Thread: 72elk

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Been talking with comp Cam and found out that the springs were supplied with the wrong retainers for my application so I've ordered their recommended retainers and locks. I also asked there tech group what Cam they would recommend their response was Cam kit k12-423-8 502/510 lift, 224/230 duration @ .050 on a 110 lsa. I would really like some comments on this Cam from you guys that understand this stuff better than me. I will be running 4.10 greats.

Just checked out the Cam kit....don't need all the parts ant too many $$$$. What about the specs?

Originally Posted by States

What about the specs?

That cam will want a static compression ratio of about 10.00:1. Current thinking is that an iron-headed street motor should be capped at about 9.5:1 because of the propensity of pump gas to detonate with iron heads. My thinking is that if you carefully de-burred everything in the combustion chamber, on the piston crown and the spark plug electrodes and threads and used a fuel/air ratio sensor in each collector of the headers to set the proper fuel mixture, you could probably get by with the 10.00:1 static compression ratio on pump gas with no detonation. You would also need a tight squish/quench of 0.035" to 0.040" to create turbulence in the chamber just as the spark plug fires.

The cam is one of Comp's Extreme Energy grinds. I personally do not care for this technology, but some fellows are OK with the noise generated by the extreme ramps. With the 110 degree Lobe Separation Angle, it will be difficult to create much intake manifold vacuum for power brake operation, if you have power brakes. Power begins at 1900 rpm's, so you will need a minimum of 2,500 stall in the torque converter.

My best guess is that you told them you wanted a lumpy idle and this is what it costs to have a lumpy idle. Everything else has to take a back seat.

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Didn't ask for lumpy idle, just asked for their recommendation, not even set on a comp Cam yet. I would prefer to stick around 9.5:1 compression. Any recommendations at what I should be looking at? Comp Cams did say that with the heads/springs/retainers I have that I am limited to a max lift of .525.

Originally Posted by States

Didn't ask for lumpy idle, just asked for their recommendation, not even set on a comp Cam yet. I would prefer to stick around 9.5:1 compression. Any recommendations at what I should be looking at? Comp Cams did say that with the heads/springs/retainers I have that I am limited to a max lift of .525.

How would I do it ?
0.030" overbore to 4.030"
Stock stroke at 3.480"
Cubic inches 355
L31 heads with ~65 cc chambers (chambers generally pour a little larger than advertised)
Keith Black KB193-030 hypereutectic pistons w/ 5/64" rings (makes 9.5:1 SCR) This piston has a compression height of 1.561", so I would cut the block decks for a block deck height of 9.001". This will make a zero deck motor. (1.74" crank radius plus 5.7" rod length plus 1.561" piston compression height equals 9.001"). Using a Fel-Pro 1003 head gasket that compresses to 0.041" will give you a 0.041" squish/quench and will insure that the motor will run on pump gas without detonating.

Have your machinist insure that the angle between the heads and the intake manifold is zero so that there is no leak. If there is a bottom gap due to differing angles between the manifold and the heads, this will allow the motor to suck oily vapor from the crankcase every time an intake valve opens. Often, this is mistakenly blamed on valve seals or the piston rings not sealing up. So, make sure the intake manifold and the heads are dead nuts parallel top to bottom and end to end before final assembly. THIS CANNOT BE OVER-EMPHASIZED. if the gap is at the top of the ports, it can be found by spraying a combustible mixture onto the manifold while the engine is running, but if the gap is at the bottom, no such finding is possible, the motor will be an oiler and there is nothing you can do about it except disassemble and re-machine the surfaces or buy new parts and cut them to fit. Your machinist will know what to do it you show him this post.

Knowing what I know about motor oils, I will never recommend a flat tappet cam in today's world. Anyone doing so is just asking for trouble unless he takes various precautions and includes an oil supplement with every oil change. Extreme lubricants phosphorus and zinc have been eliminated from off-the-shelf motor oils, so you must add these chemicals to the oil in order to insure that the lifters will not frag the lobes of the cam. There are other precautions that can be taken if you just absolutely have to use flat tappet lifters......
http://www.crankshaftcoalition.com/w...ips_and_tricks

With 9.5:1 static compression ratio, my pick of cams would be a hydraulic retro-fit roller, Howards # CL110235-12.
https://www.summitracing.com/parts/hrs-cl110235-12
The lobe separation angle of 112 degrees will allow production of more intake manifold vacuum for power brakes. This is always a back and forth choice, with a smaller LSA favoring more low end power, less top end power and less intake manifold vacuum or a cam with a larger LSA favoring less low end power, more top end power and more intake manifold vacuum. Regardless, if you have power brakes, you need to address that need as well as the need for power. Most OEM cams are ground between 114 and 117. Most hot rod cams are ground between 112 and 106. You will have to figure this out for yourself. I made the choice of 112 for you because I think this will make enough intake manifold vacuum for power brakes and still make good power. Everything in a street motor is a compromise.
Intake duration at 213 is perfectly matched to your 9.5:1 static compression ratio. This cam will work with a 3-speed or 4-speed overdrive transmission. I would match it up with a 28" tire and a 3.50 to 3.73 rear ring and pinion with a non-slip unit of some kind.

I would use a minimum 2000 stall converter and a 2500 might work even better. Use a 10" unit that is build for the purpose rather than a 12" converter with the fins bent over.

Use 1 5/8" long-tube headers with an X or H tube installed immediately after the collectors. You may also want to install an air/fuel ratio device in the collectors that will tell you whether the mixture is rich or lean. 2 1/2" pipes from the collector to the rear of the vehicle with mufflers of your choice somewhere along the way will be fine. I like to run the pipes all the way to the back bumper to prevent my ride from sounding like an amateur build and reverberating the sound under the vehicle against the body or bed sheet metal.

