I just aquired a 84 camaro for 150$. Has a good 600cfm holley (why i bought it) and I figure I can get tons of little crap worth having off it.

Anyways what CC are lg4 heads? 58cc? Ive heard people say you can port the crap out of 416 heads. I now have a set and figured It wouldnt hurt to try.

 

https://www.thirdgen.org/techbb2/sho...ht=porting+416

 

I'll let you know. I'm porting a set right now just for that purpose:

 

Yes i have a set on my 350 now.
Search my posts for the hows and whats.....

They are thouroughly ported with 1.94x 1..60 valves.
Chamber volume will be right around 61/62 cc's with the bigger valves.
Mine are shaved to 52cc's. (12.65:1 cr)

Seems to run real well. Haven't had a chance to rug it yet though.

Going to try to get it to the track this weekend for some thrashing.

 

I already searched for the post on how to port. Most people use them on 305s tho. But Im gonna maybe try my luck and stick them on my car.

So they are like 60cc heads? It so thats good because my compression wouldnt be that bad then.

I have 9.6:1 right now with 64cc heads.

BTW the car hasnt even been cranked in 2 years and the guy said it wouldnt start. We stuck a battery in it and it ran. The guy was like WTF. LOL its still a real piece.

 

Have a look at a set of modern heads with a fastburn chamber.
( vortecs, Protopline etc). You'll see exactly where the chamber needs to be layed back to unshroud the larger valve.

The 305 heads can't be layed back near as much to make them
exactly like this but the areas to work are the same.
Spray a garden hose into the intake port and observe the water as it leaves the port, to see the high flow area pattern.

 

They are supposed to be 58cc, but I checked these at just a tad over 56CC. Even at 58cc, your compression will probably be higher than you expect. You can install 1.94 intakes pretty easily, and 2.02 if you open the side of the chamber even more (which would probably help offset some of that compresion gain).

 

With a thick head gasket could I get the compression at a reasonable level?

 

You can calculate the cr yourself here:

Compression ratio Calc

 

I dont know the specs of the pistons or anything.

 

Well that's going to make a difference. You could go with a FelPro 1044 (compressed to 0.051") to drop the CR a bit, but you'll really need to know the other data as well.

BTW - I bumped the runners from a measured 161/56cc to 174/63cc and still have polishing to do. Chambers are 59cc with the valves unshrouded but not yet lapped. I've only got about 10 hours in the heads, between spring pockets, stud boss cutting, tapping, cleaning, bowl porting, and blending. These castings must have a little more nickel and/or less tin in them, since the carbide burrs seem to work just a little harder on them. I had a ****** of a time tapping the stud holes, too, with a new TiN coated tap. (Yes, Martha. I DID realize the stud holes weren't quite 0.375...) I should be ready to try twisting one of those goofy half-axles by later next week.

 

you don't want to go very thick on the headgasket though - opening up the piston/head clearance that far is going to ruin your quench distance, and everything I've read says the reduced quench will leave you more prone to detonation than with the slightly higher CR and good quench.

Just spend a bit more time polishing the chambers - add a few cc's there...

 

Im having second thoughts about doing the porting now. May just part the car and save for some vortecs or world sportsman IIs.

I think Im gonna save for a t56 first tho

 

There's not much of a quench area with dished pistons anyway. Until you get the rest of the engine data, you don't really know what you're dealing with.

 

wouldn't that mean you'd want to maximize what quench you have?

Besides, just pulled the heads off my '86 LG4, and they're 4VR flattops. Bore mics at stock, so I'm pretty sure it's not been rebuilt, and the advertised CR works out right with the flattop pistons.

Anyways, as for ported 416's on a 350, I might be able to report in a few months...
It turns out the LG4 has been running for the last 6 mos in 7 cylinders. In the carnage of destroying the one rod/piston, the #7 cylinder got two nice cracks up the side (pretty sure the crank counterweight snapped the rod against the bottom of the bore)
So, that engine isn't getting the quick and cheap rebuild I had planned, and I'll probably put a 350 in (it would have eventually gone in anyways, but needs more $$$), and use the 416's instead of the large-chamber 882's that 350 came with...
It'll be a fun summer!

