You know that you can get a custom ground cam right? Call TA, or Scott Brown. Tell them what you are looking for and they can suggest something.
:Brow: Edit: Actually I recommended earlier on in another post that was kind of a hybrid between the 212 and 284, milder, but will have a bit of lope and more friendly to your compression range. Remember the cam listings you see in those catalogs are just to give you an idea...and there's many of them to pick from and about twice as many opinions on which cam profile should be used Most engines you read about on these forums are overcammed... But such is the seduction of a lopey idle. The Buick 350 head won't flow much past .400 lift on intake and about .450 exhaust (when untouched), and even fully ported (I use the term 'fully' loosely) won't flow much past .500 lift. Intake durations @.050" ranging from stock to about 205* will give a stock sounding idle. Keep exhaust duration at .050" between 8* to 12* more than intake. Exhaust lift can be the same as intake, or you can give it a little more, from like .005 to .015 more. There's so many variations it'll drive a person nuts. The closer to 210* you get the harder the idle will hit, but it will still be 'smooth' and not lope. Much past that, and it will start to develop a 'skipping' sound as it transitions from smooth to lopey. At around 220* intake duration it will hit like a slow galloping horse. Beyond that, it gets rougher. These characteristics can be adjusted and tuned/tweaked to give a lopier or smoother idle. Keep advertised duration somewhere between 50 and 60 (give or take) over the duration @.050". Keep Center line at 110* since your goal is lope without sacrificing drivability. ---------- Post added at 09:50 PM ---------- Previous post was at 08:57 PM ---------- It could be as simple as choosing the TA 284-88H cam. It has a nice lope, with a power range from 2700ish to 5700ish RPM, and needs about 1/4 point less compression than the 290-94H. There are some here who run this cam with much success, though it took some tweaking to get it to behave. My cam suggestion earlier was in-between the 212 and the 284, more lope than the 212 but better mannered than the 284, and needing less compression. Custom grind: .455/.465 lift 220*/230* @.050" 270*/280* advertised 110* lobe center This equates to 5* overlap @.050" (compared to the 212's 4* and the 284's 6.5*) and 9.75:1 compression at exactly 8:1 dynamic.
well the engine is actually all finished being machined and the short block assembled so i dont want to have the shop take it apart in order to zero the deck, looks like the ta 290 is out. Im looking at the ta 284 or the comp cam 268, how does my combo look with one of these cams? im guessing a smaller stall converter.. custom ground cams mean more money! ide rather stick with one thats proven, if anyone has some combos with either of these cams please let me know.. ooh and the shop closed before i was out of work so i have to get it in the morning :ball: but i did get a new engine stand!
284 would give some lope . still need convertor gears headers, make sure you have cam degreed at machine shop if they do it right it should run good. get a timing chain that can be advanced not just stock replacement as I had 1 that left my cam retarded to far and motor was weak and wasted a lot $$ getting that figured out. I would also run it slightly advanced . but machine shop should be able to advise you if they know what they are doing add an H or X pipe to it as that will help it lower rpm also
Well the block is back from the machine shop. I had a friend take it in to have the machining done he left the block but forgot to bring me the build sheet and theres one problem... the paint! the shop said they didnt have buick red so we told them to leave it but they painted it black!! ill order some buick red when i order the camshaft from ta. the block was bored .040 because of that cylinder with the rust and new pistons were used. So now what does this do for my compression ratio? how do i got about measuring it? heres a pic of one of the pistons.
You need to accurately measure everything. First, the volume of the piston dish, the distance from the edge of the piston to the deck at TDC, the head gasket thickness, and the amount of volume in the head combustion chamber. Then you plug the bore (3.840) and stroke (3.85), and the aforementioned measurements into a compression ratio calculator (like the one I linked you to), and you will get your static compression ratio. You can't guess at anything, or assume any measurements if you want accuracy. http://www.carcraft.com/howto/ccrp_0509_how_to_blueprint/viewall.html http://www.mokesinc.org/index.php/topic,8882.0.html
what is the ccs of a stock 1970 350 head?? ---------- Post added at 08:29 PM ---------- Previous post was at 08:17 PM ---------- i guess the sock cc of the head wont matter, im going to have the heads milled .020 to match the 040 gasket vs the stock one which will change the combustion chamber correct? The piston dish is at 10cc, the piston to deck clearance is at .090, a .040 gasket (but heads milled .020) a 3.840 bore size and stroke of 3.85 this calc (http://www.csgnetwork.com/compcalc.html) puts me at what with the head cc size?
