Adding to what olds307and403 said, measure your pushrods and piston to valve clearance if you mill your heads. Or to be safe if you decide to mill your heads, get that much shorter pushrods. And your intake would need milled to match as well.
Stock Buick 350 10.25:1 Pistons?
- Thread starter joesregalproject
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joesregalproject,
After doing some reading (Ok - alot of reading) I'm still somewhat concerned as to what your motor has in it for rods and pistons. The largest confusion comes down to the rods - I've found multiple sites indicating both a 6.385" and 6.358". From checking the compression and quench distance with the parts I could find it would be REALLY good if you had the 6.385", but I'm going to guess that yours are 6.358". Onto piston and head chamber volumes, the bulk of the available pistons seem to be in the 24-25cc and the heads are either 50.5cc or 55cc.
What I'm implying is you need to find out exactly what you have, check (measure) the bores and determine if your pistons are reusable. Measure your piston to deck clearance to confirm that number, and then pull it apart and confirm rod length and piston compression height.
If I were you, then a call to TA Performance would be in my future - those guys are Buick PURISTS and they know Buick's platforms and they have always been helpful when I've spoken to them. Have your year and casting numbers ready when you call them.
Mr. Sony's comment above needs to be considered - to a certain point. What I mean is that you can cut the heads and block a certain amount due to use of hydraulic lifters - up to .025-.030" will work with a GM style hydro lifter, and this should leave you in good shape in terms of intake alignment and pushrod length, but I agree with him 110% that cutting a bunch to raise your compression is going to create issues with intake alignment and pushrod length (by intake alignment I'm implying intake sealing also.) If you go that route, then you need a competent machine shop to pull this procedure off and you'll need an aftermarket set of pushrods FOR sure.
From the info I've found, the Buick 350 is not like a Chevy SB or BB in terms of combustion and chamber design. It is much more similar to a Ford where a small chamber head is used with a big dish piston and compression is adjusted up or down via deck height. This implies that your low compression smog motor most likely has a bunch of quench which is too much for any real performance type building in the stock form. With this in mind, there are documented builds with these that make a strong Vortec build look like poop. It's accomplished via head porting (which you can do on the cheap), block deck cutting, and machining the intake to get it to fit correctly. Pushing the compression to 9.5:1, getting your quench distance to .050", grabbing an appropriate cam and making 400HP and close to 450-500 ft/lbs is more than possible - but not on the 'ultra cheap' that you mentioned you were after.
Lastly, your used cam you picked up - IMHO installing a used FT cam is flirting with disaster and I wouldn't do it. But your motor with some minor tweaking, on the cheap, will be a really nice torquey motor better than it is now, just not a high HP build. Keep your eyes peeled for a set of long tube headers (if the exist.)
Jim
After doing some reading (Ok - alot of reading) I'm still somewhat concerned as to what your motor has in it for rods and pistons. The largest confusion comes down to the rods - I've found multiple sites indicating both a 6.385" and 6.358". From checking the compression and quench distance with the parts I could find it would be REALLY good if you had the 6.385", but I'm going to guess that yours are 6.358". Onto piston and head chamber volumes, the bulk of the available pistons seem to be in the 24-25cc and the heads are either 50.5cc or 55cc.
What I'm implying is you need to find out exactly what you have, check (measure) the bores and determine if your pistons are reusable. Measure your piston to deck clearance to confirm that number, and then pull it apart and confirm rod length and piston compression height.
If I were you, then a call to TA Performance would be in my future - those guys are Buick PURISTS and they know Buick's platforms and they have always been helpful when I've spoken to them. Have your year and casting numbers ready when you call them.
Mr. Sony's comment above needs to be considered - to a certain point. What I mean is that you can cut the heads and block a certain amount due to use of hydraulic lifters - up to .025-.030" will work with a GM style hydro lifter, and this should leave you in good shape in terms of intake alignment and pushrod length, but I agree with him 110% that cutting a bunch to raise your compression is going to create issues with intake alignment and pushrod length (by intake alignment I'm implying intake sealing also.) If you go that route, then you need a competent machine shop to pull this procedure off and you'll need an aftermarket set of pushrods FOR sure.
From the info I've found, the Buick 350 is not like a Chevy SB or BB in terms of combustion and chamber design. It is much more similar to a Ford where a small chamber head is used with a big dish piston and compression is adjusted up or down via deck height. This implies that your low compression smog motor most likely has a bunch of quench which is too much for any real performance type building in the stock form. With this in mind, there are documented builds with these that make a strong Vortec build look like poop. It's accomplished via head porting (which you can do on the cheap), block deck cutting, and machining the intake to get it to fit correctly. Pushing the compression to 9.5:1, getting your quench distance to .050", grabbing an appropriate cam and making 400HP and close to 450-500 ft/lbs is more than possible - but not on the 'ultra cheap' that you mentioned you were after.
Lastly, your used cam you picked up - IMHO installing a used FT cam is flirting with disaster and I wouldn't do it. But your motor with some minor tweaking, on the cheap, will be a really nice torquey motor better than it is now, just not a high HP build. Keep your eyes peeled for a set of long tube headers (if the exist.)
Jim
Jim,
Thanks for doing all that research for me, I really appreciate it. I knew that if I decked the block the intake needs to be machined to match and pushrod length needs to match or valves need to be cut. I actually had a set of heads that were decked .010, had a 3 angle valve job, and had the valve stems cut to match. I regretfully sold them before I bought this motor.
Like I said before, I'm trying to do this as much on the cheap as I can, really trying to avoid machine work if possible. My idea in posting this thread was to find out if raising compression is as simple as swapping pistons, which it appears is not the case. So I'll stick with my stock 8.5:1 compression. No biggie. Ive got less than $400 in the complete engine w/all accessories, gasket set, rod and crank bearings and piston rings. As far as the cam goes, it came with the correct valve springs and I paid $50 for it. I've reused flat tappet cans before, but I can understand someone being concerned about reusing one. Again, thanks for all the research!
Joe
Thanks for doing all that research for me, I really appreciate it. I knew that if I decked the block the intake needs to be machined to match and pushrod length needs to match or valves need to be cut. I actually had a set of heads that were decked .010, had a 3 angle valve job, and had the valve stems cut to match. I regretfully sold them before I bought this motor.
Like I said before, I'm trying to do this as much on the cheap as I can, really trying to avoid machine work if possible. My idea in posting this thread was to find out if raising compression is as simple as swapping pistons, which it appears is not the case. So I'll stick with my stock 8.5:1 compression. No biggie. Ive got less than $400 in the complete engine w/all accessories, gasket set, rod and crank bearings and piston rings. As far as the cam goes, it came with the correct valve springs and I paid $50 for it. I've reused flat tappet cans before, but I can understand someone being concerned about reusing one. Again, thanks for all the research!
Joe
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