3900 headgasket on 3400 head and other lz9 info

[ericjon262]

I was really just going to raz Shaun about doing a VVT delete.

if I can't get a cam ground for an LZ9, I might end up without VVT when I get to that point... that being said, I'm a real idiot, I'll make it happen somehow...

Thats a clean install in that 88.

Dam Str8. Attention to detail pays off.

we have a bunch of work in it, and there are still some kinks to work out, but it runs and drive nicely. he was helping me bleed the brakes on my garbage and let me drive it to the parts store. it gets up nicely, especially because it's a stock engine. it would be nice to see what a cam would do to one.

I really wish I could convince him to start a build thread and keep it updated, but he doesn't want to do that for some reason.

[Shaun41178(2)]

Good luck on getting a drop in cam for an lz9. Call any cam company. The people on the phone will check their catalog and tell you they dont offer one.. Then they will say its not worth thier time to make any. And in reality its not.

What you have to do is convince a company to make a non vvt cam based off of the lnj cam. Comp cams makes the 3x00 cams, because the journal size matches the 80s sbc style cam blanks. Its all about having the blanks supposedly

It seems companies dont have blanks for the journal size of the lz9 cams. I called years ago and couldnt find one. Now maybe things have xhanged.

You could always have a custom cnc billet cam made to your specs. Expect to pay 700+ for a one off.

The lnj cam at 200 bucks is decent but cam spacers and a cam with more lift and duration will give another 30-40hp. The lnj cam will keep power around 240 bhp.

Even with how cheap theae engines are alot of people still arent jumping on them.

[ericjon262]

yeah I wasn't figuring it would be as easy as "hey comp, I want a cam" I have a stock cam here, and was intending on taking measurements and cutting a blank or two, and having that ground.

[pmbrunelle]

Aren't there places that grind new lobe profiles by simply removing material from a customer-supplied factory camshaft?

[The Dark Side of Will]

Aren't there places that grind new lobe profiles by simply removing material from a customer-supplied factory camshaft?

Delta is a common regrinder in the 4.9 community. They have standard grinds for 4.9's, as I understand it.

Web is a premium regrinder who can weld material on to cam lobes and then grind whatever profile the buyer wants.
http://www.webcamshafts.com/

Mark the crazy Ferrari guy got Comp (or Crane?) to grind his home made blanks from round for... ~$100 a lobe.

[Shaun41178(2)]

Aren't there places that grind new lobe profiles by simply removing material from a customer-supplied factory camshaft?

It depends. Most cam places won't regrind a cam with pressed on lobes. Lz and lnj are pressed on.

Delta did jupsons 3.9 r egrind but not sure if it was quality work as upson never got a good dyno number. No one else I know has done a lz regrind

[ericjon262]

Aren't there places that grind new lobe profiles by simply removing material from a customer-supplied factory camshaft?

Delta is a common regrinder in the 4.9 community. They have standard grinds for 4.9's, as I understand it.

Webb is a premium regrinder who can weld material on to cam lobes and then grind whatever profile the buyer wants.
http://www.webcamshafts.com/

Mark the crazy Ferrari guy got Comp (or Crane?) to grind his home made blanks from round for... ~$100 a lobe.

That's not nearly as pricey as I expected it to be.

[The Dark Side of Will]

Aren't there places that grind new lobe profiles by simply removing material from a customer-supplied factory camshaft?

Delta is a common regrinder in the 4.9 community. They have standard grinds for 4.9's, as I understand it.

Webb is a premium regrinder who can weld material on to cam lobes and then grind whatever profile the buyer wants.
http://www.webcamshafts.com/

Mark the crazy Ferrari guy got Comp (or Crane?) to grind his home made blanks from round for... ~$100 a lobe.

That's not nearly as pricey as I expected it to be.

For his 48 valve V12, it was pricey... He had absolutely no other way to get any kind of cam, though.

[The Dark Side of Will]

yeah I wasn't figuring it would be as easy as "hey comp, I want a cam" I have a stock cam here, and was intending on taking measurements and cutting a blank or two, and having that ground.

Aren't there places that grind new lobe profiles by simply removing material from a customer-supplied factory camshaft?

It depends. Most cam places won't regrind a cam with pressed on lobes. Lz and lnj are pressed on.

Delta did jupsons 3.9 r egrind but not sure if it was quality work as upson never got a good dyno number. No one else I know has done a lz regrind

I was thinking that if I build a VVT Northstar, I'd have to assemble cams... Precision ground rod with some keyways cut + about three dozen 8620 rough lobes, a deep fryer and some liquid nitrogen... easy peasy.

