I have a Chev 350 2 bolt main from sometime in the mid 70's, I was wondering what the tallest lift is that will fit the stock heads with stock springs. I have headers and will be installing an Edelbrock Performer RPM intake manifold with the stock Q-jet, should I aim for large overlap and duration to crutch the poor flowing heads or would it be best to choose a tamer cam until I can upgrade the heads? I know this is nowhere near an optimized combination, but what kind of power do you think I'll be able to pull out of it? Thanks in advance for your help.

 

Stock heads? Probably 882's. Go with a small duration cam, as much lift as possible, but small duration (so you're limited to small lift). That's got such an abysmal compression ratio that a big cam will just bleed off compression and it'll barely run.
Compxe 256 or so. That'll get the engine to run the best, sadly to say. You might get into the 275HP range. You need smaller chamber heads to bring up the CR of that smog dog. The intake and Q-jet will work good.

If you're looking for some cheap power, 416 (305CID) cylinder heads are a good addon to that type of build. With the stock 12cc ish pistons, the 58cc 305 heads bring up the CR to where you can use a bigger cam. When they're ported you're all set.

 

Thanks, there are a few 305 engines in the local junkyard, I'll grab a pair of those. With the added CR from the 58cc heads, how much larger can I go on the cam? Roughly what would it cost to port those heads to flow a little better? I thought it would be cheaper in the long run to save up and get a pair of aftermarket aluminum heads instead of investing the money to port smog heads. If i do port the 305 heads, should I mill them to further raise compression, or would I then need to mill my intake to match?

 

Don't just grab any 305 heads, only post 1982 sorta thing.
last 3 digits in casting number of
416
601
081 will work, but you won't find those lying around...

You don't want to pay someone to port them, then it's not worth it. Pick up an electric die grinder (or air if you've got a big compressor), and do it yourself. It's not as hard as it sounds. And yea, porting smog heads is a waste of time (ie, the stock heads on your 350, 882 and the like), the 305 heads I recommended aren't "smog" heads per se.

If you'd rather save up and buy aftermarket heads, that's your call. I ported 416 heads myself and like them. A lot cheaper in the end.

No, you won't need to mill the 305 heads to bump up the CR, you'll be knocking on the door of 10:1 as is.

 

The amount of lift you can run on a stock set of heads won't be any different if you pick up a set of 305 heads. Bottom line is simple: to increase the lift on stock heads, you either increase the installed height or have the guide bosses milled down.

The cost for DIY porting is fairly cheap. Just comes to whatever amount you put into porting tools.

The drop from a ~76cc chamber down to a ~58cc chamber is fairly big. Shouldn't be a need for milling.

 

Alright, in that case, where do I find the casting numbers on cylinder heads? I have a dremel with an assortment of grinding stones, will that be enough to port them? What am I looking to modify on them to port them? What kind of cam should I look for with these heads, ported or not? Sorry about all the questions, but I don't want to screw anything up on my first parts swap that goes beyond general maintenance.

 

Pop off a valve cover, you're looking for an 7-8 digit number between the valve springs.

Dremel's do not have the torque to port a cylinder head. You need something with the 1/4" collet for the larger abrasive stones and sanding pads.

 

I got some 081's.. I slapped 'em on my 350.

How come they are hard to find? Just curious

 

oh, I figured LG4's are more common.

Any cutlass, caprice, Monte Carlo etc etc etc will have 416 heads on a 305 between -82-87 or thereabouts. Common as dirt.

Any truck or van would have 601s, those are also common as dirt.

But TPI 305 camaros? I don't see those at all in the pick-a-part. They only have the crappy cars in the PAP in Calgary, but the prices are low. TPI camaro's (when found) are usually picked clean by the people that think Camaro=fast.
At least from what i've seen, 416's would be easiest to find.

 

I ran .480 lift with my stock 416s when they were on my old 305. Never had a problem.

Also have a friend that is running the same .480 lift on his stock l98 heads with no problems. He has been running them for almost a year.

 

Thanks guys. What sort of duration should I be using with the higher compression heads?

 

Pick your cam dead last. After you have your intake manifold chosen, and in hand, carb, and most importantly heads. What heads, how much porting, etc etc. what final CR you'll have... Then, and only then, is it a good idea to pick a cam.
FWIW, my similar combo has a Compxe268 and runs just great.

 

Well, first off, what RPM range are you shooting for? What is the car's basic function, daily driver, weekend warrior, or trailer queen? I chose my cam on the basis of idle quality and RPM range. I want a lopey idle with an RPM range of 2000-6000 RPM, and my car will be a weekend warrior.

I built everything else around that. 3:73 gears, 2800 stall, sfc, stb, traction control, etc. I believe I will get the car into the 13's.

I chose a solid cam with 236* at .050 and a .495 lift. Then I installed a set of 1.6 to 1 roller rockers that bring the lift up to .528.

The lift doesn't have to be that much, but with stock springs I would try to keep it below .480 to be on the safe side. Not saying it wouldn't work with more, but why risk it if you don't have to?

