STAR

iTrader: (1)

I'm planning on porting my stock 243 heads and would like to use a .040 gasket over stock. Is this change enough to require shorter pushrods? What distance can be had before the need to change pushrods?

djfury05

iTrader: (30)

It will depend on how much preload you are running on your lifters. I changed mine from ls1 lifters to ls7 lifters with my cnc'ed 243s and I had 7.400 pr's before. I used stock gm mls and measured pr length and it came to 7.3 at zero lash. I checked the lifter specs for proper preload and with my 7.400s I had .100 preload which is more than acceptable so I re-used my 7.400 pr's. Stock graphite gaskets when compressed are around .050 I believe and stock gm mls when compressed are around .052-.054, or so I've read. With yourself wanting to use a .040 gaskets you will be .010-.014 thinner give or take.

silverZ98

iTrader: (6)

everything i read when building my motor the ls7 lifters like .050 to .075 preload so .100 preload seem alittle much. i know when i did mine i ended up with 7.325 push rods thats with the .050 for the preload. was all so told alil less on the preload is better than being tight. just valve train alil nosier but was told it would be with the lobes the cam ground on too

djfury05

iTrader: (30)

I will do some more research on it.. valvetrain noise is similar to cam only which was just slightly louder than stock.. I have wanted to try different length pushrods and the car is at RPM right now so maybe we can swap in different pr's and see how it sounds. I do get what your saying though. With less preload would probably come less wear and tension on the valvetrain increasing longevity at the cost of noise and vice versa.

silverZ98

iTrader: (6)

are the repairing it? or you just not got it back in town yet?. suxs it happed man.
i got 4 different lsx style book i have read before and during my motor build and even called a few ppl that have built many lsx motors and they all said about the same thing and i messrued my push rods like 4 times to make sure lol. i know i went on the light side of preload but so far so good for the last 400 miles of break in. the xer lobes on my cam are alot more aggressive than my old cam so i blame alot of the noise i hear on that and alil on the light preload set up. im hoping to get car to rpm in next week or 2 to have it tuned all most to my 500 miles for the clutch break in

STAR

iTrader: (1)

I already have a cam in the car and have upgraded the pushrods and the valvetrain is very quiet and pulls strong to redline. If I replace the gaskets to a .040" and lets say I mill the heads .020 that would be a difference of .030" respectively. To keep my geometry the same and with the same preload I have now would that require a pushrod .030 shorter?

djfury05

iTrader: (30)

The car never left the dyno lol.. it happened on the last pull.. so far I have acquired Art's old motor which had flycut pistons and rotating assembly and I'll be taking that to RPM Monday and then they'll send all the parts to Danny Perry for him to do his magic for me. Heads will be sent back to AI for fixing.. hopefully for free due to what happened and why it happened but we'll see. Should be up and running again by January id hope.

djfury05

iTrader: (30)

You are correct sir as long as whatever preload you end up with falls into the lifters recommended specs

01ssreda4

iTrader: (96)

Absolutely no point in speculating. Find your preload you want to be at, then measure for pushrod length, and if by some stroke of luck, the length you need is what you already have, well your piece of mind is the reward for your patience in measuring. But I'd be willing to bet you will be ordering pushrods. $100 to ensure your valvetrain lives a long and happy life is a small price to pay

silverZ98

iTrader: (6)

i agree i did mine and went on the light side of preload but feel its done right and i got what i need. even with a lil bit louder valve train. but the cam has some to do with that too