dirty white boy
50 yr old Juvenal delinquent
should not have any eye brows if stock!
thats correct these factory roller cam 318s is close to 9 stock!Ok so I dont know why i didnt think of this before but I looked in my part info book and for 85-86 318 pistons the comp height is listed at 1.76 so with that number it puts me .062 in the hole instead of .100 if I put that on the calculator it gives me a cr of 8.87 that's no eyebrows either. That's is not as low as I thought. A quick and easy .015 off the heads will put me over 9:1 that is very doable. Of course I really know until I pull the heads and measure my pistons and cc my heads.
Apologies for the thread derail.
Regarding Comp stuff, why is that? Hardening? Ground for smaller tappets? Poor quality control? Poor customer service? I am not trying to be a smart ***, I'd just like to know because I am considering one of the following cams for a 1991 hydraulic roller LA360 build I am working on, shooting for a 9.5:1 compression with machining block and possibly the heads, pistons, and gaskets.
Lunati 20200712
Voodoo Retro-Fit Hydraulic Roller Cam - Chrysler 273-360 282/290 - Lunati Power
Requires 2800 stall
This will most likely require a new torque converter, as my current TC is a 2400 stall
XR274HR-10
20-811-9 - Xtreme Energy™ Retro-Fit Hydraulic Roller Camshafts
requires 2000 stall, and I can get away with a 9:1 compression
I can keep my current 2400 TC
XR280HR-10
20-812-9 - Xtreme Energy™ Retro-Fit Hydraulic Roller Camshafts
requires 2500 stall
Maybe I can squeak by with my current TC 2400 stall.
As it stands with the above three, I am kinda leaning towards the Lunati, and will eat a lot of Ramen, peanutbutter and oatmeal and spend that few hundred grocery bucks on a new TC.
I know I will have to go with new springs no matter what I get, even if I decide to just go with a mechanical flat tappet which I would actually prefer, since I really dislike the large mass hydraulic roller lifters when compared to mechanicals, which require lighter springs. (It looks like I'm going to want to talk to AJ about some math regarding speeds, gearing, tire size, HP, and rpm at the traps, and I've been procrastinating on that, heh).
Clean out your in-box, I have a XR280HR-10 cam that I am not using.
There ya go... that's how it's done. With those numbers above, I get 8.6 SCR with a 1.755 CH (.067" below deck) and no eyebrows but adding 1 cc for the gap down to the rings, a .028" thick head gasket. So that is close to your 8.78 number.Here is some more brainstorming if you do the math 3.31/2=1.655 + 6.123 for the rods - 9.6 for the deck that puts us at 1.822 (max compression height at top of the block) so if I am .1 under the block then that leaves us a piston height of 1.722. The largest c h piston i can find in the cheap range (ie speed pro etc) is 1.755 with no eyebrows. That will put me at 8.78 then if I could mill my heads a little let's say .020 that that will put me at 9.18. That Is about where I want to be. That is still gonna run me about 140 for the pistons plus machine shop labor for getting the pins pressed and heads milled. But this would be a better bottom end. If the bores are good and not wore
Just for info.AFAIK; as far as I know.
The early rods are lighter than the 73 ups, maybe as much as 100 grams.
Therefore to maintain balance, you would need the matching pistons and crank.
Yeah understood. I just was relating someone else's measured height below deck for some '68 318 pistons from a post here on FABO, in which they seemed very confident. It lined up with my '68 273 piston numbers, so I ran with it..... but now you have made me question that again.nm9
in regards to my source in post #154,in the book, they didn't say where the numbers come from. But I see the same numbers in the Bulletin Book
Ok thanks buddy I wasnt sure on those heads I looked it up and I found a list that had how much was need to remove 1cc for a bunch of different heads I didnt see 302 heads so I just went with la 318 heads it said .005 so that what I went with for 360 heads they had it listed at .0048. Either way if I'm above 8.5 I'm not going mill anything....yet ;).There ya go... that's how it's done. With those numbers above, I get 8.6 SCR with a 1.755 CH (.067" below deck) and no eyebrows but adding 1 cc for the gap down to the rings, a .028" thick head gasket. So that is close to your 8.78 number.
For milling the smaller area of the 302 clamber mean you will have to mill something like .007" for each cc taken off. So milling .020" would get about 3 cc's off and if the chamber start at 65 cc's then that 62 cc result would get you to about 8.9 for SCR. Getting better. I'd go at least .030" and also measure those head chamber volumes carefully, they may be smaller than you think. If you get the chamber down to an actual 60 cc's then you get to 9.1 per my numbers, again, using the .028" thick head gasket.
With that, you are at around 7.3 for DCR IF you advance the cam timing to an ICL of 104. That is a ton better than where things were heading before.
