I have to say my 475 BBB was a LOT of fun but I realized a full race motor on the very busy roads here was about as useful as an ejection seat in a helicopter. So being an all or nothing type, I'm going back to stock. Last time my car was stock was 1988! Low comp, 350, qudadrajet, iron everything. Any mods I make will be to increase, OMG I can't believe I'm about to type this....., fuel mileage. I'm going to run a mild 200-4R and keep the 3.73 posi. I saved all of the original stuff but will need to rebuild the 350. I wonder if head porting would increase mileage? Nahhhhh that's crazy. I might balance the rotating assembly though. I've been out of the SBB loop since about 2004. Right now I need to locate a set of plain old cast .010 or .020 over pistons. Anyone have any ideas? Thanks, Andy
Andy The 1746 Silvolite cast 8:1 compression pistons come in std, .020, .030, .040 and .060 http://www.summitracing.com/search/...ast-aluminum/compression-distance-in/1-805-in Use with the Isky Mile-A Mor cam 671-M http://www.iskycams.com/Wc900150ef8c44.htm The best compression ratio for mileage and still use regular gas would be 8.75:1 (Using the Isky cam) You could take .030" off the block and .025 off the heads You would have stump pulling power right from an idle Next option is the Sealed Power cast 10:1 compression pistons. http://www.summitracing.com/search/...ssion-distance-in/1-835-in/brand/sealed-power With these pistons you take as little as possible off the heads and block. It would also be a good idea to clean up the combustion chamber and remove the locating boss near the spark plug hole. You should end up with 60 cc chambers and around 9.6:1 compression Use the Crower level 3 cam. It will pull strong from 2000 rpm and still give good gas mileage. http://www.crower.com/index.php/camshafts/buick-350-compu-pro-hydraulic-cam-276-hdp.html Paul
Thank you Paul! That kind of sucks you can't get the stock 9:1 pistons. I hate to have to cut the block. I ordered the cam from Scott Brown two days ago.
This comes up frequently and several of us have spent a lot of time looking at off the shelf cast pistons including the V6 pistons. You end up near 8:1 or 10:1 without machining the heads or block. The only option for compression in between is forged 4032 alloy pistons from Autotec or BWE. Then there is always custom 2618 alloy pistons from any of the other piston makers. What are the specs on the Scott Brown cam you ordered? (If you don't mind) Paul
Another idea for a cam is the Crower level 2. It needs less compression than the level 3 and is a little milder. I hear it's pretty good.
It depends on your block but most advertised 10 to 1 pistons are calculated at zero deck. Your pistons stock sit about .090 down hole more for 75 up blocks. So stock 10 to 1 pistons will be in the low 9s hyperutectics will give 9.25 area unless mill stuff and they have in .020 .
Sealed Power and KB/Silvolite cast pistons have between a 23-25cc dish with a 1.805 CH (Low compression) or a 9 cc dish with a 1.835 CH.(high compression) That is near 8:1 and 10:1 as they sit in the hole without any material machined off the deck or heads Have you found something different? If so that would be great! Paul
Wiesco 5120a has 25 cc dish with 1.855 comp height or look at h522p. . Still have to measure how far they are in hole. Still have to measure how far in the hole they are its not " as they sit in hole" that's not quite how it works.
Ok I worded that wrong. Sorry about that! I simply meant that the 10:1 piston compression ratio is not rated with the piston at zero deck The piston type request at the beginning of this thread was "plain old cast" The H522P is a possibility if it's not a problem getting 8 pistons. . Paul
I have used the 522 for 5 builds easy to get 8 .flatlander and summit both have them. Poston used to sell them.I ended up using steel shim heads on 1 build with a poston 118 cam .came on strong after 3000 rpm. Was a swift 14 second car.getting ready to open that motor to yank crank and rods for a custom set of rods and pistons and crank.the goal is an 9.25 to 1 build. 260 FM flow on heads custom cam 460 HP build with a MSD atomic fuel injection. custom shorty headers 2800 stall and 3.73 gears.
Thanks I appreciate the info. Keep us posted on the outcome. What's the volume in the 4 valve pocket dish? Paul
The cast slugs from Summit (Speed Pro) come in 2 flavors: 1.805 CH (.070 below deck) with a 24.74cc dish (low comp), and the 1.835 CH (.040 below deck) with a 10.18cc dish (high comp). This is with a 10.187 deck height block. Low comp costs about 160 bucks and come in sizes up to .060 over, while the High comp costs about 300 bucks available in either .030 or .040. With 58cc heads, .040 gasket and .030 overbore, the low comp will be 8.02:1 where they sit in the hole, or 9.05:1 with a zero deck. High comp's are 9.73:1 where they sit in the hole and 10.6:1 at zero deck, with the aforementioned parameters. Gary
If you are going with big valves and unshroud the valves your head chamber will end up 61-62 which will drop compression also.
will post when I find out. He said it was the one a lot of stock appearing guys run. This worried me a bit but he assured me mileage would be good. Has anyone done a comparison between one of these Scott brown cams and the factory cam?
From what I've read, some of the 'stock' racers run a cam with .392/.408 lift @ 1.55 with their unported heads, though they will not disclose the other specs such as LSA, ICL, or durations, they do say they have a lot of duration and idle smoothly @ 600 RPM while raising the front tires a foot off the ground. There's more to this than meets the eye, and I can't help but sense there's a rich goldmine of (relative) power and economy just waiting to be unearthed. Some speculate the 'stock' engines are producing somewhere around 375 HP (and who knows what torque), launch with 4000 RPM stalls and stupid steep gears. They milk everything they can within the rules, so it won't be your typical Joe-Blo engine build. But we can certainly learn a thing or two from the pros, as well as perhaps discover something 'new' for ourselves along the way. While I'm not implying the beloved Buick 350 has magic flowing through its molecules, it certainly has enamored me and many others with its capabilities, if one is simply curious enough to dig deeper and understand the engineering that holds it all together. Gary
cam is IN .296/263 EX.313/283 lobe separation 112 I would much rather go 8:1 on the pistons and cut the head to get to 9:1 if possible. Nothing has been done to the heads since '88 so I'm going to have them rebuilt.
I'm wanting to get this car back on the road ASAP. I need to order pistons so I'm thinking hard about my DCR and CR. I believe my engine was designed to run 89 octane. The way I remember it, 89 was regular in those days. Today, regular is 87. I never tried 87 in mine when it was stock. I was still buying 89 leaded gas when I rebuilt my 350 the first time with 10.25 pistons and started burning premium gas. Has anyone built a Buick 350 that ran well on 87? SCRATCH all that... Trying to run 87 is more trouble than it's worth. As much as I'll be driving this car, I'll just run 10.25 pistons and buy the gas it needs to run right.
