This is my first time posting anything, although I have read topics on The HAMB many times and have certainly been appreciative of all of the knowledge shared. It has helped me out many times. This should explain how I made my 1970s Chevy 350 block accept 1990s roller cam parts. I became tired of having my cams fail when trying to do the initial break-in, and I WAS doing them correctly. I had two flat tappet cams fail in a row (I have since become much more picky when selecting cams and lifters) so I wanted to try out a roller cam because they basically don't have a break-in procedure, no revving to 2,000 for twenty minutes with your toes crossed or anything; start it and let it idle if you want, as far as I know. I searched the internet from one end to the other to find the info on how to do this conversion since I don't have easy access to free parts for simple test fitting. After much hunting and reading I eventually found enough of the info I needed to get started. I wanted to list everything I found and then built so that anyone who finds this will hopefully have an easier time getting started with this engine modification than I did. You will need lifters for a 3.1 or 3.4 liter V6 and I think they came in a lot of other displacements as well. They were used in many GM cars including the 2000 Monte Carlo. Part numbers I have found for example are: HT2270, L2270, GM 17102014, 17120070, 8171200700, Melling JB2270. I bought a cheap set of Chinese Ebay lifters (was low on cash at the time; they were only $73. They felt cheap too, but so far none have failed!) and forgot that there were only 12 in a set so I had to buy four more. Got Melling ones at O'Reilly's for $20 a piece. Quality seems really good. They were trying to sell me AC Delco lifters for 120 something a piece! Had to have them look up the Mellings by the part number, the computer would only list the ridiculously priced Delcos. The lifters are the correct height and .842" diameter. The lifter bores for late model blocks are taller than early small blocks as are the roller lifters which will cause the oiling hole to rise out of the block when the valves open, the V6 lifters are close to the height of a flat tappet as is the oiling hole. I used a roller conversion camshaft which uses the old style timing chain setup and has a fuel pump lobe. Have been running the factory pump pushrod and distributor gear on it, also. You will need a cam thrust button and timing chain cover with the dimple for it to run in. The late model engines have a thrust plate that does the job of the button in keeping the cam from walking fore and aft. There is nothing to bolt it to on the old engines, though I have read that the factory roller cams will fit. If you want to use one of them you may have to figure out what to do with the retainer and they use a different timing gear bolt pattern. I am running an Elgin Retro-Fit Hydraulic Roller E-1231-P; .457/275 Retro-Fit camshaft with the following specs: RPM Range: 1500 to 4000 RPM Intake Valve Lift: 0.457 in. Exhaust Valve Lift: 0.457 in. Advertised Intake Duration: 275 deg. Advertised Exhaust Duration: 275 deg. Intake Duration @ .050 in.: 202 deg. Exhaust Duration @ .050": 202 deg. Lobe Separation: 104 deg. Intake Centerline: 100 deg. Firing Order: Standard Cam Gear Attachment: Bolt-On Usage: RV, Low-End Torque Listed on eBay now for $295. This is in my C-20 truck I use for a daily driver and it works fantastic for around the town and highway driving. Carbureted with a Holley 600 4160 and gets 10 mpg or so. Also have a Performer intake and 1 5/8" long tube headers (I HATE manifold to exhaust pipe gaskets) with 2 1/2" pipes. Stock cam grinds much of the time have the wrong lobe separation angle for good flowing exhaust systems, just so you know, probably were optimized for manifolds and quiet mufflers. Heads are late 80's TBI truck heads, 65cc 1.95 1.50, .035 gaskets, stock dished pistons, and makes just under 9.5 compression I think. Straying off topic slightly... You will then need a Spider or lifter retainer spring or whatever they call it, the Dog Bones that keep the lifters from rotating in the bores, a set of 7.4" LS pushrods, a couple of 9/16" bolts, three 1/4" bolts and nuts, some 1/4" bushings or bunch of washers, a piece of 1" steel bar, a piece of 3/8" plate scrap, a couple feet of 3/4"x 1/2" channel iron, and a welder. This is when the fabrication skills need to kick in. All of the instructions I found said to drill and tap three holes into the center oil gallery to bolt down the spider, which I thought was a BAD idea. I instead made a fixture to hold the spider in place. I stood the round bar up in the circular place in the front china wall, and cut it off below the top of the wall. Clamped it in place with Vice Grips and drilled a 3/8" hole about halfway down the round part of the front china wall about 45° to the center line of the block through the block and rod. Threaded the rod and bolted it to the block. The shape of the wall stops it from rotating in any way. I drilled the top bell housing bolt hole the rest of the way through into the lifter valley and