When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Time for a fun shot. This is the drivers view at 178 mph in a 7.6 sec dragster. And it's only a small block! But 700+HP. The convertor launches at 6600 rpm. Light it up and open that door!
The big fat red button on top of the steering wheel is called the "oh ****" button, Any idea what it is for?
Good question. The rods are one of the off shore brands. (I found out since they are Pro-Comp) I went with the I-beam rods as he has used them with good success in race motors up to 8000 rpm and 700 HP for 100s of passes down the 1/4 mile. Strong enough for mine. He goes with the H-beam rods for 800hp and up. These are less expensive, lighter and stronger than resizing, truing, and refurbishing stock rods. Plus I got mine .25 in longer than stock. He said they are a no-name brand that he gets direct from the source so nothing that I can recommend here.
Back to the engine assembly. The rest of the shortblock assembled quickly from this point and without drama. I got to get really messy helping with the Lucas oil used for bearing lube. I may not start this for a while, and he said this stuff won't run off the bearings, while the engine is in storage, unlike engine oil. I wiped down the cylinders with my bare hand and two good squirts of ATF for some ring lubrication.
Oh I almost forgot, he had previously measured every ring in it's correct cylinder, and filed them to fit, before I installed them.I forgot the end gap, but he sets street motors a little wider to protect the ring from end-butting if the motor gets a little too hot. Sounds like protection from a typical vette issue. They will almost touch when running and warmed up.
I was pleased to see how level the piston top is to the deck, we wound up with almost zero quench, maybe .005. That should be good for swirl, compression and power. I was surprised to see how much the pistons rock in the bore, even with .005 wall clearance. Look at piston close-up in the shot below, it's all the way up. With almost zero deck, one edge of the piston would literally be slightly above the deck while the other was down in the hole a bit. You could bump the piston with your hand and it would change. Part of that is because these are the harder 2618 alloy forged pistons, with low 1% silicon, that expand more than the others, and rattle a little bit when cold. They will tighten up and be be quiet when warm though. I actually loved the rattle of the pistons and the lifters on my LT-1 and this should be the same. All the mechanical noises let you know the engine was something special. Not quite like a ferrari sound track, but the Chevy version. I also like the purr of my LLT V-6, but that sure would not sound correct here.
After torquing all the main caps down, the short block is done! I tried to help with the torquing but my wrist wouldn't allow it, as I am only two weeks out from wrist surgery. At least I got both hands back!
Now this gets bagged for a while while the head work begins. That may happen next week. Stay tuned for updates. In the meantime I need to see if my hand will allow me to remove some of the tin off the old motor that we will need soon.
Oh I answered my own question from earlier, that is a 76 lb crank that spins around, and 24 pounds of reciprocating pistons & rods that move up and down at 100 times per second. Scary to think about. I think they should be renamed beefy- or strong-blocks.
Ok the 100 lb forged steel crank is in place in it's new home. If you look closely on the leftmost counterweight, you can see the two new fresh drill holes left over from the balancing. The new rods & pistons are 130 grams each lighter than stock, and you can see how much material had to be removed. These holes are also present on the other end counterweight. 130 g x 8 yields about a 2 lb weight loss! All that lighter reciprocating weight yields more power. In reality it's only about a 10% weight reduction. Each piston weighs 598 g and each rod weighs 862g. So they are definately hefty. Each rod weighs almost 2 lbs and each piston 1 lb. Does anyone else think it ironic that 454 grams = exactly 1 pound? Anyone else curious how many pounds of steel are spinning around in these things?
The crankshaft is a 7416 casting which was used in 70 LS6 Chevelles. But also in truck motors and marine motors thruout the 80s and even the 90s. 7416 LS6 crank
Well we have had some engine delays but the build is back on track now. My best friend and engine guru had a stroke a while back and closed the shop for a month or so. His two sons and I got some customer jobs done and out the door. Well Jeff's doing better now and this week he and I were able to spend some time on my LS6 build-up. The bad news is his right arm is not too good, but the good news is I actually got to do the machine work, and be his hands, while he was at my elbow. That was a really cool experience doing my own cylinder heads and using his equipment worth 10s or 100s of thousands of dollars. Here are the 074 Snowflake heads mounted up on the valve seat cutting machine.
