I need some advice from all you engine builders out there. (Hopefully Vortecpro or Gosfast will comment)

I could use some advice on whether or not I should replace the solid roller cam on my BBC C3. I have never had a Solid Rollers or a BBC before. (I did run a 70 LT-1 solid lifter for 30 years)

My Problem:
My best friend (a drag racer / machinist) built me a tough 454 LS6 clone around some OEM GM "074" aluminum heads.
The problem is it is a Solid Roller motor and I have heard horror stories about rocker bosses breaking off on these old heads, roller lifters failing, roller pins destroying the whole engine, etc. etc.
That is not what I want. But since he has passed on due to COVID and I do not know where to turn.

Car background: I am doing a frame off restoration on the whole car. I intend to drive all over with it after I retire, soon. I may autocross it a few times or drag race it once or twice. Cam is an Erson SR 270/280 230/238 .629 lift. Lifters are Morrell SR with pressure fed rollers. The car needs to be able to cruise at 2000 and rev to 6500.

My QUESTION: Are these heads really that fragile? Are the current 240# / 550# 475# rate springs too stiff for the weaker aluminum rocker bosses on these old heads?Anyone have some experience with these old heads? I intend to put 20,000 miles on this car. And do not want the heads/engine to explode or have to re-build/replace the rollers frequently. A couple people have recommended I put in a hybrid / HR setup in it like AJ or others. Those cams have much lower intensity ramps and I could go with much softer springs. More like HR springs. Maybe 150/450? Would this make the heads & roller lifters less likely to fail? I would rather keep the heads if they can be made reliable enough. I am not sure if I can trust it as-is. If I need to change anything I should do it now before the motor even goes in the frame. I am more worried about potential breakage than I am the HP.

Thanks in advance!

 

First, that's a very mild solid roller cam....so it should be easy on parts. 650 open isn't insane pressure...but getting up there for a street cruiser. I run a lot more than that and have driven mine cross country a few times.

But solid roller stuff has to be paid attention to. Keep an eye on lash. it's not a big deal..you'll easily notice when one sounds different. When it does..stop and check it. If the lash has opened up...don't fall into the trap of "Oh..I must have missed that one on last adjustment". No...you didn't. Something has changed. Could be a roller, a pushrod, a rocker, a valve tip or even the cam...but find out what it is.

Lifter life depends on the quality of the lifter and design as well as cam and how much you drive. Big Blocks are much harder on things than small blocks due to valvetrain weight and pushrod angles. I've got small blocks driven a LOT that are still going for years and years. A bushing style lifter is more forgiving. "IF" something happens they tend to keep rolling and not chew up the cam vs a needle one that will flat spot the lifter and cam. I've been running needle type in mine for years and just keep an eye on them. Typically I pull them out every couple of years to clean and inspect. After visually looking at them....I clean them in laquer thinner and dry them out well. Only then can you truly feel any roughness in the rollers. many folks just do a replacement/rebuild at a given time. I've had good luck with Crane, BAM and Morel (sold by several cam companies under their name). Also ran some Comps. Either way, make sure you have the ones with pressurized oiling to the axles and if you can afford it...do bushing style.

To original question...for what you're doing it sounds like a GOOD HR cam could be fine. That lift and RPM range is easily in a happy spot without getting crazy. In addition to using lighter springs, look at lightened retainers also. BBC HR's these days can get near 7K pretty easily without a lot of fancy and expensive details work. Again..get GOOD lifters. Yu can't cheap out there.

To me..the ONE thing a hyd lifter is supposed to do is be quiet. But many folks are using pretty aggressive lobes with them and using special lifters to handle the increased ramp rates and spring loads and complaining of the noise they make (often noisier than a solid roller). Plus...the springs those cams need cause the same issues as a solid roller other than the Hyd lifter does cushion things a little.

I've tested solid rollers on a hyd roller cam in a 555" engine. It picked up about 10 HP average and of course allowed me to keep revving it well past 7000 RPM. Lash was set at .002" cold.

As far as your heads...yes they can be a little fragile and most have been broken years ago. If you can add a stud girdle under your covers, that would be a big help...or convert to shaft rockers.


