Hi guys, Solid vs Hyd Flat tappet Cams.

I am trying to figure out which way to go for a cam/heads upgrade. I have done a fair bit of reading on the subject and still can't make a choice. A forum search was no help. So I'm after real world feedback.

I have a mild 71 SB 4speed, 336 gears, 255/50/17 tires.
Car is a weekend toy(street).

I have pretty much decided on AFR 195cc straight plug heads to give me room for more cubes later.

I have never had a solid cam before and am interested in giving it a go, if there are valid reasons for doing so. I know valve lash needs to be adjusted periodically, but that doesn't scare me.
Solid cams seem to have slightly more lift and 0.050" duration for a given Adv duration. But would that make much difference?
Sorry for the long post. Any help would be greatly appreciated.
Cheers
Mick

 

IMHO, the only advantage of a hyd setup (flat or roller) is less maintenance (ie valve lash).

 

that and the solid will wear out after about 25k miles.

its a minor inconvinience and a minor cost in comparison to the oodles more power you can tap into through a solid roller. WELL worth it.

 

Do what?! I find that a little hard to swallow...real hard in fact...so I'm gonna hafta

EDIT: You must be talking about the solid roller. My bad. I'm with you on that. I don't think they have the longevity of the flats. That's one reason I went with a solid flat cam.

Brett

 

A roller cam would be nice, but I've decided to stick with flat tappet cams at this stage. Just can't justify the added expense right now.
What sort of life expectancy could I expect out of a solid flat tappet cam? any different to Hyd??

 

The solid flat cam if well maintained should live as long as the rest of the items. The cam and lifters could last a life time it's the springs and pushrod tips that suffer from increased lifts and duration.

My buddy Lt1er on this forum has had his motor together for 12 or so years since we rebuilt it with the Crane 238/248 114lc and something like .526/.543 lift with 1.6 roller tip rockers. He runs it to 6500/7000 all the time in his 4 speed car.

 

Youll notice I DID In fact state SOLID ROLLER. I wouldnt go with a solid tappet, Id go with a hydro in that case.

 

Ozzie, Go solid.

It is easy to swap out if you change your mind later. Match it to your compression ratio and you should be pleased with it. Solid will produce a little more power and have a higer RPM limit as compared to hydro. There is some lost motion inherent to the hydraulic lifter design. Solid cams will lift the valves a little faster/farther because of it.

David Vizard did some dyno work and found a little HP from lashing hydraulic cams down farther to where almost all of the available travel in the hydraulic lifter was removed. The effect was to have zero lash in the valve train and very little hydraulic bleed down possible. The lifter would follow the cam lobe pattern without any bleed down like you would get if you lashed them at snug - plus 1/2-1/4 turn like we usualy do. This is opposite to zero lashing the valves to prevent hydraulic valve float. Interesting reading if you get a chance.

I have a hydraulic in my Vette because I do not want to open the hood any more than I have to on that car. I have solid lifters on one of my other toys. No worries with either type but solid is the way to go on a toy if you can handle the lash routine once in a while.

-Mark.

 

Thank's for all the info. Solid sounds good so far.
I don't know my Comp Ratio because I'm not rebuilding the whole engine(yet?), but with 68cc AFR's vs GM 76cc, It should be about 9 to 9.5:1. Anyone have some good solid cam recommendations???
cheers
Mick

 

This is the above cam I talked about. With aluminum heads I would shoot for 10.5 compression or so. In a 355 that would take 62-64 cc heads and flat tops.

http://www.cranecams.com/?show=brows...tType=camshaft

 

I would never go back to Hyd. flat tappet cams. The solids I have had have performed extremly well and you can rev until your springs give up. The maint. is overstated. I have about 6K on this cam and I check it about twice a year but it is always right on. Yes it makes a little noise but who cares. I like the sound of the solids.

 

Not real clear on a lot of this, so I'll just throw it out for someone more knowledegable to comment:

as far as lift, I believe it is measured by lobe lift X rocker ratio. Would you not have to figure in the clearance between valve and rocker arm as a negative on the solid, because the lobe has to ramp up to eliminate the clearance between the rocker and valve tip before lift starts? How much does the internal part of a hydraulic lifter have to move before you start to get valve lift?

In the '60s and '70s, hydraulic lifter design was such, that the lifter would pump up about 4000-5000 rpm, so everyone used solids for performance. Newer design performance lifters will rev (at least in my case) to over 6000 rpm without pumping up. That's why I go with the hydraulics.

 

I drove over 10k miles with my solid cammed engine and checked the valve lash and it was still close to perfect.. 10k miles is usually about 2 - 3 years for the average C3... I wouldn't consider that to be high maintanance...
Solid cams make more HP.. I personally only go with solid cams in my engines...

 

Crower has a good line of solids. Their cams have heve good intensity numbers (Low). To figure intensity, subtract dur @ .050" from the advertised duration. The lower the number, the better.
http://www.crower.com

 

Im a Comp Cams bitch hahaha used em in all 2 of my engine rebuilds hahaha they do make a solid product as far as...solid...cams go.

 

If your pistons are cast, dont even think about a cam that wants to go over 6000rpm. If your compression is no more than 9.0 (and remember you have aluminium heads) a solid of 230@050 would be a nice fit. Manifold design also dictates cam size.

 

For the money and the performance, you can't go wrong with a solid flat tappet. I did the research and that's what I bought...a complete Comp solid cam kit.

Brett

 

Thanks again for all the good info. From all the positive comments for solid cams, I have decided to go for it. I didn't consider Crower, so I shall check it out.
I like the look of the Isky Z25 .480" lift 240deg@ 0.050, 278deg Adv duration. It's the smallest solid I could find on thier site, but it still might be a bit much for my application.
Those guys with Solid Comp cams, which did you go for?
Any comments about the Xtreme Solid line?
Single or Dual pattern?
Sorry about the never ending questions.

Cheers
Mick

 

That's a secret!!

When mine is in and tuned, I'll send you an update.

Brett

 

C'mon Brett.... You can tell me. I won't tell anyone.... Honest

Cheers
Mick