hybrid question, yes i searched

[Mr_Efficiency]

I know if i use a 3.1 bottom end with a 2000ish 3400 top end I need custom length pushrods cause the 3400 uses the fancy fulcrum (i think thats what they were called) rockers. but I also found out that if you use a 94-95 3100 top end you dont need custom length pushrods cause they use the same style rockers as the 3.1.

So does that mean I can run a 3.1 bottom end with a 2000+ 3400 top end with 94-95 rockers and i could use the stock length pushrods?

thanks

[TazMan]

No you still need custom pushrods. They hadn't change to roller rockers yet. They were stamped steel rockers but they have the same 1.6 ratio as the roller rockers.

[Mr_Efficiency]

I knew they were 1.6 ratio, I've heard of guys that have gotten away without custom length push rods cause they used the 94-95 top end. guys on TGP forums have put the 94-95 3100 1.6 rockers on with stock length pushrods no problems.

[TazMan]

I knew they were 1.6 ratio, I've heard of guys that have gotten away without custom length push rods cause they used the 94-95 top end. guys on TGP forums have put the 94-95 3100 1.6 rockers on with stock length pushrods no problems.

I asked this question a long time ago and I was told no by several people. I don't remember the reason it worked for some people. Something about a certain set of rockers that fit on this heads cause they were stamped steel, but worked with the old pushrods. I know I was told I would absolutely need custom length pushrods.

[3100 MPFI]

it is not so much the ROCKERS that is different, but the LIFTERS.

The 3.1 uses FLAT TAPPET lifters which sit FLUSH to the block mounting areas. The 3100 uses ROLLER lifters which protrude, and are held in with ANTI-ROTATION bars. So the 3.1 I think will have LONGER pushrods, and the 3100 will be SHORTER.

Just because they did it and it workes does not mean they are seeing the full gains.

When I had the camshaft in my 3100 REGROUND to custom specs, I just reused the stock pushrods. When I finally got around to replacing the stock pushrods with some CUSTOM ONES (that made up for the difference in material that was removed for the regrind), I got a NOTICABLE gain.

You would be better off taking some measurements, and then having some custom pushrods made.

[Mr_Efficiency]

and i probly shouldnt even bother asking but i guess you cant just swap out the lifters can you?

[TazMan]

and i probly shouldnt even bother asking but i guess you cant just swap out the lifters can you?

Well I think that was what they were doing. IIRC, there are a set of stamped steel rockers that bolt to the 94-95 heads and work with the old pushrods. If I'm right, I'm sure someone here has used them and will chime in soon.

[bszopi]

You can't run hydraulic roller lifters on a flat tappet cam.

[3100 MPFI]

One thing you could do is use a 3.1 MPFI cam (it will fit), and normal FLAT TAPPET lifters. You can then use the 1994-1995 heads with the stamped steel rockers, and the 3.1 MPFI pushrods.

That might work for you.

If you change the lifters (from one style to the other), then you have to do the cam as well.

[Mr_Efficiency]

I'm using the 3.1 bottom end, so I dont need to change the cam, I'm just wondering if i can use the 3.1 lifters in the 3100 heads.

[bszopi]

The lifters are in the block, not in the heads.

[IsaacHayes]

treeZ24 is running stock 3.1 pushrods with 3400 heads. He has aftermarket rockers but not sure if that makes a difference they are still 1.6:1. It may vary depending on your cam setup but he said on his it was close enough so he ran them. His car is fast too.
His cam specs:
duration = 210* at .050" (256* advertised) with .295"cam lift @ 112* c/l

Of course you are going turbo so a re-ground cam for boost would have to be considered if you are wanting a cam.

[TazMan]

The lifters are in the block, not in the heads.

I feel so dumb for even asking this but a google search didn't really help me much. I don't know why but I thought "lifters" was just another word for rockers. Sorry for still being such a noob. I'm still trying to get all the terminology down. So what are the lifters.

[bszopi]

The lifters are the parts that ride on the camshaft:



For valvetrain order, it goes CAM, LIFTERS, PUSHRODS, ROCKER ARMS. The ROCKER ARMS are mounted on the VAVLESPRINGS, and actuate the VALVES.

[Mr_Efficiency]

3100mpfi said the lifters was the reason the pushrods wouldnt work, but if i use a complete 3.1 valve train, cam, lifters, pushrods, rockers, with 3100 heads I should be ok right? I'm pretty sure thats what was said above but i just want to clear it up and be sure.