JIM

 

The porosity of those Winters castings is laughable......some guys don't even like to weld them because they crackle and pop while doing it......if you ever see one with the boss broken off...it looks like coral....no lie.
Jim has solid advice.....use a girdle and tie them together if you want to keep these. No...650 is not insane pressure but it is about 200+ psi more than these castings were ever intended for.
If you want to put 20k miles on these heads......I would go HR and lighter over the nose pressure. A quality lifter is key here......the LS guys are spinning 7k with bullshit lifters but as Jim said also...the valve and pushrod angles are much greater...

Jebby

 

You actually said it best.....200+ psi more than they thought would ever be used.....they were designed for flat tappets with .600" or less lift and long slow ramps. That's less than 400# open territory.

JIM

 

Thanks! Jebby and Jim
You guys are the best!
That is exactly the kind of feedback I was looking for!

My current spring is 240 seat, 550 over the nose with a high intensity solid roller cam. (40 degrees intensity) Not 650.
You have both confirmed for me that it would be prudent to change that cam to a lower intensity HR profile (55 degrees intensity) which is more than happy with lower HR spring pressures somewhere in the 100/150 seat to 400/450 over the nose. About 100# less everywhere. And not that much higher than the 110/315# springs these heads came with from the factory.

And my main reason for doing this is to be easier on those old castings. Coral !?! That almost made me laugh! You understand my dilemma well. I really do not want to do a cam or head change or pull the engine again once this car is built. Right now it is just a frame.

I do have excellent Morel Ultra Pro Solid Rollers with needle bearings and full time pressure oiling. They can supposedly handle 800# springs and 8000 rpm and I will not be stressing them near that hard, so that is a plus. Do they sound good?

Someone mentioned monitoring the lash, or any changes to it, as a way of identifying a roller problem as it is developing. Before engine self-destruction. That is my plan as well. That is also one of the reasons I want to stick with a SR vs a HR lifter, to more easily monitor the roller wear. Plus I believe it will rev better.

Yes .002-.004 tight lash cold is probably where I will start, and measure it hot at least once.

However I do NOT want to run a stud girdle. Stock valve covers are planned. Thus one of the reasons for my abundance of caution. Hopefully these changes are enough?

It will be primarily a cruiser, but will see short bursts to red-line, when I have enough room!. LOL
Hopefully it will rev like my old LT-1, just with a lot more HP & TQ.

An aluminum flywheel may also be needed I think?

My HP BB experience is limited to just a single drive each on 3 cars: a restored 427/435, a Baldwin Motion L88 street car, and a 10 flat drag car. But those memories are very vivid indeed. Those memories are the driving force behind letting my LT-1 go and building this car.

Leigh
Building my dream car, one bolt at a time!

 

FWIW I’m running a set of winters aluminum heads with a HR cam and .580 lift with zero issues. Actually it’s the second set I’ve run with this cam.

not a ton of miles but no issues with studs

 

Just think how different things would have been back then if they had done the 049 or 820 head in aluminum…..GM would have had a world beater….
The smaller oval port would have made the spring pockets and stud bosses stronger too….

Nothing wrong with a mild solid and those lifters are excellent.
Mild solids are super reliable….

Jebby

 

Make sure to get the cam on a real steel core...not austempered iron. I also always opt for the pressed on iron gear so I can run stock distributor gears with no hassle.

JIM

 

Ok Guys this is the new custom Hybrid cam I came up with after talking to Bullet. What do you think? Do you like it?



The main thing is it has slower ramps and I can lower the spring pressure some 100# or more. Down to maybe 150/400~450ish. Way less than 240/550#.
Second priority was a touch more duration to rev just a little higher. It peaked and was flat from 5300-5600 before.
Due to the really tight lash, it might even have 6 or 8 degrees more effective .050" intake duration, than either of the other two.
I had 15" vac at 850 rpm before. Just as long as it does not drop too much. That's why he wanted to spread the LC from 110 to 112.

 

I think that is an excellent choice given the specs and the fact that you consulted with Bullet on it.........some sharp people over there.

Jebby

 

Probably going the right way...but that's still not much cam overall from appearances..but of course the whole lobe shape tells the tale in a comparison.