Man look at the shadow on that piston. .090 deck height? uzzled: You're gonna have to shave those heads like they're going into the marines. Head cc is supposed to be 55cc, but I have heard some were 58 or so. Not sure. At least the piston dish is 10cc, that's pretty good, but as far as they are in the hole, they need to be flat top or even domed. Just work with what you have I guess eh? At that depth, without using any calculators, based on off the top of my head, you're sitting at 1.1 compression less than 10:1, with the heads untouched. So 8.9:1 static, Shave off .020 from your heads and use .040 gasket and you'd be sitting on around 9.4:1....this is guestimation before you do any calculations. Do the math and let's see how accurate my guess is. This will determine how much off the heads you need to go, may need to take off around .040, bump comp to 9.9:1 for the TA 284 cam. This is based on my guess, so disregard these numbers and bust out the calcs. o No::Comp::idea2::grin:
ok the calc showed 9.4 to one with the heads at 55cc and a .020 gasket , will the cc change because im already milling the heads .020 to make up for using a .040 gasket? the shadow might be a little more then it really is i dont know if i had the piston all the way up when i snapped the shot.
Wow that was a lucky guess. lol I figured the .020 off already to get your 9.4:1, which would be where you'd be with a .020 steel gasket and standard head cc. As a 'rule of thumb' for every .020 off the heads you gain an extra .5 comp. So all you have to do now is shave off .040 from the heads, use the .040 gasket and you'd be sitting on about 9.9:1, which is about .35:1 comp less than 8:1 dynamic for the TA 284 cam, which is a comfy safe zone for your CA octane and you have some room to play with the timing. The engine should run ok with this setup. Since quench isn't ideal (but then is it ever? Look at the combustion chamber design for the Buick 350), the lowered compression below 'ideal' should give you a nice buffer for spark knock on premium. Redo the math though. Double check, triple check, and wait for more replies other than mine. Make sure you know for sure. Engine looks great! All it needs now is some Buick red. Edit: shaving .020 off the heads will reduce their cc's of course, though I'm not sure by how much. I just know the 'rule of thumb' where for every .020 off you get about .5 point of compression increase. I'm sure there's someone here, maybe Sean who would know the details on the head cc's. This equates to this: you need to take .020 off the heads anyway to get the 9.4:1 with the .040 gasket, so take another .020 off the heads, giving you 9.9:1. Shave .040 off the heads and use your .040 gasket. Most importantly, wait a while for others to respond so you can get confirmation input other than mine.
Sweet looks like im on track!! yeah ive redone the calculations and done it on a few different calcs to make sure. Yeah im happy with the way the block came out other then the color! some red paint is on the list with the 284 hopfully ill be ordering it within a week or so.
get the specs from machine shop on pistons. they look like basic replacements which will net 8.5 static with a .040 gasket I assume you talked to machine shop before they changed the pistons. I would have went for the hyperutectics would have net you around 9.25 to 9.5 with 40 thick gaskets and have valve ressions so big valves can be used later on. im thinking supercharger motor to turbo motor and the "rule of thumb" is 020 is off block not head and still only an estimate
I believe the stock 350 heads are about 58 cc, but you MUST measure yours. Milling the heads .020 IS NOT THE SAME as reducing your gasket thickness from .040 to .020. Milling the heads will reduce the chamber size, so again, you must measure. Assuming you are correct about the piston dish cc, using 58 cc, .090 in the hole, .040 gasket, I get 8.8:1
I do not think there is much point in worrying about the compression ratio as you do not want to use adjustable or custom length pushrods. Like Larry says you should be under 9:1. I feel you would make the engine a dog unless you use a smaller cam like the TA212.
I understand but milling the heads 020 will lower the head ccs right? which will raise compression? and make it seem like the 040 gasket is an 020. Thats why i put the gasket size at 020, even with the head ccs at 58, even though after milling the heads it will be lower, im getting 9.22. The number i got earlier was with 55cc if anyone knows how many cc's you lose from milling the heads 040 ide like to know. Sean Larry posted earlier that different length push rods are un avoidable with a upgraded cam so im adding that to my growing list. Does shaving the heads 040 and using a 040 gasket seem like a good bump for the compression for the ta 284?
Well maybe you'll have to wait even longer. Everyone wants to tell you it's not the same but doesn't offer any calculations to show it. No, it's not the SAME, but it's close. 8.9:1 was a straight up guess for me, without any machine work. I added (rather subtracted) the .020 for the 9.4:1 Measure your head ccs so you can get it exact. The guess work was just for fun. Best to be 100% sure. I'm not offering any math and said outright that it was all guesses. Anyone else care to join in to back up the 'it's not the same' argument? (you can get answers around here, you just have to prod them a little) :Brow:
I am pretty sure what Larry meant to say was that if the base circle of the camshaft was different than stock then you would need either custom or adjustable pushrods. If the new cam has the same base circle as the stock cam then you do not need new pushrods unless you mill the block or heads. You keep saying you want to use stock pushrods so only mill 20 thou off the heads and then your stock pushrods will work as long as the cam is the same base circle measurement as stock. Call TA to find out. Yes there will be a TINY difference between a 20 thou thinner gasket and 20 thou taken off the heads. I would be surprised if it was enough to change 0.05 compression, this is a minor factor in the equation. I would do one of two things: 1. Measure everything, heads, pistons, piston to deck depth, and find out what your actual compression ratio is. Then mill the heads to get 10:1 static compression and use the TA290 cam. 2. Mill 20 thou off your heads, toss in the TA212 cam and have fun.
