I'm fixing to put a GM remanufactured 350 with 15,000 miles on it, in my TA. Should I rebuild my lg4 305 heads and put them on the 350? Will it be worth it?

 

I'd think that they wouldnt be as big as those for a 350 (as in not allowing as much flow...size is the same, i'm not stupid haha), but i guess it would maybe be OK....i'm no expert but i'm just thinking smaller displacement=less flow needed....

 

Actually, the 305 heads have a smaller combustion chanber than the 350 heads. This means more compression which means more power. Of course, the smaller valves can offset this. If you work your magic on the 305 heads, you can make them perform well for a stock casting without spending a lot of money.

 

So, if I put bigger valves in the 305 heads, they would be the best? And give me a lot of power?

 

Buy an $80 die grinder and some carbide cutters then do a search on sitting bull.

BTW you will be porting the $h|t out of your 305 heads... And much power can be had in that manner...

 

The LG4 heads aren't bad. There's better, but it's a matter of what you're willing to spend vs. what you're willing to live with.

If this GM 350 of yours has dished pistons, then the 305 heads are a good start. The only valves that need to be larger are the intake, and 1.94" is fine there (they're 1.84" now). You should plan on replacing the valve springs, since the stock parts aren't very good, and being 18 years old doesn't help. Have a machine shop look them over before you do anything to them to ensure they don't have cracks, and also to find out if they need guides replaced, etc. While you're at it, the stock rocker studs are pressed in, which have a bad habit of pulling out. Have them pinned or replaced with screw-in type. Talk to the shop about what they'd charge to do that work and the intake seat enlargement, and the final valve job and assembly when you're done porting.

Check out this site for what it takes to port heads: http://www.sa-motorsports.com/diyport.htm . It's pretty much what Sitting Bull has on his site. Those directions also come in the Standard Abrasives Deluxe Porting Kit.

Personally, I chose to avoid all the machine shop costs and went with the World Products S/R Torquer 305 heads. I did the porting myself, but they already had the larger valves, good springs, screw-in studs, and are argueably better overall castings than the factory 305 heads. I'm on the lookout for a 350 shortblock to slide in under them.

 

Not all 350's have smaller chambers. L98's had 58 cc just like the 305's came with. LT1's have 54cc chambers. However, they are matched with the right pistons to keep the compression down.

 

I am going to assume he ment to say bigger. And L98 heads have 64cc chambers. The corvette alum. L98 heads had the 58cc chambers, regular iron L98 heads are a standard 350 preformance head.

 

Yea I meant bigger. But most "crate" or buildup 350's use 64cc heads.

 

where can I find the World Products S/R Torquer 305 Heads?

 

Jegs and summit both sell them. Just click around on their sites or type in S/R Torquer heads and they should come up.

www.jegs.com
www.summitracing.com

 

I picked mine up from Competition Products, unassembled. Best price I found at the time (and still was last time I looked).

 

If you are going to buy new heads just get heads designed for a 350.

here's why -

S/R torquer head (pair) assembled - $740(jegs)
Protopline lighting (pair) assembled - $799(flatlanderracing)

The Pro Topline heads will make way more power than even ported S/R torquer (BTW S/R stands for stock replacement - ie for racing classes that require a stock head).

And if you were going to flow the above advice and port the S/R torquers add another $120 for grinding stones/cutters and a die grinder.

Personally the only reason I could see buying S/R torquers is for their intended porpouse - on a 305. Now If I had the heads on a 305 and scored a 350 I wouldn't hessitate to put them on but buying 'em for a 350 seems pointless to me.