threaded it for the other 3/8" bolt. Drilled a hole in the plate towards one edge, cut the end off of a small piece of pipe at an angle, and welded it around the hole in the plate. Then bolted the plate to the inside of the rear china wall. This is a good time to check that the distributor will clear the plate going in because it is close. I cut the channel iron to fit between the round bar at the front and the plate at the rear and welded them all together. I don't remember the measurement, but I had it suspended about an inch above the center of the lifter valley. It will later have three holes drilled to bolt onto the spider. The areas around the lifter bore tops will need to be massaged with a grinder. The bore tops themselves were fine on my engine. They were flat as cast almost perfectly to a 90° angle to the bores. The dog bones will rest on them and the lifter tops protrude through the dog bones. Where there is material that needs removed is where the lifter valley sides meet the flat surface of the bore tops, the bottoms of the 'bumps' coming down from the inner head bolts, some of the extra material of the casting process on the ends of some of the bore tops, and the outside edges of the dog bones needs to be radiused. Most of the grinding does not remove much more than the sand texture of the metal. The corner of the valley side meeting the bore top surface needs to be dug out a little and four of the bore tops have extra material that sticks up higher on one end- grind it down to an even plane with the rest of the surface. The 'bumps' cast into and protruding out of the sides of the lifter valleys end just above the lifters and wouldn't be a problem if they didn't get in the way of you placing the dog bones onto the lifters. Their lower edge needs to be rounded off. Additionally, the #1 exhaust lifter bore may have extra metal needing removed around the front outside edge and the #8 exhaust lifter bore has extra metal that sort of runs up to the distributor opening that may need removed. Radius the dog bones on the edge that is in the corner of the lifter valley, this keeps a person from having to grind out a square corner which would probably result in a cracked block. Also, radius the top center and it will help with clearing the 'bumps'. After I ground all I that could see to off of the block and dog bones, I lubed up and installed the cam and sprocket. Going one cylinder at a time I installed its lifter set and test fitted the dog bone making certain that the dog bone did not bind as the lifters moved through their whole rotation. I did not put any oil on the lifter to dog bone interface making sure it had the best chance to bind if it was going to. I was able to do all of the metal removal with an angle grinder, a Dremel for the tight space at the front of #1, and I radiused the dog bones with the side of my cutoff saw wheel. Just go slow and test fit often. Once all of the dog bones were able to be installed I placed the spider on top of them and bolted in the bar I made to hold it down, then marked and drilled the three holes for bolting them together. I did not have any bushings, So I ended up using a bunch washers on each bolt to get the proper distance between the bar and spider so it would have good pressure holding down the dog bones. I used a chisel and staked each nut to the bolt. Wouldn't be good if all those little pieces got loose and started trying to go down the oil return holes! The lifter height will be taller than with flat tappets and causes a stock length 7.8" pushrod to be too long. I did not figure this out until I broke a rocker stud. With stock self aligning rockers the inside of the slot was hitting the stud. By the time I progressed this far I had more money and bought a $150 set of eBay Crane knockoff full roller rocker arms, they eliminated any worry about not having enough travel, though with the right pushrods the stock ones should have worked correctly. I then measured the pushrod length with a length finder. I think it came to 7.5" or so and the closest cheap ones are 7.4s for LS engines so that is what it got. As far as I can see, the rocker geometry is good enough. I have been using this engine now for over 7 months every day with no issues. I have found that they are noisier than flat tappets, but not too much so. Also, test fit the distributor before bolting on the intake for good, I learned the hard way. One other thing, I mocked up the contraption in another block and then installed it into my truck motor. I found that my truck block was slightly longer and I had to shim the back mount with a thick washer. Both blocks had the same casting number, but were made two years apart. Could give a person problems trying to transfer between engines. I don't check my email or messages often, just so you know. Thank you!
Pretty slick way around things. Heck of a first post! edit: good tip on the lifters. I read a post here on the HAMB that a fella had an early roller engine but came with flat tapper cam. So he too found out the need for the v6 lifters as well. I think the oil hole was too high on factory roller v8 lifters?
