Its Just Me Posted May 31, 2013 Share Posted May 31, 2013 I have a close friend who purchased a ZZ502 crate engine from GM a few years ago. Being who he is, he immediately (0 miles) swapped out the original GM hydraulic roller cam and lifters for a custom grind. He has the GM cam & lifters in a box in his house and will sell them to me for $100. I have a 1969, 4-bolt main 427 from a corvette that needs an update (last rebuilt in 1983 by a teenaged me). I'm hoping to keep the original forged pistons (advertised in 1969 as 11:1 with the cast iron closed chamber, rectangle port heads), install aluminum heads in an effort to lower compression and improve breathing, an Edelbrock performer RPM air gap intake and my 850 DP Holley. My intention is to make this engine more street friendly than its current configuration (and potentially more power & torque within a realistic rpm range). As part of this plan, I would like to update to a roller cam. So the question is...will my buddys Gen 6 GM roller cam and lifters physically fit in my Gen 4 BBC? I would guess that I can't expect a direct drop in, but I have some room to pay for some machineing etc if it's not counter productive. And as a second question, would the original GM cam grind work well with my 427 or should I consider some reworking of the cam profile? Assuming at this point, that I would look for an rpm range of 1500-6500 rpm. I have a Ford toploader 4-speed transmission and a 12-bolt posi w/3.73 gears behind it that I plan to keep in place. The car may see some track time, but mostly a tire roasting street car. And by the way, it's in my '70 Chevelle, but please don't let that bias your answer. I know I left a lot of unknowns out there, and beleive me, they will be addressed at the proper time, but for now I just want to know if its worth pursuing this $100 cam/lifter option. Thanks Scott Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted May 31, 2013 Share Posted May 31, 2013 Hi Scott, the ZZ cam is a popular swap for people who want a roller but don't want to spend a lot of money. Yes it will work, I think the only thing you have to do is use a Gen VI timing gear but I'd have to confirm that. You also need the "dog bone" keepers for the lifters from the ZZ and the valley plate the holds them. If you're looking for 6500 the ZZ cam won't do that, at least making any power. The power curve on that cam is done by 6000 with a good set of springs. It would depend on what the original engine configuration was to determine if the old cam would do anything for you. In the ideal world because you have a collection of different parts in mind (no problem with that you just need to match it up) a custom grind would go far to make it all work together. That's spendy but the rewards are great... Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted May 31, 2013 Share Posted May 31, 2013 Davey - but will his 69 427 block have the provisions to accept the "dog bones"? And there's no bosses to bolt down the plate that holds the keepers. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted June 1, 2013 Share Posted June 1, 2013 I have a few doubts about the gen 6 set up working. As Mike questioned, the provisions to bolt down the plate and the way the way the lifter bores are machined flat at the top on the late roller motors. The cam is retained by a plate, you could probably use a button. You could probably make it all work but it would probably cost more than just the price of the cam. I think a set of retrofit rollers would be the way to go. Quote Link to comment Share on other sites More sharing options...
Heckeng Posted June 1, 2013 Share Posted June 1, 2013 You guys are right, the dogbone lifters won't work because of the maching being lacking. The retainer plate/spring will also not work. I have heard that the older blocks WERE drilled for a retaining plate type of cam retention system which the Gen 6 uses. I actually like that cam quite a bit for street driving. It is easy on parts and it makes decent power for what it is. Also, being smaller in duration it will help keep compression higher than a larger cam. Get some good Morel lifters, a retainer plate, and you will be good to go. Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted June 1, 2013 Share Posted June 1, 2013 yeah good point on the dog bones guys, it would be easier just to use some retro lifters...The street Morels are not too spendy and would be fine with that cam. Some of the early blocks are drilled for the plate but the bones are an issue... Quote Link to comment Share on other sites More sharing options...
