I am going to start a 305 to 350 swap over the next year for my 85 Z28 w/ LG4. I've been researching finding the right parts, and I am going to start with the Goodwrench 350 Shortblock and bolt on parts (similar to the 1999 Chevy Hi Performance build).

I
want to use my Q-Jet (with better hangers, jets, etc.), Edelbrock Performer 3701, headers (with the AIR tubes), a full header-back exhaust, and one of the Comp Cams Xtreme Energy grinds.



I want this engine to completely bolt into my engine bay. Including AC, and Functional EGR and A.I.R. components.





As for heads, I was considering the aluminum 113 heads from the L98 Vettes, until I learned that they have no heat crossover passages for the EGR.
I do not want to go the Vortec route because of the intake and again, no heat crossover.




I want to go aluminum, and I was looking at these heads from Summit. http://store.summitracing.com/partde...5&autoview=sku
They're summit brand parts, will their quality be top-notch?
The site claims that this set of heads has the EGR Heat Crossover.



Will these heads allow my motor to make decent power?
What size intake runner and combustion chamber should I be looking for to build a street 350?



Also, I was looking into Trick Flow's Super 23 aluminum heads with 62cc chambers, and 195cc intake runners. http://store.summitracing.com/egnsea...=KeywordSearch
I was reading some posts that the larger runners will destroy the motors low and midrange torque. Is this true?

Which heads are best for my application, if any of these? If not, what do you all recommend?

 

It depends.

I didn't see you give specifications of your application.
I see it's going to be a smallblock in a camaro, but that's about it.

 

Since you are limiting yourself with the intake manifold, yes, larger ports are going to hurt you.

The Summit heads would be okay, but with the dished pistons of the Goodwrench, effective compression will be low. 58cc iron heads would be about right, and 62cc & aluminum both take you in the wrong direction (although still better than the 76cc heads that came with the engine).

I hope you aren't considering using the Goodwrench cam. But, the heads can only handle .480" lift (probably limited by the springs), so you'll have to take that into account when choosing a cam.

 

I want to use a COMP Cams Xtreme Energy cam. Not sure which one yet.

Am I correct with the absence of EGR Crossovers on the 113 and Vortec heads?
Would the 113 heads be a good choice for my 350?

With the summit heads, could I use a thin head gasket to raise compression and beehive springs with 1.6:1 rocker arms to increase the lift?

Is there a better manifold choice that I could go with to use EGR?

I would like to stick with aluminum heads to save the weight, but if cast iron weighs in to be the best option (no pun), do you have any suggestions for my head choice?


Finally, I saw these heads for a 305 on the TrickFlow site. Would they work?
http://www.trickflow.com/partdetail....5&autoview=sku

 

Start with a short block that has hi perf flat top pistons.
You're backing yourself into a corner of limitied head choices by starting with a low perf junk dished engine base. Start with a quality built remanufactured 350 with good Hyper flat top pistons. Summit and Jegs both sell these, among many other sources.
http://www.blueprintengines.com/
http://store.summitracing.com/partde...5&autoview=sku
A good base for a nice 350.

 

CHP Magazine build a goodwrench 350 in 1999. I want to buy a new shortblock, and I liked the build that they did. Is there a GM shortblock with flattops ?

I really want to gather more info on the above cylinder heads

 

Yes the GM 350 ZZ4 short has flat top pistons.
many of the Popular "ready to run" crate motors like what Edelbrock sells are based on the GM ZZ4 350 short block assembly. It has a high quality forged crankshaft.
A good base to start with.

 

Would the trickflow 305 heads work?
56cc chambers. 1.94/ 1.5 valves. aluminum 175 cc intake runners

 

I don't see why they wouldn't, but why are you looking at 305 heads if you're building a 350?

I don't think you ever gave specifics about your application. The more specifics you give the more accurate your answers here will be.

 

My specs are on top. GM Goodwrench shortblock, COMP 274-H xtreme energy hyd-flat tap camshaft. Edelbrock performer EGR intake (3701), Hooker 2055's into some 3 inch catback.
I'm just looking for the right set of heads for a street 350 with AIR and EGR hooked up. I want a fun little street car/daily driver to play with.

I noticed that the numbers on the 305 Trickflow heads are similar to and better than the GM 113;s. The Super 23's have a 175cc intake runner [compared to the 113's 163cc] and the super 23's have 56cc Chambers {compared to the 113's 58cc} and both heads have the 1.94/1.5 valves.

 

The 113 Corvette heads do not have the crossover, but had the EGR plumbed externally, similar to what the LT1 has. Why not just use the externally-plumbed EGR setup that the TPI Corvettes used? Then you could use the 113 heads and have a functional EGR system. I don't see why that system wouldn't work on a carb manifold as well...?

