Well it has been a slow start, but I am finally moving forward with the turbo project.

Couple of things I am interested in.

1) Is anyone using Cometic MLS head gaskets for their Chev turbo engine? My engine builder wants to use them and they seem to be a bit difficult to come by, but I have heard that they are out there. What other type of head gasket are you using for higher boost applications?

2) Anyone using hydraulic roller cam? If so your input would be appreciated, or for that matter any input is welcome.

There are at least 756 other things I'll be asking as this thing moves along, but I'll settle on these for now. As always I thank you in advance for your 2 cents worth.

Paul

Which engine and how much boost?

I heard the HG is about $175.

MBHD

Cometic HG are well known/used on turbo engines. They may seep when cold but seal when hot and don't blow out if the surfaces are properly prepared. Some folks that I know just add barrs stop leak to help with the little bit of seepage.

The 4200 gasket is a MLS steel and have no issues with sealing boost.

CNC, the gaskets are for my 250 and we are planning on 16 lbs boost.

Hank, I think $175 is just fine if they seal as well as my engine builder says. They just seem to be a bit hard to come by. Cometic says that they don't have any in stock at the moment.

Paul

Paul,
I contacted them also, no luck.

MBHD

Bummer, maybe someone is sitting on a spare gasket or three. Heck, I would even toss in a case of Molson Canadian beer to get my hands one one.

Paul

Were you planning on O-ringing the block. Also, it wouldn't hurt to drill the head bolts in the block to use 1/2" bolts. Is this going to be a race engine.

His 250 should already have 1/2 " bolts stock. You know that.
How about some 9/16ths bolts? Don't think there is enough material though.

The left front of the low deck block is weak as it is w/1/2" bolts.

MBHD

Mc Goo,

I don't know if hyd. rollers will work on an inline six because of the oiling passages, I have never heard of any existing.

I do know how to get Cometic gaskets, but dam I don't drink beer, what can I say !

Mike Kirby had Isky make a hyd roller cam for one of his customers.
That was the same time when I purchased my solid roller from Isky also.

MBHD

HA! HA!

MLS gaskets from cometic are the best for sure, they have to make tooling to stamp them out this is were the cost comes.

The reason some have sealing problems is the reason they want you to use a 50 RA or finer surface. some use copper coat and some use HYLOMAR spray, I like this best. If you have a problem.

OH! you can get them from the exclusive dealer Mike Kirby I think he paid for the tooling.

The reason MLS gastets work so well, as you know when an engine fires it tries to lift the head off the block, so you need something with spring to try and keep the combustion seal this is what they accomplish very well.

Harry

I have been e-mailing Mike for a HG for a long time now , but no responce & I can't seem to find his website anymore.
Is the website down?

Guess I should call him since he has not responded to my e-mails.
Is he OK?

The thing I do not like about the MLS gaskets from Mike is that they have a 4.125" bore IIRC?

I would be happier w/a 4.0" bore HG.

MBHD

Turbo, I will consider a bribe of what ever your favorite beverage is if you can steer me towards one of these. (some great coffee or tea perhaps?) Thanks for the tip, but it sounds like Mr. Kirby is a tough guy to get hold of. I will try though.

This is not a race engine per se, but it will see some track time and a lot of street/highway use.

Paul

Using a hydraulic roller in these engines has been done successfully quite a few times. Its just a matter of gathering the right components from various other engines to make it work. I started a post almost 2 years ago about offering solid and hydraulic roller cam cores for these engines.

How did you make out with your Hydraulic rollers? I noticed in your profile that you share a similar approach to this hobby, applying modern technology to classic cars.

Listening to the guys at the engine shop, they explained some of the advantages of modern hydraulic roller cams over flat tappet design. It seems to me that there is no comparison.

