I'm new to buick just came over to the torque side LOL. I'm building a 350 and noticed no quench area at all is it just my casting did buick ever cast quench heads are was this a design flaw. Thanks in advance for any knowledge.
My guess is that the Buick 350 uses an open chamber head design so that the valves are not shrouded. Another factor is the fact that the 3.8 inch bore is way smaller than lets say a SBC, so to gain breathing efficiency they picked an open chamber head. In general, all other things being equal the open chamber head can breath better than a closed design. The Buick 350 also uses the tall narrow intake passages like the LS engines now use. With head porting these heads can breath very well! Look in my sticky above to learn about head porting possibilities. The Buick 350 also has pistons that sit deep in the hole and I think that is why they decided to use a open head design. This way the engine is not temperamental with regard to the depth of the piston below the deck. This is why it is easy to take a 9:1 compression 2 bb Buick 350 from 68-70 and mill the heads to get close to 10:1... No need to optimize the quench because there is no quench to be had. The only tough part is getting above 11.5:1 since the valves get too close to the heads without custom pistons. This is because of the wide open head design. Fortunately many people do nnot want high compression on their 350s. You will notice that any engine with closed chamber heads it is VERY important to get a zero deck on the piston so that you can get the quench. Even adding a 20 thou thicker head gasket can cause loss of performance and even detonation.:beers2:
Ok question answered there's no head made with a quench area. My heads have 1.94, and 1.5, i've noticed alot of shrouding on the cylinder side but have no flow numbers because i'm just going to run it like it is for now. The head work was done in the 80s so i'm sure there is room for improvement just looking at them the 80% deferential look a bit close but who knows. Well anyway hope the efficiency isn't affected to much by the lack of quench and I thank you for the info have a nice day
No problem, I guess i could have just said: All the Buick 350 heads from 68-80 are open chamber design and saved myself 10 in LOL! Interesting that they are ported! Cool! Let me know the casting numbers and I can tell you what year they are. Also show a pic of the pistons so we know if they are dished or not. You have a nice day as well!:beers2:
No problem i've alway said the only bad info is no info LOL. it's dark so I can't get a pic of the pistons now there not in the shop but the trw # is L2343. And the head cast is MP1243452 don't know the cc yet but I think they've been cut because i've got some old recites that came with the car.I haven't looked up any specs either so any you have will be nice including stock deck height ect. THANKS
The heads are 76 versions. Normal is 58 CC who knows what they are now. The pistons should have a compression height of 1.810" and a dish of 10 cc These are the high compression pistons. The pistons are normally about 0.0580" in the hole Deck height is about 10.18" 1.92500 is 1/2 Stroke to use to calculate compression 40 thou is the head gasket compressed (42 thou before)
Thanks for the info like I said earlier i'm going to run it as is but i'm going to plan the next build carefully and see what I can make her do. But for now as long as it's consistent i'm happy .
I always wondered about the lack of quench on the 350 too. I don't think Buick engineering had any concern with anything other than what made a reliable engine in the day, much less forseeing what's now being done with forced induction and all the other crazy things we're doing. We're quick to trash the '75-'76 455 heads because of the same open chamber design; makes it more difficult to get a higher compression ratio for those who want it. Do the aftermarket Rover heads have quench? I haven't looked, but now I'm curious. Seems like from an aftermarket standpoint it would be better to have it built into the head and let the piston design handle the rest for all the various applications. Devon
I've read something about rover they bought the patent on the aluminum block are something like that. Are the engines similar? And i've been running this through my head alot from a engineering point of view if the rest of the system was perfect lets say perfect atomization no fuel adhesion no fuel drop out why no quench. Of course i've been known to over think things LOL.I've experimented with quench ports with up to four degree of timing improvements with a .030 quench (and yes fellows I know thats tight I was playing with fire ).so just imagine going from no quench to quench I for one think that final mixing makes a difference.
Yes Devon the Rover heads are a Quench type design. From 61 to 63 Buick produced the 215 all alum V8 and in 65 they sold the tooling to Rover who the produced the design in the 3.5L to 5.0L up till 2006. This is where Buick went to the iron 300 then 340 and finally the 350. I should call Dennis Manner and ask him why they went with an open chamber head on the 350. Even with the old 215 it seems that Buick felt it was best to change compression with the pistons so I think that is a factor. Another factor is that Buick had sold off the V6 design to Jeep and then bought it back and built it on the same assembly line as the Buick 350.. This is how the 231 V6 came to be the same bore size as the 350... Interestingly the Buick 215 and Olds 215 where almost the same except small changes mainly the head design. The Buick 215 had an more open head chamber and was typically better for racing. Domed pistons were utilized. High comp engines featured different pistons vs the low comp. Same heads were used for both engines. The Olds 215 had a wedge shaped/quench combustion chambers which was better for low octane street use. The difference between the low and high comp engines was the heads, same pistons. They even turbocharged the Olds 215, I have one here in my shop right beside the Buick 215. Stay tuned, the first chapter of my book about Rover and SBB Performance going into detail about all of the history of the engine from 1961-2006 (from the 215 to the 5.0 rover)
I have heard that GM used open chamber heads in order to meet emissions restrictions. Open chamber heads burn more completely. I also have a feeling that the Buick 350 with a long stroke and small bore compared to other 350s would not benefit from the closed chamber heads because of the already small bore to suck the air and fuel out of the head. The Buick 350 responds very well to even just a 40 thou bore, it helps the heads breath.... If you sonic test and find a good block you can even go 75 thou on the bore which would help head flow big time!