For reference...a really good street cam I used in my old 427 was the Comp 288 street roller. It was the first version..not the later Xtreme. It was a single pattern cam with 244/244@.050 and .623/.623 lift on a 110 LSA. It idled great with good vacuum. On a chassis dyno it peaked around 5750 (would show a little higher on an engine dyno typically).....but at 7000 RPM it only dropped 6 RWHP. The thing would idle around in high gear with 3.36 gears at 1000 RPM. It didn't seem to care if I short shifted it or wound it to the moon...it was always ready. Ran low/low 11's@123 in pure street trim other than slicks. Launches were very soft to preserve the stock rear...but MPH was enough to go in the 10's.

The heads were iron Merlin oval ports with really nice porting that flowed 324 CFM on intakes and 88% on exhausts- hence the single pattern. I was truly impressed with that cam for a street piece. I know Lingenfelter used it in his 496" street motors also.

It's not radical by any means...but just flat works. If it was cut on a steel core with pressed on iron gear it would be a nice piece also.

JIM

 

Just when you think you know a few things a conversation like this comes along. I never knew the castings were crap. But that being said I have been in the metal industry for 37 years now and we do see some castings. The way it is done and the refinement in casting has made them a lot stronger and less core shift and more complete castings. These 2 responding to this conversation have more knowledge on the tip of their tongue than I will ever imagine. I really enjoy the in depth discussion these 2 bring on.

 

Listening to Jim here I believe you wouldn't hurt to go in the 240's for duration on the intake.......the Rec Sewer port has little velocity and low lift flow numbers so hanging the valve open is really how to make these work......the port is plenty big so to get the charge in there, hold the valve open......
The Comp 288 is a great all around piece...agreed......but he had Merlin Ovals with some work.....these heads were the Gold standard years ago and they still are outstanding compared to others....how well it would work on a Rec is debatable....but I doubt it would be terrible.....I like older grinds as they are versatile and easy on parts....
I believe as grinds got "better" they got more focused on straight up power....and that requires sharp ramps.....sharp ramps against a heavy spring is akin to a hammer hit....and the cycle fatigue on an old Winters head takes the brunt of this......
Also...as you say Leigh.....the tight lash has more effective duration....see if they have a little longer intake lobe.

Jebby

 

Thanks guys! You two have more BB experience than I will ever hope to have.

My number one priority to preserve the old heads is to get the ramp speed down. This allows the softer springs. My SR had a Hydraulic Intensity (HI) of 40. By spreading out the adv dur the HI goes to 56 using a HR profile cam. The old extremely slow ramp GM L72 solid cam had a HI of 64. So I am trying to split the difference and enable the softer springs, but not quite as soft or slow as OEM. If I had newer/stronger heads, well that would allow more spring.....

Within that constraint, and still trying to keep some idle vac and low rpm cruise ability, only a very small increase in intake dur is possible, and even there we are spreading the LC from 110 to 112 to help this. The prediction is my 15" idle vac before might drop to 13" now. That should be ok.

I will never get the power Jim got from his Merlin heads b/c the exhaust flow and ratio on these heads is horribly low, it's only 311/203 CFM for 65% ex, so it needs the exh dur crutch.

And Yes I will use a steel core with a pressed on iron gear again this time too.

I am fearful of adding any more duration because that will also add adv dur, and the bottom end will fall off quickly. I already have more overlap than Jims 288 SR roller. The short ramps on that SR cut adv dur and overlap and helped it run really well down low. I can't really do that with these heads. My overlap will be almost the same as a OEM L72/LS6 cam, or an LT-1, so the low rpm feel should be similar to those. The extra adv dur is gonna cost me .5 DCR tho from 8.4 down to 7.9

So basically Bullet and I felt this is as far as I could "push" an HR profile and keep good street manners.

And yes Bullet was extremely knowledgeable, and they have an amazing amount of lobe profiles to select from!

 

So how high do you want to rev it? Rectangular ports "get busy" after 5000-5500.......so to really enjoy them...they need some RPM. The factory L72 cams peaked HP relatively low and would have been better off with a good set of ovals...which we proved many times by sticking L72 cams in 427/390's and killing on the street and track.

