overdrive Posted February 20, 2012 Share Posted February 20, 2012 When I bought my '70 SS in Kansas 4 yrs ago, the young lady said she had bought it from her brother, and he and a friend had rebuilt the motor. The original block is gone but it has an L 16 9 dated (1970) block and '68 dated 100.9 CC heads from a 427. I didn't get much information about the rebuild except there weren't but a few thousand miles on it and it was bored .030". It ran great until last Oct. I took the car to a car show about 25 miles from here to put it in the unfinished class and before I got back home it was backfiring thru the exhaust and some rockers were rattling. I recently pulled the intake to find 2 flat lobes on the hyd. flat tappet cam. Last Sunday I pulled the motor to disassemble and clean/inspect the internals before putting in a new cam. I was happy to find the pistons are TRW hypereutectics and have .100 domes. Today, I took the valves out of the heads and there are no hardened seats. I may reuse the heads and have the seats upgraded on the exhaust. I also found that the block has 4 bolt mains and it has a forged crank in it! Now I'm thinking I just may go ahead and put a roller cam in it. I'll likely never put the car on a track, I'll just drive it to cruise-ins and shows. I want to use pump gas and keep it under 6500 rpm. I'd like to get about 550 hp out of this motor later, if not this year. I'm thinking I may not want to spend any money on the cast heads and then replace them with aluminum later. What cam do you guys think I should get and which heads? I haven't started looking into those parts yet. I've alot of reading to do if I'm going to build it with the upgrades. All the motors I've built had flat tappet cams and cast heads, and I was building for dependability and mild performance increases. I'd like to go faster now. Thanks! Dan Quote Link to comment Share on other sites More sharing options...
Dans '70 Z20 Posted February 20, 2012 Share Posted February 20, 2012 Hey Dan, Just to give you the set up my builder went with. Keep in mind it was first rebuilt as flat tappet and then after never being started on a stand was brought back to convert to hydraulic roller. I did this for piece of mind with the low zinc content in oil and flat tappet cam failures I witnessed as of recent. Which is probably what you experienced with yours. Orig 454 LS-5 (.30 over). Using my stock heads but ported and polished and fitted with dbl valve springs, manley SS valves, beefed push rods and Crower SS roller rockers. 10.25:1 TRW forged hypereutectics domed pistons (with head work final 9:75:1). I am using a Performer RPM intake. with 780 cfm Pro Systems carb. I will be running Sanderson BB3 Blockhugger 3/4 length headers also. Since doing more of a pro-touring/ resto-mod set-up I didn't want headers to hang low. These have 1 7/8" tubes to provide better breathing. NOTE: I went with SS roller rockers so that I can use a stock height valve cover with trimmed drippers. Wasn't building a drag car so didn't want a drag car look. My builder recommended sticking with a Crower cam since that was the roller rockers I was using. This is the cam he chose for mine. Crower cam LSA 110 / Gross Lift 563/587 / Power band is 2330 -5550rpm which is perfect for a street car. With this set-up car should have moderate idle, can run on pump gas, should have plenty of vacuum for power brakes and should be around your goal of 550hp. If my plan originally was to go with aluminum heads he may have done my lower end differently but at the time of first rebuild I was just looking for forged pistons with a moderate cam. Things happen, you make new friends (that you gotta keep up with) and your plan changes slightly. Plus my builder said .... "if your paying the money to go hyd roller you might as well get a benefit!..." Hence my current set-up. LOL Should be turn key by the end of summer so I cannot tell you much more at this time. Getting anxious! Dan Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted February 22, 2012 Share Posted February 22, 2012 Dan, sounds like you have a really solid foundation for something really fun. What I would do is call Straub, give him your goals and intentions and see what he can do for you. At the very least you will walk away with a very well matched valvetrain that should give you years of fun to come. I went roller around four years ago on the Bu and it made all the difference in the world as far as reliability goes. But it did seeming break everything else.lol. Obviously a set of CNC AFR 305s would be nice. But nothing wrong with a nice set of worked ovals to keep in a budget. I'll give up the 50-60 HP and keep $3k in my pocket. Quote Link to comment Share on other sites More sharing options...
Dans '70 Z20 Posted February 22, 2012 Share Posted February 22, 2012 My thoughts exactly. Not building a race car. Plus then I would have to find a place store my #'s matching heads safely. Can't lose 'em or have them stolen if they are on the car. Unless of course the whole car is stolen and then I won't need 'em. LOL I was also recommended the AFR's if I ever decided to go aluminum heads. But for the 30-40 HP gain did not seem worth it. You will gain a lot of torque down low with an oval set of AFR's but with a BB, lower gear set in tranny and a slight 2600-2800 stall I should be OK down low for what I am doing. Remember one thing. Think about your ultimate goal with the car. You have to take everything into consideration motor, tranny, stall & rear gears. If the whole package is done right it is very rewarding. I think it is wise to speak to people with experience before jumping the gun. I am sure you have a respected builder in your area to speak to. The last thing you want to do is re-do something that you already paid for because it doesn't match a new item you want to add which was part of your goal. Either save the money and do all you want at once ....... or have a plan and build to that plan as you go to avoid paying for things twice! Dan Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted February 22, 2012 Share Posted February 22, 2012 Here's an interesting cylinder head shoot-out. At the end of the day, you can save a ton of money getting less expensive heads and not even give up a tenth on a street car. http://www.carcraft.com/techarticles/ccrp_0803_big_block_cylinder_heads/viewall.html Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted February 22, 2012 Share Posted February 22, 2012 Here's an interesting cylinder head shoot-out. At the end of the day, you can save a ton of money getting less expensive heads and not even give up a tenth on a street car. http://www.carcraft.com/techarticles/ccrp_0803_big_block_cylinder_heads/viewall.html Not feeling the "Peanut Port" monniker. They should at least refer to them as big ovals. I still have a set of real peanuts of my 90 SS and I am not sure they will ever see anything again. Mike, how are those Edelbrocks feeling like? Misses you at the track rental.... Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted February 23, 2012 Share Posted February 23, 2012 I don't want to hijack the thread, but I'm happy with the Performer heads, and I couldn't beat the price . Dan, I think you'd be happy with them too. They are the best bang for the buck. I still haven't had time to get the slicks mounted or the MSD done - super busy lately...no track yet.... Quote Link to comment Share on other sites More sharing options...
overdrive Posted February 24, 2012 Author Share Posted February 24, 2012 You guys have been very helpful. Thanks! Dan Quote Link to comment Share on other sites More sharing options...
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