 

Eyes,

Yes, a tighter quench area should help control chamber flame front travel and detonation. He originally mentioned using th e'416 castings on a 350. With flat tops, that would create a pretty high compression. In my case, they're going on the lowly '81 L81 Corvette to raise the pathetic 8.21:1 static to around 9.38:1. They used dished pistons and 76cc chambers - what were they thinking? In your case, the flat tops should provide a good basis for a quench zone in the chamber, so you would want to use a tighter gasket to maintain that.

I only suggested the .051" gasket to control compression if he couldn't open the chambers through porting. With dished pistons, there is little chance of creating any kind of effective quench area.

 

O.K. After polishing, I'm at 177cc on the intake side (yes, I remembered to screw in a rocker stud this time), 64cc on the exhaust, and back up to 58cc in the chambers. I'll update their performance on a 350 in the next week or so.

 

Let me know. If it does well I may try it. I wish they were 64cc or so tho. Im afraid to run 10:1+ compression on 93 octane.

 

wow, how much work did it take to get them out to 177cc?
That's slightly larger than vortechs, so at least the runner size is dead on for a street 350...

As for compression, most aftermarket dished pistons come with a 'D'-dish, not the stock 'bathtubs'. A 12-18cc dish would put things in the right range. Or, just lay back the chamber wall a bit more for a few more cc's.

 

I matched the ports to these templates:

 

Eyes,

If you are building these specifically for a 350 and never plan to use them again on a 305, I'd the cut chambers open around both valves to minimize shrouding and open up for 2.02/1.60 valves. Your port volumes will get even larger that way. I don't know what the final chamber volume would be, but you could control that with the radius of the cut. Use an adustable boring bar, flycutter, or if you're lucky enough to have a shell mill of the correct radius, go nuts with a plunge cut.

I didn't get that carried away, and only went with 1.94 intakes, 1.50 exhausts. I'm only temporarily using these heads on a friend's old 'Vette while we build his roller case. It's a learning experience for him, so it may take some time. He's following my frequently advised scheme of building a separate engien while the car is still driven, budgeting time and cash as necessary. It also allows a lot more though and detail for each facet.

The heads will probably eventually go on my '86 305, so the chambers have to remain smaller at the deck. I've unshrouded the intake valves as much as I dare, and have a meager 0.120 clearance at the perimeter of the seat, and that tapers back to about 0.075" at the deck. I'll let you know how that works out.

 

on these 416's with 2.02/1.60...with only deshrouding..they were at 64cc..

 

O.K. It took a little longer than I had planned (we always run into those little nuisance issues that need more attention, don't we?). After repairing A.I.R. tubes on the factory SS exhausts, replacing seized studs on the intake, air duct repair, and rewiring some of the melted harnesses, yada, yada, it's back together and running. The cam is run in, and the lash has been reset hot and running after break in. It still needs a little "Quadrajet Magic" secondary tuning and shift point adjustment, but the cheap heads and cam added plenty of "pop" to the previously lame little 'Y' car. A few test drives around the farm after fluid changes provided more kick in the pants than before. Even with the secondaries not opening as they should, and the timing at stock base on 89 octane, there was no disputing the increase in torque at higher RPM, and no noticable loss of torque at lower RPM. For less than $300, the gains were well worth it.

 

Terrific Jeff!

I just KNEW you were gonna love these little 305 heads

 

I liked my 416's, even with minor porting on the one set provided a great increase in power and that was with the stock valves! I dunno the largest valves we ever used were 1.94, my machinest said he tried 2.02's in a couple sets before and ran into heat cracks later on down the road. The set my dad worked over for me are alot better then these POS Dart heads!!