I have a 72 351cleveland 2v. I’ve rebuilt the motor and put a 4v manifold for 2v heads. Running a Holley 600, header and a comp cam 268H in it. I had lots issues with the motor. To make a long story short I pulled the 2v heads off and put 4v heads and manifold plus a different cam ( I don’t know what Cam it is) . The problem is that it had lots of high end power with nothing in low end.
So
I have decided that I’m going to put the 2v heads back and put that Comp cam 268H back in the next week or so. I had lots of problems with the timing and I’m worried that the problem I had before will happen again. My question to you all is how do you install the 268H cam Straight up or change the timing gear to off set the degree? Could that be why I had issues before? This is above me pay grade.
Comp makes all of their cams with the intake centerline 4 degrees advanced, so install on the nominal (zero) timing chain option. Comp’s trying to nudge peak power lower and slightly improve idle vacuum.
I’m worried that the 268 will not get you the broad street power you’d like. This is an ongoing problem with Cleveland builds - as in “going on” since 1972. That 268H has a 110 deg intake-exhaust separation (LSA), which I have never found Clevelands to like. Years ago (when new) I used a cam with similar duration but 114 LSA, and had power all over the tach. Today it is claimed that Speed Pro sells a version of it url]https://www.summitracing.com/parts/slp-cs-173r/overview/[/url], but I haven’t used that modern one and cannot vouch for it. Better might be a near-peer to the good '72 Cobra Jet cam, which I think Lunati comes close to with http://www.lunatipower.com/Product.aspx?id=3029&gid=340
You didn’t say whether the 4V heads were the '70-'71 closed chamber or the '72-up open, but my opinions apply to both. And unless you want to enter a new career in obsessing over dial indicators and degree wheels (try it, it’s addictive!), just install any of them on the zero lug.
Your post is what I have been looking for! Reading post after posts and not finding what I feel to be an honest answer.
I’d hate to say it but the 4v heads were from a fraudulent purchase that lead me to deleave the motor the 4v heads came from was a 72 Cobra Jet. Which turned out to be a 73 and not a Cobra jet! Ebay! It’s a long story! The motor runs better but do power on bottom end.
The second cam you mentioned…Do I need to by new springs? Or can I use the springs from the 268H cam?
By the way the first cam had no specs on it.
The second one is a copy of the '72 CJ cam. If they’re stock 2V springs that are 40+ years old, you might want to freshen the springs.
Sounds like you may be at 9:1 CR. If building one today, I’d reach for that Lunati guy.
First one - one I had in my 10:1 '71 4V:
290°/290° advertised duration @ 0.004"
0.505"/0.505" lift
Exhaust valve opens at 84° BBDC
Intake valve closes at 74° ABDC
62° overlap
219°/219° duration @ 0.050"
114° lobe separation angle
Intake lobe centerline = 109° ATDC
I have new springs but there for the comp cam 268H.
I’ll call them tomorrow and ask for springs
Use the springs you have. No need to go down in pressure.
How do you know if my springs for the 268H cam ( there new) compatible for this cam?
I’m ok with using them as long as they will be fine with this cam
I seem to have low vacuum. Around 11-12. Don’t know why? Took the motor apart and checked the rings, pistons,heads cam is a smith idle cam. Hope that doesn’t impede this new cam.
So I called summit and ordered the Cam,lifters and springs. Pricy! Hope this will make her run better. It won’t be in for a while( month) so I’ll let you know what the outcome is.
I have a D2ZZ6250B I bought new back in the day and ran for some years as a young pup. Cam is marked “BV” where the “B” is backwards. Still have it! Was (is) a great cam and is in great shape. Not to muddy the water, but I’d sell it if you were interested Butch.
P.S. No low end is why I kept telling you the 2V heads were the way to go!
Lol
Yeah you were correct on one thing but not another!
I tried putting the 2v manifold on the 4 v heads and no way! The ports on the 4v heads were larger then the manifold itself
Do you have spec’s for this cam?
Just an update!
Finally received my Lunati cam but they sold me Chevy keeper. Hade to purchase the correct one since my original keeper wouldn’t work. Put her all together added antifreeze and found that the water pump gasket leaked. The good thing was that the motor hadn’t been started yet. Pulled the water pump and replaced the gasket with a liberal amount of silicon. Let sit for 24 plus hours before adding antifreeze again. Let it sit while I went to work. Come home no leaks! Woohoo! Pushed her outside to begin the dreaded Cam break in! Started her up did the 30 min breakin dumped the oil and filter. Add new then took her out for a drive. There was only one issue. There was a strange smell! THE SMELL OF RUBBER!!!
You guys were wright in the cam choice and to that I thank you! Drives like a totally different car! Finally! Robert you were right all this time special thanks to you and your lengthy phone calls! And I would have bought your Cam if I hadn’t already purchased this one. Thanks again guys
Whew, I’m still at work, but greatly relieved I haven’t made an ENEMY!
Man, nothing like a cam change - fraught with worry and annoying things like that Cleveland timing cover - that scores!
Congratulations on then hard work and now on to supertuning like 45 years ago -
Lol
Yeah I’m happy. Thanks for the advice