[ericjon262]

Aren't there places that grind new lobe profiles by simply removing material from a customer-supplied factory camshaft?

Delta is a common regrinder in the 4.9 community. They have standard grinds for 4.9's, as I understand it.

Webb is a premium regrinder who can weld material on to cam lobes and then grind whatever profile the buyer wants.
http://www.webcamshafts.com/

Mark the crazy Ferrari guy got Comp (or Crane?) to grind his home made blanks from round for... ~$100 a lobe.

That's not nearly as pricey as I expected it to be.

For his 48 valve V12, it was pricey... He had absolutely no other way to get any kind of cam, though.

yeah, my comment wasn't meant to imply I thought it was cheap, it was just less than I would have expected.

[Shaun41178(2)]

20210508_191822~2.jpg (774.16 KiB) Viewed 4838 times

I took this pic a while back. This is a stock 3900 piston. It was tough to get an accurate measurement but it was around .036 in the hole give or take.

I measured a non factory headgasket with approx .057 crush with some feeler gauges.

There are some drop in forged ls1 pistons that will work on factory rods for anyone wondering. Aftermarket hypers too if available.

[The Dark Side of Will]

20210508_191822~2.jpg

I took this pic a while back. This is a stock 3900 piston. It was tough to get an accurate measurement but it was around .036 in the hole give or take.

I measured a non factory headgasket with approx .057 crush with some feeler gauges.

There are some drop in forged ls1 pistons that will work on factory rods for anyone wondering. Aftermarket hypers too if available.

Does that mean that it uses the same pin diameter and compression height as a 5.7 LS?

[Shaun41178(2)]

Ls1 aftermarket has three different rod pin sizes. .927, .943, .945.

GM spec says 3900 piston pin is .943. There are a few forged pistons with that pin.

For the compression height You want something around 1.33 or 1.34. That will bring the piston near flat with the deck height

I used an off the shelf forged je piston with a .945 pin. My machine shop just honed out the rod bushing .002 to fit the je pin and the bore for the je was around .005 overbore

Summit has a nice guide where you can select ls1 pistons based on bore, pin size, compression height and will show all the piston options to choose from.

[The Dark Side of Will]

Ls1 aftermarket has three different rod pin sizes. .927, .943, .945.

GM spec says 3900 piston pin is .943. There are a few forged pistons with that pin.

For the compression height You want something around 1.33 or 1.34. That will bring the piston near flat with the deck height

I used an off the shelf forged je piston with a .945 pin. My machine shop just honed out the rod bushing .002 to fit the je pin and the bore for the je was around .005 overbore

Summit has a nice guide where you can select ls1 pistons based on bore, pin size, compression height and will show all the piston options to choose from.

Summit's parametric search is pretty good.

0.927 is old school SBC size

[ericjon262]

not sure if it's been mentioned here or not, but the LZx headgaskets are specific to the front or rear head, the coolant holes are different sizes across the gasket, I assume for flow optimization.

[Shaun41178(2)]

You inspired me, Shaun.

Based on your pics of your oil pan in your turbo system thread, I looked up the PN for the engine mount bracket that goes with the LZ4/LZ9 (and LX9?) oil pan.
Here it is:





It *LOOKS LIKE* it might just drop onto the stock Fiero mount with little to no modification. I don't know if it would place the engine higher or lower than what you have now, though. I guess I'll have to quit jaw jacking and find out.

https://www.fiero.com/forum/Forum2/HTML/146058.html

I emailed this guy. He said he bought a new stock front motor mount and I am guessing that same bracket. 2010 Chevy impala.
He said it bolted right on, didn't have to redrill a thing. He doesn't have it fully mounted yet so he wasn't able to comment on the height or anything else but it's probably a straight drop in

Just made the LZ that much easier

[The Dark Side of Will]

Well... wooops, maybe not.

https://www.fiero.com/forum/Forum2/HTML/146058.html#p4

[Shaun41178(2)]

That's interesting.

The bracket is no longer available from gm at least not the part number from what Will posted.

Not sure if the lx9 front bracket is the same part number

[The Dark Side of Will]

That bracket wants to locate the engine mount directly under the crank pulley, per the photo on Old Europe.

The engine mount is offset to the rear of the crank pulley on both '84-'87 and '88 cradles.

[Shaun41178(2)]

So it appears I have been somewhat vindicated in modifying my stock 88 bracket and oil pan.