RamAir95TA

iTrader: (2)

PV clearance has very little to do with lift. If the piston is at the top of the stroke, do you really think that the valve will be all the way open?

bowtienut

iTrader: (1)

97 6speed, I fully agree. Either optimize what he has now, or, as Mikey V so eloquently put it, dont dick around - jump straight to a SR setup
I understood your point about the meager (20 hp) gain he was looking for, which is kinda insignificant to what he already has.

97 6speed z

Quick 95LT1, "the small base circle cam issue" affects the cam he ultimately chooses to use because he may NEED a small base circle grind to prevent rod to cam clearence on his 396 c.i. stroker motor. Not all of us use only 3.750" cranks in our strokers!

quik95lt1

iTrader: (7)

this right here is THE most misleading statement ive heard in quite some time now.........do you have any experience yourself running solid roller cams??



OP........first off lets cover the "required maintenece"
with a mild SR cam which is all you will be running with a good valvetrain the system will virtually never need to be adjusted.......i check mine every oil change and it NEVER moves even with the absolute beatings it goes through and the high valve lift >.700........
2. Noise - Again lashed correctly and designed properly you would be supprised how quiet they can get
3. stree driveability concerns- has absolutly 0 to do with SR vs HR........has 100% to do with the lobe design of the cam.......

4. Common myth that you need 300#lbs of seat pressure.........wrong........a proper SR valve train and cam needs no wheres near this.....i run a mere #215 spring setup at #220 seat pressure.......couple that with leightweight valvetrain parts and a jesel shaft setup and i have headroom well in excess of 8000rpm........

conclusion is if you find yourself a good and competent company/person that can design you a efficent valvetrain system the car will run great.....make awesome power..........and be durable WITH the Solid cam........which is why i refered you to Advanced Induction

good luck on your build

also by no means am i trying to start and argument as much as just conveying proper and solid infortmation and knowledge to the OP for his application

quik95lt1

iTrader: (7)

thats what i was thinking............

20hp is 20hp with a high horsepower NA setup 5hp is a big gain.....

correct but this will not hamper the lobe lift he can run in his application........and fyi a 3.75" crank such as mine does require a small base circle cam........slap over .440 lobe lift to it and you'll be supprised how close that lobe does come to the rod

bowtienut

iTrader: (1)

When you're close to maximizing the potential of what you have, yes it certainly is! I don't think he's that close. Considering his M6, his dyno hp is only about 20 more than what I'm seeing here with my 350 with a 228 dur HR. Are those heads weaker than well-ported GM castings at lower (sub-.600") lifts ?? Do they really respond well to another .100" valve lift? If so, then the SR definitely makes sense. I certainly wouldn't waste time and money on trying another HR cam.

97 6speed z

Quick 95LT1, well since you asked ......... NO I don't have any experience running a solid roller cam setup in a SBC.

But just FYI I did campaign a 1966 Chevy II SS 327 c.i. 4 speed car through the '66 - '67 NHRA seasons in AA/S which ran consistanly within .05/.09 of the then AA/S NATIONAL record, and ..... I shifted that 3.250" stroke 327 c.i. motor all day at 8,000/8,200 RPM with a solid flat tappet cam in it. Tell me do YOU think a solid roller setup is harder to manage than a solid flat tappet setup at 8,000+ RPM???

As to the second point I highlighted in your post above ........ A small base circle cam will DEFINITELY affect how much lobe lift you can have for any given duration. Look we would all like to have "square" cam lobes so we could fully open those valves instantaneously, but valve train acceleration off the base circle limits how fast we can go ...... given a fixed time, (i.e. "duration"), to do it in. Try calling ANY custom cam grinder and ask for a .900" base circle cam with a .440" lobe lift with a duration say of 240 degrees @ .050" ............ and see what they tell you. Believe me there is a reason why NHRA Pro Stock motors run 1.875" base circle cams!

Finally, to the last highlighted point in your above post ........ NO a 3.750" crank in a 350 LT1 block does NOT require a small base circle cam. I've built several 383 SBC stroker motors, and, I can assure you that with the proper choice of connecting rods ..... a standard base circle cam will swing just fine in a 383/386 SBC build!

