Shop left a message on my phone yesterday afternoon, saying that they have the block all measured up for the compression height. They made a special wrist pin so they could use the stroked crank, and new rods for measuring each hole. So now we have to decide what kind of piston top and what not to go with, and what company...thinking we may use Diamond Pistons. Should we do a flat top with valve reliefs, or a small dished top? We are trying for a zero deck height...just whatever thickness the head gasket is for quench area. We are also still wobbling on roller cam or hydraulic. (Cost is the only major factor here.)
If cost is a factor then order pistons and flat tappet cam from Scotty brown at "buyracingpArts". I would go with a slight dish or you will be too high in compression. About a 6 cc dish most likely and the valve reliefs will add to that. I have two engines with diamond pistons and they were $1000 U.S. Where as Scotty is selling a comparable setup for far less. I think it was $189 for a custom spec Ed cam from Scotty too. Keep in mind that Scotty has the blueprints from TA for the Alum heads so he is already offering a piston that will work with the head as far as the valve reliefs in the piston. I may have to modify my diamond Pistons to clear the valves in the alum heads and TA moved the valves. Also keep in mind there is no quench when using the iron heads being they have an open head chamber. In an ideal world what you would do is measure the head chamber CC, decide on your head gasket thickness. Calculate the compression height needed on the piston to get zero deck with your rod and stroker combo. Then the last variable is the dish CC... The camshaft will have a large effect on the desired static compression ratio. I would build it for about 10.5:1 with a healthy cam it would bleed down and give you good dynamic compression ratio...
Head chambers will be measured once they are here, and rebuilt. Hope to get them close to each other with a quick resurface. Will probably only do a clean up of the ports, and port match the intake/exhaust. Shop said the compression height is 1.750" to get a zero deck height with the Nascar rods, (6.450") and the stroker crank. (3.970" stroke)
What diameter piston are you going to use? Do you have another block sonic tested or are you going to use the first one you started with? Derek
Excellent! Hope to get them cleaned up, and checked over...then do a quick clean up and port job on them before getting the bigger valves installed.
Back to picking a camshaft.... pro's and cons of each: roller: (pros) -not much chance of a cam lobe failure -no special oil needed. -more efficient when compared to flat tappet cams. -anything else? roller: (cons) -expensive -expensive roller lifters required -need shorter push rods, chromoly. -need cam button (yes, or no?) -need different distributor gear on MSD distributor? -need heavier springs, which may require more machining of the heads. -may require machining of roller rockers if springs are too big on the O.D. -anything else? hydraulic flat tappet cam: (pros) -cheap -can make some decent power. -anything else? hydraulic flat tapped cam: (cons) -higher rate of failure, possibly ruin entire engine. -require special break in oil, and additives at every oil change afterwards. -anything else? Son wants a lumpity bumpity cam. -engine block has all oil mods done. -bored 0.060" over -align-honed after main studs were installed. -crank stroked to 3.970" -NASCAR take out rods, 6.450" in length. -heads should be early style with TA big valves installed, and ports matched, cleaned up. -TA SP3 intake -Holley 750 double pumper/mechanical secondaries. -complete MSD ignition (box and distributor...no advance on distributor.) -Doug's aluminum coated headers -2200 stall (which can easily be changed when engine is swapped out.) -3:73 gears with Detroit Tru Trac locker -4 core rad with twin electric fans -electric fuel pump -295/50/15 rear tires -need to go to shop and talk about the pistons. They said the compression height is 1.750". Car is just for street/strip use...no long highway cruising. -will be replacing pushrods anyways. -will be replacing lifters as well...just didn't really wanna spend $800.00 on roller lifters... -will be replacing valve springs anyways -will use a positive style seal on valves.
You should wait until they open the heads up for the bigger valves first before you do your porting or you'll have to do the bowl area twice. Tell them to just rough the valve job in before you pick them up to do your porting, if you need any advice feel free to give me a call and I can walk you through it. Derek
You can certainly rough in the port work before the seats are enlarged. You just need to know the throat size you are aiming for. The existing VJ gives a fantastic sight line to your work. Most of the time you can port all the way into the bottom cut.
