Now I know most of you boys say there’s no point in upgrading a 305, but I’m gonna do it anyways because **** it why not.

In a few months I’ll be getting stock 059 Vortec heads, Edelbrock Vortec intake, Edelbrock Performer 600CFM carb SKU: #14063 (might go 650 or 700), and a COMP Cams Xtreme Energy 224/230 camshaft. I’m keeping the flat tappet, not switching to roller.

I’m just trying to find out what I need to do to the valvetrain. My 305 has 60k miles on it since its last rebuild. I’m assuming a double timing chain set up is a good idea, not sure which one to go with though. I’ll most likely take the 059 heads to get rebuilt, what parts should I add to them to compliment the new cam?

If y’all can help, please give me advice on what I should do with the entire valvetrain.

Thank you, GnarlyBird

 

With current cams and lifters going flat I’d rethink a cam swap. Even with light spring break in and high zinc additives. What cc are current heads and compression? Cam lift of cam your thinking about? If the heads arnt new, do a valve job and new springs to match the cam. If over .470-.480 might look into tapping for screw in studs.

 

It’s getting a flat tappet cam from COMP Cams no doubt. I’ll put the cam specs below. Stock 305HO heads, 9.5:1 compression from factory, the 059 Vortec heads will maintain that compression too. Plan is to find cheap, decent condition 059 heads on Marketplace and taking them to get rebuilt, possibly put in stiffer springs to match the cam but not sure what I’d need to get.

 

Iirc the vortec heads had a stiffer spring for the roller cam. You wouldn’t want a stiff spring with flat tappet cam.

 

Sounds good, I’m trying to find 059 heads from a flat tappet engine though, not sure if it makes a difference. This is my first time doing semi-major work to an engine.

 

OK, since ya asked "Eff it, why not?" , , , , I'll take that as an invitation for an answer

Because getting a 350 block equipped for a roller cam with put ya SO much further ahead toward the performance that, deep down, ya know ya want, yes Really, REALLY want......

And that "Stage 3" 700R4 deserves to be behind

Bonus points for turning that nice new roller cam 350 into a 383, and really pinning your azz back into the seat when ya mash the go pedal.

 

yeahh but that “why not” is just a “it’ll be funny and i have the money to” in disguise

 

I've got my popcorn and am patiently waiting for Sofakingdom to chime in (LOL !!!)...

 

 

​​​​​​​Can't be bothered. Nobody listens to me anyway.

 

First, springs and retainers. Even when new, they were around 80 lbs. seat pressure, and after 40 years they couldn't have become any better. They'll float more than a canoe on a glacier. The obese retainers/rotators only worsen the situation, and really offer no tangible benefits. Even the later stock "lightweight" retainers are an improvement.

Second, the pressed rubber rocker arms used to fight those weak springs. The stockers are almost adequate to operate the valves under 80# springs without crippling deflection. That will only dampen some of whatever upgraded cam profile you might install.

Third, the lifters. Since they don't roll, and they aren't going to like most modern engine oils.

Fourth, the rocker studs. If a respectable cam profile with adequate springs and sturdy rockers are installed, the studs themselves have the potential to deflect enough to sacrifice good valve control and/or un-press themselves from their cast bosses in the heads.

Of course, none of that even begins to address the valves and runners. The stock valves are reliable enough, albeit small, while the seats and runners are acceptable for what a lower-output 305 was intended to do.

The top of the rabbit hole looks like a cam/rocker/spring kit, but by the time you dig down to the elusive rabbit itself, the other end might look more like a 4-inch bore and entirely different head design.

If all you desire is a bit more responsiveness and durability, the cam kit with springs/retainers/rockers may be worthwhile. If you expect a measurable increase in performance, those parts alone are unlikely to deflect the needle much at all.

 

I don't agree that a cam will net minimal gains, but I do think that's too much cam for a stockish 305.

 

That's a lot of cam for a 305. Would be pretty aggressive in a 350. Plus, personally haven't had very good luck with Comp's Xtreme Energy cams.
I would go with something like a Summit 1102 (204/214 @ .50) will work with the stock valvetrain and be pretty nasty for a street engine with enough vacuum for brakes.

 

Not to argue with the Rockies Rocket, but that cam alone between stock 305 heads wouldn't make a night/day difference. It might not be too much cam on stock valve sizes, and might release 10-15HP with no other head/valve work - maybe. Since GnarlyBird mentioned switching to 059 Vortec heads, That resolves some of that question, and addresses it even better if those replacement heads get some attention first. Consider that the enlarged chambers are going to drop compression, and you might need to address the non-existent EGR to keep them cool enough for street driving. Before destroying your PayPal account, it might be educational to investigate the heads/intake used on the L99 engine as a potential template.

