Which port do I use for vacuum advance? I prefer ported vacuum. Carb is '78 350 Buick, 800cfm. Engine is '76 350, Rebuilt TA HEI dizzy, 268 comp cam. Same qjet I have, picture is of one I bought off ebay on Monday, same part #. Oh, and as a side note, how should I install the camshaft? I installed it dot to dot last time, what would installing it "straight up" do in comparison? Any help is appreciated.
The port low on the right above the mixture screw should be ported vacuum. For the cam, isn't dot to dot straight up?
I would degree cam. You may want to advance that cam depending if you bumped compression up on the 76 engine from the stock 7.7 actual compression. I had that combo. Ended up using hyperutectic 522 Pistons at 9.8 compression to make some kind of power out of it. Others have had luck with that cam . I have not. Use the port to the front drivers side by acceleration pump for distributer vacuum
I used the .030 silvolite/KB hyper pistons #657p(?) with the dish. I think they're 8:1 or 8:5 to 1 static compression. I installed the cam dot to dot (crank at 12 and cam at 6, straight up would be both at 12, yes?) on the first go around, and I loved how it performed. Plenty of grunt but pulled very well upto 5500rpm. It's a DD, so the cheaper gas I can throw in it the better. High compression doesn't mean a lot to me.
Dot to dot is zero. Both dots up is 180 off. You need a advance retard lower gear to change timing. Mostly on double roller sets with 4 advanced and 4 retard. The 657p has a compression spec of 1.800. That's more then likely .090 to .100 below deck for about 7.7.with about 24 cc dish. Advance cam 4 degrees and shave .060 off heads for about 8.9 compression and you may make some decent power in my opinion. Otherwise yank Pistons for the 340p (9.25) or the 3.0 Buick century piston flattop at 9.9. It may run fine but I expect it to be about 160-170 hp as long as your happy that's what counts.
Don't most comp grinds have 4 degrees of advance ground into them? And if I swap to the 340p, and do nothing else, that will up it to 9.25?
The 340 is about 9.2 if all else is same yes. Varies slightly depending on .030 or more but not much. Some cams have that some don't. I have had a cam be 9 retarded. So don't bet on it being right without checking it. And timing gears could be off some too.
Are these the same piston, just a different part number? They cost half as much, and they're the same type and brand of piston I have. https://www.summitracing.com/parts/uem-1746-030/overview/make/buick Although the pictures don't match at all, which always annoyed me about summit.
Basically the 76-80/76-84 Buick 350/3.8 v6 Pistons. Slightly less dish and .005 taller compression height. The change is minimal. Maybe an exaggerated 7.9. Virtual no different. . If your Pistons are newer Consider shaving heads. .050 will net 8.7 at a 44 cc chamber. That's if your Pistons are good and useable. The 340 is 1.835 height with 10 cc dish vs the 24 cc on these
I thought 350 Buick heads were all more or less 55-58cc, or is that 44cc after the heads are shaved? And is there a 10:1 piston that is hyperutectic?
And I don't quite think my engine was only 170hp, 250 at most at the crank seems more like it. Car did 14.7 in the 1/4 at 93mph weighing 3800lbs with me in it and all my tools, 2.41 gears, 195/75/14 tires, and a slippy th350.
Yes you said it was pretty strong. Maybe something was better on your combo then mine. Yes 44 is after being shaved. 58 cc is about stock. You can go with the 3.0 v6 Pistons. 1734. Flat top. It's about 10 to 1. I can't seem to find the h522p Pistons anymore. They where hyperutectic with a 1.855 height and 10 cc dish.
If I were to go that route with the V6 pistons, they'd fit exactly, no problems, no machining required, yes? And which should I get, 1.805 or 1.808 compression distance, whats the difference? More compression?
On Summit's site, the flat top set of 6 pistons are 1734-030 and the singles are S1734-030. Does the S just mean single? That's the only difference between the two I can see.
Here are some; https://www.summitracing.com/parts/slp-h522cp30/overview/ They're v6 pistons though so you'll have to buy an extra 2. Derek
Wow, those pistons look wild. Then again, it is summit. That piston in the pic could be Isuzu for all I know. I think I'm gonna go with the 1734s when the time comes. https://www.summitracing.com/parts/uem-1734-030/applications/make/buick?prefilter=1 The picture at the very least looks like my pistons, just with no dish. Same brand as well.
The pic is pretty accurate on the 522. They where pretty much all anyone knew to use back in the 80-90s. I have used them myself. The 1734 is flat. Never used them. But have seen them used a lot. They are cheap enough. Just sit down hole a lot. . But they do work good enough.
After seeing the compression height difference between the 657p (current pistons) and 1734 (3.0 pistons), I'll probably just stick with the 657p pistons and get another 268 cam. The combo worked good for what I wanted, and it sounded way too good to mess with. I don't really want to do any major mods to my block because once you do, it's done. No going back. I could shave my heads, but you get more bang for your buck if you will shaving the block down rather than the heads. Also being able to toss 87 in it and have it run perfect is a big plus for me. Thanks for all the info and advice anyway, I'm sure someone will find it useful in the future.
i would look at the crower level 3 cam advanced to 108. A few here have had good luck with it in a lower compression engine.
