Hey gang, just getting ready to assemble my motor and I'm getting some conflict about the cam I planned on using between some friends, my engine builder and the guys that ported my heads. That said; I'll give a rundown on my combination. - JE flatops, 0 decked 11:1 comp. - 464 block, with oil mods. - stock crank, and rods. Shot peened and balanced. - TA Stage 1 aluminum heads ported, flow numbers are around 320 on the intake and 220 exhaust side. - SP-1 intake port matched. I was going to run TA's 310 cam - 515/232 with 110 LC. I orginally wanted to maintain some streetability in the car (71 GS) That's why I went with the 310. Now I know I have gone a little more radical than I had planned:Brow: but does anyone think my cam selection is too small for this setup All so, will I have too much cylinder pressure with the 310? I'm a little confused right now on where to go with this, so any input would be greatly appreciated.
Does anybody use anything but a TA came besides me. I had comp custom grind a solid flat tappet for me and I am very, very happy with my engines performance. It has succeeded everybody's expectations including mine. I feel most of it is with the cam. Comp claims thier new ramping profile (I can't remember what it is called) is one of the most efficient and power porducing on the market.
Streetablity, 11.0 comp, and 232 at .050 don't go together in my book. YOu would have to run race gas because of the cylinder pressure so what's streetable about that? Depending on Lobe seperation, you should consider something between 245-255 on the intake which should allow you to at least run pump gas on the street with the right timing. Plus with driving on the street, the more cylinder pressure you run, the hotter the motor will run and the more work it will take to try to get it to run cool. Being you said "Some Streetability" means to me that you don't drive around with a/c on and drive it back and forth from work everyday. I drove my GS around town and took it to work on nice days with a 255/265 108 lc cam. It sounded awsome and to me it was plenty streetable. I even ran power brakes with it and it idled at 850-900. I ran a 2004r w/9" converter which made it that much better. Of coarse, I only ran 10.0 comp and I never ran race gas even with the nitrous.
Thanks guys. I think I'll be selecting a little beefier cam for this set-up. As far as selecting a custom grind from comp; I live in the Toronto area and there are not alot of serious BUICK builders around. Thus it's hard to get a good overall strong opinion on subjects like this. That's why I posted. Up here, when you tell people your building a BUICK, they look at you like you have two heads! I've only been into BUICKS for about 2 years, and this is my first 455 build, so I don't feel I have enough savvy to make to make a good custom grind selection. For this build it was just much more convenient to select one from TA, as they sure have a heck of alot more experience than me. Jim
If you have the JE flat top pistons and are zero decked, your compression is over 11:1, more likely 12:1 +. You will not be able to run pump gas no matter what camshaft. If you are looking for a cam that has good streetability, yet will take advantage of the work on your heads, look at the TA 290-08HL. Anything much beyond that will begin to compromise power brakes and force you into a big converter & steep gears. A combination like that will give you a 600 HP daily driver (if you can afford the gas)! Dave
Dave, thanks for the reply. I bought the J.E.'s from you guys. At the time I was of the understanding they where 11:1 pistons. When I crunch the numbers in the comp. calculator with campbellenterprises.com, I come up with around 11:1 These pistons do have a 20 cc valve relief in them. I'm using the orange crush gaskets as well.
Playing with the DCR calculator, and starting with a 10.95:1 SCR, in order to end up with a 8.3:1 DCR (max on 93 octane, aluminum heads, good quench), you'll need the intake valve to close around 71 deg (advertised) ABDC. Putting the intake center line at 106 deg, this gives you a 290 deg adv int duration. This is roughly a 240 deg duration at 0.050". With good exhaust flow and AL heads, I would keep the exh dur roughly the same or only a little more. My swag at it would be: 290/290 adv, 238/238 @ 0.050", 110 LC, 4 deg advanced (I believe Jim W./TA has one similar to this) or a custom (like Lunati) 290/295 adv, 240/245 @ 0.050", 110 LC, 4 deg advanced.
Scott: Thanks very much for your input. What is your reason for keeping the intake and exhaust duration close together? I was considering the cam Dave @ TA said (TA 290-08HL) duration is 238/248 on 110 LS. Do you think this is too much of a dur. gap?
guss: Jim W. has done some dyno testing and has good results with a single pattern cam and AL heads. It's because the exhaust flow on the aluminum head is so much better. However, you have more flow on the intake side than most, you might need more exhaust duration to account for the difference in flow between exh and int.