Yep, those numbers you list are for open chamber heads. The amount needed to mill for each cc reduction in chamber volume goes up when the chambers become closed.Ok thanks buddy I wasnt sure on those heads I looked it up and I found a list that had how much was need to remove 1cc for a bunch of different heads I didnt see 302 heads so I just went with la 318 heads it said .005 so that what I went with for 360 heads they had it listed at .0048. Either way if I'm above 8.5 I'm not going mill anything....yet ;).
136 on ebayYep, those numbers you list are for open chamber heads. The amount needed to mill for each cc reduction in chamber volume goes up when the chambers become closed.
BTW what kind of price are you getting for the Speed Pro's?
Those are different ones the ones I'm talking about didnt have a pic of the pistons he sent me a message with more pics they are factory 318 pistons no eyebrows. According to my book 645 is the same thing my engine already has so those are probably identical rods and pistons that is in mine lol I will just stick to what I have its not the extra money to me. Especially if I'm at 8.5 cr that is ok for street use. I would rather be above 9:1 but I can always tackle that later. I read a post on here where a guy milled 302 heads to 57ccs according to my numbers it would only have to remove less than 5 ccs to get to 9:1! Give or takeBTW, I edited my last post with some more info/questions... we keep typing at the same time LOL
Those 273 rods should weigh the 726 grams. The rods you have in the '80's engine should weigh the 758 grams; that -645 PN looks right for the later, heavier rods. That is the one matter that may cause balance issues for using the early rods with the later crank. The heavier 273 pins should be able to be used to correct this but it is not a straight gram for gram change if the weight is added at the top end of the piston-rod assembly. Bobweight has to be computed for the original and new combination and the pin weight adjusted to make them match. The math is not hard!
Can you get access to a precise gram scale locally?
I think I see those pistons and rods on eBay. Look at the dish on the top of the piston; that is going to add something like 7 cc's + or - to the chamber volume and drop SCR and DCR by at least 0.5 points. Plus they are .040" over.... looks like non-starter to me.
Mmmmm.... I stuck my neck out and made an educated guess at the .007" number.. so, well OK, maybe .006" for 302 chambers. .0053 just computes out too small, even for the early 273 head chambers, which is what they are talking about with that .0053" number. If you milled off .030", then the difference is only 1-1.5 cc's anyway. So, let's compromise on .006" milling per cc and you'll be darned close. If you over do it with milling, it is only going to make it better. I can't imagine much price difference if any to mill .020" vs .030".According to this it says .0053 to remove 1cc does this sound about right?
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Mmmmmm...... Backwards logic..... 8.5 is (marginally) OK for casual drag racing since you will rev the crap out of it everytime you launch and can use a high stall TC to get past any low RPM 'dead zone'. Low CR on street/driver use is only OK for grandma going for groceries, or hauling logs. 8.5 is 8.5, nothing better and DCR will be the mid 6's which is below the DCR of a stock 318.Especially if I'm at 8.5 cr that is ok for street use.
Yea I agree with you I'm gonna pass that the same thing that is in I now. And as far as the milling numbers go I wasnt trying to prove you wrong or anything I believe you that's just the info I had found and was going off of before you commented on that subject. Furthermore milling of the heads is not a top priority right now that will be a later project if I am not happy with the performance when I'm doneMmmmm.... I stuck my neck out and made an educated guess at the .007" number.. so, well OK, maybe .006" for 302 chambers. .0053 just computes out too small, even for the early 273 head chambers, which is what they are talking about with that .0053" number. If you milled off .030", then the difference is only 1-1.5 cc's anyway. So, let's compromise on .006" milling per cc and you'll be darned close. If you over do it with milling, it is only going to make it better. I can't imagine much price difference if any to mill .020" vs .030".
IMHO, I don't think I;'d bother with those eBay rods and pistons. There are better ways to spend those $$.
Yes absolutely agree. But I do kinda drive like a grandma soo.....Mmmmmm...... Backwards logic..... 8.5 is (marginally) OK for casual drag racing since you will rev the crap out of it everytime you launch and can use a high stall TC to get past any low RPM 'dead zone'. Low CR on street/driver use is only OK for grandma going for groceries, or hauling logs. 8.5 is 8.5, nothing better and DCR will be the mid 6's which is below the DCR of a stock 318.
Edit to add: You mention getting down to 57 cc's; that would be an interesting approach..... put the $$ in milling and save $$ on pistons. Assuming pistons .075" down in the bore, flat tops, and .028" thick head gaskets, you're around 9.25 SCR, and DCR is now back up to around 7.3-7.4 with that cam. Keep in mind that when you mill that much, then milling the intake side of the heads may become necessary (more cost), AND you are going to possibly push the heads down far enough that the pushrods might be a bit too long. With some tricks, you may be able to get past the pushrods (IF it indeed any issue, which it may or may not be; it's a case-by-case thing, and completey dependent on the individual parts). That may be your lowest cost approach and forget any piston/rod changes.
Let me ask you (yall) this stop light to stop light will a cam like the xe256h or xe262h or luniti voodoo. Be a huge noticeable difference in the cam I have now? Like what are we talking here half a sec difference 0-60 or a couple secs lol