Stock Crank 355 Build - Opinions Welcome
03-22-2016, 09:34 PM
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Stock Crank 355 Build - Opinions Welcome In the process of dropping my motor to freshen it up. It used a bunch of coolant last year, blew some white smoke, and oil pressure was a little questionable. The motor is original with about 60K and coming off a head and cam swap last spring.
Just looking to build a reliable motor that will be used 95% for cruising. Might take it to the strip or road course once a year for fun if I ever get the rear end, suspension, and brakes done. Probably around 400 RWHP +/-.
I found a reputable shop that knows the LTx platform and they quoted me a decent price for machining and assembly.
Just hoping a few of you guys could glance over my plan to make sure I have a solid list of parts for my build.
I am looking at the following rods and pistons to go with the stock crank.
Rods: http://www.summitracing.com/parts/sca-26000716
Pistons: http://www.summitracing.com/parts/mle-sbc250030f05
They are lighter than the stock units so I think the motor should rev a little a quicker and also be under less stress at higher RPM's.
I am planning on staying with the 2 bolt mains.
I plan to have the rotating assembly internally balanced so I can just have any future flywheels or pressure plates neutrally balanced.
I will be reusing the parts below that have about 600 miles on them:
Lloyd Elliot LE2 ported heads (reuse)
LE ported intake (reuse)
Advanced Induction Cam 226/234 Dur, .566"/.566" Lift, 110 LSA (reuse)
Morel 5315 Lifters (reuse)
Comp Hi Tech 7938-16 7.100” Push Rods (maybe reuse?)
Advance Induction Guide Plates (reuse)
1.6 Comp Pro Magnum RRA (reuse)
PSI 1511 Springs (reuse)
Cloyes Heavy-Duty Timing Set C-3039 (reuse)
ARP 134-3601 Head Bolts (reuse)
30 lb Bosch III Injectors (reuse)
Machine Shop Requirements:
-Perform all necessary inspection, cleaning, and machine work on block.
-Torque plate bore and hone block for .030” over.
-Align hone mains.
-Deck block to maintain 11.5-12.0 compression ratio with new rods and pistons
-Inspect, recondition, and internally balance stock crank with new rods and pistons.
-Inspect and pressure test heads. (Heads have already been milled about .030” by Lloyd Elliot when ported.)
-Install new cam bearings and freeze plugs etc.
-Assemble long block.
Thanks for any thoughts or suggestions!
Just looking to build a reliable motor that will be used 95% for cruising. Might take it to the strip or road course once a year for fun if I ever get the rear end, suspension, and brakes done. Probably around 400 RWHP +/-.
I found a reputable shop that knows the LTx platform and they quoted me a decent price for machining and assembly.
Just hoping a few of you guys could glance over my plan to make sure I have a solid list of parts for my build.
I am looking at the following rods and pistons to go with the stock crank.
Rods: http://www.summitracing.com/parts/sca-26000716
Pistons: http://www.summitracing.com/parts/mle-sbc250030f05
They are lighter than the stock units so I think the motor should rev a little a quicker and also be under less stress at higher RPM's.
I am planning on staying with the 2 bolt mains.
I plan to have the rotating assembly internally balanced so I can just have any future flywheels or pressure plates neutrally balanced.
I will be reusing the parts below that have about 600 miles on them:
Lloyd Elliot LE2 ported heads (reuse)
LE ported intake (reuse)
Advanced Induction Cam 226/234 Dur, .566"/.566" Lift, 110 LSA (reuse)
Morel 5315 Lifters (reuse)
Comp Hi Tech 7938-16 7.100” Push Rods (maybe reuse?)
Advance Induction Guide Plates (reuse)
1.6 Comp Pro Magnum RRA (reuse)
PSI 1511 Springs (reuse)
Cloyes Heavy-Duty Timing Set C-3039 (reuse)
ARP 134-3601 Head Bolts (reuse)
30 lb Bosch III Injectors (reuse)
Machine Shop Requirements:
-Perform all necessary inspection, cleaning, and machine work on block.
-Torque plate bore and hone block for .030” over.
-Align hone mains.
-Deck block to maintain 11.5-12.0 compression ratio with new rods and pistons
-Inspect, recondition, and internally balance stock crank with new rods and pistons.
-Inspect and pressure test heads. (Heads have already been milled about .030” by Lloyd Elliot when ported.)
-Install new cam bearings and freeze plugs etc.
-Assemble long block.
Thanks for any thoughts or suggestions!
03-23-2016, 06:36 AM
#2
Looks like a solid plan.
