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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Not sure that would be possible to use oem lifters in a non roller block. Especially since oem roller blocks have raised pads for the lifter bore, hence the reason to buy +.300” taller lifter bodies when goin to a link bar setup
machine work and spacing would not make it cost effective imo
Not sure that would be possible to use oem lifters in a non roller block. Especially since oem roller blocks have raised pads for the lifter bore, hence the reason to buy +.300” taller lifter bodies when goin to a link bar setup
machine work and spacing would not make it cost effective imo
It reads like you missed the point of the reduced base circle cam dropping the OEM roller lifter. And after reading Skinny's post - looking at his table - it doesn't look possible. No I don't want to do any machine work either.
Basecircle has nothing to do with using oem lifters in a non roller block
You arent making up the pad height with a base circle and that should never be considered due to the pressure angle
There was a thread a while back on converting non-roller blocks using OE lifters. I don't remember the specifics but seems like a lot of work. I scrap non roller blocks. I have a bunch of OE roller blocks, some 4 bolt mains. Don't see why anyone would invest in a non roller 350.
..... I scrap non roller blocks. I have a bunch of OE roller blocks, some 4 bolt mains. Don't see why anyone would invest in a non roller 350.
Anyhow. making progress.
Below 270 degrees duration a flat tappet doesn't give anything to a roller. And if your really want to get the valve moving fast mushroom lifters will do it.
Glad to see your moving along with that build. But you didn't do any grinding. No stand-offs in the lifter valley either. More of a daily driver effort then and I like it.
Basecircle has nothing to do with using oem lifters in a non roller block
You arent making up the pad height with a base circle and that should never be considered due to the pressure angle
Then how could anyone use a reduced base circle cam then? But it's done all the time. And as far as I know there ain't no retro-roller lifters sized just to match the "pad height". Lifter angularity is determined by the cam grinder as the grinder should know the maximum ramp rate and angle.
and yes some cam lobes arent for reduced base circles. Some are designed for reduced base circles
there is an acceleration limit and most lobes arent pushing that limit. Reduced circle still gets done but theres no reason to with todays rods. Alot clear fine with 383’s and unless you are building a max effort solid roller with a ton of lobe lift it shouldnt be an issue. But some ppl will run reduced base circles but just keep in mind its harder on the lifters and could potentially be harder to control with valvespring so may need more pressure.. Theres alot of variables there
Below 270 degrees duration a flat tappet doesn't give anything to a roller. And if your really want to get the valve moving fast mushroom lifters will do it.
Glad to see your moving along with that build. But you didn't do any grinding. No stand-offs in the lifter valley either. More of a daily driver effort then and I like it.
I've never done the standpipes or screens in the lifter valley. I have the vizard book and I get the theory but meh..
The machine shop didn't do any mods to the block. I've has the primary oiling mods and stuff done on previous builds but not on this one.
and yes some cam lobes arent for reduced base circles. Some are designed for reduced base circles
there is an acceleration limit and most lobes arent pushing that limit. Reduced circle still gets done but theres no reason to with todays rods. Alot clear fine with 383’s and unless you are building a max effort solid roller with a ton of lobe lift it shouldnt be an issue. But some ppl will run reduced base circles but just keep in mind its harder on the lifters and could potentially be harder to control with valvespring so may need more pressure.. Theres alot of variables there
I had to run a 1.050" base circle on my 412 to clear the rods.
What's the theory behind the smaller base circle being harder on the lifters? One would think the roller has less distance to travel and would wear less.
I'm trying to visualize what's happening here with a smaller circle. If you have the same lift and same degrees, doesn't the lifter just travel a reduced circumference?
Its more sideloading on the lifter body and bore which can wear the clearance out some over time
the problem is if you pick a lobe profile that isnt designed for a small circle and grind it on that small circle you get the higher pressure angle or basically steeper cam lobe and that is where the side loading comes from. Also may load the roller axle shaft abit heavier.
