jammovette

SON Of A $&%(&!! Just wiped the original flat-tappet cam on original 390 hp car. So much for Mobile 1. Should have used Zinc additive but thought synthetic would be enough protection. On the bright side, wanted to upgrade to roller set-up, nows the time to do it. Do I still need Zinc additive if I upgrade to roller cam/valve train?

jammovette

just did compression test range: ranges from 120 to 95. This doesn't look good. Worn-out BB. What's a set of original 66-390 hp heads worth? Maybe time to part motor out and buy a crate BB. Block is 69 vintage I believe. Any suggestions.

drewdog66vette

just went thru this exact thing. mobil one is great for new engines. blows for flat tapet cams.... i am sorry. just went to a roller cam. much smoother and much less choppy idle if you know what i mean. so, i would suggest a bit more aggressive roller cam, i miss my choppy idle clatter.... but the car moves better and is more reponsive.... good luck and i am sorry. i would suggest castrol gtx.....screw the synthetic... do a web search... lots of articles.

jammovette

I have a roller cam in another 66 BB I own, VERY RESPONSIVE.... This one should sound good when done, sidepipes and aggressive cam. Will look into Mobil 1 articles, can't be half bad if they put it in the old 4 cam/32 valve (90's)ZR-1's and maybe the 09 supercharged one too. I believe my low compression is due to the famous valveseat leaks on the left bank.

6T7L71CPE

So, which "rollers" did you use? Comp or Crane or ?? Thanks

jammovette

Competition Cams all the way, my machinist where I took the heads to swears buy them, he would know, he sees what comes back worn out and what doesn't.

MikeM

If the rest of the engine is worn out, why would you be highlighting the worn camshaft and crappy(?) oil at this point in time? sounds like the camshaft maybe should be worn.

jammovette

Mike. I rushed to judgement, after I got an engine builder to look at it, he determined the bottom end is just fine, the loss of compression readings are due to valve seat leaks on a couple of cylinders. Cam wear due to no zinc, rest of motor would be just fine without zinc. It has been smoking a little just after start up if sat for a while.hence, the leaking valve seats. He says motor is in great shape to upgrade to roller set-up. Question is, do I take a perfect date matching 66 390 hp heads and port,polish,and mill for more performance or sell heads and buy an aluminum high perf. set. Cost difference I don't know? Any help/ideas? James

MikeM

I have no idea what you have in mind for your car. If that was my car, my engine, my wallet, I'd do a valve job on it and put it back together with another flat tappet cam. I don't see any advantage to reworking the heads, especially milling them to get more compression. I think it's money down the tubes.

If you modify or sell off parts of your original engine, you'll likely devalue your car to many potential buyers.

jammovette

[IMG][IMG]http://i182.photobucket.com/albums/x45/jammovette/pets018.jpg
[/IMG]http://i182.photobucket.com/albums/x45/jammovette/pets024.jpg[/IMG]
Pic of car, kinda original, kinda not. Original BB rear end diff.,original BB heavy duty suspension, Original unrestored BB gage cluster, original front end withminor repairs, original 390hp heads. Everything else including block and trans. long gone. Would original heads on this car make it worth more than a set of Dart, Brodix, or equivelant heads? Without the original block, I would say alll bets are off and lets modify without destroying,like flaring or narrowing rear end, roll bars, etc. I believe once you go that far. you enter the point of no return and car will devalue while you sink more money into it. Just my own opinion, and yes the black BB is flared in pic. James

62Jeff

I'd say that having the original heads (although you probably can't prove they are original) adds one more "+" in the "is it real or is it fake?" questions that a prospective buyer would ask.

If you have all the original big block bits, but the block and transmission, well that makes a better case for it being an original big block car.

jammovette

Sorry, pics did not go thru

NEVERL8

I was not in your exact situation but when the L79 had to get rebuilt I went with a full roller setup and reused the existing stock heads. I did have the heads rebuilt with screw in studs, did the usual port matching, had a 5 angle valve job and basically cleaned them up.

I really like your car and it is obviously not for the NCRS types. Given what I see and your comments about the bottom end of the engine being good I would convert to a roller setup, clean up the existing heads, put it back together and drive the hell out of it.

Now, if you go to a roller setup you can install a more aggressive cam, beef up the valve springs a bit, put in some roller rockers, and get some very nice power out of the setup without having a choppy idle and other driveability issues. The roller cams have much steeper ramp rates and can really wake up the airflow into the engine.

I would go with a complete comp cams setup. Talk to you engine builder. The techs at comp cams are very good at matching parts up to meet you performance and driveability goals.

Though my engine is a small block I did get a true 350 dyno HP out of it with 9.7:1 compression on 91 octane fuel using a roller cam, 1.6 ratio roller rockers and 130# valve springs. Thing sounds like a solid roller engine at idle.