Thread: New small block build help

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I want to build a small block similar to the 70 Lt-1 I drove in high school. I really liked the sound, power, and high revs it would turn. I would like to use the original heads, intake, and similar cam. What compression do I need to be at to make everything work? I realize that 11:1 is probably too high, so what works with today's gas?
Would a ZZ4 short block work with my parts, or would the compression be too low?
Any ideas for a build would be greatly appreciated. I haven't messed with the car in years, but am eager to get it running again.
1964 Chevelle SS with 4 speed

Thanks

Welcome to CHR!

The LT-1 certainly was an incredible engine. The RPO LT-1 motor was first introduced in 1970 (and there after officially referred to as “LT1” no hyphen). It was rated at a very conservative 370 horsepower at 6,000 RPM. As you mentioned it was 11:1 compression (still “doable” today with premium gas) and it was built with all the good high performance pieces in the GM parts box – including a mechanical flat tappet cam. The heads were the #186 castings on the 1970 LT-1's - 2.020 intakes, 1.600 exhausts, and screw-in studs. The high rise aluminum intake was one of the best factory pieces to ever come out of Detroit with a 4160 style Holley carburetor it pushed a fairly heavy Corvettes to14 second ETs.

ZZ4 is intended to be an aluminum headed roller cam engine that is thirty years newer in technology. IMO, it would not be well served with the 1970 LT-1 cam and 186 heads. A complete ZZ4 crate engine would really cook in your 64 Chevelle and would be a good choice (as would any number of crate engines in the $2,500 - $5K range).

If you’re set on building an engine, you may want to also consider a 383 - but definitely build with a hydraulic roller cam. Tons of build knowledge here from Pat McCarthy, Jerry Clayton and others who are more than willing to share with those who genuinely want to listen and learn. Tell us a bit more about what you end goal is, i.e. cruiser, daily driver, bit o’ drag racing and what you’ve got in mind for budget.

Regards and once again, welcome to CHR.
Glenn

Welcome to CHR! We're glad to have you here, and hope you'll stick around through getting that Chevelle back on the road and more. Like Glenn says, you really shouldn't even consider a flat tappet cam, because the changes in oil additives (took out the zinc) make them unreliable. My engine was built at 10.3 to one compression and needs 91 octane to be happy, and I sincerely wish that we had cut it back to 9 or 9.5 to one. You'd be surprised how many places don't have three tanks any more, and you never know how long that premium has been sitting in their tanks, either. Lastly, I know it's one of those Memory Lane trips to say "Yeah, I've got the double hump heads with the big valves....", but head technology has come a long way in the last thirty years, and aluminum heads help you dissipate heat soooo much quicker which will help you in that compression ratio arena for one thing.
I second Glenn's advice that you at least consider a turn key crate engine for your Chevelle. Unless you're wanting a numbers matching, all original, deep pocket restoration targeted at a serious collector I think you'll be happy with what you find. You can always keep the OEM stuff in the back room, and change back if you want the numbers matching thing.

And to close,

Originally Posted by glennsexton

If you’re set on building an engine, you may want to also consider a 383 - but definitely build with a hydraulic roller cam. Tons of build knowledge here from Pat McCarthy, Jerry Clayton and others who are more than willing to share with those who genuinely want to listen and learn. Tell us a bit more about what you end goal is, i.e. cruiser, daily driver, bit o’ drag racing and what you’ve got in mind for budget.

Regards and once again, welcome to CHR.

Thank you for the replies so far. Yeah the Chevelle was a blast to drive back in my younger days. My father purchased the car from a neighbor in 1970. He immediately ordered the Lt-1 to replace the original 327. He gave the car to me when I was 13 or so.
I have been studying crate engines (especially the ZZ4), but have never driven a roller cam engine. I have read that they don't sound like "muscle car" engines. Is this true of all roller cams? It may be superficial of me, but I really love that Lt-1 sound. Or any built small block really.
The Chevelle will be a cruiser, not daily driver.

Thanks again!

Well the only sound that I know of that an original LT-1 may have over a new roller is the tic-tic-tic of the lifters when cold (or when in need of adjusting!).

The ZZ4 with a good set of ceramic coated headers (good for heat and stay pretty forever – trust me here), 2-1/2” exhaust with a cross over and a set of 40 series Flowmasters with dumps just before your rear wheel openings will be the sweetest sound you’ve ever heard. Not having to fiddle with the engine will be a big plus as well. All of the components have been selected to perform well I‘d even go so far as to recommend a 750 Q-jet and you’ll think you’ve died and gone to heaven the first time you nail it and those big secondaries open.