Use a 14" diameter X 4" tall air filter assembly so the motor can breathe.
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Wasn't planning on doing anything with the block. Has good compression (see numbers in earlier post) and doesn't burn any oil. $$$$ are main reason. Also as stated earlier I've got a TH350 tranny, no overdrive. Would the suggested Cam, gaskets and other top end items still be a good fit?

I keep hearing that using a flat tapped Cam is a no no. I've got a 1969 sbc with vortec heads so from what I've read it allears as though I would need to use a retro fit roller Cam which are pretty pricey. Tech inspector 1 gave me a great plan above but I don't have the money to do everything he has suggested. If he or others could help me out on some of decisions I need to make it would be appreciated.
The engine in its current state runs good, has consistent compression on all 8 cylinders and burns no oil.
Transmission is a 350 TH recently rebuilt with installation of a Trans Go shift kit. I know I will need to change torque converters. Looking at a 2500?..
Need to change rear end to a 4.10 ? With posi.
Need a Cam that will work between around 1800 to 5500 rpm.
Will be putting on headers with an H cross.
When pulling the heads I will determine if I will look at pistons to see if I need new ones , suggestions on what I need would be appreciated.

Once I tear into the engine in my 76 Vette the cam and lifters will be replaced by a Howard's flat tappet cam. There are only a couple of manufacturers I would trust and Howard's and Isky are two of them. IMHO, the rick to breaking in a flat tappet cam is spring pressure and the proper oil. I will break in the new cam with the worn springs currently in the engine and some ZDDP additive. After the cam is broken in I'll apply air pressure to each cylinder and replace the springs with the ones that came with the cam.

I keep hearing about money as a barrier to doing the build correctly. I've told the story many times that I was on a budget of $50 per week when I was building my '27 T roadster. I wanted a set of All American coilover shocks for the front that were $550, so I had to wait for 11 weeks to get them.

The proper way to build a motor is to begin with the bare block and have your machine shop verify the mains and cut the decks to ZERO, based on the "stack" of internal parts that you will use. Then, the thickness of the head gasket will determine the SQUISH/QUENCH, which should be 0.035" to 0.045" ideally. Cutting the block decks will also give you a "square" block that will allow the heads and intake manifold to seal up and insure that all combustion chambers are the same volume to make a good motor. If you or anyone else reading this thinks that the decks or anything else is square on a production block, then I have some land in Florida that I'd like to sell you.

You can half-azz the build if you want to, but I really don't want to be a party to it. Now, sit down with your wife, make a REAL budget for the build and stop being silly. If it's $10 a week, OK, it's $10 a week. I can show you how to make a flat tappet cam live in your motor, but it takes some doing. NTFDAY (Ken) knows how to do it, look at the post just above this one. Here's the rest of what it takes.....
http://www.crankshaftcoalition.com/w...ips_and_tricks
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i have at least 20 builds out there with grate motors and flat tappet cams . new cam, new lifters and correct break in is all important . so far i have not had a failure. but in any future builds i will use ls motors or at least go roller motor . my days with mr. goodwrench truck motors are over. i can score an ls1 with trans and all acc for around 2500-3000 .

i remember those days Tech . it took me about 4 months to buy my first set of cragars . could only buy one at a time .

Has anybody heard of or have experience with PRW lifters? Should I just forget about using roller lifters and stick with stock lifters

I hear you guys and I don't need to seem whiny. I'm retired with my only income is SS. I can budget things out but will be a very long process. Here is where I'm at now.
Vortec heads
Comp Cam beehive springs with retainers and locks
Mr Gasket stud pin set
Edelbrock AVS 650 carbuator
Edelbrock RPM intake

What I know I need
Headers
Mufflers
Posi rear end and new gears
New torque converter
Rocker arms
Push rods
Bolt and Gasket sets
Valve Covers for Vortec Heads
Cam and lifters

I've got about $3,000 to finish off the the above and anything else I can accomplish. Any thoughts where I can save $$$$$ ? I'm not comfortable replacing the rear end myself. I've worked on engines and trannies but never differentials.

Ever thought of buying somebody elses project motor complete?? I had a buddy, he bought a show car with a motor (454) with less than 3000 miles and sold it to the machine shop for 600 complete, every bracket everything because he wanted numbers matching, there are a zillion take outs out there, same guy just sold his Novas small block complete carb to pan for $800 with edelbrock heads and new carb, you could drive the thing it ran great, sometimes building a motor is way more expensive than buying a crate or take out, just know what your getting and check it out well, my thoughts of being on a budget, nothing wrong with having to be conservative but building is generally more expensive I have learned.
Heck your talking small block stuff here, its not rare. Yeah my next motor will have roller lifter but do it right if you do flat tappets, check the cam manufacturers recommended oil and break in procedure, not a bunch of strangers on the net, you ask 10 guys and get 10 answers (though those on here are really good) but fact is if that cam goes bald and you tell Isky you did what Joe on the net said they will not only laugh they will most likely tell you see if he will warranty it then and your out at least $300 more. I use a flat tappet Isky( hemi build) and they where VERY clear on what to use, they said Brad Penn, not his break in oil, just straight Brad Penn period, I called and asked about using Brad Penn break in oil and the tech said, did it say break in, I said "No" and he said then don't use it. Use there recommended oil afterwards and drive the hell out of the thing, like we did for 50 years with flat tappet motors with the right oil.....Best of Luck

As I have said many times, the problem with using a flat tappet cam in today's world is that the oil companies have removed extreme pressure lubricants from the oil that used to protect the contact point between cam lobe and lifter. I'm going to post this link again because it includes all the information that you need to make a flat tappet cam work in today's world.
http://www.crankshaftcoalition.com/w...ips_and_tricks
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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