My friend is porting my iron heads. There is a valve swap that helps too. What do I need to tell him to put in?
Are you asking about high performance valves like in Stainless steel? or Buicks 455 Stage 1 package valves? Anyways as you know your cars i'll risk MY embarrassment by mentioning the 455 Stage 1 valves were 2.125 inch. on the intake and 1.75 inch. on the exhaust compared to the standard 2.00 inch and 1.625. Buick just took the standard heads off the line and machined them for the bigger valves and opened up the chamber a bit around the bigger valves to which the chamber looked a little like a heart shape.
I see you posted about the 350 heads. Maby it was a mistake posting on this BBB thread.. I think the 350 'Stage 1" valves are valves that TA performance offers??
Does your friend have a flow bench to guide his porting work and maybe more importantly at least do a before and after flow test? If not then tell him to stay the heck away from the short turn area of the port, especially the Exh port short turn! This warning is true in regards to both the BB heads and the SB heads. A big gain in flow especially when stepping up to bigger valves is produced by the valve job itself.
he does he used to be the machinist at the local machine shop and kept all the tools after it closed.
thats what i was thinking. i was going to just have install the bigger valves. is it worth the trouble? id love to find some 72 iron stage 1 heads to start with so i dont have to pull mine until they are ready.
Bump! I think members miss this thread.. You say your machinist is good. On a good porting effort and the time the shop puts in I would think the bigger valves are worth it. I'm not experienced enough myself though and go by what I read. Why are you thinking just the 72 Stage 1 heads? If it's for the cooling passages I think the proper gasket and plugs?? will allow the 70 heads? Not sure about the 71's but same thing with the gaskets.. Side by side of stock and stage 1 head chambers. The bottom is the stage 2 head but the combustion chamber is basiclly the same..
71 heads i think are the same as 72. i was thinking 70 had differences besides just that with cr and such. I want to stay on cheap gas. Like in my other thread just want the car good highway driver. It will spend its life cruising and car shows. Im over the speed bug to say but would like it comparable to a modern car performance wise. I know ta sells the stainless valves but they are kinda steep. Is there alternative for less.
I know people that have had very hot small valve motors. A big valve motor will probably be faster, but depending on the cam you use probably not always worth the hardware and machining. Yep, I've done it to all of mine but still something to think about
The higher compression on the 70 motors is probably 90% or more in the pistons that have a smaller dish. You really don't want to even use 91 octane fuel?
The larger 70 Stage 1 heads had I believe 66 cc combustion chambers and the standard heads with smaller valves have 69 cc Chambers. Don't the Stage 1, 66cc combustion chambers increase CR? He might want to stay with the smaller valves heads if he doesn't want to increase CR. Of course I don't know how much CR gets increased with the 66cc Stage 1 heads. VET
No its a headache to go with 91. If I was only going to race it or drive it once in a blue moon maybe but I possibly will be driving it 400-500 miles sometimes. So the only mods I want to do will not hurt or increase mpg and be cheap to run. This car is my cruising car so id rather be slower than have to sacrifice if that makes sense.
im not sure either the 72 rivieras ran on regular 87 i thought. Im probably just going to stick with the stock valves and port them. I think with the cam efi headers e fans exhaust and the port work i will have a decent runner.
There's an exception, though...1975 and 1976 Buick 455, with the lowest factory-rated static compression ratio of them all, 7.5:1 if I remember right...and they probably measure a point less like all the others. There are two factors in play for '75-'76, an even shorter piston compression height plus even larger volume "open" combustion chambers in the cyl heads. And warning, many folks have been fooled by the '75-'76 pistons at first glance, as the dish appears shallow like 1970, BUT the edge of the piston was dropped, putting these things even further "down the hole"! See https://www.v8buick.com/index.php?threads/piston-cc-73-76-and-2362p.102066/ A good rule of thumb is go custom or stock replacement '70 piston design at the least, and simply avoid the '75 - '76 heads altogether. Devon
