I am looking for a good pair of heads for my 1986 305 TPI with stock 58cc heads. I am interested in world castings, and am wondering what kind of increase in power u can get from the torquer 305's, or should i step up to the regular torquers with the 67cc's. If the cc's are higher, how can I raise the compression? I heard u could mill the head, but i dont even know waht that is. Im new and need lots of help!!

I have a 212/218 comp cam in the works, as well as headers and hi-flowing intake. If this helps at all.

 

86iroc, If you put the 64cc heads on, you may only loose a half of a point of compression. There are methods to calculate this?? .5 is nothing. As far as the world products heads, they are just a little better than stock...not much. As i said before, go with the trickflow 23deg heads. they cost about 1100. Or for a little more you can get the AFR heads for aprox 1300. I have a line on these heads and can send you in the right direction to get a good price on them. Also, if you do get the AFR heads, they can mill the heads to any size cc chamber you want. And stay away from the G2 twisted wedge heads! If you decide to get the trickflows, you want the 23 deg heads.

 

if you're getting heads, I'd say definetly go with the AFRs, they are overwhelmingly the best. To mill a head is simply to cut a layer off(or several layers) of where the block and the head meet. This makes the compbustion chambers smaller. Another way to get the compression up using the 64 cc heads is to pu in higher compression, domed pistons. While you've got the motor apart you might want to think about a rebuild. This would help out with power and you woulnd't have to worry about old parts failing. While you've got the block apart, put in a new cam, try a copm extreme energy 252 or 258, then the car will fly!

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'86 IROC 5-speed
305 LG4
edelbrock performer rpm intake
edelbrock 600 cfm carb
msd pro billet hei distributer
'95 3.23 rearend
hotchkis rear suspension
PST front polygraphite suspension
"speed kills. buy a f@&d, live forever."

 

I would advise against domed pistons as they interfere with flame front travel and aren't really worth the effort.

My suggestion is, if you're keeping the 305 and don't want to spend obscene amounts of money on heads, to get a set of L98 aluminum heads. They're 58cc like your cast iron and flow a whole lot better. They also clean up to flow significantly better with minimal work.

Used can be found from $400 per pair and new are only around $900 per pair.

 

What kind of power gains would you get from a L98 Aluminum head set. Are they really good for the 305? Would you get more power from the L98 over say the world heads.

 

Here we go again

1. aluminum dissipates heat quicker than cast-iron, which means it will draw heat away from the combustion space. For a given compression ratio, the aluminum heads will be less efficient than their cast-iron counterparts.
2. Heads designed for a 4.00" bore are not the best choice for a 305(3.736" bore).
a. even with 1.94/1.5" valve combo's you may need to notch the bores on a 305 for the valves to clear. With 2.02/1.6" valves(standard on the TFS and AFR heads) you can count on it, so you will need to remove the valve seats and replace them with smaller ones.
b. once you get the 1.94/1.5" valves installed, you will still have shrouding problems(the valves will open too close to the cylinder walls), which will compronmise the flow at all lift points. The AFR's and TFS's are designed for a 4.00" or larger bore, not a smaller one.
3. The TFS and AFR heads have 64cc chambers, the chamber on stock 305 heads is 58cc. Expect to lose at least a full-point of compression, unless you mill the aluminum heads. Once you mill the heads you may need to have deeper reliefs cut into the pistons to avoid interference(which ironically will lower compression), custom length pushrods(which may require enlarging the pushrod guides) and have the intake milled to match the heads.
4. Once you have milled the heads, notched the bores, had new seats and valves installed, cut the piston reliefs, etc., etc., your wallet will likely be $500-600 lighter, and you will have an expensive set of heads with compromised flow.

or you could just buy an assembled set of 305 Torquers, which:
1. have the valve centerlines relocated towards the center of the bore to alleviate valve shrouding with the 'big' 1.94/1.5 valve combo,
2. have the same chamber size(58cc) as the stock 305 heads, which means you don't need to boost compression for lost efficiency(the 305 Torquers are cast from cast-iron)
3. can be bought with either pre-'87 or '87-later types of intake faces and valve covers bosses
4. can be bought assembled, which makes them a near 'bolt-on'(no extra machining required)
5. cost $700 or less(do some shopping) for an assembled pair

[This message has been edited by 88IROCs (edited November 09, 2001).]