Since Chevrolet never offered this engine in a configuration similar to what I am shooting for, I see no reason to stick with old technology throughout the build. (except for me, I am old technology

Paul

I was considering the hydraulic roller to offset(at the time)the problem and concern with the lack of zinc in our engine oil, and its effects on flat tappet cam style engines. At that time, the concern regarding the oil was shared by many, but the interest in considering a hydraulic roller conversion wasn't. Granted, it can be a pricey upgrade, but it is immune to the ongoing degrading of our engine oil, as all our modern engines use that technology. In time maybe the interest will grow, but it is doable now with little problem, just the initial cost of the cam and lifters being the most costly.

After doing to engine builds in the last 3 years (350 and Inline 250) I have done alot of research and thought about the zinc content. I use Brad Penn Break-In oil and then Brad Penn 10W30 as daily oil. I have had no issues and seems to be real high quality oil.

Moving along slowly, but at least moving.

Well still planning on going Hyd roller. I will report back on that topic soon.

I have had no luck trying to chase down the good head gasket. My machine shop is considering o-ring option, but I still have a wee bit of time before that decision has to be made.

One quick question that I know has been around the table one or seven times. Lump or not with a turbo eninge? From what I can see there is a benefit to the addition lump port even with a boosted engine. I would appreciate a couple points of view, and also on the newer style lump that seems to be available.

Did I mention that I am still looking for Cometic head gasket?

Another item I am considering is Harland Sharp roller rockers. My friends that run them on their V8 eninges are happy with them and have had no issues. Anyone else using them? I know I may have to lose the Offy valve cover due to clearance issues, but I think that is a small price to pay.

Still having fun though.

Paul

You dont need to loose the Offy valve cover if you use a spacer & you still might need to round off the corners of the first & last rocker arm.
A couple guys here make them.
As far as lump or no lump, well, when you are forcing air/fuel into a cylinder, your cylinder head design is less critical.

Adding lumps will help, so it would be worth doing.

Too bad Tlowe did not compare a non lump head when he turboed the 250 on the dyno.

MBHD

If you can't find a dealer to help you, call cometic directly.

If they don't make one as a shelf stock item, they can cut one for you.

http://cometic.com/custom.aspx

Thanx for the tip.
I have just fired off an email to Cometic. I'll report back on their reply. Hopefully I will hear back soon.
My engine builder had touched base with them, but I don't think he persued a custom option.

Hank,
The outside rockers on the Harland Sharp set are already rounded off. I was looking at the inside of my valve cover and thought that even with a spacer it might be an interference fit.
I did notice that Tom Lowe has a tall cover available. I'll get in touch with him to get some feedback.

Cheers,

Paul

McGoo, Tlowe also has roller rockers made for him exclusively that eliminates the need to clearance the corners of them for valve cover clearance. No valve cover spacer is required either. Also, I have found a solution for the distributor gear hobbing on my roller cam blanks and am moving forward right now. I bought a 12 ft stick of material to get 5 of them roughed out and machined to get ready to send and be hobbed and copper plated. These can be finished as either a hydraulic or solid roller version. So before long the hydraulic roller setup can be available to those who are interested in it. The Slant 6 Chrysler and Ford 300 guys are anxious to get some also. If you can't get a Cometic head gasket, you might have to consider a copper gasket as an alternative, which with an o-ringed block you will have no issues or concerns.

I think that with the results shown to him/us with the lump/no lump combos that were tested it would be safe to say that the same results would be expected to be seen when compared to a turbo engine if you did or didn't use lumps in that type of application.

Thanx CNC,

I agree that the theory behind addition of lumps should apply regarless, I just always like to get someone elses 2 bits worth. I see a new style of lump out there now too that I will look into.

My knowledge of all things camshaft related is very limited, so I have to rely on the machine shop to guide me through it. I am interested to hear how you make out the the distributor gerar issues though.

Thanx for the heads up on Tom's rocker arms. I sent an email off to him earlier today regarding a few of his wares.

Paul

A few years ago I contacted Cometic about making me a special head gasket for my inliner Ferds. It took a trip to their office in Concord Ohio and a personal visit from me to convince them to make me a laminated gasket. And they were not willing to emboss it - apparently that's where the expense of making these multi layer gaskets is. So they made me a couple of flat non-embossed gaskets which I cut apart, made my own embossing dies, stamped and reassembled.