If the lobe is designed right with the smaller circle it doesn’t necessarily have those issues. It depends what you are doin, more max effort you try to get the bigger the cam you need, the more choices of lobes you have with standard larger base circles. A milder combo may not need to worry as much.
Its more sideloading on the lifter body and bore which can wear the clearance out some over time
the problem is if you pick a lobe profile that isnt designed for a small circle and grind it on that small circle you get the higher pressure angle or basically steeper cam lobe and that is where the side loading comes from. Also may load the roller axle shaft abit heavier.
If the lobe is designed right with the smaller circle it doesn’t necessarily have those issues. It depends what you are doin, more max effort you try to get the bigger the cam you need, the more choices of lobes you have with standard larger base circles. A milder combo may not need to worry as much.
I see. I had to draw this out. So the faster ramp rate due to the decreased circumference yet same lift and duration puts load on the lifter bore when the lifter is being forced up the steep ramp, so it's going to push on the outside of the left side and the inside of the right side. That makes sense.
Although in theory a faster ramp will also open the valve quicker which could aid velocity. Sounds like a pro and con.
I see. I had to draw this out. So the faster ramp rate due to the decreased circumference yet same lift and duration puts load on the lifter bore when the lifter is being forced up the steep ramp, so it's going to push on the outside of the left side and the inside of the right side. That makes sense.
Although in theory a faster ramp will also open the valve quicker which could aid velocity. Sounds like a pro and con.
-- Joe
You got it now. There are limits as to how fast you can accelerate the lifter. Faster gets harder on the valvetrain and increased wear of components.
You shouldn't do that (reduced base circle) unless your engine components require you to do so. Unnecessary wear & tear.
You got it now. There are limits as to how fast you can accelerate the lifter. Faster gets harder on the valvetrain and increased wear of components.
You shouldn't do that (reduced base circle) unless your engine components require you to do so. Unnecessary wear & tear.
Got the heads back. Blended the valve job into the Chambers. Was going to assemble them but realized I ordered the wrong retainers. Guess I'll be doing that next week.
ordered some Prussian blue too. Lloyd told me there was no need to lap the valves and they can go in any seat. I will see how good the valve job is. Gonna do a test with that then an assembled leak test, then cc them.
134lbs seat, 337 lbs open with .132" clearance for coil bind. (seal to retainer is .134").
Considered shimming a little more to bring that coil bind clearance tighter to avoid spring surge, but I don't want too much pressure on the LS7 lifters. Supposedly it's not recommended to exceed 140/350lbs on those.
You ever see a high speed video though of valve springs at 6200-6800 RPM ? Modern springs are designed to bind coil to coil leaving the clearance on the last coil as an aid in dampening and preventing spring surge. It's a big deal on race cars and sport boats, but yeah not really an issue on something that hardly ever sees that RPM.
Right it is important to use the springs range. Its generally recommended to be somewhere between .050-.070 or so. Some go tighter, some can go looser.
I was referring to spring pressure on ls7’s being fine. 150/400 is common in ls world
Right it is important to use the springs range. Its generally recommended to be somewhere between .050-.070 or so. Some go tighter, some can go looser.
I was referring to spring pressure on ls7’s being fine. 150/400 is common in ls world
The only thing I don't like is the factory valve guides don't have the holes centered for the valve, so the valve seal isn't perfect. I'm tempted to cut the guides down to .500 to center the seal.
It's amazing they don't leak from day 1... I wonder if I should just leave it. I don't have a .500" cutter in the shop I'd have to order one.
I think I see the valves have been unshrouded. I know you said you were installing larger valves and I regret not opening up the chambers for larger valves. And your larger intakes reach the edge of the chambers also. Thx for the pix as I worried about the intakes out past the edge as unique to mine. So now I'm researching chamber/valves coatings. Not sure if it will reduce detonation/knock or possibly increase it but it does increase power and protect the valves.
