A mechanic suggested me using this setup for a rebuild on my 84 Z28 with LG4 with 5 speed.
-bore .030 over
-mild cam
-a set of 283 heads
-performer intake
-Headers w/o Cats

He said the heads are very similar (in performance) as the new vortex heads and will only cost me $50. What kind of performance do you think I can get from this setup? Is it worth rebuilding the 305? I would like to be a little different than everyone else with my car. Thanks for the tips.

Jay.

 

Those heads will be in no way similar in performance to Vortec heads. They will have larger combustion chambers (lower compression) and less flow. I would not pay to have my motor downgraded like that. They also won't have accessory bolt holes. That's not a really big deal though, as long as you don't mind having no alternator, power steering, or A/C.

Your existing 416 casting heads will be fine, with some mild port work. That would consist of cleaning up the "bowl" area right under the valves, and smoothing the "short side" radius as much as possible, and like cleanup and polishing on the exhaust side, and removing any fetures from the combustion chambers that are even remotely like sharp edges.

My recommendation would be to use flat-top pistons like the L69 had, NOT the stock LG4 replacement ones which would be dished. I'd suggest a Comp XE256 or XE262 cam, the 262 would probably be better since you have a stick shift car. Get new valve springs and rocker arms with it, the Comp 1412s would be fine and will fit under your valve covers with no modification whatsoever. Get rid of the stamped sheet metal ones for sure.

Get some kind of application-specific headers such as SLP, Edelbrock TES, Hedman, or Dynomax; but DO NOT get the ones for LG4. Instead, get the ones for something like a 88 or 89 350 TPI with single cat, and a 3" exhaust.

Don't waste money on the intake manifold, it will do basically nothing for your car's performance.

"Different" for the sake of being different is a very bad idea. Most of the time that means "loser". Understand what your car (not just the engine) needs to make it faster, and work in that direction, regardless of whether it's different or not.

 

i pretty much agree, he covered all of the generals. 283 heads wouldn't have a chance competing against vortec (not vortex) heads.

 

Early heads had soft valve seats, not made for unleaded gas. I kinda doubt the seats have been replaced if you're getting 'em for $50. Depending on the casting numbers, some 283 heads were the "power pack" heads with 62cc chambers, they flowed well for their time but not nearly as well as the vortec heads.
Depends on what kind of money you want to spend...and how fast you wanna go. you can rebuild the 305, go the vortec top end route, add a cam and have 250 HP at the crank and spend under $2K.
OR just get a crate 350 like this..
http://www.sdpc2000.com/cart.asp?act...id=128&pid=110

 

Thanks a lot guys for the info and help. I like the sound of the 350 with headers and 3" exhaust. I am not looking for huge HP or fastest car in town, but just something thats reliable and fun to drive. Thanks again.

Jay

 

If you think that you have the means (mental and tool wise) they have a guide to do all of that stuff in this month's issue of Car Craft. Just joking! I am sure even you could do it. No really, it isnt that hard!!!

 

Green is exactly right, that's why I mentioned the head porting. For $19.95 you can get a die grinder at Home Depot, and $30 something gets you a Standard Abrasives kit with all the stuff to port a couple of sets of heads, complete with an excellent instruction book. Rent a small air compressor. For less than $100 you can add an easy 20 HP to your car.

$10/HP is a generally accepted benchmark for decent value in a street buildup. If you can get HP for $5 apiece, that's a sweet deal.

You can disassemble the heads yourself, just put them on a piece of plywood or something like that and whap the retainers with a hammer and a ¾" socket or something like that. The retainers and keepers will fly off so be ready to find them and throw them all in the trash, you'll be replacing them anyway. Then get them cleaned up, get them back and port them carefully per the instructions in the SA kit, and then send them back to the shop for a valve job and all that.

 

The SA Deluxe Porting Kit is around $40 now. The instructions are excellent, and even use 305 heads in their pictures. The most I had ever done on heads before was intake gasket matching, and I got through this without any major hassles. You'll probably need more than a "small" air compressor, though, as die grinders like air flow. I didn't gasket match the intake manifold ports, but if you don't get an aftermarket intake, you should do that to the stock manifold.

