[slowbird]

Originally Posted by ponjohn

I completely agree. The OF / 295 SD combo is good in most combos for mid to low 11's. It is hard to beat the level of performance from a proven combo.

Nothing an iron head and flat tappet cam can't do. We should raise the bar some.

[PAUL K]

Originally Posted by slowbird

Nothing an iron headed flat tappet cam can't do. We should raise the bar some.

^^^^Truth^^^^ and I agree. A lot of money being spent for average results

[TCSGTO]

Originally Posted by slowbird

Nothing an iron head and flat tappet cam can't do. We should raise the bar some.

How many of these can run 92 pump and have more than 1 good stop with power brakes in a real 2 ton street car?

[TCSGTO]

Originally Posted by tom s

they probably dont run enough spring pressure!Tom

They generally run much more than we do. Probably has more to do with that funky porcupine geometry and bigger,heavier valves. SBCs get away with much less pressure.

[Dave Bisschop]

Originally Posted by PAUL K

^^^^Truth^^^^ and I agree. A lot of money being spent for average results

Really, please lay out some of these iron headed flat tappet combo's that are being bolted together by your average enthusiast and running sub 11.50's first time out in 3800+lb cars that have plenty of vac. at idle for power brakes and run on 91 octane. Not saying this kind of performance can't be accomplished with iron heads and a flat tappet as we've done it ourselves but the combo's are much less street friendly for your average owner.



Formula8, FYI we have dozens of customers running the hybrid setup like you are doing with zero issues using the Crane 99893 springs installed at 1.780-1.800".

Overall the hyd. roller set-ups have been very reliable and 95+% of the ones we've sold (well over a thousand at this point) are using Comp cams hyd. roller lifters and the 99893 springs and out of those we've had some issues with about 2-3% of the lifters. We have customers with tens of thousands of miles on their set-ups with no issues.

I'm all for having some extra spring pressure for a little more insurance especially for those running the solid roller lifters and turning higher rpm (above 6000), but having 200 on the seat and 600 open on a 245/252 .400" lobe lift cam is overkill. For years and about 500 passes (same set of Comp Cams 859 lifters) we ran a 279/283 @ .050" .650" lift solid roller in our 413ci iron headed engine in our 65 GTO with 200lbs on the seat and 575lbs open pressure going through the traps at 7500-7600rpm with no valve float issues, the lifters never failed and were put in a street motor when we sold the car.

Way more spring pressure than required not only eats up power it also puts more strain on valve train parts and cam bearings so while I always prefer to have a little extra, having way too much isn't the way to go either.

We use beehive springs on occasion and P-dude has a great set-up that he's proven to work very well, but at the end of the day I'm always looking at the most cost effective way to do things while maintaining long term reliability. For most of the hyd. roller combo's we do we've had nothing but success with using the 99893 springs and chrome moly retainers, we can certainly set-up customers heads using the same springs and retainers P-dude uses but there's a $400.00+ extra cost involved. There are some cheaper beehive springs available as well but we've seen some reliability issues with some of them so I just prefer a dual spring personally. quoting Steve C. this is a very good reason why "I've been fortunate over the last 20 years or so. I've only had one instance with a solid roller application that almost led to issues... I broke the inner coil on a dual valve spring and limped home."
If he would have had a beehive or single spring fail it would have led to catastrophic engine failure.

We do a lot of CNC porting and head machining work on LS heads for other shops in our area and what's interesting is that they are typically removing the beehives and going with a dual spring as they get into larger cams

[jonmachota78]

I haven't seen you guys mention it unless I missed it. My understanding is that the hybrids live longer on the street because of the tight lash they run so the lifter bearing don't get hammered constantly like a solid roller cam does. It's the lash that hammers the lifters. Hybrids and hydraulics are easier on parts.

[Steve C.]

