So like the title says, I'm going to switch from TBI to TPI pretty soon here, and I'm trying to plan out my build. So far I already have heads off of a H.O. 305 Trans AM, 4416 heads, and the TPI off of it. I'm also going to pick up a LT1 cam off of my buddy.

So really my question is, for relatively cheap, what can I have done to these heads that could potentially help out? I'm already planning on having them gone through. I have a L03 lower end, and I'm not planning on changing pistons or doing anything nuts with the cam. Should I change out the valve springs with anything specific? Would changing valves help out my 305? If I go roller rockers, does anyone have any suggestions?

Really, I'm basically just asking, when I do this build, does anyone have any suggestions for these heads/cam that would help this setup work a little nicer? I was reading that I can put valves in it and run the heads on a 350, I can change springs and put big cams in it. I'm not looking to do all of that with these heads/engine. I want some decent performance from them, but in these particular head's stock configuration, can I have them modified to perform better for my LT1 cam/TPI swap?

Thanks for any wisdom or guidance

 

Really nobody? I can't believe nobody here hasnt done anything to 4416 heads being run on a 305

 

From what I understand the only thing worth doing to them is installing 1.94" intake valves and blending the bowls to match.

A site search here should yield a lot of info. Lots of additional info on non-3rd Gen sites as well.

 

And I did that, but the application was on a 350SBC, not a 305. I figured the performance might suffer when the bigger valves were installed and it was used on a 305

 

you can benefit from a 1.94/1.50 valve install, other than porting and polishing, you may need a valve spring set to match the cam, i don't know the specs on it off hand.

 

Okay so I guess I've been thinking about this the wrong way ... should I decide to have the valve changed out, and maybe a port/polish done to the 416 heads, what cam should I run using a TPI intake? I wasn't thinking correctly about using a LT1 cam, because the LT1 cam thread I read was if I was going to run it with my old TBI setup.

So, lets say I have a 305 HO motor with 416 heads, full 3" magna flow, shortie headers, and a 3.73 Torsen Zexel rear. Full tubular rear parts, strut tower brace and wonder bar up front. Just got 16" formula wheels. Has a stock rebuild 700R4.

All that in mind, what's a good cam for a modified head, 305 HO w/ tune port? I'm assuming I'll need springs, maybe injectors and a tune?

 

The 305 is close enough to the 350 that most recommendations will apply to either. The exception is the valves due to the 305's smaller bore, where larger valves would get too close to the cylinder wall and either contact or get shrouded (blocked flow).

The TPI intake will limit the engine's potential to 4500, maybe 5000 rpm. The LT1 cam is a little more, but not much, bigger than stock.
In the 350 discussions, the LT4 HOT cam or similar aftermarket cam is the the largest recommendation while retaining the TPI. This has even passed emissions.
LT4 HOT cam = 219/228* @.050, 272/281 advertised (@.006), LSA 112*, .328/.328 lift w/ 1.5s = 0.488", w/ 1.6s = 0.525"

And from Sofakingdom...
I'd suggest, for going with the TPI, the Comp "304" or "502" grinds. The specs might not "look" all that different from the HOT cam, but the objects themselves are...

 

One question that I haven't seen asked, and is relatively important...What do you want the car to do?

 

I'd like a "good performer" and by that, I mean make "more power". I would call this build a budget build, only because this 305 I only want to tide me over while I do body work and chassis work until I'm ready for a larger engine, say a 383 stroker, or a LS swap, etc.

Either way, a 350 engine could possibly be in my playing cards, but really the main reason I want these heads, and this intake, is simply because I already have them, and they were had for really cheap. That being said, I want a "fun" street car. Not just stomp it and do burnouts, I want an engine that someone would say, huh that's a quick 305. I'm not looking to impress the LS guys, or impress someone with a 350. I understand a 350 is better all around, but I'm looking at it this way.

I'm honestly okay to stay with my 305 TBI setup, but with these parts on my shelf, and only minor gaskets/labor required to swap to a higher performing TPI setup, I'm here asking myself, why haven't I already done the work to gain the additional HP that's setting on my shelf. So if I'm going to dive in, lets at least make the most of what I have. I get that the 305 isn't the best platform to work with, cause bang for buck is stronger with other blocks, but it's what I have, and we're looking at peanuts to gain more power out of this block.

So "fun street car" isn't quite it, more like, gaining "more" power from my current 305 while I work on other parts of the car and just plain enjoy driving it. So, lets say my stock 305 TBI gets me a generous 190HP, lets say I'd like to see the edge of a 300HP number if possible. Doesn't mean I "need" 300HP, but lets set a humble estimate of 240-270HP.

So basically I'm at the "lets throw a couple hundred bucks at this thing and see what this 305 will do". Does that mean I'll machine in bigger valves into my TPI heads if it'll cost hundreds for head work alone, well possibly if these numbers will work in favor of me. Basically I'm trying to be stingy here. I'm not afraid of ideas for different intakes, but considering I have a TPI/heads combo just setting on my shelf doing nothing, I figured I might as well make a tasteful camshaft/head choice as long as I'm doing the work.