Curious why the head rebuilder didn't cut the guide boss for you?
Congrats as those should be nice performing heads and I wish I had the beehive springs but I got the budget spring upgrade using my stock hardware (retainers & locks).
I think I see the valves have been unshrouded. I know you said you were installing larger valves and I regret not opening up the chambers for larger valves. And your larger intakes reach the edge of the chambers also. Thx for the pix as I worried about the intakes out past the edge as unique to mine. So now I'm researching chamber/valves coatings. Not sure if it will reduce detonation/knock or possibly increase it but it does increase power and protect the valves.
Curious why the head rebuilder didn't cut the guide boss for you?
Congrats as those should be nice performing heads and I wish I had the beehive springs but I got the budget spring upgrade using my stock hardware (retainers & locks).
Thx for posting.
Hey man,
Yes they had to be unshrouded. The heads were milled .010 after the valve job which put them around 51cc, and after working on the chambers they ended up at 55cc.
I sent them to Lloyd Elliott to do the valve job. He cut the seats and the valves. I asked him to just cut the seats/valves and provide feedback on my porting. He said my porting was pretty good, just not as much as he does on his LE2 heads. Fine by me, I'm not an expert.
So when he did the VJ his machine cut the radius into the chambers around the seats, so I had to blend that up into the walls on the chambers. Came out pretty good I think.
The cutting guides was a last minute thing. I noticed the factory guides are installed solid then drilled off the seat, so the holes end up being offset on some of them. This would cause the seal to ride unevenly on the valve. So I cut them down to .500" which essentially centers them on the ID so the seal rides perfectly. Set the springs up, did a wet seal test, and a final cc of the chambers and installed both heads.
Then I did my pushrod check. 7.195" pushrods seem to work best based on pattern and checking angle at mid lift, although with hydraulic lifters it's a little hard to be spot on. I'll most likely end up re-checking the wear mark on the valve tip after 500 miles.
Anyhow. going sledding in vermont (hopefully) this weekend, then I'll be back on it next week. Hoping to get the motor back in the car and get started on the 6spd swap. and then my girlfriend wants me to start re-doing one of the bathrooms.
That was fun. She flipped her sled over (3 times) on a mountain in Vermont. Towing it back to an access road so we could get it on a trailer was a blast.
Anyway. More progress last night. Motor should be going in by the end of the week.
That was fun. She flipped her sled over (3 times) on a mountain in Vermont. Towing it back to an access road so we could get it on a trailer was a blast.
Yikes! Hope everyone is OK.
I've had to tow one sled with another a few times. No fun.
I'll try and wait to hear from you on your electric water pump results. I want to use the Summit pump too but would like to hear from your experience. Also found a $25 "delay after break" relay to let it run for up to 3 min after the engine shut off. Needs a relay anyways but all this nice to have stuff adds up. What I save with the Summit pump pays for the relay.
I'll try and wait to hear from you on your electric water pump results. I want to use the Summit pump too but would like to hear from your experience. Also found a $25 "delay after break" relay to let it run for up to 3 min after the engine shut off. Needs a relay anyways but all this nice to have stuff adds up. What I save with the Summit pump pays for the relay.
I'm probably going to either tie it into the fuel pump relay circuit, or use the AIR injection pump circuit. No plan on circulating it after engine shut off.
Yeah, I've kinda got a lot into this car now but it's a cool car. Mid 90s corvettes are fun little street cars.
There was a thread a while back on converting non-roller blocks using OE lifters. I don't remember the specifics but seems like a lot of work. I scrap non roller blocks. I have a bunch of OE roller blocks, some 4 bolt mains. Don't see why anyone would invest in a non roller 350.
Anyhow. making progress.
So I'm reading about another Gen II owner that can't get a double roller set to fit under the Gen II timing cover. Though I didn't get to see it for myself he said his Gen II timing cover hit the thicker DR timing set and had to use a single roller set for enough clearance.