I like engines that "don't hit a brick wall" or "fall off" after peak HP....but i also don't mind revving them and build accordingly. You see lots of dyno test that quickly end at peak HP and don't show you it tanks right afterward. That's a terrible combo because you're only in the max power area for a tiny bit of time...then grab a gear and you're way back down the curve. Same concept they talk about with "area under the curve" in cams. The valve is only at .600" for an instant...but it spends all the rest of the time at .200/.300/.400 twice...so those flow numbers are very important! A "FUN" motor will make peak power...and hang on past that point to allow you to keep pulling. So let's say it makes 500 HP at 6000 RPM...and at 6800 it still making 480...and when you shift it falls to 4500 or so.....what is the power down there? Maybe still 450 or so? If it peaks at 6000 and you have to shift right there and it falls back to below 4000...the power average through the gears will be MUCH less...and you'll get spanked.

Don't get too hung up on the numbers....the true effect of overlap on a roller will be much different than a flat tappet because the valves will be open a lot differently due to the ramp speed of the roller. A big valve motor is also impacted more by whatever overlap you have vs a small valve. BUT...larger ports that are a little lazier are less impacted at the low lift points at overlap.

Don't get stuck on an LSA number either. LSA is a by product of the actual valve events..not a specific goal. You can juggle it but you have to pay attention to how it was achieved. To widen it...did they just retard the intake lobe...or advance the exhaust..or a little of both...or different amounts? Same if they tightened it....which lobe is where in relation to the piston. Really look at actual opening and closing points...and then look at actual lift at .200/.400/.600 etc to get an idea of what's going on.

An engine that "hangs on" like i describe is "living on the exhaust port". That's what's needed to make power past peak...you can get it with a kliier port...or more duration on exhaust. But remember..exhaust really wants to get out of that cylinder. It's got a lot of pressure and a piston pushing it out...so you typically need more lift on intake side than exhaust. Adding exhaust duration with an earlier opening point cracks the valve when the piston is still being pushed down..which kills TQ. This is why a lot of hotter OEM cams are single pattern and on tighter LSA. They were maximizing mid range power knowing the heads were a limiting factor..so they worked with what they had. Now..if you're revving higher...you need to open the exhaust earlier and longer....but usually not worried about lower end power because the engine is operated in a higher RPM range.

Again..that Bullet cam is a good one..and will rev as high as you want....but it will peak power at a lower RPM without an incredible amount of head work. You've got enough head to support well over 600 HP...but the cam will want to peak way down in the mid 5000's. Now that might be Ok because those heads will just be getting started and should allow it to hang on pretty well.

Not a perfect comparison...but I built a pump gas 555" for a magazine project. It had dart 335cc CNC heads..very nice.

We tested it with a 270/274 .696/.669 112 LSA solid flat tappet. With a 1000 HP carb and a Vic Jr single plane it made 685 lb ft at 5000 RPM and 761 HP at 6400 RPM. Just for reference..when we let it breathe with a big single plane and a Dominator it made 715 lb ft at 4900 RPM and 810HP at 6500 RPM!

Then a HR with 254/258 .720/.680 112 LSA . The "little carb and intake" made 707 lb ft at 4600 RPM and 760 HP at 6300 RPM with hyd lifters.
With solid rollers on the HR cam it made 710 lb ft at 4600 RPM and 771 HP at 6300 RPM.

Next a solid roller with 268/276 .788/.714 on a 112 LSA. To be fair...we had also done an oil swap here that added HP on the top end also...but it made 690 lb ft at 5000 RPM and 791HP at 6500 RPM. For reference that "big intake and Dominator" again let it breather and it made 849HP at 6700 RPM and TQ only varied by 6 lb ft between 4900-5700. Strong!

Point of all that is we were trying to pick somewhat similar cams that would live and make power in a similar RPM range. Ck out the specs vs the RPM ranges. That HR was really good as far as low end TQ and I can vouch for it running deep in the 10's at 130'ish mph in the first shakedown runs at the track with some teething issues using the little intake and carb in a C3 stick shift street cruiser.

I've seen some well scienced out 238* HR's with low .600's lift peak HP in the 5800-5900 range on 496's with well ported iron ovals and dual plane intakes. But they are out of steam in the 6200-6300 range.

That 288 street roller is theoretically a 44* hyd intensity.....but all I can say is it works well and has incredible manners. The better intensity numbers typically give better manners. That Bullet will likely act similar but I expect it to be even milder. just depends on what you want.

