3500 head max lift

[3400-95-Modified]

I am doing a 05 3400 with a 3500 top end, and using a 3400 upper plenum for install purposes. I was wondering what the max lift is for a 3500 head... I was looking at milzy's cams and wasnt sure if I could run a stage 2 cam on a stock set of 3500 heads. I'm assuming with the cam I should also get new springs.

Any info would be appreciated.

[rickykline]

i would say no to the springs unless you want the ls6 springs.. the 3500 springs are stronger than ls1 springs.. i proved that by wasting my own money.. i think ben has a flow sheet showing what they flow up to .500 lift... search for it and see.. good luck jon..

[Superdave]

With LS6 springs and .015 shims your max lift is right around .560.. stay closer to .550 for saftey

[SappySE107]

Find a bronze or composite polymer distributor drive gear if you get a steel cam like the MMS cams. Cammotion recommends them.

I am getting 2 regrinds right now and will hopefully get some specs that are possible from a regrind. Even with buying new non press on roller cams I won't be spending 400 bucks on cams.

[farmerz24]

but who would have this bronze or composite drive gear?

[SappySE107]

If I knew, id have them on the store.

[AaronGTR]

Did you mean oil pump drive gear? If he's using a 3400 I wouldn't think he'd be using a distributor. I thought you couldn't use one with the newer engine because of the size and position of the LIM/UIM?

I didn't know cammotion recommended a different gear material for using with the billet cam (and Milzy never said anything of course) but we're in the same position as you... if we new where to get them we'd have them. I'll just have to keep running the stock gear and see what happens. If it breaks then I'll see what I can do.

As for valve springs if you use a stage 2 cam, or a regrind with that much lift and duration, stock 3500 springs definitely aren't gonna cut it. You'll need Ls6 springs, or comp cams 26915 (very close to LS6 specs) or 26918 springs.

[onefastV6]

I called Cammotion, the guy I spoke with stated that the cams are made from "8620 billet steel and that a bronze or composite gear is recommended"

Maybe this is something that Milzy over looked however it is something that should be looked into. Fortunately, I haven't heard of anyone with his cam running into a problem as of yet.

[Superdave]

I know Moonwell is running the stock gear w/o problems. I have a billet roller cam in my SBC and using an OEM HEI dizzy and never heard of this...

[SappySE107]

Ok, i have a part number for a bronze gear so now I gotta get pricing tomorrow (hopefully).

Oil pump drive is the distributor drive gear. Its all the same thing.

[3400-95-Modified]

So do these cams not come with a oil pump gear on them? or is milzy just putting on stock gears from old cams? Little confused on that statement.

But I did gather that it is the spring that determines "max lift" by its bind height... Also I should run the LS6 or comp springs if I plan on a stage 2 cam. Now I know what shims do and all but are they necessary or did you shim the springs to get a desired seat pressure?

I know on the small block I work on in the race car we shim them to get them to all match, seat wise, since the machinist doesn't mill the seats all the same he will measure the height on one and usually cut all the spring seats the same, makes us chase our tails but it's not hard to get them all the same.

I may go with a stage 1 cam for streeability purposes... This car is a daily driver and I'm not so sure on how well a stage 2 cam would do for that.

So now the next question is Should i buy a cam from milzy? Or should I send one of the ones coming out of these two engines i'm buyng out for a regrind and then get longer pushrods? Also who is doing regrinds in the area? Or should I just ask you to get me one Ben?

I'm also confused on how you can get the cam reground without causing any issue on the lifter end of everything as far as how it sits in the bore and how deep in is in the bore. More info on that would be great Ben.

Thanks

[bszopi]

The cam gear is machined on the cam, and its that gear that causes the issue. The gear that "should" be replaced is on the actual oil pump drive.

As far as a regrind goes, you can send it off to any of the major cam companies (Comp, Crane, Crower) and get a regrind done for around $120 with an approx. 1-2 week turn-around. With that and custom pushrods, you'll still be under the MMS cam price.

As far as issues with the lifter sitting in the bore and such, the cam is only ground down maybe a few tenths (probably only several thousanths), so the lifter really isn't going to be sitting in the bore much deeper. It would basically be the same as a Milzy cam because the lobe can only be so tall, therefore to achieve the lifts, the base circle needs to be lower.

[3400-95-Modified]

The cam gear is machined on the cam, and its that gear that causes the issue. The gear that "should" be replaced is on the actual oil pump drive.

As far as a regrind goes, you can send it off to any of the major cam companies (Comp, Crane, Crower) and get a regrind done for around $120 with an approx. 1-2 week turn-around. With that and custom pushrods, you'll still be under the MMS cam price.

As far as issues with the lifter sitting in the bore and such, the cam is only ground down maybe a few tenths (probably only several thousanths), so the lifter really isn't going to be sitting in the bore much deeper. It would basically be the same as a Milzy cam because the lobe can only be so tall, therefore to achieve the lifts, the base circle needs to be lower.

Ok got ya, the more I think about it I understand it. Since you mentioned how the lobe can only be so tall and that would mean the base circle has to shrink, that make sense to me, but on milzy's site they say nothing about needing custom pushrod lengths.

So on top of all of that, What is a good grind to have done that will run nice, put down power, not be phased by nitrous? and with all of that will the grind company let me know what pushrod length I should run after it's ground?

bszopi I know you did a custom grind but you were un able to tune so it didn't work out too well. I'm not worried about the idle being a little rough because that would sound sweet.

Anyone know what kind of oil pump drive gear comes on a 05 3400? by chance would gm have changed to a bronze gear?

I guess I should start tearing into my 3400 so I can send stuff out and source items and whatnot now...


Maybe I should just take Milzy's stage two specs and have that done as a regrind. I think I have them somewhere.
Found em

Stage 1 NA - .305/.308 lobe lift (.488/.493 valvelift),
209.4/213.1 duration,
110 LSA, 108 IC

Stage 2 NA - .347/.349 lobe lift (.556/.559 valvelift),
222.1/225.7 duration,
110 LSA, 106 IC

[AaronGTR]

Milzy doesn't say anything about custom pushrod lengths on his website because you don't need them with his cams. They aren't regrinds, they are brand new billet steel cams so the base circle size is the same as stock but they can have more lift and duration than stock. When you regrind a stock cam you are removing material from the base circle to make the lobe effectively taller which is why you have to get longer pushrods to account for the difference in lifter height.

It's doubtful GM changed the material of the oil pump drive gear since they've been using the same cam the whole time. The only reason for changing the gear is because of the different material that the billet cam is made from.

Yes, using shims is necessary. They keep the springs from chewing into the aluminum cylinder heads, and they also help keep them centered over the valve guide.

If you decide to get a regrind instead of a billet cam, don't use one of the stock cams out of your engines. They are hollow core with press on lobes and it's risky doing regrinds on those because they aren't as durable and might spin a lobe. There's a company who sells stock replacement 3400 cams (I don't remember the name, someone here knows) that are not press on lobes and I think they are solid core too. Thats what you want to start with. A brand new cam.

[3400-95-Modified]

Ok I'll start looking into a "new" cam.

Also on the valve spring note, will these springs all fit with the stock seal/seat on there, because that acts as a shim in a way to protect the aluminum from the spring. Or do you have to hack up the seal/seat to get this to work?

I'm trying to figure out what I need to do before I go buy all this stuff and find out I either dont have enough or I bought the wrong things. It's easier to have all the answers in one place on what to do.