I appreciate the ingenuity, but if you’re ok with using cheap eBay lifters for this and those are $80, plus your 4 $20 each Melling lifters…wouldn’t these have been a drop in without all of the work of the dog bones and spider for about the same $? https://www.ebay.com/itm/3947405302...6e08cd7450cbbdddc64c6cf2e8891f6d48747c6d56d2c
The main reason I did not use any of the cheap link bar lifters is that I watched a few YouTube videos where people were bending the link bars and/or pulling out the rivets by hand and demonstrating how loosely they were held straight. No one was really complaining much about the lifter internals, so I was more concerned about one turning sideways in the bore than with anything else. Oh, and I would have probably tried to buy a set of 16 the first time if I hadn’t been up too late playing on ebay and not remembering that a V6 doesn't have as many lifters as a V8! Then once I had them I didn’t want to wait on four more so I just forked over the cash at O’reilly’s. Thanks to everyone who appreciates my work!
Thank you Kingdamf15. Your efforts have paid in the months since assembly. So you have good cause to share the tricks used to get it right. Not being a racer I can appreciate the choice of grind specs. Nice when a plan comes together. HI 5
GENIUS! I like how you figured out how simple pieces of mild steel would work with the stock parts. I see the pieces of towel stuck in the bores. Did you do the grinding with the engine partially assembled in the truck? Thanks for sharing this!
I think you may be thinking of my story... I had an '87 Monte SS 305 engine. Hot Rod Magazine article stated "if the engine has the bosses for the retainer plate and the spider, the block will accept factory roller components". My block had all that although the spider bosses were not drilled. I grabbed a factory roller cam/lifters/dog bones/spider/retainer plate (and a store bought, correct timing chain set) from the wreckers for cheap. Installed and immediately had issues. What the magazine article failed to mention was that some early "roller compatible" appearing blocks have stepped lifter bores so standard factory roller components will NOT work. Due to the step in the lifter bore, the oiling hole on the taller V8 roller lifter was exposed and caused a massive rush of oil all through the lifter valley. (found this while on my engine test stand luckily). I created a thread on this site (when I first discovered the issue) and got several suggestions. One was to install bushings in each lifter bore to eliminate the step. I believe this would have worked but was not worth the expense as it was just a lowly (and stock) 305. Someone else suggested I use shorter V6 roller lifters. Although this may have worked, due to the huge difference in the design of lifter valleys between a pre-87 block and a post-86 block, a VERY large amount of material would have had to be removed from every lifter bore on my '87 block in order to lower the existing lifter bores down to the height of your typical pre-roller SBC which is what the originator of this thread is using. I am glad I chose not to take that route as I ended up returning the engine to flat tappet only to find the block itself had an internal coolant leak. Thankfully I found this issue on my test stand too. Into the the bin it went. Soon after I tossed the 305, I found a recently rebuilt 1990 (I think it was) non-roller 350 for $150, installed all my roller stuff (this block truly was roller compatible as it did not have stepped lifter bores), added an early (pre-computer) HEI, the carb intake off the Monte 305 (it worked with the TBI heads), a Quadrajet and ended up with a great running engine. In my case I installed a GM melonized distributor gear on the HEI though. My only issue with the my choice of parts was the factory TBI roller cam did not have the fuel pump lobe so I had to run an electric fuel pump. Thanks to the originator of this post for going into such great detail regarding what it takes to "rollerize" an early block using factory stuff. I wonder if used (wrecking yard sourced) V6 roller lifters would possibly be a better choice than new "cheap eBay" aftermarket replacement stuff. A picture of the stepped lifter bore ...
I have absolutely no idea why they did it. My '87 block came with a flat-tappet cam and stepped lifter bores, my '90 (or possibly '95, I can't remember for sure) was a virtually identical block that also left the factory with a flat-tappet cam but no step in the lifter bores so clearly the step was not needed to allow for a flat-tappet cam. That being said, '87 was the first year of the block change (this was also when they went to the one-piece rear seal) so maybe GM didn't quite have it all figured out at that point and figured the step might be needed for flat-tappets so let's just go ahead and do it To be honest, that doesn't really make sense to me either but I have no other explanation for it.
Wow! I have never seen tis stepped lifter bore you speak of, and have had sbc for over 40 years. Interesting!