I am running a Comp 07-305-08 (220/230, 114°LSA .510/.520") on a stock 350 and it idles almost as smooth as stock, produces more than enough vacuum for power brakes, even under enlarged valves/ports/runners with tight (54cc) chambers.

 

IDK....I hear you, but maybe we need to clarify what's a big diff and what's not? What's "worth it" and what's not? I've saw a full second drop in ET from a Summit brand cam & lifters ONLY swap in a 305. Sofa is cringing right now (and really, I do too when I think about it now). but 30+ years ago I swapped a flat tappet cam and lifters ONLY, and dropped a full second. That's more than 10-15 hp, IMO it was totally "worth it", for ~$89 bux. Was it the "right" way to mod? Probably not but it lasted over 60,000 miles, into two new owners and then the car disappeared from my awareness. Maybe I got REALLY lucky?

The combo the OP is talking about will probably be pretty soft and lazy down low, but it ought to have a fun kick up higher and make good sounds and feels.

 

This entire idea is a waste of time. The Vortec era has came and went over two decades ago. Factory assembly line Vortec heads are junk. Lightweight, thin wall, crack and warp prone cast iron junk. They were the best factory assembly line cast iron head GM installed on a truck. Mexican Vortec heads are even worse because they give you half the Vortec hyped HP & TQ gains over the junky assembly line installed Made in Canada Vortec heads.

You use the Vortec head design because you are already married to it because you already have an intake that you just absolutely just have to have. You don't choose Vortec.

Vortec was for poor people to make some power when there wasn't a huge selection of good cheap aftermarket heads to buy. Vortec were in the junkyards in fresh wrecks cheap as dirt and at GM for cheap because GM was still making them everyday until 2002.

Now a days the cheapest, junkiest Chinese SBC head is way better than a Vortec head and you don't have to get married to an obsolete intake manifold design.

Oh and good luck finding a machine shop these days that can cut anything straight and do the job right that isn't going to take until you die of old age or it costs you more to rebuild then just buying new heads.

 

That last sentence is a major reason that bolt-ons are so popular now. Finding an automotive machine shop any more is not easy. Like radiator shops, custom exhaust shops, frame shops, and upholsterers, every little town used to have two machine shops, and that increased with the size of the metropolis. Divide that by the number of shops that can actually perform reliable (straight/flat/square/centered) work, and it's like opening a duck's bill expecting to find fangs. Since "valve jobs" used to be very common, there was a market for the services.

 

I can't resist.
The original question was regarding a valvetrain upgrade wasn't it. Not the 305 vs 350 debate. Or the flat tappet story.
So, even the if cam choice isn't ideal (at least from my perspective), it does give an idea of what the profile might be, the RPM range and how to handle it.
If you want to stick with Comp (and I can't vouch for their current quality including their flat tappet lifters), the simple answer is the beehive spring and associated retainers that they recommend.

https://www.compcams.com/beehivetm-v...d-825-i-d.html

That spring is spec'd with a 1.70" installed height which is the Vortec spec.

If the heads are unmodified, I believe the 059 use a self guided rocker arm like the 062. With the minimal spring pressure and the better than the old days of keeping pressed in studs pressed in, just go with the OEM arrangement. No screw-in studs or guide plates. Simple. It wouldn't hurt to upgrade the rocker arms though. IMO, there's something to be gained from at least a roller tipped rocker (but self-guided).
To qualify the above, when Vortecs were new, I bought a set from the General and used them out of the box. Springs included. That was with a Comp 268H flat tappet cam (albeit a Clevite copy) on a 9.8:1 350. It happily went well past 6000 RPM although that was ill advised. One missed shift and it zinged past 6500. Two bent exhaust valves later...It made no sense to go past 6000 ever as it was done making power well before that but sometimes showing off gets the better of you (it was a burnout for my country neighbors kid!).

Anyway. that's my 2 cents.
As for the 305 thing. Two things are needed to substantiate building one. One you already have it. And two, you like the V8 sound. It did it once between 350 projects and don't regret it one bit. It sounded wonderful. Hell, my first engine project back in the 70's was a 307. So there!

If you want to talk cams, that's another story altogether.