I'd suggest closer to 11.5 CR than 12.0 if you're going to get it hot running full power on a summer day on a roadcourse on pump fuel. But I have a feeling you'll be closer to 12 if Lloyd decked the heads by .030".....prob around 53 or 54cc chamber volume.
Get that quench down to at most .035". Better to keep that tight than open it fearing the bump-up in CR.
I would err on the "retarded" side when installing the cam. With that CR and the ability to rev it to 7000 (good pistons and rods), the engine will want slightly more duration, and retarding it would help. Also would help bleed off some of the dynamic compression down low.
How many miles on those valvesprings? You might want to replace/upgrade if you're thinking high revs.
I'd suggest closer to 11.5 CR than 12.0 if you're going to get it hot running full power on a summer day on a roadcourse on pump fuel. But I have a feeling you'll be closer to 12 if Lloyd decked the heads by .030".....prob around 53 or 54cc chamber volume.
Get that quench down to at most .035". Better to keep that tight than open it fearing the bump-up in CR.
I would err on the "retarded" side when installing the cam. With that CR and the ability to rev it to 7000 (good pistons and rods), the engine will want slightly more duration, and retarding it would help. Also would help bleed off some of the dynamic compression down low.
How many miles on those valvesprings? You might want to replace/upgrade if you're thinking high revs.
Last edited by bowtienut; 03-23-2016 at 06:41 AM.
03-23-2016, 10:17 AM
#4
I forgot to comment on the 2-bolt mains.
If you plan to rev it to 6800 or beyond, I would stud the mains when you line hone it.
I ran bolts in mine and my caps were walking. Thinking more about it, I believe that was more the cause of the rough looking main bearings rather than debris getting in them, since the rod bearings looked fantastic.
I know you'll have lighter pistons, but I just don't know where that fine line is. Studded 2-bolt mains are a bit added insurance and lots cheaper than splayed 4-bolt.
Here's a writeup I did after my h/c stock bottom finally gave it up:
https://ls1tech.com/forums/lt1-lt4-m...alvetrain.html
If you plan to rev it to 6800 or beyond, I would stud the mains when you line hone it.
I ran bolts in mine and my caps were walking. Thinking more about it, I believe that was more the cause of the rough looking main bearings rather than debris getting in them, since the rod bearings looked fantastic.
I know you'll have lighter pistons, but I just don't know where that fine line is. Studded 2-bolt mains are a bit added insurance and lots cheaper than splayed 4-bolt.
Here's a writeup I did after my h/c stock bottom finally gave it up:
https://ls1tech.com/forums/lt1-lt4-m...alvetrain.html
03-23-2016, 10:44 AM
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Thanks for the replies guys. I appreciate useful the info. I have been working on and reading about cars for 20 years but this is my first complete performance engine rebuild. I thought I could carefully swap the heads and cam on a 60K mile motor last year and be good to go, but I must have missed something. Hoping to get this rebuild right the first time.
I do have main studs spec'd out on my parts list. Just left some of the smaller stuff off this thread.
Regarding "retarding" the cam. Would it be better to just look at a different cam to better suit the rods and pistons? I was considered going a little bigger but the car will be mostly for street duty. Kind of shooting for something that has a decent powerband and feels quick. Not really looking to squeeze out that last tenth at the track or peak HP number. I was hoping it would stay in the powerband when shifting at 6,800 +/-.
Also, I have not looked into it, but is there a lower timing gear that would work with my existing timing set to adjust the cam timing? I am keeping the stock water pump.
I will tell the builder to aim for 11.5 CR to be safe. I know they were planning on zero decking the block and then setting the quench with the head gasket. Any problems doing it this way? Going to have them mill my intake to fit since it did not fit great after the head swap.
Valve springs have about 600 miles on them, but have problem been installed on the heads for 3 to 4 years. Would it be a good idea to put new ones on? I know they lose their strength after a while.
I do have main studs spec'd out on my parts list. Just left some of the smaller stuff off this thread.
Regarding "retarding" the cam. Would it be better to just look at a different cam to better suit the rods and pistons? I was considered going a little bigger but the car will be mostly for street duty. Kind of shooting for something that has a decent powerband and feels quick. Not really looking to squeeze out that last tenth at the track or peak HP number. I was hoping it would stay in the powerband when shifting at 6,800 +/-.
Also, I have not looked into it, but is there a lower timing gear that would work with my existing timing set to adjust the cam timing? I am keeping the stock water pump.