I had a lifter fail in a BBC and broke the block. It was a comp cams roller and the recomended lash was .028 and .030 so that is what I ran..I thought that was too loose but figured the cam company knows more than me ..well now I am paranoid .My new engine has a Crane grind and the cam card said .026 and .028..but to be safe I set them at .017. My question is...will this hurt anything? I used to think that the recomended lash was just whatever made the best power on the dyno...but since reading this board the last few months,I gather from the posts here,that the lobes on the cam are designed for a certain lash....that it isn't just a tuning thing.So, what effect(other than making the engine think it has more cam) will running a considerable amount less lash than recomended have?

Answer......

It depends on how the clearence ramp was designed. It'll either have no effect on valvetrain stability, or it'll help. It won't hurt anything but performance.

It's not the tightness of the lash, it's the velocity of the cam at that point that dictates how hard the lifter hits the cam. You can have a cam designed for a looser lash that has less velocity at the lash point then a cam designed for a tight lash.

Source: http://speedtalk.com/forum/viewtopic.php?t=8265



( Does this relate to the typical .006" lash used on the Hybrid set up with the solid roller lifters ? And a fwiw, my comments here regarding valve spring pressure are for the most part regarding the solid roller set up not using hydraulic roller lifters. Nor do I have a issuew with the Crane spring as long as it measures correct and used in conjunction with adequate pressure for the intended use )


.

[Dave Bisschop]

Originally Posted by Steve C.

It's not the tightness of the lash, it's the velocity of the cam at that point that dictates how hard the lifter hits the cam. You can have a cam designed for a looser lash that has less velocity at the lash point then a cam designed for a tight lash.

Source: http://speedtalk.com/forum/viewtopic.php?t=8265

.

I'm not convinced that statement is 100% correct, I know from experience with our race car, that when the springs were getting to the end of their life (borderline valve float going through the traps) if we tightened the lash up a few thou from the .028/.030" recommended by the cam manufacturer it would help at least finish the race weekend, which leads me to believe that less lash reduces lifter bounce.

When it comes to requiring more spring pressure on the hybrid set-up vs. running a hyd. roller lifter with all things the same and no more rpm is being sought with the solid roller lifters there's no reason why more spring pressure is required (lots of smart people at Comp Cams and other cam companies, but there seems to be a lot less smart people answering tech questions a lot of the time and you can call and talk to 10 different people and get 10 different answers). I did a back to back, same day dyno test with a 246/252 .400" lobe lift hyd. roller cam in a 468ci engine swapping from hyd. to solid roller lifters and there was no indication of valve float turning the engine up to 6200-6300rpm, using the 99893 springs set up around 1.800". The solids showed 6-8 more hp over the hyd. above the torque peak. Maybe if we backed the lash way off there might be something there, but until I actually see some solid back to back data to prove that the solid lifters need more spring pressure I'm just not buying it.

Valve, retainer and spring weight all have to be taken into consideration when figuring out how much spring pressure is required for an application along with how aggressive the cam lobe is and how much rpm the engine needs to turn to optimize the combo.

[ta man]

Originally Posted by slowbird

Nothing an iron head and flat tappet cam can't do. We should raise the bar some.

Try 87 octane,850 rpm idle,13.5 inches of vacuum,11.40's/119/120mph with a mild 3.08 gear,mild convertor,3900 lbs..driven 200 miles to the track roundtrip.Running the same valve springs and lifters since SD assembled the heads in Dec. 2008!Pretty easy to achieve.....

Plus my wife ordered these heads to surprise me with no clue what she was doing other than Dave and Marcel asking her questions to ask me!Homerun in my books!

[Larry Navarro]

Originally Posted by grandville455

Use the 116 wall pushrods, From Mike jones of jones racing cams , when I was running the hybrid setup...

With a hydraulic roller cam, running solid roller lifters. If you're hot lash is more then .006" x Rocker Ratio, you're off the end of the ramp, and not doing your valvetrain any good, so if you have to go to .003" cold, to keep the lash point below .006" x Rocker Ratio, then set it at .003"

Hey Darb, so your saying that the old faithful hybrid is optimized with lash at .003" vs. .006" ?

Dave?