And to the OP, yes ....... Good Luck! with whatever you decide to do.

quik95lt1

iTrader: (7)

lot going on in that post that im not getting into..........my main point im talking about is the durability and streetability of a solid roller on the street.......if YOU have never ran a solid roller on the street i find it difficult to justifiy your claims based off of a solid flat tappet cam in a 60 year old engine.........again by no means am i attacking your experience nor inteligence however comming from someone who DOES have experience running solid rollers on the street i can offer what i did in the above post........and yes i also do understand the concept of base circles/acceleration/jerk/lobe profile and the concept of base circle and rod clearance........however as i stated in "HIS APPLICATION" the duration vs. lobe lift issue should never arrise.........

i dont want to clutter the OP's post so i will end here........again
good luck with your cam choice and changes

Puck

iTrader: (17)

In a street SR setup like the OP wants, he won't need any exotic parts or high spring pressures...especially with the imposed 7k RPM limits. On a street lobe without crazy .020 numbers a #220 closed spring would be fine, and live a long happy life. I would run shaft mounts either way for piece of mind if you have the money, but in all honesty a stud girdle and quality stud mount rockers should be fine. I am running 260# closed, but my lobes are "square" and not what I would recommend for most cars that see street duty.

They are out of the box, so the low lift intake flow may very well be the same or lower then a top tier ported stock casting. Because of that you may make more average power and even run a quicker ET then with the AFRs when using a baby cam. The exhaust flow will be stronger though, and I am willing to bet they don't stall nearly as early, so should benefit from higher lift cams more then a stock casting that may actually lose flow with too much lift.

I was spec'd a cam with .73x" at the valve based on my flow bench results - the flow hits a plateau from .700-.750 and doesn't lose any cfms so in a real "race" setup I could have ran even more lift...some of the crazy SBC guys on sites like speedtalk are running .750+ lift solid rollers on "street" cars that run 9's NA. .

Mike V has the right idea with his combo - seemingly "aggressive" parts, but with a great attention to detail and a quality valvetrain he can still drive it on the street if he wanted to and not have to replace parts every 2,000 miles.

joelster

Cool! Put up some pics. I like the older drag cars and the stories too!

Call lsmeng.com and have them build it. My LT1 runs a .900" base circle, with 25x/26x duration and lobe lift of .423". If you run light/stiff parts, then you don't need a pro-stock spring to control the motion, and it can be done very effectively. Pro-Stock engines need bigger cam diameters because they spin over 10,000rpm and use springs with enormous pressures. As for LT1's a huge spring may cause a thinner camshaft to flex, but i've never heard of one breaking. Not saying that it hasn't happened, i've just never heard of it.

I agree with the proper rod part. There is a HUGE difference in the amount of clearance between certain H-beams and I-beams. Not only in rod-camshaft clearance, but in rod-block clearance needed. I have a 4" stroke crank and it fits fine.

97 6speed z

Several excellent posts in this thread that I had not acknowledged earlier, namely by, RamAir95TA, Bowtienut, Puck, and yes even Quick95LT1, but I highlighted your post above Quick95LT1, because I didn't want you to think I've never run solid flat tappet SBC's on the street before. Believe me before GM came out with roller blocks in 1986 ......... everyone going fast was running solid flat tappet cams on the street. And, I also wonder how different, in principle, you think that 8,000+ RPM '66 327 SBC motor is to what you are currently running in your car?

But ....... let's not get too defensive here. We all have different opinions based on our own individual life experiences dealing with cars/motors we have built or are currently building. The GREAT part about a board like this is that we can ALL offer them up to others who may lack that experience.

Now since I have acknowledged all the great posts here for the OP, let's re-read his posts and "concerns". The OP won't run 1.6:1 ratio rockers on his exhaust side, NOT because he might not make more power like Bowtienut suggested, but because he's worried about PTV clearence at TDC despite what RamAir95TA posted. Does anyone else who's posted in this thread other than the OP ...... really believe this???? Also, the OP wants MORE lift to better utilize his current heads but, (for example), he is already running .588" lift on his exhaust side now, but remember, .619" lift is too much lift and ...... causes PTV issues????