Keep us informed as you decide!
Glenn

Originally Posted by Ncsumd

I have been studying crate engines (especially the ZZ4), but have never driven a roller cam engine. I have read that they don't sound like "muscle car" engines. Is this true of all roller cams? It may be superficial of me, but I really love that Lt-1 sound. Or any built small block really.
The Chevelle will be a cruiser, not daily driver.

Much of the "sound" was from a mechanical (solid) lifter camshaft, so a solid cam (flat tappet or roller tappet) will have to be included in your build in order to enjoy the sound you are recalling. The source of the "lopey" sound is the timing events ground into the cam when it is manufactured. The lope is actually the sound of the motor being inefficient. Any cam you bolt into the motor will have an rpm operating range of about 3500 rpm's. It will be efficient from idle to 4200, or from 1500 to 5000 or from 3000 to 6500 or from 5000 to 8500 or whatever. If the cam is ground to operate higher in the range, then it will be totally inefficient in the lower rpm ranges. That's what you're hearing with the "rump-rump" idle of some of the motors being built today. If the motor makes power from 3000 to 6500, for instance, then it will be inefficient and down on power at any rpm's less than 3000. That's when we must crutch the motor up if it's a street motor. We do that by using a numerically-higher rear gear ratio (to allow the motor to get up into its operating range sooner) and a looser torque converter if we are using an auto trans.

Now, since power brakes depend on intake manifold vacuum to operate the brake booster, we will need about 18 inches of mercury or more to operate them properly. The nastier the cam grind, the less manifold vacuum we will produce, so it may be necessary to convert over to a hydroboost system if you use a particularly nasty cam on the street. Do not place your life and the lives of your passengers on a vacuum cannister that stores vacuum. It will be used up pretty quickly in a panic mode and you could find yourself without brakes of any kind.
Installing A Hydroboost Brake System on a Chevy

I think that if I wanted to do this using ZZ4 stuff, I'd order a partial assembly.....
GM Crate Engines ZZ4 Partial Engine - part number 12561723
This would give you the steel crank, good rods and hyper pistons, less cam.
"This partial engine includes the ZZ4’s forged steel crankshaft and comes with LT1-style pistons and connecting rods. It does not include the camshaft, cylinder heads, lifters, timing set, front cover, oil pump, oil pan, balancer, or flexplate. All parts needed to complete the engine assembly are available from your GM Performance Parts dealer."

Current thinking puts the cap on static compression ratio at 9.5:1 with iron heads and 10.5:1 with aluminum heads, if the motor is to operate on readily-available pump gas. You must determine the heads you will use ahead of time, in order to know the chamber volume and be able to figure the static compression ratio, so that you can figure the cam to use. Cams are matched to the SCR, they are not just snatched out of thin air without knowing anything (although most of what I read in these forums tells me that is the way most cams are chosen, right out of thin air without knowing anything about the motor's static compression ratio or anything else about the motor). The intake valve is still open as the piston begins to climb up the bore on the compression stroke. Where the valve finally closes in relationship to the position of the piston is what determines whether or not you have a motor that will make you happy. The intake valve closes with the piston being at some point ABDC (after bottom dead center). For instance, with an iron-headed motor built at 9.5:1 SCR, a good position to close the intake valve (using 0.050" tappet lift figures for the cam timing) would be with the piston at 35 degrees ABDC. Closing the valve at 20 degrees ABDC (not enough cam) would trap more cylinder pressure than the fuel could stand and the motor would detonate. Closing the valve at 50 degrees ABDC (too much cam) would trap an insufficient amount of fuel/air mixture and the motor would be a "weak-suck" (fosdick) operation with the car owner complaining of a lack of power.

Visualize the piston coming up in the bore and pushing the air/fuel mixture that was just pulled into the cylinder....back out of the cylinder and back up the intake tract. This is what makes the "rump-rump" sound. Again, it is the sound of the motor being inefficient. The first time the air came through the carburetor venturi, fuel was added. As the air is pushed up past the venturi again, the venturi adds more fuel. It doesn't know whether to shyt or go blind. Now, we have an impossibly rich mixture that will be a bear to tune for. The only thing we can do is use a loose converter and get the motor revs up past the inefficient part of the range.
Bottom line: If you're building a Top Fuel motor, then cam for it. If you're building a street motor, then cam for it. Don't let your common sense be overcome by the allure of "rump-rump" if you don't know how to make concessions for it.