I was too busy to get many pics, sorry bout that. But the new guides got inserted and reamed to size. Then the valve seats got touched up with precision cutters, not stones. 3 different angles/cutters. Don't remember the numbers. These heads have had some very good porting done on them before, so we just made sure the seats tapered very smoothly back into the ports. Jeff keep checking the short side radius on both intakes and exhaust and they are some of the smoothest I have seen, not like stock heads at all, no ridges, seams or bumps. I got to set the cutters up but for the best finish he always did the final cut. Lots & lots of measuring. Then I put grinding compound on the valve and we checked the position and width of the seats again and again until it was what he wanted. Certain width, certain distance from the valve edge. These should make some good old-school power! New bronze valve guide inserts were installed by yours truly. Don't worry I was just a pair of hands for the real master behind me. Also have a good look at the port work.
Then we talked cams, retainers and springs. I let him convince me to upgrade into a solid roller cam. We went with a custom grind, from Erson cams, 230& 238 dur @ .050 with .629 lift. It's a street roller with 270/280 advertised. It was less duration and more lift than I was expecting. He was insistent on this smaller of the two durations we were discussing, due to my 3.23 gears and CR trans. Said it would be a dog off the line if we went to the 238 that I picked. Duration wise, It turned out to be halfway between a ZZ502 (224) and a factory L72 (242). It should make way more torque below 2500 than the bigger one, and with the roller profile and lift it still will make way more power than an L72 cam. On a 110 LC. It also turned out to be almost exactly like a popular Straub HR cam, 239/246, just in a SR. I wanted the solids for the extra 500 or so revs, the 50g lighter SR vs HR lifters, and the authentic solid lifter rattle effect. springs are IIRC about 240/450 with some featherweight Titanium retainers. Should peak at 6000, rev clean to 7000 but have enough idle vac for PB & things. Oh - Pressure fed Morrell SR lifters.
Rods and Balancing:
Now Jeff is really on a roll. The 2618 Alloy pistons are the tougher of the forged alloys and what is used in race pistons. He set them at .005 cold I think. They expand a little less than the cast ones or the 4018 hi-silicon forged, so they will rattle a little bit when the engine is cold. Well isn't that what a SHP BB or SB is all about? The rattle is part of the experience. I loved that in my LT-1. It really does go away quite quickly as the engine warms up, and no it might not last 100,000 miles either. Oh well. I should be so lucky to be able to drive this SHP BB that long!
A lot of time and tender care went into the rods and pistons. First everything got weighed on a .01 "centigram" triple beam laboratory scale. I had to show them how to read it that well, they were only reading it to .1g. Close enough I guess. LOL Way better than the new parts were, as-delivered. Brand new rods and pistons were off by several grams from one to the next. Grinding with a dremel tool commenced until all rods and all pistons were within the same weight +/- 1.5 g. The rods have balance pads on them for this purpose. Then the rods were weighed on each end. Then the balance pads were ground on each end to the smallest of the available numbers. Several grams were removed from each rod to lighten them for quicker reving, I forgot the amount. Then each rod end is ground to balance all eight small rod ends and all eight big rod ends. Everything is within 1 g or 1.5 g when done. Couple of hours here, but I said Jeff was meticulous, and he is not done yet. New Rods lightened to minimum and balanced both ends to under 2 g Pistons and pins weighed and balanced to under 1g Bronze bushed rods for less cylinder wall friction for power Connecting rods painstakingly weighed on each end by 0.01g lab scale Sorry those H-beam rods are not for my lowly street motor, they are for a 1000HP blower motor.
Next up is piston/rod assembly. The rods have bronze bushed small ends for less friction on the piston skirts and more power. That means they go together with spiral locks, which is actually very quick. But during assembly all the rods and pistons will be paired together with their total weights in mind, so that all the assembled rods & pistons now weigh within 1g of each other, or less.
Crank balancing:
Now that we know the final "bob" weight the crank can be balanced. I got needled again about being "cheap" and not going with a stroker crank, but we are way past that point now. Jeff had several GM steel cranks laying around since so many of his race customers are going to stroker cranks. We picked a good one, that was maybe .010 under, and had it polished and balanced to my pistons. That adds power too. It sure takes a long time to build a motor this way. So many meticulous steps. But if each one of these "special touches" adds only maybe 6-8 HP, and we do a dozen or so of them, hmmmmmm.... Now we are talking! That's the difference in a blue-printed motor vs just a rebuild.
Jeff keeps busting on me about spending near $9k on this thing, when he swears he could make way more power than that for almost half the money. But I just keep telling him, then it wouldn't really be an LS6 anymore, it be just a 650HP big block. That's not a bad thing, at all, it's just not the end result I have in mind. I found out a long time ago if you build an image of the completed car in your head, before you begin, then you will not be detoured by a thousand little decisions that pop up as you move along.