Its Just Me Posted June 6, 2013 Author Share Posted June 6, 2013 Thanks for the input guys. Before I got any responses to this thread, I had already decided that the ZZ502 cam would be a better fit in my 454 Monte. I don't "need" a new cam, but I thought if I could get into a roller set-up for around $500 it would be a great upgrade to my engine. Since the gen 6 lifters and dog bones won't work, all I would be buying is a cam (though still quite cheaply). By the time I get new/retro lifters, a retainer plate, rocker arms and push rods, I'm way over my budget (which I really didn't have in the first place). I guess I'll just keep flat tappeting along. Thanks again. Scott Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted June 7, 2013 Share Posted June 7, 2013 Just keep using that oil with the zinc additive!!! My 454 ate a lobe with regular oil....I'm still kicking myself for that. Quote Link to comment Share on other sites More sharing options...
Its Just Me Posted July 10, 2013 Author Share Posted July 10, 2013 I can't seem to walk away from this...It still seems like a great upgrade to my street engine for minimal cash. Is that a snowball I see a coming??? UpDate: I purchased the cam, roller lifters, dog bones, lifter valley plate, pushrods and the valve springs, caps and keepers, all from the 502. For $100 I might add. I understand that I can't use the 502 lifters, dog bones or valley plate in my Mark IV. My plan is to purchase some retro lifters, change out the original timing gear/chain set for one that uses the retainer button to eliminate cam walk. I will swap out my valve springs, retainers and keepers for the 502's and buy a set of roller rocker arms. I had previously purchased a set of 781 heads to replace the existing peanut ports, so a teardown was on the agenda already. My question now is...which push rods do I use? I have my original 3/8" Mark IV rods, and I have a set of 3/8" Gen 6 push rods. The Gen 6 (502) push rods are shorter than the Mark IV's. I assume that's because the roller lifters (GM) are taller than the flat tappets of the Mark IV (but I haven't seen them side by side, so I'm making an assumption here). Will the retro rollers be shorter, thereby allowing the original Mark IV pushrods to be used? Or are all roller lifters taller requiring shorter pushrods and now I need to use the Gen 6 (502) pushrods....Or am I way wrong on all accounts? Can someone set me straight? As a bit of history/future/pipe dream...The car is a '71 SS454, it has a set of 1-7/8" headers, 2-1/2" Flowmaster dual exhaust, an edelbrock performer intake, a 750 vacuum secondary carb and HEI ignition (yes, I will change the distributor gear to be compatable with the roller cam). It currently has a set of peanut port heads on it and a cam of unknown spec. I'm guessing that the CR is somewhere around 8.5:1. My winter project consists of this roller cam swap and to install the rebuilt (stock valve size) 781 casting heads. I will confirm my actual compression ratio and target 9.5:1 by milling the 781 heads if necessary. My pal that I got the cam from has a TCI "Street Fighter" 4-speed overdrive 700-4R trans with a lock-up converter that I'm very interested in, and then a gear swap from 3.31 to 3.73's. My goal is to have a great running, strong & very reliable street engine and I'm really hoping to knock down 18-20 mpg. This car is not a daily driver, but we love to take it on long cruises. Hoping to bring it to the Eastern meet next year. Does anyone see any potential problems with this plan or have any comments or suggestions? I'm still in the planning stages, so lets hear them now. Thanks Scott Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted July 11, 2013 Share Posted July 11, 2013 Retrofit roller lifters usually use a .400 shorter push rod. I don't know how the gen6 units compare. Good luck on the 18 to 20 MPH Quote Link to comment Share on other sites More sharing options...
Its Just Me Posted July 11, 2013 Author Share Posted July 11, 2013 Thanks Mike, I'll check the original push rod lengths, subtract .400" & compare to the Gen 6 push rods. Yeah, the milage thing may be a bit optimistic, but if you don't reach, you can't grab! I currently average 12.2 mpg & hope that the 0.70 final o/d trans and a lock up converter will push me toward 15 mpg...I'll be quite happy with that. Scott Quote Link to comment Share on other sites More sharing options...
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