 

Help me to understand. You indicated you want to keep all bolt on stuff and functional egr. This says to me that you want to meet emissions. Then you said you want xe-274. That says to me maybe emissions are not a requirement. What is the goal with this engine?

If emissions matter, then you most likely need a smaller cam. Comp does have some that are ok for emissions. Call them or one of their competitors and they will give you a recommendation.

Not sure if you would be interested. But if you are wanting to retain egr & qjet, there is an intake manifold that allow this to be done with the vortec style heads even w/o a head crossover passage. GM Performance Parts # 12496820. It uses an external egr pipe from the header to the intake manifold. Just FYI.

I think you would also want to use this adapter kit from edelbrock to get the exhaust out of the header. Just more FYI

http://www.edelbrock.com/automotive_.../2000/2899.pdf

I plan to take the external egr route on my camaro. But I am not there just yet.

Also not picking on ya, but the combination of the inexpensive shortblock but using aluminum heads doesn't make sense to me. Aluminum is nice but it is the expensive way to go with heads. We are only talking 50 lbs weight saving with the aluminum, and if price is an object you could go iron.

I also believe the xe-274 cam has more lift than either the summit aluminum or iron vortec heads can handle out of the box.

 

Sorry, I didn't really consider a 350 with headers to be an application.
I was talking more about transmission, gearing, compression ratio, fuel type, and desired RPM range.

If you're running an automatic with your carburetor and need great streetability then I'd say to choose a head with 180cc intake port volume or less. You can't go wrong with these:
http://www.airflowresearch.com/180sbc_sh.php
You'll want the small combustion chamber version.

I'd also suggest going with a cam with much shorter intake duration.
I think the Comp XE262H with 1.65:1 rockers would be a good match assuming you're running an automatic trans.

 

The b body tbi replacement engine has flat top hypers.I used it,put on the new zz4 heads,and swapped the cam out.It also has PM connecting rods.In Hindsight I would have gone with a larger cam and maybe different heads.But the new casting zz4 heads are better than the production 113`s.If I knew then what I knew now I would have atleast bought a zz4 crate and spent almost the same amount but I did mine over a couple years as I had the money,without benift of this website.

I`m sure we`ll get a visit from kevin91z28 or something but your desire to stay emmisions compliant is admirable,Just curious if you have smog checks where you live.If its a daily driver I understand your desire to keep the smog equipment,but as little as I drive my car I decided not too use it.(less components too worry with and no smog checks in a 5 state area)Many people have used those headsm with the externaly plumbed EGR.There ar several threads about it in the archives.

There are better heads and shortblocks to use than i did prolly almost as cheap,close in price or not much more.I just wanted to stay close to third gen availabilty/style and it will support my goals.

 

One thing I thought of after reading this... you want a larger cam and EGR... but the larger cam may make the EGR system basically useless. Not in that it won't function, but that it would be almost pointless to have on there.

I'm suggesting this, because having an LT1 in my '97 I'm starting to build up a little bit and doing some research on, GM ditched the EGR system entirely on the LT4 engines because of the cam. It had enough overlap that the cam itself created its own EGR effect, so there was no reason for them to have the EGR system on there as well.

Just a thought though. Admirable that you are trying to stay emissions compliant, whether or not you actually need to pass a test. I am trying to do the same with my LT1, even though I don't have to pass any sniffer tests, or even a visual.

 

 

If the cam you choose has more than about 45* of overlap, I'd consider leaving off the EGR system... with that much or more overlap, the cam itself acts as an EGR system. Thats why many LT1 guys that 'cam up' their engines disable the EGR in the ECM and remove the components, and will still pass a sniffer test just fine (assuming the cam isn't TOO radical of course).

The main difference between the LT4 cam and the same year LT1 cam was not that the LT4 cam was bigger (it was about the same size for duration and only a little more lift) but the LSA was shortened from 117* in the LT1 down to 112* in the LT4. The result was the extra 5-6* of overlap that made it possible to ditch the EGR system. Its also what gave the LT4 its signature aggressive idle.

Same goes for the LS1 crowd... the '00-02 LS1 in the Corvette and F-body didn't have an EGR system because of the cam grind... it acted as its own EGR system.

From what I've been learning about the LTx and LSx builds, its pretty safe to disable the EGR system when you install a cam with 45* or more of overlap, because it becomes its own EGR system. If its still a reasonably sized cam, it will likely still pass an emissions test without the EGR system, for the same reason the LT4 and '00-02 LS1 could without the EGR system.

 

That is actually pretty cool. Unfortunately, I have emissions requirements in New York.

305sbc, I want to use a t-5 or a t-56 trans. I already have a t-5. I'm not sure of my rear gear ratio (its in my stock 1985 z). Operating Range: idle-6000 RPM. I want to use 92 octane pump gas. The car is just a street car. No serious racing, just messing around on the highways.

