i cant find any information on this, or im just looking in all the wrong places. can anyone clear this up. is there any noticeable difference between small valve and large valve E heads?
thanks

 

Are you asking if there's any way to identify which size valves without pulling the heads off the engine? If so, then the answer is no. They're the same castings, the factory just cut out the valve seat for whichever sized valves the application called for. John

 

The difference is valve size and small valve heads can be adapted to take the larger intake valves.

 

is there any noticeable performance difference?

 

That depends on how you drive it. I've always like the idea of larger intake valves, but I can't say that I feel a difference on a daily driver. We'll see what other members experiences are. John

 

First, keep in mind that only the intake valve is larger (2.070" vs 2.000"). The exhaust valves were the same in both. The larger valve diameter gives you a larger valve curtain area, which is the cylindrical space between the valve head and the seat that is one of the bottlenecks in port flow. The larger intake results in a 4% increase in curtain area for comparable valve lift. Of course, the advantage of a larger valve (and thus more curtain area) is increased flow for a given cam lobe profile, but naturally the curtain area is only one element in total port flow.

 

If they were still on the motor, between the casting number and the VPN derivative, could you determine what they are. I would guess a 2bbl car would ,more than likely have the smaller valves, where a 4bbl mighthe have the larger ones.

Although, that would assume Toro's all had 4bbls. And that's not the case.

 

Well that's a new concept.

 

ALL big block factory 2bbl engines came with small valve heads. In 72 Ga Heads had small valves on the low-compression 4 bbl 455 engines too! Not sure if any E head 455 4 bbl motors had small valves? Joe P ??

 

4 speed & L-77 cars regardless of trans came with big valve Ga heads. All others came with 2.00" valves including the Toro. Up to & including 1971 Toro engines always had big valve heads.

 

In 1970, only Toros and 442s got big valves. All other E heads got small valves. Of course, we're talking 2.000/1.625 vs. 2.070/1.625, so the difference isn't dramatic, and it's only the intake that is different.

 

haha. smart as*. Sorry, I was sitting waiting for an appointment, and I was using a tablet. Didn't check myself.

 

I figured it was an auto-incorrect but you never really know, a "medical condition" is appropriate when folks are talking about performance and 2 bbl carbs at the same time. Unless there's more than one 2bbl carb, that is.

 

Haha. that's very true!