The 10:1 pistons will net too much compression unless you can use the .060" head gasket (and will put you .020" in the hole). What you'll need to do is use the 8.5's, zero the deck, use the cheaper .040" composite head gasket, and shave .020" off the heads. That will yeild you the 9.5 static you need with the TA 212 cam. Your quench will be about as good as you can get and risk of detonation is minimized. I think I remembered all that correctly...my meds are making my head a bit cloudy. :eek2: ---------- Post added at 05:34 PM ---------- Previous post was at 05:32 PM ---------- Heck I'd be happy to live in mine, I'd be cuddling up against that engine and sleeping like a baby. lol Is that pathetic or what ---------- Post added at 05:40 PM ---------- Previous post was at 05:34 PM ---------- There isn't a gasket diameter calculation? That would make it slightly lower.
Didn't we figure that the 8.5s are too far in the hole and by the time you took enough off the block and heads you would also need to take a bunch off the intake manifold side and get shorter pusrods? Head gasket diameter was 3.830 Yes, that is pathetic unless you had one of the old Buick limos with frig and TV. Paul
TA's 8.5's and 10's are the same except for the disch cc's I thought? That puts them .020 in the hole then. Hell I forget, that thread was many posts ago! Otherwise, you'd have to use the 10's and use a super thick .080" gasket if you were to zero the deck. You're going to have to true up the intake anyway unless you just threw it all together and ran the 10:1 SCR.
TA 10:1 are the only 1602s they have on the shelf. I was offered a set of TRW 340P here on the forum. Jim Weise sold them to someone who wants to sell them to me. I asked Jim what the dish cc is on those and his reply was about 8cc. Because there is no provision in the calculator for the amount taken off the head. I'm going to figure a .060 gasket (.040 gasket +.020 head shave) and it comes up to 10.18:1 and I'll just call it 10:1. Did I do that right?
If you are going to the trouble of buying new pistons then just use the 10:1 pistons and a 284 TA cam and live hapilly ever after. My other suggestion is to have Mike at AMP do the heads, then CC them when you get them back and THEN sort out what you need to do if anything to get your desired compression.... Likely you can just mill the heads 10 thou and the block 20 thou and then use the 40 thou thick gasket and be on your way with stock pushrods... This takes into acount you are not using the steel shim gasket the 68 engine same with. Why try to build an engine around the 212 cam when the extra compression will allow more camshaft and better fuel mileage most likely.
Well, I was listening earlier in the thread when someone said going above 10:1 will likely cause me to add octane boost to every tank. Mike at amp said his 2 reference builds using 212 cam were 9.5 and 9.7 with the 12 cc dish TA 1602 pistons. An TRW 8cc dish would put it just a bit over 10.5:1. Would I need the additive or not at that SCR or were the talking about DCR above 10:1? If so the TA 1602 is my piston. If I can save 150 bucks buying the TRWs and not have to deal with octane boost then I would do those.
The DCR should be kept under 8:1 with an iron head. The best thing to do here is what Sean said. Have Mike do the head first and he will measure the combustion chamber volume after the head is done. Mike should also be able to open up the chamber a little to keep it at 58cc (or more) after surfacing the head. Use the TA 1602 piston and actually measure the dish volume to make sure it is 12cc. Have your machinist take the minimum off the block deck to get it true. Then use the head gasket thickness to adjust the compression ratio. The head gasket will be copper. Example: if the piston is .020" in the bore and the head is 58cc, then a .060" gasket will give you a 9.55 compression ratio with a 7.98 DCR. If you want a little more margin use a .066" head gasket. After you look at the price difference between the .040" composite gasket and the .060" copper gasket you will figure that it is cheaper and easier to do as Gary and Sean suggested and trade the TA 212 in for the TA 284-88 cam. Paul
To summarize this for you: 1. If you use the low comp pistons then a TA212 cam is better matched 2. If you use the high comp pistons the TA284 cam is better matched 3. Do not get to detailed with your compression calculations till you know your actual head CC and piston depth in the hole. Then compare the piston pin height from the stock piston to the aftermarket piston you pick and then you will have all the info needed to calculate the compression and go from there... Many times people spend hours crunching numbers and buying all sorts of parts and then find out the heads have been milled and are already at 50 CC and it throws everythign off... In an ideal world everything is measured before ANY parts or machine work is done...
lol This is what I said to do several posts back... but yeah, do as Sean said to do and you'll be fine :laugh: G
Yeah! I know! Don't get your feelins hurt Gary! Sometimes it takes the right format for my brain to absorb things.:laugh: It's not like I didn't hear ya... It's like it had to be said the right way at the right time. You said it in the middle of a traffic jam in my skull! LOL!!!! Much thanks to all who participated in the exercise. It was fun and I promise to keep everyone in the loop while this endeavor progresses.
Yep, back in post# 31 sorry bout that! I went back and added you to the credit list and even gave you top billing. This short term memory thing can be a real pain. Jeff, good luck and thanks for letting us share in your project. Paul
lol c'mon guys I was teasin around again. It doesn't really matter as long as he gets the info he needs. Just cuz I said something in the middle of one of my monolog paragraphs (notice I try to keep reading as painless as possible and break up the post into little paragraphs) doesn't mean it's gonna get noticed or sink in right away. It's good to get more than one opinion anyway! Man posting in these forums is way more fun than I would have ever imagined. lol Git'er done man. Keep us posted on how it's coming along and you can get help if you run into any snags. G