Other thing is, more cam requires more ignition timing. A lot more.
Less than 220 degrees duration @0.050" tappet lift with <2000 stall converter, <725 carb, dual plane intake.....12 degrees at the crank, 36 degrees total with old-style combustion chambers. 34 degrees total with fast-burn chambers.
Less than 240 degrees duration @0.050" tappet lift with <3000 stall converter or manual trans, <750 carb, dual plane intake......16 degrees at the crank, 34/36 total.
240+ degrees duration with 3000+ stall converter, 850 carb, dual plane intake......20 degrees at the crank, 34/36 total. Actually, when you get to this point, it is simpler to lock out the centrifugal advance altogether and just run 34 or 36 at the crank, without any centrifugal at all. Add vacuum advance plugged into the intake manifold as you see fit. Electronics manufacturers make devices to retard the ignition timing upon starting, so that the motor will not kick back against the starter.....or......you can interrupt the power line to the coil and install a momentary push-button switch that you can push when cranking the motor. Just a simple normally-closed push button switch mounted on the left of the steering column will do. Crank the motor with your right hand and interrupt coil power with your left hand. As soon as the motor is turning, let go of everything and she will be running.

I would opt for a set of heads that are a little newer in technology than those 43 year old examples from an LT1. As I said above, iron heads, 9.5 limit, aluminum heads 10.5 limit. More static compression ratio will support more cam, so go with aluminum heads if you want to get over the top with "rump-rump". Also be aware that the intake runner volume must match up with the motor's intended purpose. For a 350 street motor, 180cc's would be a good place to start. A high-rev motor might want more, 190-200, but be careful, there is a tipping point here. If the runner is too large for the available cubic inches, the motor could be a slouch until way high up in the rev range where it is really moving some air and packing the cylinders. For a street motor, err on the conservative side (for instance, 150-160 for a 327, 170-180 for a 350, 190-200 for a 383 and so forth).

Now, of course, there are heads and there are heads. Some flow well and some do not. Best flowing heads on the planet are from Air Flow Research. I don't think anyone will disagree with that. Here's an example of the head I would choose for you if I were tasked with it.......
http://www.summitracing.com/parts/af...make/chevrolet
With the ZZ4 pistons and 65cc chambers of the AFR heads, static compression ratio would be ~10.2:1, perfect for an aluminum-headed street motor on pump gas. Have your local machine shop cut the block for zero deck and use a Fel-Pro 1003 head gasket.

This would be my choice for a solid roller cam for the above combo at 10.2:1 SCR......
12-771-8 CompCams XTREME ENERGY − Best in street machines with 2800+ stall, 10:1+ compression with 3.73-3.90 rear gears, makes power 2500-6500, 280/286 @advertised, 242/248 @0.050" tappet lift, 0.570"/0.576" valve lift, 110 degree lobe separation angle. Call Comp on the phone to make sure this cam fits your block, whatever block you end up using.
If automatic trans, use a real 10" 2800-3000 stall converter, not some fosdick re-twisted 12" unit.

For max power, use a 750 cfm carb mounted on an Edelbrock Performer RPM intake manifold. That carb/intake combo will make more power on a 350 than any other combo from idle to 6500 rpm's, trust me. With a 2800-3000 stall converter, you can use either a double-pumper or a vacuum-secondaries carb, your choice, either will work great. Same scenario with a manual trans, use either carb. My favorite is a 750/800 cfm Rochester Quadrajet on a spread-bore RPM intake. Cliff Ruggles can tune one of them for you that will seem like driving an EFI motor.
http://www.cliffshighperformance.com/

A good set of 1 5/8" equal-length, tuned headers, with an X or H pipe before the mufflers would top off this combination. Mufflers of your choice with pipes extending out to the rear bumper with a nice set of tips. Don't even THINK of terminating the pipes under the car. (M-I-C-K-E-Y M-O-U-S-E)

I would expect such a motor, properly assembled and tuned, to produce 450 hp and 475 ft/lbs of torque, with outa-sight throttle response.

More later........

Thank you for taking the time to post that reply. You gave me some good information, and things to consider. I really appreciate all the replies I've received.

My Chevelle is a 4 speed, btw.