And if I need 3K to get me out of my "cheap HP" mentality, then I'll scrap the idea of doing any custom work to it, and just throw all my stock TPI parts on it and call it a day. Again, this engine wont stay in here forever. Heck, if the damn thing blew up on me, it would probably be like doing me a favor.

 

To be honest, I kind of regret not building my 305 and putting the 350 in. The 305's make plenty of power. I'd say go with the LT4 hotcam, since it's going to be cheap, and better than stock. I'd spend the majority of your money on your heads. Have them completely gone through, and I mean COMPLETELY. Port n polish, bigger valves, deshrouded, and stronger springs just for being on the safe side. That should easily get you close to 300hp.

I'm only recommending the LT4 cam, because that's probably the cheapest option. An big(er) cam is going to require tuning to get the most out of it, and considering not people tune OBD1, and it's expensive to start doing it yourself, the LT4 is just more cost effective.

 

Now that' some solid advice I was looking for

I'll look into dropping them off at the machine shop and getting estimates. I will most likely go this rout, depending on cost. I don't want to put boat loads of money in them though.

Now say, I were to go to the machine shop and ask them to deshroud my heads, what exactly does that mean? I'm not 100% sure I even know what it means. Do you mean clean out the area behind the valves? And I get everything else, but that's what I'm stuck on.

So my list for them is: clean, port/polish, bigger valves, new seals, bigger springs . I'm assuming I'll just give them the heads and let them source their own parts? I mean, I can buy valves and stuff from summit, and valve stem seals and what not. I honestly don't really know how to pick out my own valves and springs ... I don't know what's good/bad about each choice that's out there.

 

Check out my 305build thread titled

"LO3 Rebuild (HP Estimates)"

91' bird 305 TBI T-5, trick flow 175 cc heads, 4.10 gears, lots of suspension upgrades. 24mpg @ 2500rpm hwy. 8.80@ 84mph 1/8th on street tires... 8.000's soon

 

Because the 305 is a small bore engine the reason you can't put big valves into it is because they will be too close to the cylinder walls. Since you'll be putting bigger valves into the heads, it's not a bad idea to make sure that they aren't going to be too close to the walls to prevent good airflow, which is basically unshrouding/deshrouding. It may or may not be necessary, so just tell the machine shop the heads are going on a 305, and they should be able to tell you.

 

So I've been doing allot of research on heads, and I'm starting to lean towards a set of new vortec heads, such as these:

http://www.summitracing.com/parts/sum-151124
Summit Racing® Vortec Cylinder Heads SUM-151124

And throwing an LT4 cam in:
http://www.summitracing.com/parts/nal-24502586
Chevrolet Performance LT4 Hot Cam Hydraulic Roller Camshafts 24502586

My question is if these new vortec heads need the LT4 valve springs to go with the cam? And my lifters have maybe 5K miles on them, but I'll probably replace them anyways. Thoughts? My TPI is at my buddy's place being cleaned/powercoated right now. I'm just worried that the machine work to these 416 heads is going to cost me about as much as these Vortec heads for "similar" performance. My lower intake manifold is already slotted for the Vortec bolt pattern anyways, I figure why not get new heads, and go from there. All this still falls somewhat inside my "budget". I guess we'll call it "around" a $1K-1.5K 305 build. Just for kicks.

 

I believe the stock Combustion Chamber size is 64cc, so those heads will lower your compression ratio. Machine work will most likely be 500+.

 

If you go with Vortec heads, you will need a different intake ($$). When you say your intake is "slotted", it means the center hole angles have been opened up for standard GM heads of different years, not Vortecs. They have a totally different bolt pattern( 4 bolts per side instead of 6), and the intake ports are much taller than stock. Also, Vortecs do not have the EGR passages built into them, so if you need EGR compatability, then an EGR pipe must be welded into your passenger exhaust. It can also be programmed out of your tune.

 

Well alright then, guess it's these 416's off to the machine shop then. I didn't realize that Vortec heads had a 100% different bolt pattern, I figured they were just setup slightly different.

Alright, I'll see what I want them to do when I get estimates done, depending on how much this is gonna cost for machine work. Considering I probably wont keep this build around forever, I don't want to put a grand into these heads, more like $500-600. That way I can get a camshaft, I really like the LT4 camshaft, and still have some cash for gaskets, fluids, etc. I forgot to mention, I have a TBI computer, I'm assuming I can just swap the chip out with a TPI chip for a base tune, then take it somewhere to get tuned after I get it running.

Think that'll work out? I have a TPI harness, just not the computer.

 

Some reading for you on the L69 heads, and improvements:

https://www.thirdgen.org/forums/tech...-pictures.html
https://www.thirdgen.org/forums/tech...flow-data.html