[Will]

I'm not understanding this math. If hot lash is .006 x rocker ratio how could the required lash ever be .003"? .006 x 1.5 = .009.

What am I not understanding?

[70f400]

Plus my wife ordered these heads to surprise me with no clue what she was doing other than Dave and Marcel asking her questions to ask me!Homerun in my books![/QUOTE]

She needs to call my wife! Very Impressive combo ta man

[Dave Bisschop]

Larry not sure what Darby is talking about, but I've always run them at .006-.007" Hot, which has worked well. While there are a fair amount of guys running the solid roller lifters on the hyd. roller cams, the reality at least for the cams I've sold is that most run hyd. lifters which is really my recommendation for most applications.

[Dave Bisschop]

Originally Posted by ta man

Plus my wife ordered these heads to surprise me with no clue what she was doing other than Dave and Marcel asking her questions to ask me!Homerun in my books!

ta man has a very cool wife!! It was fun figuring out what questions she needed to ask him to figure out how to set up the heads, keep that woman happy!! she's a keeper!LOL

[grandville455]

Originally Posted by Will

I'm not understanding this math. If hot lash is .006 x rocker ratio how could the required lash ever be .003"? .006 x 1.5 = .009.

What am I not understanding?

What Mike was saying is if your hot lash is more then .006x rocker ratio, in this case 1.5 ...which is 009, you don't want to be higher then that total hot
, so if u have to set them at .003 or whatever x ratio to stay under that .009 , then that's what u do. In my case I was using 1.65's ...the .003 is just a example...but I ran mine at .003 cold, n we all know how my 4550 lb car ran!

[Larry Navarro]

hmmmm......using 1.65 myself, I just finished setting the lash at .003" COLD.......ouch

Guess I better go and change direction.

[PAUL K]

Originally Posted by TCSGTO

How many of these can run 92 pump and have more than 1 good stop with power brakes in a real 2 ton street car?

I'm not speaking for Slowbird, but the GTO in his signature ran 11 flat with iron heads, pump gas compression and an HC-04 HFT camshaft. Later it ran 10.1 with a similar HFT cam and ported E-heads. I have personally used the HC-04 cam with Rhoades lifters and ran into the 10's with power brakes and no driveabilty issues. An HFT cam that ran 11's would not have any problems pulling around a two-ton car and operating vacuum accessories... if everything was set up properly.

[PAUL K]

Originally Posted by Dave Bisschop

Really, please lay out some of these iron headed flat tappet combo's that are being bolted together by your average enthusiast and running sub 11.50's first time out in 3800+lb cars that have plenty of vac. at idle for power brakes and run on 91 octane. Not saying this kind of performance can't be accomplished with iron heads and a flat tappet as we've done it ourselves but the combo's are much less street friendly for your average owner.

I assume this is a rhetorical question since you seemed to answer this in the last sentence of your paragraph above.

[PAUL K]

Originally Posted by ta man

Try 87 octane,850 rpm idle,13.5 inches of vacuum,11.40's/119/120mph with a mild 3.08 gear,mild convertor,3900 lbs..driven 200 miles to the track roundtrip.Running the same valve springs and lifters since SD assembled the heads in Dec. 2008!Pretty easy to achieve....

Your car runs good! I ran a similar combo as yours but with ported cast iron heads and less compression. It ran a best of [email protected] mph. I had 3.42 gears but did use a 29" tall tire, however, I used a stock 2.48 gear set. The 455/3.08 gear setups have worked well over the years. Back in 1977 a board member here ran a 1968 Firebird in the first Muscle Car shootout. He ran mid 12's with 3.08 gears, 8:1 compression and gasket matched heads. He either won the event or was runner up.

[slowbird]

Originally Posted by slowbird

Nothing an iron head and flat tappet cam can't do. We should raise the bar some.

This was just my opinion based on my experience. Nothing wrong with running mid 11's with alum heads and hyd roller.
For what its worth our 69 Grand Prix with power brakes, iron heads, hyd roller and tri-power weighing 4150lbs runs 11.70's