 

Here where I live, we used to have more machine shops than bars, or churches...... Of course, dirt track racing was REALLY popular here then.... Today, the nearest machine shop is 50+ miles away, and has a turnaround time measured in MONTHS..... A LOT has changed since I first got into this hobby.... Today, it's to the point that I just can't afford it any more.... that, and I don't have the patience to wait months for any machine work..... not to mention what it costs around here these days.... Ouchie.

 

Ran that K1102 cam in a LG4 305 years ago. Was maybe a bump up from the stock cam but not much .Still very mild and car only went high 14s with headers and better intake.. Stock L69 cam was 208-214 duration IIRC.

 

Stock, the Vortec heads can only handle .430-.460" of lift before the retainers hit the valve seals. LS beehive springs, retainers, and keepers will clear .470" of lift (leaving 0.030" safety margin) without having to machine down the valve guides. This can be bumped to .500" of lift by using 0.030" offset keepers. 0.030" keepers will leave enough valve stem tip for self-aligning rockers. If you don't want to use SA rockers, you'll have to have the heads machined for guide plates.

I'm currently dailying an 87 LG4 with 85k miles and a peanut cam. I want to stay within the power limits of my T5 and I enjoy wrenching so I just want my 305 to pull to the redline instead of falling down at 4k. I just picked up a set of 059 heads off a boat motor, a GMP Vortec spreadbore intake, and an LT1(ES336 .447"intake/.459"exhaust) cam. The cam will only make 260# of open seat pressure so I'm leaving the studs. Since my motor came with roller lifters I'm planning to reuse the lifters, pushrods, and rockers assuming they're still in good shape.

 

You're going to run flat tappet lifters on a roller cam? Or are you talking about an "LT-1" cam?

 

4th gen f-body LT1 cam. 87+ f-body blocks have roller cams/lifters.

 

With the seals fully seated, stock will hit at 0.510" typically, always measure. I have had some that have 0.530" stock. Fully seat the stock seals, no problem doing it in probably 20 setups I have worked on now. LS6 Beehives and 787-16 retainers typically clear 0.550, deduct 0.050" and you have 0.500 to work with. You can usually run a 0.050" offset lock set without losing too much of the valve stem height to allow self aligning rockers to clear giving you 0.550" lift and very near the LS spring installed height spec. You can run a 0.030" lock set for ~0.530" max if it scares you. I skipped the offset locks on my 0.482/0.496 lift L31 setup, have a little more spring pressure, it will rev 6,500 rpm and makes power easily to 6,200. Been driving it close to a year now as a near daily driver. No oil burning, no startup smoke, no valve float, just inexpensive budget power. Oh while you are there drill out the pushrod holes with a 1/2" drill bit. Takes like 20 seconds a pushrod hole and will allow you to run just about any 1.6 rocker without fear of the pushrods rubbing the cylinder head. If the block deck faces and cylinder head faces are in good shape which you better hope they are, I run 0.016" rubber embossed steel shim head haskets when I install these heads to maximize whatever quench and compression I can obtain.

 

I ran a Crane 274H06 that still has many knock offs in one of mine. In a G20 van no less. It was a very noticeable bump combined with Performer RPM spreadbore and tri-y headers into a 2.5" dual exhaust. That cam was 274/274 @ 0.004, 218/218 @ 0.050, 0.450/0.450 lift, 106 LSA and a 102 ICL. Ran it with a set of home ported 601s. Easily a 300+ hp 305 and sounded a lot rowdier at idle than it really was. Just above idle it would smooth and run great.

 

As always, great info. Regarding max stock lift, I was measuring .460-.480" between the stock seals and retainers but I didn't think to make sure the seals were fully seated before I pulled everything apart. Maybe differences in the 305 L30 and 350 L31 heads? Will definitely use your tip of drilling out the pushrod holes.

 

I have setup numerous sets of 059/520 305 heads as well as few iron LT1 and L99 heads the same way.

 

The L30 305 in my 1999 Tahoe had 520 heads on it. Stock truck LS beehives on 787-16 retainers and 0.050 offset locks, 1.6 roller rockers, Lunati HE 268 flat tappet cam and Rhoads Original lifters. That Lunati cam was 268/268 @ 0.006, 221/221 @ 0.050 and 0.484 lift with the 1.6 rocker on a 110 LSA and it degreed in on a 104 ICL. Used the stock LS truck springs because the flat tappet cam did not need as much spring pressure as the LS6 springs provide. Basically the cheapest upgrade at that time for that setup. Cheap retainers, cheap locks, and some low mileage take-off LS springs from a 6.0L I had cammed.