I would not recommend spending any machine shop money on a 305 shortblock. If your lower end needs anything that involves machining, spend that money on a 350. You shouldn't use your 305 heads on a 350, though.

I can vouch for the Crane Powermax computer cam (never tried Comp). Nice idle, pulls well past 6 grand, no SES light yet.

In order for any modifications to have the desired effect, you must do something about the restrictive exhaust and air cleaner. Headers are a good start, but you must address the cat back as well. No cat isn't an option if you have emissions, but free flow cats are plentiful and relatively inexpensive. A dual snorkel air cleaner is the way to go for a driver.

I ended up with something that's fun to drive, different, and wasn't too expensive to accomplish. If the aforementioned machine shop work had been indicated, it would have raised the $/HP so that the 305 would not have been the right choice.

 

I would think this would also be a good time to rebuild the engine. At Summit or northern auto parts you can get a re-ring kit and flat top pistons cheap.No sense in trying to build what is probably a high mileage engine[84].

 

I did my mods with 143,600 on the engine. It's doing just fine.

I'll repeat, spending machining money on a 305 is not a good cost/benefits ratio move. Forget the 305 rebuild, get a 350 shortblock to work over.

If the 305 shortblock is okay, bolt stuff on it for more go-fast for the most improvement per dollar. For absolute most performance, go with 350 or more.

Don't spend money inside a 305 shortblock.

 

My z28 has 135,000 miles and smokes really bad after it sits for awhile. I don't have emissions and already removed the cat. Would an open air cleaner work or do I need the snorkel? I know a dual snorkel is better though. I got my sights set on the goodwrench 350 right now. Just waiting for the oil burning out cost a new motor. I have two kids so my toys are always third.

 

Oil will always be cheaper than a new engine.

The snorkel does help driveability a little bit, and if you use the scoops, will provide cooler air to the engine during hot weather than the open element. That's assuming you're talking about a dual snorkel cleaner, not single (a single will help the driveability, but really hurt power).

I have three kids, one in college, so toys are about 5th...

 

F'Bird-88 would have a severe disagreement with you there!!!

He claims his port and polish job on 305 heads, along with 1.94 intake valves, are almost as good as Vortec L31s.

I don't see any reason they wouldn't be, other than the combustion chambers. He has CC'd the intake runners as being 167 cc stock, not the 153 cc GM rates them at. With a little porting they ought to hit 180 cc easily. Vortecs are only 170 cc out of the box.

In any event, Apeiron has given me a set of clean bare 305 "601" castings that I'm gonna do the home porting job on, and then put on the 86 this summer. Looking forward to the experience

RB83L69,

Did you actually say that Home Depot sells 1/4 inch die grinders for 19.95? I just checked the electric ones and they are around $200 Canadian

 

With the small 305 chambers, you'll either have to use dished pistons on a 350, or really open up the chambers (not sure exactly how much you can do that). If you don't already have worked-over heads, then start with heads made for the 4" bore.

I've wondered about putting my heads on an L98 or L31 shortblock with thick gaskets, which would yield compression something over 10:1. I'm sure it'd run better than the 305 does now, but it would run even better with 67cc Sportsman IIs on a 350 with flat tops.

That's all I'm saying.

 

Yes, that is correct. $19.95 US, should be only .... oh, maybe $150 Canadian . It's air though, not electric. It is a cheapie consumer-grade thing, a 1/4" chuck Campbell-Hausfeld unit, but it seems to work fine at the level I'm using it at. At least, the one I got managed to get all the way through one complete set of heads, plus some other misc little jobs.

 

I would think that thicker head gaskets on a 350, with the 305 heads, would work out OK. Just as long as you know what compression ratio you are going to come out with. The intake/exhaust flow and 1.94 intake valve ought to be plenty for more than 400 hp on any smallblock. F-Bird says he has guys running his 305 heads on 400s and they are quite happy. So for the cost and labour involved, how do you beat that?

 

Grrr ... don't get me started on our monopoly money

That would work out to about $30 Canadian for the grinder. So if I can round up a compressor, or rent one for a weekend, I'll be sitting pretty