Pretty sure a shorter pushrod will not limit the overall lift of a cam. Besides, duration is what causes the PTV problem. Sound like either he/she doesn't know WTF they are talking about or they're out right lying about something.
OK, school me on this deal... LS1 peeps please look in.
Looking at a '04 Corvette with an LS1. engine has an LG 'X3 cam, fairly big cam, probably one size larger (too much lift) than it should really have in it for street use. He used good springs retainers etc (bought the whole cam package) and had it professionally installed.
Owner says they used shorter push rods to limit the lift and hence avoid the need to fly cut the pistons.
Car supposedly runs fine, dynos at 400+ rwhp, doesn't have any issues other than normally found in applications with large cams (like low rpm drivablity).
Seems if they used shorter pushrods, there would be slack in the valve train on the closed side of the cam. I don't know how much shorter than stock the new pushrod are.
Are they depending on the hydraulics to absorb the extra clearance and keep the clatter down?
Any thoughts would be appreciated.
mardyn
Owner says they used shorter push rods to limit the lift and hence avoid the need to fly cut the pistons.
Car supposedly runs fine, dynos at 400+ rwhp, doesn't have any issues other than normally found in applications with large cams (like low rpm drivablity).
Seems if they used shorter pushrods, there would be slack in the valve train on the closed side of the cam. I don't know how much shorter than stock the new pushrod are.
Are they depending on the hydraulics to absorb the extra clearance and keep the clatter down?
Any thoughts would be appreciated.
mardyn
1 - 18 of 18 Posts
Hopefully the seller dont know what they are talking about. You cant use a shorter pushrod to limit lift all that will do is have your valvetrain geometry off. If it was professionally installed they may have had to use a shorter pushrod to keep the geometry correct. Also they shouldnt have to flycut with the LG x3 cam unless the heads have been milled.
I thought something sounded fishy about that whole scenario.
What would it cost to have a cam changed in an LS1/vette? Any guesstimates?
mardyn
What would it cost to have a cam changed in an LS1/vette? Any guesstimates?
mardyn
Exactly what I was thinking. Sounds like someone doesnt know there stuff.Pretty sure a shorter pushrod will not limit the overall lift of a cam. Besides, duration is what causes the PTV problem. Sound like either he/she doesn't know WTF they are talking about or they're out right lying about something.
It could have been that he assumed it was installed to limit lift, when actually it was to correct the valve train geometry in the first place.... maybe he misunderstood.
either way, it's (the cam) the one thing that's keeping me from pursuing the car further.
mardyn
either way, it's (the cam) the one thing that's keeping me from pursuing the car further.
mardyn
Is it a z06? They used a reduced base circle cam in the LS6 and most aftermarket cams are regular sized...
No, not an LS6, just a regular LS1....
mardyn
mardyn
I understand about the big cam and drivability, that is one reason I havent put one in my car yet. I am thinking about a GM hot cam or a Z06 cam myself. Only because I like the drivability of my car just like it is. The only thing you can do is test drive it for more then just a few blocks. I would try and do at least a 25 mile cruise. GL I hope it works out for you.It could have been that he assumed it was installed to limit lift, when actually it was to correct the valve train geometry in the first place.... maybe he misunderstood.
either way, it's (the cam) the one thing that's keeping me from pursuing the car further.
mardyn
Mardyn, I'm betting the guy had the work done and doesn't really know what he had done (if that makes sense). Maybe find the shop that did the work and talk to them to see exactly what was done. Surely he has some type of receipt or paperwork. Cam swaps aren't that expensive, but an LS1 long block is...
Yep like said above, shorter pushrods wouldnt do anything except tear up some valvetrain if they were too short for the application.
Swapping a cam in a LS motor is a breeze! Just pull front accessories and timing cover,valve covers, remove rockers, spin motor over a couple times and the lifters will stay up in their cups. Remove cam, put in new one and put everything back on. No need to remove intake or heads.
I make it sound easier than it is but seriously, it is pretty easy on these motors. If you worried about a lifter dropping you can get strong pencil magnets and put one down each pushrod hole till it sticks to the lifter then use some wire to tie all the magnets together. If one does drop then the magnet and wire will catch it.
Swapping a cam in a LS motor is a breeze! Just pull front accessories and timing cover,valve covers, remove rockers, spin motor over a couple times and the lifters will stay up in their cups. Remove cam, put in new one and put everything back on. No need to remove intake or heads.
I make it sound easier than it is but seriously, it is pretty easy on these motors. If you worried about a lifter dropping you can get strong pencil magnets and put one down each pushrod hole till it sticks to the lifter then use some wire to tie all the magnets together. If one does drop then the magnet and wire will catch it.
On the Vette you have to drop the steering rack as well, but like posted it is pretty easy...
Sounds good to me. I would assume since he built it right, I bet the vette is very clean. I am not sure of the specs of the LGx3 cam but most likely depending on the LSA it would require that you either get shorter pushrods or fly cut the pistons. It has to do with piston to valve clearances. I don't know much about it at all, but I would call LG and ask them. Is it stock lifters or LS7's?
i have a xr281hr cam-- high .500s lift and 112 lobe sep.. and i drive it every day.. no problems with driveability. the TUNE is what matters.. most tuners will tune it to run great on the dyno, but could care less about street manners.
Yeah, it's a pretty nice car... reasonable miles for the year model, interior is like new, fairly new tires, plus the guy has already bought a new 'vette, so this one is in the way.
I'm considering throwing an offer down on it...
I'll do a little more investigating on the cam ordeal and report back later.
Thanks everybody, for the comments.
mardyn
I'm considering throwing an offer down on it...
I'll do a little more investigating on the cam ordeal and report back later.
Thanks everybody, for the comments.
mardyn
Is it on CF?
and dont worry I already have one so i am just curious
and dont worry I already have one so i am just curious
Yeah, I'll post up a link next time I'm over there.
mardyn
mardyn
1 - 18 of 18 Posts
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