ssinister550

iTrader: (8)

i have a buddy that is putting a 5.3 in a fox body strip only car. the car will weigh ~2500 lbs, have a th350, like a 456-ish gear or so, and probably like a 200 pill of spray... he's putting a edelbrock carb intake on it w like a holley 750 or something to that effect, and now for the cam: its a comp 240/244 607/610 on a 111+2 Lobe sep. I told him there should be no problems (P to V wise) as there are plenty of people running similar cams with harder lobes (I.E the MS4: 239/242, .649"/.609", 111 LSA) on stock ls1's which have identical piston to valve clearance specs as 5.3's. just wanted to see if anyone would validate my point or if there is anybody who disagrees with me and thinks this cam will hit. I understand that all lobe ramps are different and in some cases a smaller cam could be closer to hitting than a given bigger cam if the smaller cam has a harder lobe but this is an LSR cam and for example the ms4 cam has an lsk intake lobe which is a much harder lobe and i know of people running the MS4 on stock bottom end LS motors. In other words, I just want some backup so i know that im not misinforming him that indeed this cam WILL run... any help much appreciated.

hammertime

iTrader: (1)

No way to know for sure without measuring. The chances of finding someone with a cam that size in an otherwise stock 5.3 are slim to none. Asking a forum if it fits and trusting their opinion is foolish at best.

Something to consider, that LSA is probably better suited to a fuel injected engine. A carb will probably like it much tighter, albeit at the risk of reducing PTV clearance.

Longshot LCMS

iTrader: (1)

That cam is beyond the ragged edge of safe, IMO. Ultimately the only way to KNOW is to check... I wouldn't push it though. That cam is very comparable to the MS4 which is pretty much the biggest you can fit. Not sure about the dimensions on the 5.3 and what it allows though, you may be right about it being the same and allowing a cam this big... However, considering the displacement of the 5.3 I really think that cam is leaning more towards the ridiculous side. On an LS1 I'd say maybe, but it's too big for me personally... and a 5.3 I wouldn't even consider it... That's just me though.

ssinister550

iTrader: (8)

i"m not asking and just going to bank on other peoples opinions, I know it will run i just want some reassurance i guess you could say. I told him he needs to check but his method of doing things is kind of primitive to be polite lol and he said he doesn't want to check it. he says if it spins over by hand and doesn't hit he's going to run it and i told him that's not all there is to he has to consider rod stretch and heat expansion among other things but that's his deal. as for the lsa you could be right or wrong but the 111 will be fine considering i just had this cam laying around and gave it to him for 200 bucks because he didnt want to order a custom grind but thanks for the input.

ssinister550

iTrader: (8)

I know for a fact all of the dimensions are the same I've measured the free drop on all the 5.3 castings and all the ls1 castings and they're the same and the pistons all come out of the hole the same amount and the stroke is obviously the same the only difference is the bore size where the 5.3 is 3.780" bore and the 5.7 is a 3.898" bore which makes about a 20 cubic inch difference. as for this cam being too big even if it does clear I disagree because for a drag race only 2500 lb car this cam in a 325 cubic inch motor is definitely not too big especially when people run bigger cams in smaller motors all day long in race cars if this was a daily driver truck then i would agree but this is a race car (on a budget of course) so I think it is sized appropriately for the application i just want to see if anyone has any strong doubts that it wont clear. thank you for your input though it is much appreciated.

Longshot LCMS

iTrader: (1)

Well if it's a full race car I suppose I could see it being used... Drivability will suffer for sure, but if its built for WOT only I could see it... Good luck with it!

ssinister550

iTrader: (8)

thanks man

LTX355

iTrader: (15)

the early 5.3 out of 07 and down classics have dished pistons and with stock 5.3 heads with smaller valves unmilled u should have more room then an ls1 per say. to take advantage of the cams powerband for a 5.3. arp or of = rod bolts is a must or better rods along with a single plane for carb, nice set of springs and pushrods. not taking advantage of the rpm potential would make it a waste.

ssinister550

iTrader: (8)

dished pistons huh? I assume they are a similar dish to the lq9 then? good to know, that i wasn't aware of. thanks though that is even more reason why this cam should run fine... and as far as rods/rod bolts go I've had experience with these stock bottom ends and seen a factory rod/rod bolt bottom end turn (untouched from chevrolet) 7800 rpm for over a full race season with a solid roller set up so I'm going to say the factory rods and bolts will suffice. As for springs and pushrods he will be running the patriot gold .660 springs and a good hardened pushrod so the thing should be fine up to whatever RPM the cam makes power to and then some which shouldn't be much more than 7k considering the LSA of the cam, and the fact that it is a hydraulic roller cam, so it should be good to go as far as that stuff goes... but once again thank you for the input!

AznMuscle

iTrader: (7)

Just for a small window of hope..I am running a 242/248 111 lsa, bone stock bottom end. 20k miles on my set up, no issues motor wise (related to H/C set up). Need rings, but thats another issue.

ssinister550

iTrader: (8)

yea see i knew it... what are the lift specs on your cam? and out of curiosity can you tell me more about your setup and how much power your making? and what your power curve looks like?

johnster

iTrader: (27)

thats alot of cam 4 a 5.3, the 5.3l heads have a 62cc chamber so thats going to be tight,

AznMuscle

iTrader: (7)

LOL at the power curve. Not a lot of torque, but I didn't want super under the power anyway. My set up is 85mm lid and MAF, P+P stock TB, ls6 intake, bone stock 243 heads, 242/248 .621/.615 111 lsa, UD pulley, 1 3/4 LTs, ORY, SLP catback, ls7 clutch, 4.10s. 423/382 with the heavy 18x10.5 wheels on the back. In ~1600 DA with 255 18s up front, and 26x10.5 ET streets and a weak 1.86 60', I went 11.993 at 118.54. 7.8 at 93.63 in the 1/8th.

ssinister550

iTrader: (8)

yea but in a drag race car that's what you want is a lot of cam

and the chamber volume has almost nothing to do with piston to valve clearance, what matters is the free drop measurement of the cylinder head, and the height of the piston in relation to the deck surface... but 9 times out of 10 the intake valve will be closest to the piston ~10 degrees ATDC and the exhaust valve will be closest ~10 degrees BTDC, so for tightest p to v you have to figure out where the above mentioned values are ~10 degrees B&ATDC which can be done but I don't know the exact formula because it involves a bunch of trig and other mathematical craziness like something to do with the cosine effect of the valve angle in relation to how high on the lobe of cam the valve is lifting ~10 degrees B&ATDC and something about the cosine effect of the angle of the rod throw of the crank in relation to where at in the cylinder the piston is in relation to the stroke ~10 deg. B&ATDC and a lot of other things i haven't figured out yet. But as I was saying chamber volume has basically nothing to do with all of that but thank for your input anyway

ssinister550

iTrader: (8)

Huh, sounds pretty healthy yea your cam has more duration AND lift on the same LSA as mine so I def have no doubt this one will run so thanks for your input it is much appreciated