So, could I move up to an edelbrock RPM Air-Gap manifold, use a bigger xtreme energy, and loose the EGR? Would I have to change my computer to operate without the EGR?

Also, how does the AIR system work?

 

The AIR system just feeds fresh air to the cat converters so that they warm up more quickly. Thats basically all its for.

If you have to pass emissions, then if the EGR was there before, it will have to be there during the test/inspection. I don't know whether or not they actually check the functioning of it though, but it does have to be present and 'hooked up' at the very least to pass a visual.

The RPM air gap manifold will not work with a factory Qjet (which I assume you'll be using if its gotta be smog legal), its a square bore manifold for a Holley or Carter 4bbl. It also has no heat crossover or EGR provisions.

What I would suggest, if you just want a fun street car... on your 305, use the Corvette 113 heads or 416/601/081 iron heads (I prefer the 601 myself, smaller chambers and a better chamber design, great for a hi-compression 305), the L69/LG4 aluminum intake, factory Qjet and distributor, with a set of smog legal headers and a Comp XE256 or XE262 camshaft, a high flow 3" cat and a 3" catback exhaust of some sort. Would ake plenty of power, sound nice, and is probaby tame enough to pass emissions with proper tuning. Hook up the EGR system and make it functional if you can. Why not, if you already have the parts, right?

The CCQjet computer is a fairly 'stupid' computer, and will not need any adjustment of its parameters with only a mild cam change like going to an XE256 or XE262. An L69 ECM would be ideal if you can find one though, as it has a more aggressive tune from the factory than the LG4 ECM did.

 

I really would like to go with a 350, I've driven a few L98 Camaro's, and they've got some guts! I'm sorry, I meant the Performer Air Gap.

 

So build a 350, its still legal, as these cars did come with a 350 at one point. If the Perf Air Gap has EGR, it should be legal, but I doubt it does.

 

Back to my head selection question, which set of heads should I use?

 

I'd suggest either the 113 Corvette heads or the 601 305 heads with larger valves installed (1.94/1.50... 1.60 for a 350). The 601 heads are a very good factory casting that breathes fairly well stock (as good or better than stock 113 heads) and has a pretty good chamber design. They also have an exhaust crosover, making the EGR system much easier for you to deal with. They came in all kinds of early-mid 80s vans and trucks with 305s, so they arent hard to find.

I had a set on my 350 with a bunch of nice mods done and they made lots of power... never ported ether. Just bigger valves, shaved down valve guides for more lift, and machined for screw-in studs and guideplates. Fantastic heads, but I changed up to a 200cc World head after those.

 

You've got about four suggestions so far. Are you having someone build your heads or are you looking for something to just bolt on?

The TFS head you asked about seems to meet your requirement for EGR and lift capacity of the springs with the Comp XE274H cam you specified without any extra work on a 350 engine.


What else are you looking for exactly?

 

There is an RPM q-jet version available. No EGR, no Air Gap style available.

If you don't have visual inspection, you can use that intake and probably pass the sniffer. The ZZ4 cam has enough overlap that the factory conversion kit dropped the EGR in the later versions. But, they still used the ZZ4 intake, which is basically a Performer EGR. And, the ZZ4 used 113 heads.

To keep the package emissions-passable and keep its proper manners, you'll want to design around the cam. I'm not sure an XE274 would make muster. Maybe, but an XE268 would be more likely.

 

I agree. I have the XE274 in my 350, and while its a great cam, I wouldn't recommend it for anything that has to pass emissions unless its a big small block, like a 303 or 406 or something. It just runs too dirty at low speeds to make it a reasonable expectation for it to pass in a smaller engine like a 350. The XE268 is a much better choice there IMO.

What I`d recommend is to find a later model 350 with the roller cam provisions, and use the LT4 hotcam. Its capable of lots of power, sounds really nice, but its still very possible to pass emissions with it fairly easily. The LT1 guys do it all the time. Would take a little more fine tuning to do with a Gen 1 350 with a carb, but it shouldn`t be too hard to get it to pass.

 

So, what happened with this?

For the most part, I'm with the rest of the people here, that a bunch of your choices contradict each other. If you're just worried about a visual inspection I don't see why you're that worried about EGR provisions... just mount the EGR and I'm sure that you'll have enough overlap to get some real EGR function. Since few of us have to deal with NY emissions, we don't really know what you have to do to pass. I know that here in MD they used to do a visual inspection that literally went "open the hood, check the emissions lable, can you find all the emissions devices listed?" My brother had a car that he would literally set the EGR and the EGR adaptor on the intake as he pulled in, and throw it in the trunk.

As far as passing a test... what test do you have to pass? idle or IM240?

Remember, it's easier to adjust midrange in an injected car, so the cam that one person got away with on an injected car may not work with the carb, unless you're an absolute carb tuning wizard. There are also a number of ways to get around tuning/emissions problems if you're willing to play games with it.