rollers.
There is no advantage to flat-tappet besides the cost. Flat tappets require more oiling to the cam lobes.

A 1988 block is 1-piece rear seal. It's the newer style for the SBC1 engine.

Grumbles

Well I've got some pretty spiffy news that changes just about everything.


The motor is NOT from a '93.

It's a '96 Vortec block! So unless you guys think the factory vortec heads suck, I'll definitely be using them. Also, this means it's Roller as well if I'm not mistaken, and if not I can simply cannibalize my roller 305, something I had already intended to do to retrieve my L98 cam.

I think I may have just gotten a smokin' deal! I still have questions though. Can I replace my cam without removing either the heads or crank? Should I simply keep the factory cam or will the L98 perform better?

InfernalVortex

iTrader: (4)

If the motor is stock those Vortecs still need work to handle a serious cam. At least a spring change. An xe262 flat tappet cam is about as big as you can go with flat tappets, and roller cams will have to have some VERY small durations to get lifts that work within the limitations of those heads stock. You'll make okay power, but the durations on those roller cams get real, real small when you're lift-limited. The big advantage of rollers after all is how quickly they can ramp up the lift and keep the valves open.

If you're willing to pop off the heads then all bets are off, you can get em done right and put a monster cam in it and go to the races.

Otherwise you're gonna deal with factory limitations.

Grumbles

Part of my gig is that I'd like to shoot for maybe a max of 300 hp and do as little as possible in the realm of custom modification. This is not because I'm lazy or scared, I've done my own porting before with positive results, however I will be putting this larger motor in front of a notoriously weak transmission (factory t5) that as far as I know has 180k on it already. The tranny shifts smoothly but I'd rather not take my chances, ya know?

I have a set of .550 lift springs on a set of boat anchor heads that i could swap in relatively simply. The question is whether or not I should crack this sucker open. I will already be spending a minimum of $140 on the proper manifold. Do we know for sure whether or not all Vortec blocks 96+ were roller, and if so, will it benefit from a mild cam (such as my L98) or is the factory cam fairly stout?

What is the max lift on the factory valve springs?

305sbc

iTrader: (3)

Pull a valve-cover and get the head casting number. If they are real Vortec heads then they already have extremely good port shape.
Roller? yeah they are supposed to be.
I could be wrong but every one I've seen with the plastic timing cover had a roller camshaft. You could pull a pushrod and measure the length. Roller lifters use a shorter pushrod.

There shouldn't be a lot of difference between your L98 cam and the Vortec roller, if that's what it is. They are great for cruising and torque, but could hit 300 HP with a good intake and exhaust headers.
If it's a Vortec and it's running ok, then just put your intake and exhaust on it and run it as is. That would be very lucky.

It's a bit of trouble, but you can swap valvesprings without pulling the heads if you're very careful.

Grumbles

Thanks a lot 305sbc, your info has been invaluable.

I'll crank it over by hand, see if there's any trouble.

What casting numbers am I looking for?

Grumbles

So I popped a valve cover off and not only did I find out it was a roller with #062 heads, but there were ARP bolts and what looked like fairly recent moly grease still present, which makes me think this motor may have been recently serviced!

Cranked it over by hand and it seemed to turn okay. i think I may have very possibly stumbled upon a very nice engine.

Grumbles

So I've stumbled onto a minor roadblock. This motor is outfitted with an oil filter adapter that runs an oil cooler line, which would be all well and good if it didn't get in the way of my headers. Pic here:



Any idea what the p# is for the fitment to use a standard filter?