More pictures to come after I visit today.
AND THIS MY FRIENDS IS HOW RACING ENGINES ARE BUILT...
I was an apprentice in a a race engine shop when I was 18-19 for 3 days a week... one of my jobs was sorting pistons rings pins and cir-clips then matching the lowest weight... 3 grams off of each reciprocating assembly is nearly an ounce for 8...AND an ounce off your reciprocating is WORTH more than 100 pounds off your vehicle weight in a road race.
remember reciprocating weight must be accelerated from a DEAD STOP 2 times every revolution... so any weight removed gives you more power to accelerate the vehicle NOT the reciprocating assemblies.
Last edited by firstgenaddict; 07-20-2019 at 10:31 AM.
AND THIS MY FRIENDS IS HOW RACING ENGINES ARE BUILT...
I was an apprentice in a a race engine shop when I was 18-19 for 3 days a week... one of my jobs was sorting pistons rings pins and cir-clips then matching the lowest weight... 3 grams off of each reciprocating assembly is nearly an ounce for 8...AND an ounce off your reciprocating is WORTH more than 100 pounds off your vehicle weight in a road race.
remember reciprocating weight must be accelerated from a DEAD STOP 2 times every revolution... so any weight removed gives you more power to accelerate the vehicle NOT the reciprocating assemblies.
Exactly! Many people assemble engines every day but that doesn't make them an engine builder.
Very nice build.
Exactly! I have enough skill to assemble (bolt together) this engine, but not build it like a race engine. He's probably built 2-3000 drag race engines in 40 years! And the experience is priceless. I am constantly hearing we built/tried: a, b & c and c worked best because....
I have worked there a little bit, mostly doing grunt or assembly work never machine work. But with Jeff being ill and him needing a steady set of two hands, I actually had the opportunity to do my own machine work on my own cylinder heads. Even though I had never done this before. How cool is that! How many people get this kind of opportunity? And since he is my best friend his experience and watchful eye was right there just an inch away every step of the way, so I know it was done right.
A lot of guys can claim to have built their car, or even their own engine, but their own blue-printed race engine? Not as many.
And hand me down titanium retainers make nice "bling" too.
I also realize not many people have the opportunity to be inside a race engine shop close-up during an engine build, so that's why I am sharing pics with you guys.
Late to the post but I would add a few 'tips" to kick around with your machinist.
First would be a real good idea to drill pin-oilers below the wrist pins in those rods (same as the ones in the H-beams in your photo above), and you are better served with the I-beams over the H-beams. Not sure why or when Eagle and Scat stopped drilling below the pins, they did them at one point, at least on their H's!
Second, once you decided to change to the roller platform (if I read that right in an earlier post AND assuming you're still going with the 074's) you should have asked your machinist about putting in the correct R/A studs at least for the exhaust's! It's almost mandatory on those weak castings considering the roller platform is now in play?
Also, would have recommended using the MkVI stepped-nose cam deal (uses a simple thrust plate for built-in end play) along with a Torrington brg MkVI timng set. No more cam buttons. We rarely use the buttons any longer on almost ANY builds here including the early SB's!.
(Add) What piston (brand and part number) are you using, just curious?
Thanks, Gary in N.Y.
P.S. On a side note you'll pick up approximately 30 HP by design with the roller cam alone, it "frees-up" that much "frictional" HP. Also here's a shot of the correct ARP stud set for those 074's/077's. Also remember those are small runner casting as-is, they were 290 cc's (OEM) on the intakes, unlike their 325 cc cast iron counterparts! Anyway "good-luck" with your build and here's the studs.
Last edited by GOSFAST; 07-20-2019 at 04:24 PM.
Reason: C-Add
Thanks for the tips. I'll let him know if he doesn't already have those in mind.
It's good to hear from someone with experience with the old 074 heads.
In your opinion with the addition of those studs with this .630 lift SR cam will that be enough strength in the rocker studs? Without taking more drastic measures?
You must mean this pin oiling hole here. Looks like they are in there. Looks like you caught something I didn't even know about.
Pistons are Icon forgings, 2618 alloy, with a 27cc dome, .290" high, and raised pin location due to .25" longer rods 6.385". CR should be around 10.25-10.5 with the open chamber heads. I'm sure we'll be cc'ing everything if it's not been done already. There is a dome pic earlier in the thread. in Post 20.
I see two bolt holes on this block near the front of the cam. If that is where the bolt in roller cam thrust bearing goes we might already be setup for that. Something else I didn't know.
Thanks for the tips. I'll let him know if he doesn't already have those in mind.
