Re: Whats involved in installing larger valves?
 

Im pretty sure the 781's and 049's have 260-265 intake runners. Could be wrong. What size valves do you have in there now. Stock they were 1.72 and 2.09. Usual upgrade in 1.88 and 2.19. Ive gone all the way to 1.88 and 2.25 and yes, I have more money in them than if I bought brand new. Started off with $100 a pair castings and went from there. Wasnt too bad until I had put seats in everything.

Re: Whats involved in installing larger valves?
 

I still have the stock size valves. I am sure I read all the oval ports including the peanuts where 230.
This probably explains why I did not see a increase in power when I changed from the small ovals to the large. The valves are the same size and the intake runners are the same.

Still wondering what size of intake runners I should go to?
310 to large?

Re: Whats involved in installing larger valves?
 

These are prob too big but I bet he will take a little less. Atleast this will give ya a idear whats out there.

Rob

http://www.chevelles.com/classifieds...1&cat=6&page=5

Re: Whats involved in installing larger valves?
 

The "Peanut port" heads have intake runner volumes ranging from 196-208 CC. The 049/781 large oval port heads have a runner volume of 253-256 CC. Both the small and large oval ports were standard with 2.06"/1.72" valves. The L-29 intake runners measure 233 cc(S)-239 cc(L) w/2.065"/1.72" valves.
Bob

Re: Whats involved in installing larger valves?
 

I have a 489 Stroker BBC and I justed swapped my peanut port heads for a set of Large Oval 820's. Similar to your heads but they have 110cc chambers for more compression. I had 1.88 and 2.19 valves installed. You will need to have a good machine shop open up the intake and you will need new seats on the exhaust. If you are on a budget that would definitely be less expensive. I have yet to run the boat to get the results. Cant wait till spring!!!

Re: Whats involved in installing larger valves?
 

Well, ok, maybe. Ive got way more in my heads than a new pair of edelbrock aluminum marine heads with good valves. Wish I could have that money back.

Re: Whats involved in installing larger valves?
 

I learned this the hard way. Buy the newer heads. By the time you piece them together and have extensive(expensive) machine work done , you will pay about the same and have outdated inferior heads. Hard exhaust seats, bronze guides, and cutting for larger valves all cost alot. I like the Darts, they have so much more meat to them, and come cnc machined and just need a little touching up to flow like crazy. I did this to 049's 781, as well as a few others.
If you have seen shipping prices lately, why pay to ship a set of clunkers and do all the b.s.?, when you could put the money in a better place? I like the 781s and 049s with the big valves and porting, and they run very well, but it's no real deal in the end. BBB

Re: Whats involved in installing larger valves?
 

I sent you a PM....everything they talk about here is done to those heads for less $ than 1 bare aftermarket head.

Re: Whats involved in installing larger valves?
 

Also watch out with ported and used boat heads. They rot out on the exhaust side. I was very pissed to discover a pinhole after I got a pair back from the machine shop. $300 and another head later and then Had a good set of heads. BBB