 

A buddy of mine from work just told me that he has a pair of small combustion chamber (fifty something ccs) heads that are late 60's or early 70's, before all the smog regulations and such. Would these be a better or worse base than an 80's 305 head?

 

I doubt it. I'd ask him what the casting number is, then post it here to verify. There weren't any 50 some odd cc chamber heads in those years IIRC. (at least not any good ones that I know of). And if they're that old, the guides are SHOT, it'd need surfacing, probably needs a valve job, needs valve inserts if they weren't hardened etc etc.

 

He said they needed a total rebuild, so I suppose everythings shot. I guess I'll take a stroll to the junkyard on my next days off and try to find me some 305 heads in decent shape. If a few of the guides are worn, can I get them replaced separatly or should they be done all at once? Also, would larger diameter valves be a worthwhile investment or should I leave them alone?

 

Yea, you'd want to have all the guides done at once.

The 305 heads respond quite well to larger intake valves, 1.94". I did that to mine.
By the time the smoke cleared I had spent $400 CA on my heads. In spite of what others say, you can't get a decent aftermarket head for that price (canadian dollars). I could have probably gotten away a bit cheaper, but I had "the works" done to the heads.
I'm trying to think if there are any other members on here from winnipeg that might be able to recommend a decent machine shop...

 

As far as the DIY porting part goes, pick up the "Deluxe Porting Kit" from Standard Abrasives. It costs about 50 bucks and has all the stuff you'll need to do a nice home porting job, including instructions w/photos on what to do, and what not to do when porting them. Summit sells the SA porting kit. Also, you can pick up a die grinder from Harbor Freight for about $20, and you'll have everything you'll need for porting them. I used the SA kit on my 083 heads, and they turned out really nice. On the intake ports, I just size matched them to the stock Fel-Pro gasket opening. Personally, I'd stick with a set of 350 heads. You can always have them milled down some if you want to bump up the compression. If you do go with 305 heads, you may have to get the larger 1.94/1.50 valves installed since a lot of 305 heads have smaller valves. As far as a cam goes, I'd suggest a Comp Cams 280 Magnum, or the 268 Magnum if you want to go a little tamer. As cheap as valve springs are, also pick up a set of Comp Cams 981-16 springs to go with the cam. I know several guys who've run the 280 with stock springs with no real problems, but I'd put the new springs in anyways for good insurance. If you do these few things, it'll wake up that 350 quite a bit without having to spend a ton of money. Just my .02.

 

Isky cams makes a whole line of hyd circle track cams with a.450" limited lift. These are available in enough different durations to suite most typical Budget Performance builds.
I like Isky #201278 . its 234@.050 278 adv dur .450" lift and 106LSA. has a cool rough idle and very strong power from 2800 to 6000+rpm. make sure you degree it in so its slightly advanced in the motor. (102 to 104 intake C/L)
At only .450" lift there will be no need to shorten the valve guide bosses on a stock head. Even if you just pop on some valve seals that fit the stock guides.
if you do a decent job porting a set of "416" 305 heads with 1.94" valves it will work very well for you. Works a lot better than the modest lift suggests.
Needs a 2800 to 3500stall 9.5 to 10:1 cr and 3.73 to 4.10 gears. needs headers and a dual plane manifold Modify the distributor curve for lots of intial advance and use a 4.5" power valve in the carb.
If you must stick with the stock converter stall use Isky #201268 224@.050 same .450" lift and 107 LSA. Again, degree it in with slight advance. (102-104 installed C/L)

These Isky "lift limit" cams are a good way to save to cost of machining for high lift clearance.
We've tried them on the dyno. They make very strong power and torque in this type of motor.
One of these will be just right for your build.

i finish my ported 305 416 heads for less than $500 (can) including taxes. I find the finished chamber size after deshrouding a little to fit the larger valves and cleaning up the decks (resurface) the chamber is 62cc+/- a few cc's. i find this a better and cheaper overall head to finish than a 882 head for these typical budget performance 350 buildups.
Most bang for the bucks.

 

Alright, it's been a while, but here's a small update. Went to the junkyard and picked up a pair of 416 heads and they look to be in decent condition. I have a performer rpm intake manifold and block hugger headers. I'll be using a Q-jet. Found a couple cams and was wondering if either of these would be suitable for the combination. I'll be trying my hand at porting the heads, following one of the step by step threads on this site.

First cam is a comp cams Xtreme Energy 268H.
Advertised Duration: 268* Intake/ 280* Exhaust
Duration @ .050" Lift: 224*/230*
Valve Lift w/1.5 rockers: .477"/.480"
LSA: 110*

Second cam I was considering is the comp cams Xtreme Energy 262H.

Advertised Duration: 262*/270*
Duration at .050" Lift: 218*/224*
Valve lift w/1.5 rockers:.462"/.469"
LSA: 110*

Both of these come with kits that include the cam, lifters, springs, retainers and locks plus a new timing chain and gears. Are either of these suitable choices?

 

Anybody?