My cost from Cometic for the two gaskets $220.

Regarding Harlan Sharp - Again I made the effort to visit their Strongsville plant with blueprints in hand for some custom shaft-mount rockers I needed. I have found that these relatively small aftermarket suppliers are much easier to convince of your sincere desire to do business with them with a face-to-face meeting in which you lay out as many of the details of your wishes as you can. It really helped reduce their R&D costs and get the project in their line-up of jobs. Good luck.

I run a Custom made SCE pro copper head gasket with stainless steel wire o rings.

Just give them a call and they can make you one fast.

Adam

From a call/chat with comp
Those rockers are a Standard BB chevy that they make and it has vary little difference over the Standard Pro magnum rocker to look at them. I have a set of their Pro magnum rockers.So that rocker is not made for any one exclusive.So You can go to any speed shop and buy them.

It is a rocker that is cast and machined different than standard pro magnum rockers. It has the correct 1.75 ratio. The pushrod seat area is totally different than pro magnums.
And my price is very reasonable for the quality they are. Much better than aluminum rockers.
Try and buy them from any speed shop and see what the price is.

Thanx guys!

I heard back from Cometic today, and they confirmed that a MLS is not available for my application. Here is the reply,

"Paul,

I am sorry but we have only made a MLS for one style of head which Is different than the standard heads for the 250. We can make customs but it would have to be either a copper or composite gasket. To make another MLS will require tooling costs, which can be upward of $3000. I am more than happy to help you with any further questions."

Not sure I want to spend that much on a head gasket, so copper and o-ring looks like the way to go.

Tom,

Thanx for your input. Answers the question I emailed you. I get the hint that you prefer the Pro Magnum over an aluminum?
What about the difference in new lump vs old for a turbo charged application?

Paul

Paul,

If you want a Cometic head gasket , order it from Mike Kirby, IIRC they are $175.00

Did you call him?

The cylinder head layout is the same. It does have a 4.125" bore though.

MBHD

Paul,
There is really no life changing difference on the performance of a turbocharged engine with new lumps or old lumps. The main thing to do, get the head flowing better.

Thanx Tom, Look for my order tonight.

Paul

Got it. Thank You!

Stopped by the machine shop today to visit my engine. It's resting comfortably.

As soon as the lumps arrive the headwork will begin, pistons can be ordered once final combustion chamber volume is determined, connecting rods being ordered, and all that other machine shop stuff that I have no clue about.

Anyone have a spare torque plate that I can borrow/rent for a couiple of days? My shop will make their own out of a spare cylinder head otherwise.
Funny how machine shops have torque plates for almost every V8 you can imagine, but an inline 6,.........

Long weekend in August is the wishful thinking date, but things will progress very quickly once the head work starts.

Paul

Paul,
I have a torq plate. Rent it out also. Shipping to you would be a killer. Willing to do it. Pm or email me. Tom

What rods you going with?

Thanx Tom,

Email heading your way.

Rods will be out of the box aftermarket high performance rod for 250 (same as small journal SBC). Brand to be determined. Had thought about custom made rods but the cost involved seems a bit crazy considering the performance levels I am looking for.

Paul

IIRC there was a company (Eagle ?) that was making a 250 I6 rod set, correct BE width and all.

Scat and Crower also have them.

The block distorts a lot with plate bolted on with studs. The bores will distort about .004 at every bolt down to about 1" depth in block.

Sorry I didn't see this post originally. Do you have any of these cam blanks available?
Can these be finished for the 292 fuel pump lobe?

Bruce

Hank,

Somehow I missed this post of yours. I don't have Mike Kirby's number. If you email or PM it to me, I will give him a call.

If there were enough people to put up some $$ I would comission Cometic to build an MLS for this application, but at $3K I am not willing to risk the investment on my own at this time.

