Tired of looking at cam specs.......

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bizjetmech

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The saga continues........

To recap........

Car = 73 Dart Sport street car, 340, A/T, 3.23, stock TF except for Turbo Action 11 inch street type converter.

Engine = 340 +.030, Ross pistons, CR = approx 9.6 to 1, stock heads with 2.02 intakes, 340 springs/dampers, stock rods, stock forged crank, TTIs, M-1 dual plane.

Goal: Look stock. Sound stock. Run better than stock, with no "quirks", within the limitations of the heads and piss-water they call pump unleaded gasoline.......if I've got to run a little race gas, or 100LL avgas, no problemo.

Initial cam.....old Lunati 00043, 230/230 @ .050, .480 lift I&E 109 degree centerline. After I got the engine running, obviously(?) too much cam. Will idle all day at 1100rpm and 18-20 degrees of initial advance. Dies as soon as I drop it into gear, or if I back the idle/advance lower than above.......can watch it die on the vacuum gage. Ran like crap, when I managed to keep it running while in gear......wouldn't stay running long enough to sort things out.

Initially had an RPM Air Gap intake: won't work, won't let me close the hood with the air cleaner on. As I had to pull the intake anyway (to check for an intake leak in the lifter valley....none found), decided to change the cam.

After doing some quick research, decided to order a P4452992 cam from Mancini. Pull it out of the box, check the specs; specs @.050 don't look that much different than the cam I just pulled out. Did a forum search, 3 out of 4 comments indicate that this cam SUCKS, unless I have: 1) a looser converter, and 2) more gear. Neither one of which I'm interested in changing at this point in time. Evidently, this thing is more radical than it's specs indicate.

For grins, I checked out the Lunati website, where they sell a "Stock Replacement" cam: Dur @ .050 = 232/242, lift .462/.473, LSA = 112 degrees. WTF? Other than more lift and LSA, the specs aren't much different than the cam I just pulled out!!!!!!

I'm just a simple caveman, and all of this has me very confused. I'd prefer not to continue adding to my collection of camshafts and aftermarket intakes I can't use. At this point, I'm just about resigned to sticking a stock 340 cam back in it. I'm going to be pretty pissed if I spent all of this money on this POS, and it doesn't run any better than my old, bone stock low compression 340. Or worse, the junkyard, church-van 1992 360 I pulled out.

Any suggestions/recommendations for a new cam? (other than Hughes......I have my reasons). Preferably something readily available from Advance/O'Reilly's/etc., can't wait a week for one to show up via UPS.
 
Sounds like a vacuum leak or the mechanical advance is bleeding at your 1100 rpm idle speed and drops out when in gear. That 230/480 cam in a 340 should idle without much issue. A bunch of guys use taht style cam and it works well. I'd actually twist the cam ahead to about 104-106 installed centerline. I doubt there would be any issue with valve to piston clearance, still need to check.

More initial timing if the starter can handle it would help. IMO, that should idle easily at 850ish and not have the horrible drop when in gear. Should pull around 10-11" of vacuum at idle.

My 292/508 cammed 340, 9.5:1 idles at 1000 rpm and is locked out at 35-36*.
 
If it would not stay running with the Lunati, or idle under 1100, you got something WRONG.
 
I agree with former post that cam should work well with your set up
 
That cam works fine in my 340. I also have a 11" converter in mine with a Performer Air Gap intake and 650 DP Holley. It idles at 900 RPM and idles fine in gear.
I don't think the cam is the problem either.
As for the intake- you might want to try a drop base for the air cleaner before you swap the intake.
 
RustyRatRod said:
If it would not stay running with the Lunati, or idle under 1100, you got something WRONG.
Click to expand...

X2!

My stroker, with a 236/242 will idle at 500, 3-5 inches vacuum at 24 initial. Rough, but it will idle!
 
If you're not into trying to make the 230* work...

I'd throw a XE262 in it...http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=626&sb=0

Should be readily available in a short time frame, and give you plenty of vacuum to work with.

Speaking of vacuum, and not knowing what carb you have, hopefully you weren't just opening the power valve in gear and killing it?
 
crackedback said:
That 230/480 cam in a 340 should idle without much issue. A bunch of guys use taht style cam and it works well. I'd actually twist the cam ahead to about 104-106 installed centerline. I doubt there would be any issue with valve to piston clearance, still need to check.
Click to expand...

Agree!

I've said in other threads that variations of the .480/230* cam were one of the most widely used cams on street cars in my day. I did more then a handful on several brand cars. 9"/10"/11"ish vacuum numbers were the norm.
 
Fix / tune what you have before making a cam swap.
I think you have a good combo that needs dialed in.
 
