Flat tappet cam and solid lifters in a 3.1?

[trotterlg]

I am looking at cost/benifit things about cam selection. I am wondering if there is too much down side to running a flat tappet cam with solid lifters in my high compression 3.1 build. Lift at the valve will be well under .500, I have some adjustable rocker studs for the head and will run some roller tip rocker arms. It would be easy to get a flat tappet cam ground for solid lifters and then eleminate costs and problems with hydraulic rollers. Valve seat pressure will be about 125 pounds. The car is not a daily driver and adjusting the valves every now and then isn't unreasonable. Anyone with any experience with flat tappet solids in these engines? Larry

[geoffinbc]

There are quite a few solid cams out there for these engines. http://members.shaw.ca/betterthanyou...haft_guide.htm

Is this a Gen III 3100 or a Gen I or II 3.1L? You can put a flat tappet cam in any of them. However if I had a 3100 and needed high RPM stability I would convert to solid roller.

[trotterlg]

This is a gen 3 with rollers in it stock. Because I don't expect it to run 100,000 miles I was thinking it may be just as well off with flat tappets and solid lifters, atleast you would never pump up the lifters. Larry

[geoffinbc]

Well what is the operating RPM of this thing? If you don't require a solid lifter to make the engine operate then don't bother with them. The stock lifters should serve you just fine up to 6500RPM. If you need to go higher than that then yes I would go solid. But I think I would try and get a solid roller in there.

[trotterlg]

If flat tappet hydraulic will make 6,500 then that would make life simple. The 3.1 iron head engine in it now is all finished at 4,500 so 2,000 more revs would make quite a lot of improvement. Some of the hydraulics on the list show operation around 6,000, so that could be the answer. Larry

[geoffinbc]

The iron head motor is dead at 4500RPM because the cam really sucks along with a restrictive intake and heads. I have a COMP 252 cam in my Trooper and it will wind to 5500RPM easily. I have cleaned up the heads and gasket matched the intake with a larger throttle body.

That list is for flat tappet cams only. If your after a roller cam then you should talk to WOT Tech.

[trotterlg]

OK, I read a lot of the lists and did a lot of search. I found and bought this guy, price is right, think it will run good in a 3.1 with 12 to 1 compression? I could get it reground to a solid lifter profile for $45.00 if I need that. Larryhttp://cgi.ebay.com/ebaymotors/ws/eB...m=250808114376

[Superdave]

wow, you just went the wrong direction in a hurry...

[geoffinbc]

Yea that cam is no good for high compression at all. It has less duration than my 252 cam so don't expect it to rev any more than 5000 RPM. That is assuming you can get around the detonation.

For your application you should be looking for something like Crane 272-2 or The COMP 260

[bszopi]

From reading his posts, he plans to send it off to get it reground.

[trotterlg]

Wit the high compression pistons I am probably going to need a custom cam profile, at least ont he exaust side. The exaust valve needs to be closed to less than .200 by TDC or it will bump the pistons that are in it. I have a local cam grinder that will grind whatever I need, so I will start with this one and have them grind a solid lifter profile that will fit the exaust requirements. I can add a little duration and make up the lift with rocker arms. Will run the direct oiled solids. Problem with a custom roller lifter cam is the cost, $350 minimum and then the lifters for another hundred and a half, this should get it done for around $200. Then I don't have any worry about lifter pump up. Lobe seperation is close to the Crowler 03066 solid. I'm going to run a distributator and 4 barrel on it, so it is a science experment. Larry

[geoffinbc]

Well be warned it most likely is a Chinese cam and they are notorious for going flat.

[2.8/3400 1985 Camaro]

The iron head motor is dead at 4500RPM because the cam really sucks along with a restrictive intake and heads. I have a COMP 252 cam in my Trooper and it will wind to 5500RPM easily. I have cleaned up the heads and gasket matched the intake with a larger throttle body.

That list is for flat tappet cams only. If your after a roller cam then you should talk to WOT Tech.

That ^ getting a cam to move the powerband up won't do you a bit of good on stock iron heads, with stock manifolds, and as others have said, unless you are going really high RPM(7k+) there is really no reason to go to a solid cam. That being said, 6-7k will be the highest you can get your powerband on iron heads anyways(and even that might be pushing it), so basically a solid cam in your application is pointless, you'll just be adding one more thing to have to maintain. Also roller cams are better, its less friction and thus more power, and roller cam+lifters will be way less maintenance than a solid cam+lifters. If you want more peak power, your best bet is switching to aluminum heads.

[trotterlg]

This is going into an aluminum head motor, using iron head pistons, LS6 valve springs and .050 iron head head gaskets, compression should be about 12 to one. Problem is valve clearance to the pistons, at TDC there is .302 inches from the edge of the valve to the piston, so I will need to get a cam ground that gets the valve lift down to under .200 at TDC to keep from smacking the valves. A custom ground roller cam is very pricey, I could have gone with a stock flat tappet new cam for about $50.00 and had it ground, but I think I will be better off starting with a cam that is closer to what I want to end up with, so I went with the mild performance cam, it was $80.00 shipped and comes with some hydroulic lifters I will sell off, they are a little better than stock ones. Solids with the oil holes in them will eleminate any pump up problems, this is not a daily driver. Larry

[trotterlg]

I dropped the cam at the grinder and will pick it up on Monday. Seems the lifters that came with the cam are good ones and they convinced me to go with a hydrolic grind and use them, they have a cam oiling feature built in, so they say life will be good. I will know the exact grind when I pick it up, but it looks like it will go about a 225 at .050 both intake and exaust with a lift of .432 with 1.5 rocker arms. 104 lobe seperation. That will get the exaust valve to miss the piston by about .100 inch, but will have to measure it. I'll let you know how it turns out. BTW, they say that SSI cams were made by Crane? Don't know if it is true or not. Larry