I fully understand the benefits of lack of shrouding I still see shrouding even now with the open chamber. And I can also see a very good flame travel potential. But like a true hemispherical engine with these benefits they lack fuel efficiency but make extremely high HP numbers just imagine if you could get these engines to burn all the fuel you put in to them. The HP would be astronomical but I also understand that is unlikely with todays technology. On the lighter side im interested in your book please let me know when it's available .
The Buick 350 can make about 550-580 HP NA but that requires lots of head work and compression... That is plenty respectable considering the simple design from 1968. With power adders the Buick 350s WAKE up, they love nitrous, turbos and superchargers. I think a lot of that is the improved air flow through the engine, and specifically the fact that the engine has trouble filling the small cylinder bore when NA. Under just a few PSI it responds great! I am just waiting to complete some R&D projects before I have the book printed... I will keep you posted!:beer I convinced these guys to build a Buick 350, this one was built by a 16 year old named Anthony with mild head porting. It was stroked to a 370 CID which helped the torque. http://www.youtube.com/watch?v=zktYYQhCtqU
Well im going to keep working on this please don't misunderstand me I see alot of potential here there is little I see about the motor I don't like. But i'm going to fix this issue in my engine are at least try. Then when i'm finished with this i'll find something else to fine tune thats just what I do. As of now i'll just keep looking for heads are maybe check into getting pistons cut for a reversed quench if the piston doesn't get to top heavy. Well if anyone runs across any ideas please post.
One area of opportunity with the 350 is the intake ports. If you can raise the roof of both the intake and the heads then the heads flow a lot better. People have also had good luck with angle milling the heads to straighten the flow from the intake to the head. You might be able to try something like this 283 Piston: If a block checks out good you can use a Chevy 283 pistons which is a 75 overbore on a Buick 350. This is what Sonny Seal did with his 350 and it was the fastest NA Buick 350 in the quarter. Full weight Skylark at 11.08 in the quarter. I am using these low comp pistons for my turbo engine, I am just showing this pic to show you where the pistons get close to the valves: The GM 3.3L V6 has a set of pistons that are flat tops and work out to about 11:1 in the Buick 350. I have a spare set of 30 over pistons that would work well in a Buick 350. They have a lower compression height vs the stock pistons however they should not require valve reliefs and they would work well I think. You can have them for free if you pay the shipping.
I appreciate the offer Sean but if the comp height is down it's going the wrong way and the 283 piston would have to have enough meat to cut a flat quench area valve reliefs ect. Your pistons are the style I'd prefer but are probably too low on compression for my NA motor. Even on a blown motor all though I don't set much of them up I prefer something like that see the area behind the valve reliefs depending on piston deck height would provide adequate quench then the dish depth on the other side can be lowered are raised for comp needs. May I ask the head clearance on your piston and if it's tight quench like .040 are so do you experience any skirt scuffing because of a top heavy piston
Mike Philips has a sticky above about having a run of high comp light pistons made, look into that if you are serious about a good piston. Diamond makes great pistons. I suggest you go with some light pistons if you want to rev it, plus that is less stress on the rods and bearings. Here is a proven combo that runs 12.08 easily NA: http://www.v8buick.com/showthread.php?t=139310&highlight=casper If you used the above Chevy rods you could order the same pistons he used. I think he ended up at about 11.7:1 compression with the flat tops. I have yet to run my good engine with the forged rods and Diamond pistons. I am using the original 9:1 shortblock in my twin turbo car till I get the bugs worked out then I will swap in the good shortblock. I have not checked the valve to piston clearance although there should be TONS of clearance since I did not deck the block at all. I did have the block squared off but it took very little to get it there. I was at about 8.9:1 compression but I removed a little extra material from the pistons while I was smoothing them out and removing all the sharp edges. The final compression will be a little bit lower than that. My pistons sit about 80 thou in the hole. We had the valve reliefs added so that people could mill the block and or heads to get up to 10.5:1 with these pistons: 58 cc head 030 deck height = 9.49-1 compression 55 cc head .010 deck height = 10.22-1 53 cc head .005 deck height = 10.58 The stocker NHRA Buick 350 guys have good luck with milling the heads to 49 CC and decking the blocks. They can get about 11:1 compression. They also offset grind the crank 15 thou to help get the piston up in the hole. If they were allowed to go more they would obviously. They also report the engine LOVES a 60 thou overbore.