That should tune in,like most have chimed. We ran the same grind ,in a 8:1 350 Chevy,idled fine tuned. (850-900 ). Or for a completely sure move,70AAR/Tony's suggested works well.
 
by 2 cents is your carb may need some mods because of the low vacuum signal ,modify the power valve/ spring also sometimes they drill a small hole in the throttle plate near the idle/transfer slot to pull stronger on the idle circuit.I have seen stock carbs with these issues and replace with holley double pumpers every thing worked great because the carbs were set up for modified engines.
 
I ran that cam in my last car. 360, 4-gear. 2.02 heads Eddy RPM, 750 DP and I had the idle set at 700 rpm with no issues. It was very mild mannered for me on the street. You may need some more tuning on it.
 
Comments/more info.

Original Lunati Cam was degreed in......once with the keyway at "0", and later two degrees advanced. Didn't make much difference.

It acts like it has a giant vacuum leak. Plan was to remove intake and check for leaks, then change cam to something closer to stock if nothing found.......but as noted, it appears like cam #2 isn't that much different than the one I had in it. As this is the first work/rebuild I've done using something other than a stock cam, I'm having trouble figuring out what is a problem, and what is "normal" for the cam I put in.

No evidence of a vacuum leak at the top side of the intake (sprayed ether around ports when engine running). Pulled intake to check for leaks in lifter gallery, no oil in ports, or evidence of oil leakage past intake gaskets. The only thing thing I really saw was that the gaskets had more "crush" on the top side of the port than the bottom. But as noted, no evidence/oil residue at all in the intake ports.

Unfortunately, none of the .060 thick intake gaskets seem to be available locally......in fact, stuff like WATER PUMP gaskets now have to come in from the main warehouse. Dealing with the parts counter guys who know nothing, other than Chevys, Mustangs, and rice rockets with fart can exhausts isn't helping much.

I'm using a dropped base factory air cleaner. It cleared when using the stock 340/TQ intake and spread bore to square bore adapter. Won't clear by about 1-1.5 inches using the Air-Gap and no adapter.

Have had two different carbs on it........the Edelbrock 650 I had been driving the car with, and a new Holley 4160 600cfm. The Holley is actually worse. Runs way too rich at idle.

Due to work, I've had to put this thing on the back burner several times since I put the new engine in two summers ago. Gotta get it sorted out ASAP. Found out daughter #2 plans on using it for some of her wedding pictures in three weeks. Last thing I need is for this thing to puke its guts in the middle of all of this, especially when the ex- is going to be there.

BTW........vacuum advance was leaking when all of this started, replaced, helped a little.
 
Power brakes by chance?

IMO, disconnect and plug everything that is vacuum related and isolate the intake tract. See if it runs better. Then reattach things one at a time and see if it changes. If you get a change for the worse, you found your leaker.

Did you actually degree it (dial indicator/degree wheel) or just put the timing chain on lining up the dots? The latter is not degreeing it.
 
crackedback said:
Power brakes by chance?

IMO, disconnect and plug everything that is vacuum related and isolate the intake tract. See if it runs better. Then reattach things one at a time and see if it changes. If you get a change for the worse, you found your leaker.

Did you actually degree it (dial indicator/degree wheel) or just put the timing chain on lining up the dots? The latter is not degreeing it.
Click to expand...

No power brakes......just PCV, distributor vacuum. Degreed in with degree wheel.
 
XE268 - over and done. Didn't even degree it - just threw it in dot to dot. And as others have said, make sure everything else is up to snuff. I threw an XE268 in an otherwise stock 30 over 1970 340 with forged trw 10.5 flattops and it runs great with that cam. Stock exhaust too.
 
bizjetmech said:
No power brakes......just PCV, distributor vacuum. Degreed in with degree wheel.
Click to expand...

Plug it all off. PCV is a controlled vacuum leak that may be out of bounds.

Watch the timing light when it drops in gear, if it's dropping timing, you don't really have 18-20 initial. I'd also get it started and crank more timing into it and see if you can turn the idle down. Put 30* of timing on it. See if any of that 30* drops out as you dial it down. If it still won't idle down, you have a big leak somewhere would be my guess. If you can turn rpm down, it's a timing issue.
 
Have been thinking about how to find a vacuum leak, if it still runs like crap.

(The way this motor swap has gone from the get-go, there is no doubt in my mind that it will.....)

I have a big vacuum pump for servicing a/c. Has anyone ever: 1) Pulled the rocker shafts, so all of the valves are closed, 2) plugged all vacuum bleeds on the manifold, 3) Fabricated a plate with a fitting for a vacuum pump to seal to the flange under the carb, and 4) pull a vacuum on it with a vacuum pump.......see it it holds a vacuum, and/or listen for leaks with a stethoscope.

Soooooo........(question to myself).......do I reinstall the broken-in Lunati cam, or go ahead an install and break in the P4452992? Am inclined to reinstall the Lunati, since the "@.050" numbers aren't much different, and it will reduce the number of variables (and yes, I've got the lifters bagged/marked for their corresponding lobe).
 
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