I will tell the builder to aim for 11.5 CR to be safe. I know they were planning on zero decking the block and then setting the quench with the head gasket. Any problems doing it this way? Going to have them mill my intake to fit since it did not fit great after the head swap.
Valve springs have about 600 miles on them, but have problem been installed on the heads for 3 to 4 years. Would it be a good idea to put new ones on? I know they lose their strength after a while.
03-23-2016, 11:05 AM
#6
For your objectives, your present cam is pretty darn good. It's definitely easier on valvesprings than the higher lift one I was running. I think those PSI springs are marginal though even turning your present cam to 6800. I'd want 150 on the seat. I don't know; maybe you have them set up for that?
Personally, I've lost some confidence in beehive springs for aggressive cams. Mine were spec'd by AI, but clearly weren't up to the task, even running 160 on the seat. I'm not saying you won't be ok though with a limit of 6800 and your milder lobes.
The amount of retard on the cam I was thinking of is probably less than the multiple keyway crank sprockets permit. I would just check it; with a little bit of stretch on your used chain, you might find it a degree or two retarded from what AI's spec says. If not, go with degree bushings in the cam sprocket (just google that
)
Stress this to your builder: tight quench is more important than lower CR.
My preference would not be to zero deck, but rather leave the slugs .008 to .010 in the hole and use a .026" gasket.
Edit: just saw you have 3.42 gears..... yeah, I'd stick with the cam you have.
Personally, I've lost some confidence in beehive springs for aggressive cams. Mine were spec'd by AI, but clearly weren't up to the task, even running 160 on the seat. I'm not saying you won't be ok though with a limit of 6800 and your milder lobes.
The amount of retard on the cam I was thinking of is probably less than the multiple keyway crank sprockets permit. I would just check it; with a little bit of stretch on your used chain, you might find it a degree or two retarded from what AI's spec says. If not, go with degree bushings in the cam sprocket (just google that
)Stress this to your builder: tight quench is more important than lower CR.
My preference would not be to zero deck, but rather leave the slugs .008 to .010 in the hole and use a .026" gasket.
Edit: just saw you have 3.42 gears..... yeah, I'd stick with the cam you have.
03-23-2016, 11:37 AM
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Great stuff! I'll look into the springs and the degree bushings. Going to be changing to 3.90 or 4.10 gears when the car is back on the road. Was not planning on having to rebuild the motor this year....
Regarding quench, it sounds like I am better off telling them I want .035" quench instead of just stating a 11.5 CR. A higher CR with like .060" quench would be more likely to detonate I am assuming?
Is there a difference between zero deck + .035" head gasket vs pistons .009" down and a .026" head gasket? (Have not looked into various LTx head gaskets thicknesses to see what's available.)
I have not worked out all of these details with the shop yet. Just trying to be prepared on my end so this thing turns out right.
Regarding quench, it sounds like I am better off telling them I want .035" quench instead of just stating a 11.5 CR. A higher CR with like .060" quench would be more likely to detonate I am assuming?
Is there a difference between zero deck + .035" head gasket vs pistons .009" down and a .026" head gasket? (Have not looked into various LTx head gaskets thicknesses to see what's available.)
I have not worked out all of these details with the shop yet. Just trying to be prepared on my end so this thing turns out right.
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03-23-2016, 11:54 AM
#8
Yes, regardless of the numbers, opening the quench to decrease compression is a bad plan.
With the .026" gasket being a reasonably priced off-the-shelf item, I see no logic in taking extra material from the block deck.
http://www.summitracing.com/parts/mr...make/chevrolet
With the .026" gasket being a reasonably priced off-the-shelf item, I see no logic in taking extra material from the block deck.
http://www.summitracing.com/parts/mr...make/chevrolet
03-23-2016, 01:42 PM
#9
and by leaving the pistons in the hole .xx and using the .026 head gasket leaves you room on the block for future machining (decking) should that need come up...."down the road"
On the PSI spring...I am onboard with Bowtienut on beehive springs...having run the 918's for 20k mi and having one break. a single spring leaves no room for what can be major engine carnage. Fortunately for me I found my problem "before" the big bang. Checking them at 10k, 15k then 20k mi got real old. At 20k mi I pulled one to check pressure, removed retainer and had a 2 piece spring. How long it had be broken I don't know as the retainer was holding it together. Dodged a bullet big time
Might want to consider the Lunati 73925k5 kit. I got mine from Lloyd Elliott
On the PSI spring...I am onboard with Bowtienut on beehive springs...having run the 918's for 20k mi and having one break. a single spring leaves no room for what can be major engine carnage. Fortunately for me I found my problem "before" the big bang. Checking them at 10k, 15k then 20k mi got real old. At 20k mi I pulled one to check pressure, removed retainer and had a 2 piece spring. How long it had be broken I don't know as the retainer was holding it together. Dodged a bullet big time
Might want to consider the Lunati 73925k5 kit. I got mine from Lloyd Elliott
03-24-2016, 05:26 PM
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Thanks for the info on the springs. I bought the heads and cam new but second hand off one of the classifieds. I know Lloyd put the heads and springs together but have no idea on the installed height. The PSI springs had good reviews when I first searched about them so I just went with it. I'll add valve train to my research list. The dual springs sound like good insurance since I will be putting a little money into this motor.