Paul

Hi Bruce, im doing(5)Chevy Billets right now. Unfortunately, the stock fuel pump arms aren't compatible(metalurgically) with the material roller cams are made out of, an electric fuel pump is going to be the only choice when using one.

http://www.sissellautomotive.com/

Sissells Automotive


621 North Citrus


Covina, CA 91723


Phone: (626) 331 2727


Fax: (626) 331 3139

Okay,
Can I buy one?

I don't see why not.

I believe Mike has them in stock.

You are better off calling Mike than an email IMO.

MBHD

I don't think he's talking about one of his Hank, these are what he is responding to that we were already discussing before you commented.
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5 Chevy's and 1 Ford coming right up.

Yeah, I was referring to your steel cam cores. I want a custom grind. Comp has the profile I want but only lists this as a custom cam. I have not pursued it because I'm a bit behind on projects and won't need it for about a year.

Looks like your cores would be exactlly what the doctor ordred. The lift seems a little low though.

Bruce

That is just the semi-finished blank in the 3D drawing. They have a full round lobe at this point, the camgrinder finishes it from there and puts their profile on it and makes it a finished product.

Sorry, I was only trying to be funny!

Thats ok, I can see how someone could think that though.

There would be a lot less strain on the valve train without all that up and down stuff going on.

Yeah, I want a high lift, short duration roller hydraulic. I think the valve springs will be the major bugaboo. Race springs will work but are overkill for the street. About .600" gross valve lift, RPM limited to about 5252 (where torque=HP). Any suggestions?

Yeah, I know that. Taught Autoshop for many years starting in 1970.

But who cares about all the measuring systems. Good ol' American HP and Torque. That's what we grew up on and understand.

The reason I am limiting the RPM is really more to do with piston speed and valve train stress than anything else.

A pound is a pound, any other unit of measure is a percent( more or less)of the pound. Therefore if you use the correct percent the RPM stays the same 5252.

Harry

The significance of 5252 is greatly inflated.

5252? Clue me in please.

At that RPM, HP and torque are the same.

Horsepower formula; hp= RPM times Torque divided by 5252

Torque formula; torque= 5252 times horsepower divided by RPM

At 5252 rpm, torque and hp are equal (check any hp/torque graphs and see- neat)


They are very important in calculating paint slippage and how much to cut off!

To paraphrase a Garry Moore comic piece called "ode to a tooth" cica 1955 for pistons/valves in our fave motors ..."at least six on bottom an' twelve on top are needed in order to blow things op" Also "cowboys out in nevadda would ask each udder whats the madder?"

It seems all thing old things can be made new. Look up "ode to a tooth" in the encyclopedia brittannica 1955 yearbook (same year Brooklyn Dodgers won the world series).

I gotta sit down-dis is too heavy! Did I stray?

Great, thanks. I've told you all before that there are lots of empty spaces in my knowledge base as well as some spaces filled with stuff that just ain't so. Swiss cheese comes to mind. I must have been out in the sage brush gathering "udders" when that came down the information dirt road, but I knew 5252 was not a Winchester cartridge designation.

Lumps arrived yesterday, Thanx Tom!!
You might hear from the machine shop if they have any questions about the install.

Slow progress so far, but at least it's progress.

Paul

Wow, it takes awhile to get there. You have my # and I do return calls. Tom

Yup,
Not sure if that is a function of USPS and Canda Post, or just Canada Post.

We will do more business in the very near future I'm sure.

Paul

Still plugging along with this thing.

Pistons ordered today, Rods have arrived, valves are here too. Head is starting to look very unlike a stock 250 head.
Looking for oil pan for the car (Charlies seems to be a good choice so far).
Cam choice is pretty well done, Toms cam seems to satisfy my tuner and engine builder both. They prefer his cam to the custom grind recommended by Comp Cams.

I need to know what you are doing for accessorie drives. Using a non 250 balancer means bolting a pulley onto the front which of course will not line up with the other pulleys. I do have power steering, but no A/C.
I think I need to get a spare engine in here for mocking up purposes.

Paul