I really need to ask you if your DR had clearance issues? I hope to use the DR myself. And what brand/model is your DR?
So I'm reading about another Gen II owner that can't get a double roller set to fit under the Gen II timing cover. Though I didn't get to see it for myself he said his Gen II timing cover hit the thicker DR timing set and had to use a single roller set for enough clearance.
I really need to ask you if your DR had clearance issues? I hope to use the DR myself. And what brand/model is your DR?
I'm using a '95 timing cover (pin drive optispark). I'm using a L98 cloyes timing set (CLO-9-1145). No issues. I've also heard of some people having issues with some timing sets and having to clearance the cover. I did not have any issues.
Motor and trans is in. Everything is buttoned up from the bottom. I need to port the intake manifold and get that on, and it will be almost ready to fire up.
The stock manifolds are both cracked. guess that's where the ticking was coming from. I took off the heat shields to inspect them. The stainless block hugger headers don't quite fit - they hit the motor mounts AND rub the knock sensor connector. Not sure what I want to do. Part of me wants to pie cut the headers and re-weld them, but it would be easier to just spend $250 on some cheap pace setter headers that fit.
Thank you very much for the reply. At worst it will be trial and error but I see now something that does work and the w/p drive can stay off.
You could have the cast iron manifolds welded but I think returning the huggers and using long tubes is where you want to go in the end anyways.
So I see your heads came out at 55cc. I need to get mine to 60cc+ for what I want to do. I don't want to use big dish pistons as even the big dish hypers are over $300. Funny but every time I crunch the c.r. numbers I find more mistakes I had made. Sure glad I haven't bought pistons yet. Kinda regret the head work I had done but trying to live with it and make <55cc chambers work. Can't beat the price on those Speed Pro pistons you have but they are only 6.9cc dish - I think I need more than that.
Thank you very much for the reply. At worst it will be trial and error but I see now something that does work and the w/p drive can stay off.
You could have the cast iron manifolds welded but I think returning the huggers and using long tubes is where you want to go in the end anyways.
So I see your heads came out at 55cc. I need to get mine to 60cc+ for what I want to do. I don't want to use big dish pistons as even the big dish hypers are over $300. Funny but every time I crunch the c.r. numbers I find more mistakes I had made. Sure glad I haven't bought pistons yet. Kinda regret the head work I had done but trying to live with it and make <55cc chambers work. Can't beat the price on those Speed Pro pistons you have but they are only 6.9cc dish - I think I need more than that.
Thanks again for the reply.
I have another set of stainless headers in the mail so I'll try those too.
Bringing them to 60+cc isn't too bad. My friend is doing up a set right now for his blown 355. He cut the area down around the spark plug. there is a TON of material there you can remove. Shape the chamber like an AFR195.
In the end this is just a cheap street build for a '94 Corvette. Was something to do over the winter. I've gotta add up my receipts but I probably have under $4500 into the rebuild and everything.
I dragged the Formula out of the trailer this weekend and ripped around town. Vortech is leaking a little at the case seal.
I got computer locked piston shopping and compression ratio crunching. I found good looking Speed Pro pistons for under 100 bucks but will have to leave the stroke at 3.48". Shame I have to cut the block deck so much (and shave the intake to). So I may use my original rods after all. The price of rod bolts is rediculus but there's not much competition there for ARP. Not looking forward to rebuilding my old rods but now that I know how much work goes into them I'm not sure I trust cheap new rods.
I had forgot to mention you might try swapping those block hugger headers from side to side to see if that makes a difference.
I'm only $900 into my heads so far but I have plenty of time as the motor in my camaro is still strong. It's the Opti that's beginning to quit as it shows the SES light after running for 25min. Have to fix that soon.
I got computer locked piston shopping and compression ratio crunching. I found good looking Speed Pro pistons for under 100 bucks but will have to leave the stroke at 3.48". Shame I have to cut the block deck so much (and shave the intake to). So I may use my original rods after all. The price of rod bolts is rediculus but there's not much competition there for ARP. Not looking forward to rebuilding my old rods but now that I know how much work goes into them I'm not sure I trust cheap new rods.
