What vacuum can I expect from a TA 288-94H cam?

I was thinking about 13-14" Hg. I am presently getting 11", and I know I need to re-adjust my valves (roller rockers)

Also, what's the minimum vacuum I can see and still use power brakes in a really real, honest to God, I drive this car to work in traffic during rush hour car? 8" Hg? I think 11" is fine, but I really think i can squeeze a few more out inches of Mercury

 

Yes, I am. I can probably go another 2* on my initial advance, I think. The specs that came with the distributor recommended 13* initial, I'm at 12* now.

I only gave it a half-a$$ed tune today, it got dark and cold. Maybe with the valves adjusted properly and a little more advance I'll nail it. I want to see 13" at least. Thanks, Larry :TU:

 

More ignition advance!

Where is it installed at Chris?

I always install that cam between 107-108* and get 14-15" of vacuum from it, at a 750 rpm idle with a dual plane intake.

Used it many times.

Advancing this cam fattens up the mid range torque curve, with only miniumal HP loss over 5000 rpm.

I took one motor, and ran it on the dyno, with the cam in at everything from 105*-114* on the intake centerline, in 2 degree incriments, and came up with 107-108 for the right combo of idle quality, and power.

I also run at least 18-20* of inital timing advance with this cam. Fatten up your initial, and it will run much better.

JW

 

That seems to make a lot of sense. I am running this cam straight up for now. I know, I know...but I started to rain the day I put the cam in, so I decided that I better hurry up, turning the wrenches outside and all ou: I'll degree it come springtime

Do you think that maybe I'm losing as much as 2" Hg from the valves being poorly adjusted, Jim? I have no feel for that at all. The vacuum needle is a little jumpy, so I know I have adjustments to make, valve-wise. I finally got smart and made my heater hoses so long that the passenger side valve cover comes off without an act of God :laugh:

I idled this thing down to about 600 rpm and it showed no hint of wanting to stall, it just didn't sound happy. I'll try more initial come morning and see what that does for me. I need to dial in the carb better, too

 

From my experience with a number of those cams, if you went dot to dot, it's prolly somewhere around 110-114*. Typically they have to be put in on the 4-6* advance teeth to come out at 107-108.

Nothing set in stone, as I have seen a few cams that were very different, even had one I had to skip a tooth on to get it in right.

But it sounds like yours is close, you may have got lucky.. try some more timing advance, and see how it works out.

I doubt adjusting lifter preload will make much difference, unless it's a mile off.

JW

 

I might be closer to a half mile :laugh:

thanks, Jim

 

OK, I got to 13" Hg today, with my initial advance at about 20*. I am a little unhappy, because the car is now hard to start, even with a 1,000 CCA battery in good condition (12.3V at rest, 14.2V running). the battery does the trick, but it's "rrr rrr rrr rrr rrrrrrrrrrRRRRROOOOOOOOOM!". Not so good for a street car in my opinion.

I wasn't able to adjust one whole side for the valves, it started pouring rain, but my vacuum gauge is steadier now after adjusting one side

I can idle the car at 800 rpm just fine, but I'm down to about 12" Hg when I do that, and frankly the engine sounds much happier at 850-900 rpm. that rpm range at idle doesn't bug me. I am thinking some of all this is because I didn't degree the cam, which is semi-OK, because the car's getting put away very soon, now that the engine runs. I can retard the initial in storage to make it easier to start during the winter. Maybe the engine will be better at 800 rpm after I adjust the rest of the valves. I'll see tomorrow.

On the happy side, I tightened up my collectors and heads, and now the engine sounds like my Dad's SeaRay with the OMC 350...except the OMC is running an 18" long, 3" diameter straight pipe, and I've got full length headers with DOT approved mufflers and a full, 2.5" exhaust. It sounds very nice. I'll iron out the kinks and I should be on my way

 

Greatttt!!!

Glad to hear you have her up & running again Chris (I know it must have felt like a quest), but just in time to store it away for winter. :TU: :beer

You can rest easy now, for a little while. :bglasses:

 

If you have those "too small" stock 4 gauge batt cables on your car, that's the problem.

Mini starter guys do great business because of those things. We make custom 2 gauge cables for GS's.

I have yet to have a problem starting a BBB, with a stock HD GM starter, and 2 gauge cables, with a front mounted batt, or 00 with a trunk mounted one, and that includes locked timing 13-1 race motors.

And yes, you may have to degree the cam.. or just pull the cover off, and throw it on the 4* advance marks, to get it to idle as good as it can.

JW

 

I know that you are trying to dial it in, but some times you just gotta take it out for spin. I not talken about a bunch of bonzi runs . Just enough to clear it out. Then retune. I have worked on cars tell Iwas blue and went and driven them and was much easier to hit in on the head afterwards.

 

Chris....what did you ever do about the "O" lifter ?? I missed that "happy" ending o No:

 

He found a FULL set.

:grin: So he has plenty of extras... :Brow: :TU:

 

I finally located a place that had oversize GM lifters, with a lot of help from folks here. Now I make 35 psi at idle :TU:

 

Okay, now I am again in uncharted territory.

I checked the valves' adjustment, and went another 1/4 turn on each rocker (I was at 1/2 turn before, TA recommends 1/2 to 1 1/2 turns if I recall, to get 0.030" to 0.060" preload)

My vacuum needle now stays just about as steady as it did with the stock-type cam.

But I am still hearing what sounds like lifter tick. I'm still getting 13" Hg. I know lifters are suspect as of late, but I didn't hear this on the driver's side until after I readjusted the rockers

Before I re-adjusted the preload, I could hear a little tick from the passenger side, now I hear it from both sides, after I re-adjusted.

The funny thing is, that before I did this, the vacuum needle was jumpy. Now it's settled down.

The gauge is saying "you fixed the problem with the valves", but my ear is saying "you still have the same problem, but now it's worse"

I am using TA roller rockers, 1.6:1, and the tall TA cast aluminum covers. Is there something here I am missing? Like maybe the spacers are clacking on the roller rockers, and I am not used to hearing that? Are the taller covers simply acting as sound boards and amplifying that sound? I ran it with a cover off, and it was impossible to isolate the sounds to a particluar rocker, although it did seem louder with the cover on.

Also, should I do all adjustments again, on the lobe circle for each valve, but with the engine warm? Before, this was (of course) with the engine being assembled; the lifters had no oil.

It seems like I am the right track, but something basic about this setup seems to be eluding me

All I have been able to do so far is re-torque the heads, (re)adjust the valves, and run the car through the gears, to see if the engine fell flat on it's face in Drive- which it didn't. I need to re-set the electric choke, check the intake bolts, and tackle the valve train noise again today

 

I would think the rockers/preload should be adjusted after a warm up while the lifters are still pumped up

 

Are you sure nothing is

Tapping of the valve covers, since it seemed loader with them on. o No:

 

Shouldn't be any tapping of parts. these are TA heads, TA roller rockers, and TA valve covers- they should all work together. No marks on the inside of the valve covers, too- I checked that first thing :laugh:

 

Sounds like trash may be in one of the lifters.

 

How much play ended up in that one lifter?