Thread: 72elk

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Going to try and stay as close as I can to techinspecror1s recommendations. Old guys can still learn but we do it at a slower pace.

So with the added cost of block work I thinking that roller rockers may not be the best choice. Having vortex heads that require self guiding narrow body rockers I'm thinking about going with the summits sbc rocker arm kit no 12495490. Any comments? I would still be going with a Howard retro fit roller cam.

Originally Posted by States

So with the added cost of block work I thinking that roller rockers may not be the best choice. Having vortex heads that require self guiding narrow body rockers I'm thinking about going with the summits sbc rocker arm kit no 12495490. Any comments? I would still be going with a Howard retro fit roller cam.

If I didn't want to spend the money for Scorpions, I'd use the 12495490's. When you do the first mock-up of the motor, pay close attention to the holes in the heads where the pushrods come up through from the tappets and make sure the walls of the pushrods are not rubbing on the iron heads. There are 3 ways to center the rocker over the valve stem tip on a SBC, by using rail rockers or guide plates or the factory production holes in the heads where the pushrods come up from the tappet. You can use ONLY ONE of these methods. Using two or more will give you a headache, trust me. So, if you are using rail rockers, you have to clearance the holes in the heads and NOT use guideplates. You can use a Louis Tool as a guide to cut the holes in the heads a little or you can just get in there with a rat-tail file and enlarge the holes by hand to prevent contact.

Every good build should include making certain that the pushrods are the correct length. Here is the very best guide to accomplishing that.....
https://www.youtube.com/watch?v=o5is9BsH5OU&t=2s

Originally Posted by States

Did some shopping around and picked up a 010 block already bored 30 over and recently honed. Guy totaled his camaro and was parting it out. Came with speed pro hypereutecic H 6180 30 over pistons with stock rods and caps. Guy also threw in a Summit aluminum Cam cover and cam button. All for $280. Looks pretty clean, no ridges on cylinders. Taking to a shop next week to get checked out. This approach will delay completion of my build but will hopefully work out for the best

I'm pretty sure this is the piston you mean, H618CP......
https://www.summitracing.com/parts/s...make/chevrolet
These will do a great job in a street motor and are the correct piston compression height (1.560") to keep the stock dimensions on the factory stack of parts (9.000") Cutting the block to 9.000" and using a Fel-Pro 1003 will put the squish-quench at 0.041" and will also leave the motor ready to accept aluminum heads with a 1003. You have not mentioned aluminum heads, but that is normally the next change that a fellow will make, so I wanted to address it here.

Usually when fellows bolt on a set of aluminum heads, they use the stock block deck height ~(9.025"+) and use a thin steel shim gasket to set the squish at ~0.055"-0.065" or so (not thin enough to generate a good squish/quench). The aluminum heads and the iron block grow and shrink from hot to cold at very different rates and the material on the softer heads can be abraded (called fretting, where material is actually removed from the heads in certain places along their mating surfaces) and the head must be re-surfaced to use it on another build. This can be eliminated by doing it properly in the first place. Every aluminum cylinder head manufacturer that I know of recommends a composition material head gasket for use with their products. This allows a little "give" between the heads and the block as they heat and cool and prevents the fretting of the aluminum material. It's like bolting the head onto a cushion where it is free to move around a little without doing any damage. Pretty cool stuff, huh ? The GO-TO gasket for a SBC is the Fel-Pro 1003 that squeezes down to make a 0.041" squish/quench when used with a 9.000" block deck height and 9.000" stack. Oftentimes, fellows will find that they can drop down one or two grades in octane and still not experience detonation from their motor by following this prescription.

This is why I try to convince every hot rod engine builder that I talk to to cut the block decks for a zero deck and use the gasket thickness as the squish/quench. You'll need to work closely with your machinist though, and make absolutely certain that the heads and intake manifold will bolt together with no gaps top or bottom to make vacuum leaks. Your machinist will have formulas to get everything to fit together like a glove and not leak. The worst scenario is to put the motor together with a gap at the bottom of the head/intake manifold ports. You cannot find this vacuum leak with a combustible material such as spray ether like you can if they are gapped open on the topside, so every time an intake valve opens, that cylinder draws in oily crankcase vapors from the bottom of the ports that make the builder think that it may be rings or valve seals that is causing the motor to oil when it is actually caused by a mis-fitment between the intake manifold and heads.