That's plenty of exhaust, if it was flowed without a test pipe. TA's 290H cam at 238/238 on a 110* lobe center is a nice alum head "hot rod" cam. Wild, but still managable idle quality. Got a few of them running around now. Pretty easy 580-600 HP combo, if you've got the bottom end for it. Single plane intake a must. 310 a good cam, but will be off about 20-30+ HP from the bigger one. (that advertised 238* cam, actually comes in at around 240*, from a couple I have checked). Beth and Dana's wagon motor, with a 230/234/110* lobe center cam made 540 HP, 565 Tq. That's TA's "Car craft" cam, and it's a nice way to go if you want super streetablility, go with the 310 or the CC cam. The 310 would have made a bit more power, but we wanted to make sure that we did not over-cam a 4500 lbs wagon.. turned out to be a good choice. JW
When I called TA Dave said he never heard of a 290H cam. I ordered a cam with the specs above and ended up with a 296/296/, 238/238@.050, 540/540. When I recieved the cam I called TA right away. Dave said he gave the specs. to who grinds their cams and that is the grind they made. Will the diff. adv. dur. affect performance in any way? A reply would be greatly appreciated.
DCR, SCR down Can he run thicker head gaskets to lower the SCR if needed and still run the 310 cam that he originally wanted? Or will this kill the quench and the torque?
You should be fine.. it's just got a little less agressive lobe on it, which ain't a bad thing. Mike calls it a 290H, but it's a custom deal, not in the cataloge, so that could be the confusion. JW
Re: DCR, SCR down Guzz needs to let me know the TA part number of his pistons, the deck clearance as installed (or what he's shooting for) what gasket he is using, and the CC of the cylinder head. Unless I miss my guess, if he has current parts, he has the JE/SRP piston, with the 20 CC conical dish. With the typical 65-68 CC STG 1 Alum head, that works out to 11-1 with 65 cc heads, and 10.7 with 68 cc heads 10 3/4 is what I consider the limit with pump gas, and these smaller cams. Based on several motors of experience now, you can run these smaller cams with 10-6 to 10-7 compression, on pump gas, with no detonation, but it's certainly the limit. In answer to your question, if the head chambers have not been worked, which is the only way to get 64-66 CC with this head and TA valves, then that is what needs to be done here. Heads will pick up the low valve lift flow numbers, compression will come down to managable levels, and motor will make more power, than if you kill the quench with thicker gaskets. 68CC is the number to shoot for with .040 gaskets, that 4.350 bore piston with the 20 CC dish/reliefs. What your doing in the chamber is pulling the lip on the topside away from the valve, blending out all the sharp edges, and working the casting away from the valves a bit on the spark plug side. That's part of our upgrade package to these heads, and well worth the effort. JW
Jim Weise: Thank you for the reply. As it turns out the piston I have IS the 12:1 flat top. Part # TA-1611. I talked to Dave last night on the phone, and these pistons only have the valve reliefs cut in them.No conical dish. I originally was after an 11:1 piston and the reason I thought these were 11:1's was because the spec sheet says it has a 20 cc dish, and Dave said that should not have been on there. Now for my gaskets Im running the .040" Orange crush. We checked the cc of the head and it's about 66. The problem I have now is I've already decked the block to 0 height. So I'm up over 12:1 now. With that kind of squeeze do you think that's too much pounding on a stock crank. The crank was balanced and the rods were shot peened, and I have the main stud kit. Jim N
Jim, You should be ok, as long as the motor is well balanced, and you keep the rpms down. Say a max of 6200. Unfortunately, now your choices are to use a thick head gasket to get the compression down. TA has the multi layer steel cometic gaskets in up to .120 thick.. get something around .105 and that will get the compression back down to reasonable levels, around 10.5 to one.. (.100 would give you 10.6, as those pistons should have 8 CC valve reliefs in them. Your other option is to go with a .060 gasket, and a hydraulic cam in the high 240-low 250* range. That pretty much elimates running the pwr brakes, and AC or anything like that, and will require at least a 3500 stall converter, but you may sqeek by on pump gas with that deal. The best alternative is to get the right pistons, but that is not the easiest one. You could also cut .020 or so off the pistons. Or build it at 12-1. and run race fuel.. Lots of ways to handle this issue. JW
Jim, I don't have any problem running pump/race fuel mix at all. Running a thicker head gasket is my best option right now as I have 0 decked the block and really don't want to cut the pistons. My main concern is if I'm going to be blowing out head gaskets left and right. Last night I ordered the TA 290-08HL 238/248 from Dave @ TA. WOOPS. Again, too little duration for that much comp? That is, if I keep it at 12:1 Thanks Jim
Gusszgs: I get 12.3:1 SCR with a 0.040" gasket and a 9:1 DCR with a 110 deg LC, assuming 4 deg advanced. Defenitely too much for pump gas, I would guess you'd need a 50/50 mix of race gas and 93. With a .105" gasket, I get a DCR of 7.8, which is within pump gas ability. With an 0.090" gasket (if there is such a thing) I get a DCR of right at 8:1, which is good for pump gas (you could run up to 8.3:1 with AL heads and good quench, it's just that your quench is not optimal). My opinion: Use Jim W.'s last suggestion, put the 0.040 gasket in it with some race gas and go have fun racing !!