OP, we are ALL trying to give you sound advice here, but what I'm really "sensing" here is that YOU want to run a SR valvetrain for whatever reason (?), and are maybe trying to justify that decision because you think more lift for your AFR 210 heads is the answer? If what Puck said is true about you running "as cast" AFR 210's ...... maybe ...... just maybe ........ you would see MUCH greater gains with your 396 c.i. engine by having those heads ported and polished for great low to mid lift flow numbers, as opposed to jumping to that SR cam and valve train, which, (by the way), you want to keep under 7,000 RPM.

Just ...... "food for thought", and again Good Luck! with whatever you decide.

96capricemgr

iTrader: (1)

I will say I did not read all of it but I still feel it important to note that what was done 25+ years ago sets no rules for today. Metallurgy has come a LONG ways as has the understanding of the physics involved in valvetrain motion.

I know a guy with a gen 1 motor with the valvetrain developed on the Spintron turning .750lift solid roller to 8500 with 140lbs on the seat. It is all pretty high dollar stuff, but at the same time just another 23degree smallblock Chevy.
Don't get caught up in the past what is possible changes all the time.

97 6speed z

Joelster, boy do I wish I still had pictures of that car. Back in those days good camaras were expensive, and yes ....... they required film too! Also, with several home moves over the course of 50+ years ..... old photos do get lost "in the shuffle".

Google "Bill "Grumpy" Jenkins and his '66 Chevy II Much" car. My car was a clone of his 1966 Chevy II, which did hold that national record in AA/S in 1966/67. It's the car he campaigned before he went to his Camaro in 1968.

As for those "old stories", those little "high winding" 327 Chevy II's in '66 ran in the same NHRA AA/S stock class as the legendary 426 street hemi "box body" Belvideres and Chargers. Aaaaaaaaaah .............. good times!

Puck

iTrader: (17)

FWIW I have a. 9 base circle w/ .43x lobe life and 263 exhaust duration. Had to make it on a 109 instead of 107 lsa tho, comp can't do those specs on a narrower lsa using an lt1/SBC core.

97 6speed z

Puck, thanks for reminding me to respond to Joelsters other comment to.(I guess my thinking just got derailed by thoughts of that old car of mine when he asked for photos).

The cams both of you are running, namely, 25x/26x w/.423 lobe lift, and, 263 exhaust w/.43x lobe lift, (as you found out Puck when you wanted that cam ground on a 107 LSA), really represent just about the max you can do with a .900" base circle cam.

In one of my earlier posts I "inferred" that no cam grinder will grind a .900" BC cam with .440" lobe lift and a duration of 240 @ .050" on an LT1/SBC core, and ........ I'm sticking to it! As I'm sure you both know, as duration decreases, and base circle diameter decreases ....... so does the maximum lobe lift you can have.

Puck

iTrader: (17)

This is true . I wasn't disagreeing, just sharing some specs.

97 6speed z

Yes, but thank you for sharing that information!

What you experienced in attempting to get that cam ground on a 107 LSA ..... is something, I think (?), many people reading this thread might not fully understand.

joelster

FWIW, Comp was very difficult to deal with regarding a SR cam for my engine. They had excuse after excuse to not build it. They said they didn't have the cores for an LT1. So I told them to use an SBC core and machine the step for the retainer plate, and they said they couldn't do that. LSMENG handled the build of the cam without breaking a sweat. My cam is on a 105 as well.

BizZzatch350

iTrader: (33)

Formula934,

Are you running those AFRs as cast out of the box or have they had some additional work to them?

bowtienut

iTrader: (1)

Same thing I was thinking. I'd bet money he could slap my 200cc ported stockers on there and easily pick up that 20 hp he's after. But...... I am not suggesting he switch heads. He's already made the investment, and there's huge untapped potential in the heads he has in the hands of a good porter.

I also know about Comp Cam's "issues" with grinding Lt1/SBC SR cams on a tight LSA. I wouldn't use them. As long as AI is in business, any custom cam I buy will come from them.