I had forgot to mention you might try swapping those block hugger headers from side to side to see if that makes a difference.
I'm only $900 into my heads so far but I have plenty of time as the motor in my camaro is still strong. It's the Opti that's beginning to quit as it shows the SES light after running for 25min. Have to fix that soon.
I wouldn't bother reconditioning stock rods. I threw out several sets of "X" and PM rods recently. Just not worth it. The machine shops well tell you the scat and eagle rods are not as good because they like getting paid to recondition 40 year old rods.
The block hugger headers are the same each side. I ordered a different set:
These are similar to the Pacesetter C4 headers so I'll give them a try.. I just dig stainless.
which style opti are you running? I have a bunch of optis on the shelf in the shop. I feel weird about using a used Opti though.
Block huggers give you good clearance and low restriction too. IMHO much better than any stock cast manifold and a good choice for a daily driver. They just don't have a tuned length at modest RPM but heck they look nice and make life much easier for the owner while still a performance improvement. I have chromed headers on my C3 corvette and managed to turn them blue while breaking in a flat tappet cam but I don't know about SS as you won't need a cam break-in procedure.
So I'm back on with aftermarket rods. I have to work with the machine shop to grind the crank the amount I need it offset though other wise I would have to zero deck the block and shave the intake too. You wouldn't believe the final combination I came up with to get dynamic compression below 8.5. But hey its cheap and I won't have to butcher up my head chambers. So what I avoid is recon the stock rods and my amateur work on the head chambers while I can use pistons that are less than $100 (Speed Pro). I'd say it saves me at least 20 hours of my free time.
I'd like to do this rebuild for under $2K but I'm already almost $900 into the heads and I haven't keep track on how much for new tools though I'm guessing close to $500. But I love good tools and that cost gets spread out over many other projects.
So I'm back on with aftermarket rods. I have to work with the machine shop to grind the crank the amount I need it offset though other wise I would have to zero deck the block and shave the intake too. You wouldn't believe the final combination I came up with to get dynamic compression below 8.5. But hey its cheap and I won't have to butcher up my head chambers. So what I avoid is recon the stock rods and my amateur work on the head chambers while I can use pistons that are less than $100 (Speed Pro). I'd say it saves me at least 20 hours of my free time.
I'd like to do this rebuild for under $2K but I'm already almost $900 into the heads and I haven't keep track on how much for new tools though I'm guessing close to $500. But I love good tools and that cost gets spread out over many other projects.
Have you considered getting pistons with the pin bore drilled in a different location so you don't have to cut the block decks? Or getting a non-standard rod length?
Your plan will leave you with a whole bunch of "custom" machined parts that can't be easily replaced if something goes wrong. Avoid cheaping out in 1 area only to pay 2 or 3 times more in other areas. It just doesn't make sense.
Block huggers give you good clearance and low restriction too. IMHO much better than any stock cast manifold and a good choice for a daily driver. They just don't have a tuned length at modest RPM but heck they look nice and make life much easier for the owner while still a performance improvement. I have chromed headers on my C3 corvette and managed to turn them blue while breaking in a flat tappet cam but I don't know about SS as you won't need a cam break-in procedure.
So I'm back on with aftermarket rods. I have to work with the machine shop to grind the crank the amount I need it offset though other wise I would have to zero deck the block and shave the intake too. You wouldn't believe the final combination I came up with to get dynamic compression below 8.5. But hey its cheap and I won't have to butcher up my head chambers. So what I avoid is recon the stock rods and my amateur work on the head chambers while I can use pistons that are less than $100 (Speed Pro). I'd say it saves me at least 20 hours of my free time.
I'd like to do this rebuild for under $2K but I'm already almost $900 into the heads and I haven't keep track on how much for new tools though I'm guessing close to $500. But I love good tools and that cost gets spread out over many other projects.