It's good to hear from someone with experience with the old 074 heads.
In your opinion with the addition of those studs with this .630 lift SR cam will that be enough strength in the rocker studs? Without taking more drastic measures?
Ans: Those heads absolutely need the long-bottom rocker studs with the mech-roller and you'll need some type girdle also OR a set of shaft-mount rockers. The latter being the best all-around choice. I would add also, it's not a simple "bolt the R/A studs in place" deal, there's a fair amount of labor to get them in and if you do go this route make absolutely certain your machinist is familiar with this procedure or you'll emnd up needing some new heads.The exhausts MUST be double heli-coiled on all 8 and very close attention needs to paid on the 2 over the exhaust cross-over passage!
You must mean this pin oiling hole here. Looks like they are in there. Looks like you caught something I didn't even know about.
Ans: Those holes above the pin-eyes do absolutely nothing for performance, they are strictly "along for the ride", see another photo below with respect to the "correct" type pin-oiling!
Pistons are Icon forgings, 2618 alloy, with a 27cc dome, .290" high, and raised pin location due to .25" longer rods 6.385". CR should be around 10.25-10.5 with the open chamber heads. I'm sure we'll be cc'ing everything if it's not been done already. There is a dome pic earlier in the thread. in Post 20.
Ans: Those pistons with the 6.385" long rods were a good call, they are about 60 grms lighter than the same piston for the conventional 6.135" rod. The lighter reciprocating weight generally helps lowers the required bob-weight for balancing, This is a "positive" when chasing HP numbers! Having said that I would have opted for the H-beams to further lower the bob-weight with them coming in around 780 grms. at the 6.385" length?
I see two bolt holes on this block near the front of the cam. If that is where the bolt in roller cam thrust bearing goes we might already be setup for that. Something else I didn't know.
Ans: That's the 2 holes, use those with the thrust-plate/stepped-nose BB cam setup and don't look back, the final ***'y will be a "walk-in-the-park" so to speak.
Thanks, Gary in N.Y.
P.S. One final "tip", if your roller springs have any "dampeners" between the inners and outers I would toss the Titanium retainers and step down (money-wise) to some Tool-steel pieces. These go on all our roller setups now, hydraulic OR mechanical. We don't use Titanium any longer, the Tool-steels weigh about the same and are NOT a maintenance item like the Titanium's generally are!
Cam profile being re-investigated due to feedback from two very knowledgable Corvette Forum Members / engine builders.
Thanks AJRotham and Gary/GOSFAST for their expert feedback.
More news on that as it develops.
On another front, the heads have been flowed yesterday. Experienced cylinder head shop he really like the porting work that had been done, said it was very high quality. Good to excellent flow for 50 year old heads, but nothing to write home about compared to state-of-the-art technology in current AFRs etc.
Lorenzo has flowed multiple Dozens of these old heads. Highly recommended a 30 degree back cut on the valve for more lower lift flow. So it's back the the head stand to do that. Several have mentioned the need for the extended rocker arm studs in these AL heads so that will be done as well.
Did I mention this appears to be a step by step reiterative process? One step forward, one step back.
Other Lorenzo's news:
This shop is unbelievable. He had Seven sets of Snowflake heads sitting around and Five L72 427/435's sitting around waiting for 100 point rebuilds and dyno time. Oh did I mention he has a DYNO? Soon to be visited by a certain LS6. And his favorite ride? In the parking lot? A 65 396 Corvette Convertible, in red/white, 3:36 with 4spd of course, no sidepipes. All original date- matching point car! It is absolutely STUNNING. Drove it to work. And the 425/450 HP engine went thru his dyno and made 488HP with stock manifolds!. 100% correct motor, camshaft and stock heads. But I am sure they got a Very good valve job on the flow bench.
His shop will also featured in some upcoming TV show/movie about one of the Corvettes they helped build. He called it the "phantom". Said it is a 1965 Corvette: Job Number One, and it apparently went thru both GM executives and Smokey Yunicks hands. They rebuilt and dyno'd it. Be on the lookout for that one!
I am enjoying the ride! (build)
The actual riding should be fun too.
Those are pretty decent flow numbers for a factory casting head with mild porting. Should make pretty decent power with the right cam/intake. 550-600hp possibility.
I thought they were decent. Lorenzo said they had some first class porting done on them. But definately ported for a high rpm race car, the old school way of porting.
He strongly suggested I add a 30 degree back-cut on the valves, would gain me a lot of flow in the .100-.200 range, maybe 20-25%. It's only 63-135 there now a a little improvement goes a long way to making power. It would lose a little at .600-.700 with this mod but that doesn't matter as much, even on a race car and definately not on a lower-lift street car.