And without going into one of my rants about DCR..I'll just say I don't worry much about it. It's definitely a real thing and what we all shoot for...but all those calculators are worth next to nothing IMHO. You have to think about the whole intake/ex tract. I can build a 14.0 compression engine with a late enough intake closing that will run on 87 octane. But once I stuff my foot in it and the airflow starts moving and those cylinders actually get full...it will of course detonate itself to death. A poor flowing head combo will never fill the cylinder as well as a good one...so it will have more leeway. The old Busch NASCAR engines were 9.0 compression with really good heads. You better believe they required serious race fuel at WOT.

JIM

 

Jim that quote of yours is exactly how I would like my car to run. Extremely versatile rpm. Pull at 1000, cruise at 2000, rev well to 6500. That's the cam I want! "Always ready" LOL
So what kind of cam specs would you suggest?

I just need to do it with a low intensity HR profile. And remember I have the pancake flat 569 intake and a poor exhaust port. It's the round one. The I/E ratio starts at 84% but quickly drops to 66% by .400. I have heard people say the exhaust "stalls" . And the intake may be almost done past 6000 ish too. I want to do the best I can but keep those two very visible components.
So any cam advice?

 

Just taking a quick look through Comp's listings....they make that 288 in a HR version also...and I seem to remember some old testing where the power was about identical to the solid roller version. I've never compared the lobes in detail...but they are showing the higher adv duration. heck it may be the same lobes just ran as a HR. Spring pressures are pretty low on them. I wouldn't go too low with any cam on a big block though.

Ck their 4 pattern HR also....they have the added ex duration...but they also have more lift.

I spent some good time working with Billy Godbold at Comp discussing cams for a 400" SBC project I was doing for a magazine article. The project had decent as cast aluminum heads....but would be tested with an original (but ported) 2x4 intake from a 283 with two WCFB's...then an air gap dual plane with a 750 Holley...and then a single plane with same carb. The discussion circled around "where" the restriction would be from the carb to the mufflers. Overall we determined the heads weren't going to choke it much (like yours)....and the two carbs together could flow 750 CFM...so they weren't the issue. But that intake was so tiny we had to weld up the top of the runners to get it to even cover the tops of the ports on the heads! Very similar to you. Then we did same discussion on exhaust side...from headers to rams horns to straight through mufflers vs normal ones. With a restriction on the intake side...the only real option is added duration to give more time to fil the cylinders...same concept as adding duration for bad ex ports. If you have a great intake/heads and a tiny carb...(think of the old 390 cfm NASCAR carbs)....the concept is a little different...they design it to pull HARD on that carb and make it flow much more air than you think. Remember...they are rated to flow "X" at 1.5" of vacuum....think what's going on when they have 7"+ pulling on them! At the end of the day...the cam I put together was based on their XR286R lobes...but I used the intake lobe for both intake and exhaust on a 109 LSA. That engine made 500 HP with the 2x4's...and 540 with the dual plane and 555 with the single plane. That was a 248/248 with .614/.583 lift in a small block. It drives and runs great even with a 5 speed O/D lugging it down.

As you can see...I used a pretty quick lobe because i wanted it to open quickly to get things going quickly...and being a small blcok the valvetrain is a lot more forgiving.

As I've said..the Bullet cam above will do well...but i wouldn't be scared of some added duration. That 288 was in my 427 vs your 454...and Lingenfelter's 496's.

And at only 6000 RPM with your heads.....a single pattern doesn't scare me either.

Seems we're looking for drivability, long life and hard pulling fun on the street......I think we're there.


JIM

 

Amazing amount of info Jim. Thanks a lot for your expertise.
Your real world feedback on those two rollers on a BBC helps a lot.
That is exactly the kind of driveability I am looking for.
Looking at the specs on the 288AR SR and their XR288 HR all the valve timing events look very similar to this custom Bullet cam.
Plus I avoid the High Intensity lobe of the SR and the lower .520 lift of their HR.
So yes I think we are there!
Unless Bullet has any more ideas. I will ask them if they think a couple more degrees would help.
Then we will see what kind of valve springs they think this requires.

I am chomping at the bit to drive this powerhouse, but unfortunately I need to finish restoring the rest of the car first. I may have to just retire sooner so I have more time to work on it! LOL