GET EVERYTHING FLAT AND SQUARE IN THE FIRST PLACE AND YOU WON'T HAVE THESE PROBLEMS. WORK CLOSELY WITH YOUR MACHINIST. if your machinist won't spend time with you addressing these problems, find another machinist who will. This is too important to do in a half-azzed manner.
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I will be buying a new crank for this build. Any suggestions?

If replacing just the crank, i would ask the machine shop if they have one that will magnaflux good. A cast crank will work just fine for your purposes. If you needed more than the crank, like pistons too, you might opt for a 383 kit from Scat or Eagle. Otherwise, a cast crank off craigslist will work just fine, have the machine shop magnaflux it for cracks and maybe turn it down to the next standard diameter for use with undersize bearings. They will turn 0.010", 0.020" or 0.030" undersize on the mains and/or rods.

I've been checking on limited slip units. It seems to two most talked about are the Auburn Gear cone/clutch units and the Eaton disc units. Any comments or recommendations between these two. My only experience was with the late 60's GM units.

I think Auburn would get the nod if it were mine.
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The block I have has a no by pass oil filter attatachment. Any comments about this? Should I keep it or go back to a standard by pass type?

I'm putting an Eldebrock AVS carburator in the el Camino and find one area of the instructions confusing. There are two distributor vacuum ports on the front of the carb. Facing the carb, the instructions say the one on the left (passenger side) should be used for emission controlled cars then later on it say it's for a full vacuum advance distributor. The say the one on the right (drivers siide) is for non emission control cars. My engine has a hose running from the valve cover to the air cleaner and has a GM HEI distributor. Any idea which side I should be hooking up to?

Go to this site:
http://www.crankshaftcoalition.com/w...op_dead_center

Scroll down until you get to this title:
FACT AND FICTION CONCERNING VACUUM ADVANCE....
Start reading....
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Crazy good link Tech. Thx.

Thanks Tech! That article clarified everything!

Got the block back from the machine shop, washed out, squared, new Cam bearing, new soft plugs and a fresh hone. Machinest says for best reliability I should use cast iron rings, any thoughts? Also got in the Yukon Posi and Richmond gears to be installed on the 15th. Looking at getting a Scat crank and Speed Pro competition main brings as well. Any input on these selections would be appreciated.

Originally Posted by States

Got the block back from the machine shop, washed out, squared, new Cam bearing, new soft plugs and a fresh hone. Machinest says for best reliability I should use cast iron rings, any thoughts? Also got in the Yukon Posi and Richmond gears to be installed on the 15th. Looking at getting a Scat crank and Speed Pro competition main brings as well. Any input on these selections would be appreciated.

Let's let Hastings clear the air for you concerning ring composition.....
https://www.hastingspistonrings.com/...ecommendations

You should also know that different compositions require different hone finishes on the bore. Cast iron requires a rougher finish and in my opinion, will not last as long as a moly-faced ring which requires a smoother bore finish. Ask the machinist for an estimate in his opinion of the service life of cast iron versus moly-faced. If he says the moly rings will last longer, but require a smoother bore and are more expensive, then it is up to you as to whether or not you want so spend the additional jack for additional service life. I would expect a cast iron ring rebuild to have a service life of 60,000 to 75,000 miles, while I would expect a moly ring rebuild to have a service life exceeding 100,000 miles. I'm not sure what the OEM's are using for piston ring material, but my 2004 Ford F150 SuperCab has over 235,000 miles on the little V8 motor, uses very little oil and still has good power.

As far as ring width, that is governed by the width of the ring grooves in the piston. In the past, you could order either 1/16" (0.0625") or 5/64" (0.078"). I have always preferred the wider ring for a daily driver and the narrower ring for a strip or street strip motor. The narrower the ring, the less tendency it has to flutter (and lose seal) at higher rpm's because of its lighter weight. The wider the ring, the more surface area it provides to effect a good seal against the bore. Current thinking is to go with narrower rings, which will lend a little extra horsepower and therefore, mileage. Of course, if you are not changing pistons, then you will have to use the ring width you have now.

Don't know anything about Yukon, but have used Scat parts since Noah was a teenager. And of course, Speed Pro has been around forever.
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Mechanic said I could expect 100,000 with cast iron. Older guy and I'm not sure he's up to date with newest technology. Hasting site has be thinking about cast or Molly. I could expect extended periods of operating around ,3,000 rpm but have never seen temp go over 190 in it's present state