Yeah the math works out, 1.750" compression height is still a lot for a small block though! But that is quite a bit less than with a standard stroke and factory rods would require. The sbb 350 has a removable distributor gear that slips on the cam so you don't need any special gears for your distributor because you are using a roller cam, so I vote for the roller cam option. I'll PM you later tonight some info you will love that will make it a no brainer to get the roller cam. Get a hold of Mart from here on v8, he has a sbb 350 with one hell of a roller cam that will give you the lope you want if you get one like his, just make sure the pistons you get have valve clearance machined in them. :eek2: Port the heads after they are roughed out for the bigger valves first or you'll have to go back in and open up the throat area to the bigger valves again anyway or it would be a waste of time doing any grinding on them before that. Maybe give me a call and I can walk you through what to do when you do port them that will save you a WHOLE lot of time and won't make them flow worse than they do now after you're done.(assuming you haven't ever ported heads before) If I were you I would look into converting to either a 11/32" valve or better yet an 8mm valve from the sbc/LS platforms. Stick with 1.50" exhaust and get the 1.94" intake valves. The exhaust flow can be compensated with the cam, besides the smaller valve stems would give the exhaust more than the extra .050" bigger valve would anyway. .375 - .315"(8mm) = .060", that is .030" per side more area vs. only .025" per side more area from the edge of the diameter of the valve to diameter of the stem. Have the guides bronze walled to decrease size of guide to 8mm, your machine shop can advise you on that so make sure that work is in your price range. If you were going to have bronze wall guides installed anyway and you're planning on buying new valves also, stepping up to the 8mm sbc/LS valves will more than likely save you $$. I didn't see what trans you plan on using, but guessing you will be using your TH350 then I would go to a 3.90 or a 4.10 rear gear if this car won't see any freeway driving, plus if you decided to upgrade to a 200R4 then you would be all set then. This is assuming you will be doing rear suspension mods to aid in traction and strength. Got to go now. Derek
Hey Derek, I contacted SI valves, and got a quote for 11/32" valves with the correct length for the Buick heads, but they were basically $10.00/valve....so almost $13.00 Canadian each. We went with the TA big valve set. (Already have them in-hand.) With the heads Sean sent us, they appear to be in way better shape on the exhaust seats than the set we had. Going with bronze liner guides. (Unless the guides are totally whacked.) We just got the rear gear set and locker installed a month or so ago...changed from 3:08 to 3:73. Transmission was the first thing that spilt its oil all over my driveway when my son parked it, coming off the trailer when he bought it. (Just over $2000.00 in the rebuild for it....)
I probably didn't word that right, should of said will be able to do it more accurate with the bigger valves size roughed in for a beginner. I was in a hurry to get to the bank before it closed earlier so writing mistakes get made when one is in a hurry. Derek
Buy a roller, tight lsa, for badass sound. With roller you won't have to pull eng/trans again for lobe failure. I am happy with mine. Any future builds will be roller, maybe solid.
Sometimes it helps to grind in and near a VJ when you know it will be recut safely. If you already know the size you are finishing the bowl to, it's a no-brainer.
Love my setup. Roller cam 270/270 advertised duration (212/212 @.050) 113 LSA .544/.544 lift. 1.60 roller rockers. I think it will work well with some boost. https://youtu.be/KNFHmWvM9uk It's pricey but it is such a relief not worrying so much about initial break in.
I think the worry about initial breakin is way overblown. It's not that difficult. You put the lube on the lobes and lifter face. Run the engine for 20 minutes around 2000 rpm. Done. Then use quality oil with zinc already in it. Valvoline VR1 10w30 I use. I think some people run valve springs that are too strong thinking more is better. Thats not really true. Just causes more stress on parts. I can say I've been doing breakin like this for years and have never had a cam fail. I have not put a roller cam in a 350 Buick but have concerns over the added weight of the lifter. This drives use of a heavier spring to control them. That causes additional stress on other parts. Timing chain and front cam bearing come to mind. Your still going to use quality oil aren't you? So that costs no more than flat tappet oil. If cost is no concern the roller is probably better. Jacob, With the little duration your cam is running you could have kept the lift down around .450 and made the same power. Even a well ported SBB head has peak flow at about .450". After that point you could knock the head off the valve and gain very little flow.
Steve, even though max flow may be at .450" lift like you say, the advantage of having a cam that goes past the max flow lift is that the cam will still flow the same at the higher lift but here's the kicker, the valve gets opened to the max flow range faster and the valve stay there opened longer than if the lift were only at .450" max. If the lift is .450" where the max flow is as the cam rotates and the valve starts to come off the seat the air flow will only hit the max flow lift once at the top of the lobe. To make the cam stay opened longer with such an anemic lift the duration @.050" has to get bigger and bigger to keep the valve opened longer at the top of the lift. But if the valve is opened past the max flow of .450" like in Jacob's case the valve will flow at the max starting before the peak lift of the cam's lobe and continue to flow at the max at the top of the lobe and continue flow the max flow all the way on the other side of the lobe as the valves starts closing until the lift goes below the max flow lift of .450" filling the cylinder WAY more efficiently which = more power with less duration @ .050". So if the lift were even higher with his cam with the same duration @ .050" would get the valve opened even faster and spend even more time flowing max air it would make even more power. But we have to try and balance the over lift so its not so high that the spring requirements aren't more than the block can handle. Or so they don't have lifts so high that the springs coil bind. And that's why the "stock" type factory replacement cams suck and are antiquated junk in a sbb 350 with lifts below max flow. The go slow sbb 350 crowd seems to like the antiquated junk though. Derek