I was playing around with some numbers on compression ration. Just wondering if someone could take a look at them and see if they make sense? I am coming out around 11.62 CR.
Cylinder Bore Size: 4.030”
Piston Stroke Length: 3.48”
Head Gasket Bore Diameter: 4.10”
Compressed Head Gasket Thickness: .026”
Combustion Chamber Volume In CCs: 56cc (Per Lloyd Elliot, not verified)
Piston Dome Volume In CCs: -5cc (adds 5cc to combustion chamber volume)
Piston Deck Clearance: .009”
Rod Length: 6.000”
Piston compression height: 1.250”
Piston Stroke: 3.48”
I was playing around with some numbers on compression ration. Just wondering if someone could take a look at them and see if they make sense? I am coming out around 11.62 CR.
Cylinder Bore Size: 4.030”
Piston Stroke Length: 3.48”
Head Gasket Bore Diameter: 4.10”
Compressed Head Gasket Thickness: .026”
Combustion Chamber Volume In CCs: 56cc (Per Lloyd Elliot, not verified)
Piston Dome Volume In CCs: -5cc (adds 5cc to combustion chamber volume)
Piston Deck Clearance: .009”
Rod Length: 6.000”
Piston compression height: 1.250”
Piston Stroke: 3.48”
03-28-2016, 02:57 PM
#13
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Why is your bore 4.03 and the head gasket bore 4.10? Is that a typo or is the gasket really that much bigger? Id rather have one with the bore matched with the cylinder.
03-28-2016, 03:50 PM
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4.100" was the size specified for the Mr Gasket .026" thick head gasket. They probably do that so that they do not have to make a separate gaskets for each bore size. I thought it was kind of cool that CR calculator I found took that into consideration.
03-28-2016, 10:04 PM
#15
You would not want a 4.030" bore gasket for a 4.030" motor. The position tolerance from the dowel alignment holes to the bore centerline of the gasket is not controlled that closely, and you would likely have the gasket overhanging the edge of one side of the bore = not good!
03-30-2016, 02:37 PM
#17
TECH Resident
You would not want a 4.030" bore gasket for a 4.030" motor. The position tolerance from the dowel alignment holes to the bore centerline of the gasket is not controlled that closely, and you would likely have the gasket overhanging the edge of one side of the bore = not good!
04-14-2016, 02:58 PM
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Just wondering if anyone knows if the stock crank can be internally balanced and if so is it worth it? I was hoping to do this when I get my motor rebuilt so I did not have to worry about running an externally balanced flywheel in the future. I plan on going with new rods and pistons, so it will need to be balanced anyways. I did not know if it would add a bunch of labor to internally balance it at that time. Anyone have any experience with this?
05-11-2016, 10:05 AM
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Lloyd just checked my heads out for leaks and flatness. Everything looks good. I am having him throw a set of Lunati double valve springs on while he has the heads.
I found a bad cam bearing when I tore my motor apart. Looks like I need a new cam. The cam bearing journal has grooves I can feel with me finger nail.
Lloyd suggested either:
226/234 .574/.570 110 LSA (similar to what I have)
or
232/240 .578/.574 108 LSA
The car will be mostly a weekend cruiser. Do you guys think the 232/240 will feel slow on the street? The motor will be 7,000 RPM capable, but I do not want to have wind it up all the time just to feel like it is making any power. Any opinions?
I found a bad cam bearing when I tore my motor apart. Looks like I need a new cam. The cam bearing journal has grooves I can feel with me finger nail.
Lloyd suggested either:
226/234 .574/.570 110 LSA (similar to what I have)
or
232/240 .578/.574 108 LSA
The car will be mostly a weekend cruiser. Do you guys think the 232/240 will feel slow on the street? The motor will be 7,000 RPM capable, but I do not want to have wind it up all the time just to feel like it is making any power. Any opinions?