I plan on taking his advice on that.
Did I mention Lorenzo's shop is un-believable?
He just last week sold 12 OEM in-the-box sets of 842 closed chamber L88 aluminum snowflake cylinder heads, that he had "sitting around" for ages!
Did a little surfing. Nobody mentioned spring rates, but everybody had stud bosses breaking off. The long studs with double (I assume double length single) heliciols and stud girdles are pretty much a must have. What is this engine for? Appearance-correct for car shows or 10 second ET's? I know. You want both.
Ok after a week's research to make sure, the build continues. A lot of good points were brought up to me by some very respected people on this forum. And I needed time to dig into them to make sure.
The big question was: Just how strong are these exhaust rocker arm bosses on these old snowflake heads because they are known to break?
Well I got a lot of opinions and friendly advice, which believe me I appreciate. The last thing I want is for these heads to suddenly crack while I am cruising down the road. But I got surprisingly little hard data on what causes them to crack. How much is too much? The data says big lift, high rpm, like 7-8000, and huge spring pressures (700-800+) will break these heads. Maybe a stud girdle or Jesel system will prevent it, maybe not. Street rollers are recommended and are OK as is. But in-between there was very little data. My machinist and best friend Jeff has literally machined and built 5000 engines over the last 40 years. That's an average of 125 engines per year! He had the best data. Back in the day when these heads were the hot ticket, and before good aftermarket heads came out, he built 10-20 engines a year with these. Some on very hot street cars and some on drag cars. Very few broke, and the ones that did were really extreme. So his experience says they'll be fine with this cam, with these springs and no stud girdle. He picked this kind of suddenly, based on his experience, but I needed to think about it a little bit, and rationalize it.
So yes I am "pushing it" a little bit, but that was the whole idea. These lobes are only a little bit stronger and taller than typical HR lobes. 100% stock appearing LS6 on the outside, new technology on the inside, stronger than stock.
AJRotham finally agreed he would just "go for it" and I agree with that too. I think he is just jealous that my cam has more lift than his LOL. But I know he has 10-20 degrees more duration than me and a way more serious combo overall. I wanted mine to feel and look a little closer to "stock".
So the custom solid roller is here, and we are waiting a on a couple of small parts. I have Cam Doctor specs for it so we compared it to the stock L78/L72/LS6 3863143 solid lifter cam to see if it would do what I wanted. Here's what we got:
Of biggest concern to me was the low lift and overlap area so it would maintain the idle characteristics vacuum, and excellent driveability of an LS6.
The "overlap triangle" is almost exactly the same size so it should sound and idle the same.
The intake opening and closing points are virtually identical.
Surprisingly it took 12 less duration at .050 to achieve this (230 vs 242)
A tighter LC 110 vs 114 for more mid-range HP. and to achieve the right overlap.
The tighter duration number helps bring the low rpm torque back. It might not be 500lb at idle and level like an LS5 but kinda close to that. No 3000 rpm surge.
The 143 solid cam actually opens the valve a little quicker up to about .100, cause the lifters are lighter.
The roller has a much steeper slope at .200-.400 cause it is opening them faster speed. It doesn't actually catch up to the 143 until about .250 lift.
The extra .100 lift probably adds 15-20% more area under the curve. More lift has almost no effect on driving characteristics tho, but does on HP.
It should be anywhere from 30-60 or more HP stronger than the 143 cam, which I have seen multiple dyno sheets in the 480 HP range. If it's 20% that may be a 100 more.
The pressurized Morrell roller lifters should help the lifters survive idling.
They won't pump-up like hydraulics, should rev easy to 6500+ without dying off.
I'll set tight lash to get that sewing machine solid lifter sound. Maybe .12-.18 In part to help with brinelling of the roller.
I'll monitor the lash adjustment a couple times a year to use as an indicator of any wear issues, can't do that with a hydraulic or HR.
Heads:
Oh I also cc'd the 074 AL heads and found the intake volume was 290 and the exhaust 125. Ovals are 267cc volume on the intake and iron rectangulars 325. So they have better flow rate than ovals, with almost the same velocity, and the same flow as iron rect with better velocity. So a crisp throttle instead of soggy, with flow (HP). Of course latter model aftermarket heads would really open up the flow more, like from 211 flow to 274, but that's another story for a different build.
Phew...There is just so much to consider when you start "pushing" a build past stock.
04-24-2019, 07:16 PM