My kid begged me to do this on the 350 for his Z car about 15 years ago, I was highly skeptical but relented and started grinding the block. we got it together and put it in the car, he drove it for about a year and sold it. the guy who bought it still drives it I'm told.
I guess they meant that the power range drops off after 4000. It will definitely rev past that. My TBI heads I am using don't flow well higher into the rpm range so I haven't pushed it up there much. It might work better for a hot rod with some double hump heads or something with better flow characteristics at 5 or 6000.
I did do it with it in the truck after the first cam failed on break in. So many metal shavings to deal with...
So how much more was a QUALITY set of retrofit roller hydraulic over what you have tied up in time and money making this work?? I would not run the cheap ebay retrofit hyd rollers I find what you did very interesting and would be a economical way to go if using used parts and had acess to good used factory V6 lifters and the later spiders and such . A lot of guys use old/ original factory roller lifters on a new cam up grade on later factory roller engines . They are reusable unlike a used flat tappet. Millions of used V6 engines to rob parts off of for a really cheap conversion.
I think the cheapest set of link-bar hydraulic rollers I found was around $500. Probably could have eventually found an ebay auction with some used for less. I did watch for some and no one ever listed any. I did find plenty of used solid lifters and I wouldn’t mind running them, except the longevity is said to not be great. So I figured I would go for the cheap for now, check them after a few thousand miles and continue on with the experiment. Also, I think of my own labor being free since otherwise I would just be sitting in the recliner watching TV!
I wonder if the stepped bores were to put the block surface around the top of the lifter like on older small blocks? Do the lifters in flat tappet equipped non-stepped roller cam blocks sit down below the top of the lifter bore when not on the lobe?
The pre-'86 blocks lifter bore height is the same as where the step is in the stepped bore blocks. The area above the step makes the height compatible with the factory roller lifter, spider, etc. You could be right about your thought that the step is there to mimic flat tappet original bore height. Could also be they had some other anti-rotation keeper design that required that step to be there, but was ultimately dropped from ever reaching production status beyond the machined provision being available in the blocks?? Maybe a back-up idea in case the sheetmetal spider and dogbones idea proved problematic in some way ?(which it didn't) Just spitballing,,,,but somebody out there in Engineering back then could probably know.
I would be interested to see if anyone has done this on an early block, pre-70ish. I would love to use the factory retainers etc. I am thinking this may prove impossible. I had bought a file off of ebay once where the guy said you could do it, but I never felt confident enough to try.
My '87 block, the lifter bores were stepped and left the factory with hydraulic flat tappet lifters. Due to the step, this block would not allow the use of roller lifters. My later block, the lifter bores weren't stepped yet also left the factory with hydraulic flat tappet lifters. Due to the lack of a step in the lifter bore, this block DID allow the use of factory hydraulic roller lifters. Whether the block was stepped or not, they both allowed flat tappet lifters but only one allowed rollers. It doesn't make any sense ... there appears to be absolutely no reason for the step. Had the step not been machined into the '87 block, it would have allowed the use of factory rollers. The '87 block had the "stumps" for the "spider" (I just had to drill and tap them), and the front of the block was designed to accept the cam retaining plate. I was able to install all factory roller components into the '87 block, the only thing that prevented me from successfully running the roller stuff was the stepped lifter bore. I had the '87 engine running with all the roller components, the only issue was oil was blowing (that should really say "GUSHING" like a geyser) out of the lifters into the lifter valley due to part of the roller lifter being exposed, this was entirely due to the strange step in the lifter bore. I have no idea why GM did it but I can tell you, that step wasn't needed in order to run flat tappet lifters. I removed the engine from a bone stock Monte SS and have read on the 'net that I am not the first person to encounter this bizarre issue, leading me to believe that the blocks left the factory this way. That step appears to be completely useless/has absolutely no purpose. The only thing I can come up with is, '87 was the first year of the roller style block and maybe GM assumed that step was needed to run flat tappets then later discovered it wasn't. Kinda sounds like a "fail" on the engineering division as it appears to have added a machining step that was not needed. The point of my post is ... if you are interested in running a factory roller block (which makes sense due to all the issues with lifters these days), do NOT waste your time and money on a block with stepped lifter bores unless you are prepared to "sleeve" the lifter bores to remove the step.
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