My friend is thinking of building an AS SCCA camaro and we were chatting over where to find heads. The cars are restricted to 305 iron factory heads(non TPI). Are the LG4s the same as L69s?

Thanks

 

Yes. They are both 416 castings, with 1.84"/1.5" valves. Incidentally those are also the 85-86 305 TPI heads.

 

http://www.darklair.com/monte/l69.html

This site says the LG4 has smaller valves... is it untrue? I know it's a monte carlo site but L69s and LG4s should be the same as F bods.


Thanks

 

There are two 305 heads that can be called the HO head. The first is an early 305 head (casting # 601) that had ultra small chambers (53cc) with 1.84" intake and 1.5 exhaust. These heads may have been found on the early 82-84 camaro with the 305HO motors.

The later 416 head had a larger chamber and commonly found with the 1.84/1.5 valves.

The 601 head can also be found on 82-84 chev trucks that came with the factory electronic spark control (ESC).

I would debate that the 416 head may outflow the 601 head due to the unshrouding of the intake valve. But the added compression of the 601 may offset that. Both points to consider.

Mark.

 

Thanks a lot, good info to think about and/or test on a flowbench.

 

The 601 is not the HO head. It is the crap.

I have a 83 L69, the earliest kind of HO (there were no 82 "HO" motors); it came with 416 castings, 1.84"/1.5 valves. Personally I think that reports of other combinations are created by people who want to pose their 81 305 2-barrel van motor as a "HO".

 

Are you 100% positive that the 601 NEVER came on a F-body engine? I would debate otherwise. In the early 80's the 601 head was quite common. I recall seeing them on F-bodies and Trucks (providing both had ESC). I have had at least 4 sets of 601's in my history. As I don't have an original motor to backup my story ... it is just that a story as is yours.

But back to the original question. If your in a racing class that requires the use of a stock unported head, then both the 601 and 416 offer unique advantages. But it depends if there is any restrictions on compression ratios and pistons.

I've run 601 heads on two 350's. Both times I had the heads machines to unshroud the valves. As the design was power band under 5000 rpm, these heads did well. A 416 offered quite a bit lower compression ratio, and the cost of new pistons was much more than machining the heads. In the end the 601 heads were the better choice.

I never ran either head on a flow bench as it did not seem like a good investment in cash. But visually looking at them, I can't say there was any signifigant advantage in either intake port. Both had the recess under the rocker stud, interferene from the casting for the valve cover bolt, and the bump behind the valve. The bowls were poorly cast. But I suspect the 416 would out flow the 601 purely due to the larger chamber and less interference. But will that flow off set 1 point of compression? All boils down to the package.

Mark.

 

All the 305 heads I've pulled from F-Bodies were 416 castings. The earliest 305 head I pulled was a 82 LU5 which had 416's.