What is your target compression ratio ?
I don't see why you don't just open the chambers up on the heads. You could get those heads to about 65cc no problem.
Had do oval the holes in the intake slightly. I guess decking the block and milling the heads made it so the otherwise tight centric intake holes didn't quite line up. Flange gasket seal looks good though.
Gonna run my inspection camera down the runners later and check port alignment.
I don't see why you don't just open the chambers up on the heads. You could get those heads to about 65cc no problem.
-- Joe
I'm targeting dynamic compression ratio of 8.25 using the IVC degrees on common cams. I look at DCR with 3 different calculators to verify result. On-line DCR calculators are so fast and easy to use that I can try using different volume (and displacement) values quick enough though piston selection adds research time. I'm focused on the Speed Pro hypers because of cost and I really like their quality too. Sil-O-Vite has a few also but nothing under $100/set like Speed Pro.
I really would rather stay with bolt on parts if I can as time and quality should be better. I guess I should get a shop estimate for cost to rework just the chambers - thanks for the advice.
Well John Lingenfelter (RIP) said usually milling less than 0.020" (total) shouldn't need to correct the intake but if you post your total milling I can post his numbers from a table for you. Intakes are cheap and I have 3 of them so don't be afraid of milling one down as now is the time to make it right.
I'm targeting dynamic compression ratio of 8.25 using the IVC degrees on common cams. I look at DCR with 3 different calculators to verify result. On-line DCR calculators are so fast and easy to use that I can try using different volume (and displacement) values quick enough though piston selection adds research time. I'm focused on the Speed Pro hypers because of cost and I really like their quality too. Sil-O-Vite has a few also but nothing under $100/set like Speed Pro.
I really would rather stay with bolt on parts if I can as time and quality should be better. I guess I should get a shop estimate for cost to rework just the chambers - thanks for the advice.
Well John Lingenfelter (RIP) said usually milling less than 0.020" (total) shouldn't need to correct the intake but if you post your total milling I can post his numbers from a table for you. Intakes are cheap and I have 3 of them so don't be afraid of milling one down as now is the time to make it right.
I don't see why you wouldn't just re-work the chambers yourself. You could work on one and get it to the volume you need and then duplicate it to the rest. I wouldn't pay a shop to do that unless they had a CNC machine and was going to do the runners as well, with a guaranteed flowchart. But realistically, that's probably the cost of a good set of AFR's.
I've found these heads very easy to work with. There is definitely some "fixes" that need to be done to the LT1 platform, but once completed I think it's a great powerplant. A heck of a lot cheaper than the LSx stuff.
Bok, bok, bok, bok! Yes I'm chicken. I just had the heads rebuilt with over $800 in them. Carve up the chambers with the old valves in them before rebuild would make sense. Don't want to test my skills with them now.
Hey this is a budget build to gather info for bigger and better. I'd like to just find the pistons and cam to make it work w/o more time and money than I need to.
Bok, bok, bok, bok! Yes I'm chicken. I just had the heads rebuilt with over $800 in them. Carve up the chambers with the old valves in them before rebuild would make sense. Don't want to test my skills with them now.
Hey this is a budget build to gather info for bigger and better. I'd like to just find the pistons and cam to make it work w/o more time and money than I need to.
Did they unshroud the valves or did you stick with stock sizes ?
Lloyd told me to just start at the VJ and work my way out, which I did and it was quite easy. I took a little bit out of each chamber to make sure they were all the same size.
Gonna rain this weekend so hopefully I'll find time to jump on this and finish. I think I'll wire the electric W/P off the fuel pump trigger from the PCM to ensure it's running whenever the car is, then I gotta get the hydraulics installed and pedals swapped over.
02-24-2019, 01:01 PM
There are limits as to how fast you can accelerate the lifter. Faster gets harder on the valvetrain and increased wear of components. 
