67mustang302

That 270hr is a good cam that makes a lot of power in many applications; and it's not too hard on the valvetrain either.

The advantage of the 351/HO firing order was improved load distribution on the crankshaft/mains. Not really much of an issue unless you start putting more power out, then it can have an effect on bearing life, block and crank fatigue. If you have the option, it's not a bad idea, but also not necessary (the arguments for/against tend to be largely academic in most situations). Switching to the HO firing order though, also requires a different harmonic balancer technically, since you're changing the nature of the harmonics in the crankshaft. Romac makes balancers for the various balance factors and firing orders (17 different balancers for SBF). A lot of people keep the balancer for one firing order and use it with the other without issue.

Your firing order should be primarily dictated by cam selection (what's available for your app). If your balancer is in good shape, might as well use it. If it needs replacing, might as well get one that matches the firing order.

Diputado

Ok...good to know this info from both of you. On the balancer...well...that was the topic of another thread of mine about a year or so ago. The engine has a late 80's model 50-oz balancer off a 5.0...and a 164-tooth 28-oz flywheel from a '69 Boss 302. But...engine runs smooth. Barnett468 has commented on this in the past.

I'm going to sit down with the guy who's going to do the cam/heads swap for me, and seriously discuss whether or not to just redo the whole f***ing deal. Since the both of you are responding and seem to know your stuff....let me give you a little more info on this engine. According to the PO, he built it in 2004, and put less than 5,000 miles on it total (some on local strip). I've had it for 2 years, and have put about 1,000 miles on it (car has spent a lot of down time for other repairs). One of the first things I did was to replace the carb and intake (both were leaking), and I noticed that the valve retainers had some surface rust. Also, the oil filter seemed to be the SAME one first put on by PO, as it had blue engine paint overspray on it. Oil was very black and sticky. The PO couldn't remember what brand pistons he used...what type of bearings...cam specs...etc,etc. So...I've got NO IDEA what the hell is in the lower assembly, or it's condition. All I know is the thing doesn't smoke at any time, and cold oil pressure is around 45 psi at idle...dropping to about 38 psi at 190 degrees.

barnett468

the engine was rebuilt.

it has only 5000 miles on it.

the retainers were rusty.

the oil is black tar.

the oil filter was painted with the engine.

thr owner doesn't even know his own name.

you wonder if it needs rebuilding...

you can look for a ridge on the top of the cylinders and hone marks when you get the heads off.
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67mustang302

Yeah, pretty much this....

Diputado

Yeah, guys...I get the message! I'll keep you posted on the results.

Meanwhile...here's a couple photos of how the valvetrain looked when I pulled the valve covers, as well as one of how the engine looks (at least externally!) now after I replaced the old and filthy Holley Street Dominator intake and the 750 carb that was leaking fuel all over the place!

barnett468

take all the spark plugs out also and do a compression test first.

the push rods are varnished fron over 100,000 miles of use so he just tossed them back in after the rebuild . . hopefully tou won't need t do it . . its obvious that some wotk has been done on it.
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Diputado

Yeah...I plan on just going ahead with new moly rings and Clevite bearings all around. Hopefully the pistons are still good. I noticed those pushrods, too. Will be changing them to a good-quality version such as from Comp cams or AFR. I also plan on using a heavy-duty oil pump drive from ARP. Hell, this guy probably re-used the old stock one as well.

By the way...thanks yet again for the Lunati cam recommendation. I got in touch with them and gave them all my parameters, and the cam their tech guy suggested was cam #20310514 (218/226; .500/.510; 112 LSA; 108 ICL). Coincidentally, that cam is similar to a Crane cam I ran over 30 years ago in another 289 (228/228; .500/.500).

groho

I just put a set of AFR165's on mine, the smaller chamber and a good head gasket will easily get you close to 10:1. Summit has a real good desktop compression calculator. There is a multitude of head gaskets out there (thickness) to vary your compression. The other thing I wanted to mention is the roller cams run a much higher lift upwards of 600+ vs a reasonable tappet at 510. Good example, I selected a compcams XE268H with a 230 dur and 510 lift. Compare that to a similar 4-pattern roller 281QI08 with a 240 dur and a 610 lift. My point, that small combustion chamber is going to require extra effort to check piston valve clearances if you elect to go with a roller. Please do yourself a favor and do your homework before selecting a cam. My opinion, if you're going to a roller, theres many other issues you need to consider, the cost of the block work, lifter retainers, etc. You sometimes ask yourself if its easier to just go with a 5.0 and be done with it.

Diputado

Hey groho, thanks for the advice. Yeah, I told the tech rep. at Lunati that I wanted a cam that would be "easy on the valvetrain", and I also specified a max. lift of .580. From the cam specs, the cam he recommended has a gross valve lift of no more than .510 (exhaust side). Also, it's a "retro-fit" roller cam and with the link-bar lifter kit, it should be a relatively simple changeover with no block machinging required (at least according to Lunati tech support), and the only major change is the firing order. Here is a link to the Lunati info on the complete kit:

http://www.lunatipower.com/Product.aspx?id=4667&gid=137

If I am missing something here or not fully understanding this cam, by all means, let me know.

barnett468

holy c__p-, $711.00. what did you tell him you wanted?

i hope you did not buy that cam yet, your car will be a pig off the line unless you use around 3.91 - 411 rear gears.
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