I am in the process of collecting parts to redo my engine in my 68,and looking for info. on a cam selection....
The engine is a large journal 69 DZ block that has been stroked,or so...the builder from the 70s told me.It has 65 461 heads,and a old school Edelbrock X1 crossram w/6 custom Holley 2110 2 barrels.I have no clue what the specs are on the cam,or the compression ratio,but the car pulls very hard...ONCE you can get it up to around 3k,and pulls to about 78k.
here's the plans.....I have a set of old Brodix 180cc heads in the shop right now getting reworked,and massaged.I have stud girdle,and 1.6 roller rockers.I am going to run a tolune mixture,and looking for 11 to 1 compression.I did install progressive linkage on the intake,so it makes it alot more streetable.
The car has 3.55s,and a M21,and planning to install a TKO 500 for the first gear to hurry up,and get me into the rpms.
I really like rpms,but wanting to have alittle better pull off the line.This has to be a solid lifter cam.I am looking to pull up to around 6800/7200.
I;m not rich,so all I can do is take old school technology,and massage the hell out of it,and go w/what I got,so no roller cams,etc.I like the old stuff anyways.It's nostalgic.
Thanks guys,and a Merry Christmas to all.

 

I would put a small solid lifter cam in there. I used a Crane F-278-2 in my 302 and it is a sweet small solid lifter cam. Valve timing events are close to the LT-1 cam opening and closing points but it has faster ramps, more lift and slightly tighter lobe centers. I can climb hills MUCH better now as compared to the "30-30" cam i was using before AND the idle sound is the same as before. I like it a lot and will not be "upgrading" it.

The next step up would work slightly better for someone who wants to maximize top end and give up a little bottom end AND is running a more open exhaust than I have. FWIW.

-Mark.

 

Thank you for the reply,and will look into that.The thing that I have problems w/now is the vacuum to pull signal from the crossram.A 94-96 Stang ate me off the line,but he was in the review by grabbing 3rd.I was soooo pissed....I came home,and put the car on ebay.For real.
I know that there has to be a trade off,but I love motors that rev to no tomorrow....That'
s why I want to go ahead,and put the TKO 500 in there,cause of the gearing in 1st I would have w/the 3.55s out back.My muncie is perfect,and would change the rear gears to 4.11s,but really like to take this car on long adventures.....Hmmmmm...
What can I do to make more manifold vacuum?I can turn up the fuel pressure to force more gas,but the carbs are very touchy,and w/more than 2.5 psi...you blow the needle off the seats.

 

Wider lobe centers in general will spread out the powerband and should improve vacuum in general. In this case you are trying to reduce overlap to improve low speed efficency. Overlap will kill idle vacuum while it improves high speed power when used with a well tuned, easy flowing intake and exhaust system. A more restricted exhaust with mufflers and iron manifolds will not like more overlap and will have low vacuum at idle and produce no real power benefit. A restricted intake and exhaust will negate the "tuned" effect people try to achieve with more overlap - It runs like crap.

Regardless of your exhaust system - you need to improve vacuum and that comes from good low RPM efficency. The wider lobe centers will help you there. With that, you need valve timing events that favor higher RPM's without costing you too much on the bottom end. Not many solid lifter cam grinds out there on the shelf like that but there are some available.

Keep the solid lifter cam small, the lobe centers wide, the overlap down and match the compression to the intake closing angle and you should be in the sweet spot.

As always - JMO.

-Mark.

 

I appreciate the help,and hold right now w/cam tech.I am in limbo w/my machine guy doing the Brodix heads,cause he needs the specs,etc.

 

The Crane is what the guy recommended that you run.What is the the 1.6 rocker ratio going to do to the characteristics of the cam?
Thanks.....

 

1.6 Ratio rockers give you a little more lift. More lift can help if you have heads to support it. The Brodix heads should be fine. You will loose some top end RPM ability with higher ratio rockers as they will tax the valvetrain a bit more. The springs will be working harder. I am on the fence in general with the need for more lift. If you model extra lift on a desktop dyno it does not yield much added power so in theory it is not worth much. In practice you MAY see an increse but that is not a given.

If you already have the higher ratio rockers, run them. If you need to buy something to build the engine maybe you would give them a try. If you already have some 1.52 rockers - run the 1.52's and call it good IMHO.


-Mark.