Small Block help and ?s

Posted By: j.mcconnell

Small Block help and ?s - 10/27/13 03:01 AM

I had my small block Duster together and running for a little over a year but because I lived 7hrs away from where it was stored I've never gotten it to run correctly. Hopefully someone has an idea that I haven't tried.

It currently cranks fairly well but the idle is rougher than I'd expect for the cam and it makes no power. I can put it against the line lock and it wont even come close to spinning a tire. Cruising around it is far from crisp. I've got maybe 30 miles on it trying different things with no luck.

Here is an idle clip. 750rpm, neutral, 33deg timing

http://www.youtube.com/watch?v=q2p0WOPigaA

.030 over 340
SpeedPro LF2316 pistons ~10.75:1
Edelbrock #6017 340 heads ootb
Air Gap intake
750 holley with Proform main body
Comp XE284H cam 240/246@.050 .507/.510 lift
1-5/8 headers to 3in x-pipe and mufflers dumping at the axle
MSD 6AL and Learn-Burn distributor locked at 33 degrees
A1000 pump and regulator at 6.5psi
727 with a PTC converter.

What I've tried or what I know:
-No vacuum leaks that I can find with propane.
-Carb has been gone through twice. Something like 77/82 jets, 6.5PV, idle air bleeds changed to what ProForm specs for 2-corner idle carbs
-Swapped a nice billet MP distributor for the lean-burn
-Squared Transition slot but had to change it to get it to idle. It should be close now.
-Idle mix screws at 1.5turns out
-Valves have been lashed twice

During assembly I made an amateur attempt to degree the cam and thought it ended up at dot-to-dot straight up but now I'm second guessing. The only other idea I have is that we may have the cam a tooth off, but I'd hate to rip the front cover off without asking first.

Any help is appreciated.

Posted By: Hot 340

Re: Small Block help and ?s - 10/27/13 03:18 AM

I degreed in a new bullet cam for a friend six months ago, and the dots on the sprockets were a tooth off on this cam after the degreeing was done..but the old cam we took out had the dots real close on same timing chain and gear. I checked it 3 or four times just to be sure. Could be your problem if you just lined them up.

Posted By: dartman366

Re: Small Block help and ?s - 10/27/13 03:23 AM

have you checked cranking compression?
have you run a leakdown test?
I would also pull the timing cover and check the cam timing with a degree wheel and know where the cam is especially if cranking compression is low, I don't trust dot to dot on cam timing.
also what stall is the converter and rear gear ratio? and does it pull the motor down and want to die when you put it in gear, if so it probably need's a little more converter as long as the tune is good, just some things that come to mind.

Posted By: j.mcconnell

Re: Small Block help and ?s - 10/27/13 06:14 AM

I do need to run compression and leak down tests but I'm not totally certain that I've been able to load the engine enough to seat the rings. I've been able to see it noticeably puffing out of the valve cover breathers since day one. Today it was fairly cool and hard to start, I could see it puffing even before the car would fire.

PTC converter was specd for my combo and 3.91 rear gear. After getting the timing set today it did not noticeably change engine speed when I put it in gear

Posted By: 77DragracerR/T

Re: Small Block help and ?s - 10/27/13 01:46 PM

Sounds like a recheck of installed degree of cam.If anything advancing the cam 2 degree's wouldn't hurt either once you find the correct setting.

Posted By: Bad340fish

Re: Small Block help and ?s - 10/27/13 01:55 PM

I'm with the other guys, you need to do a compression and leak down test before you go any further.

Thats a good looking car!

Posted By: 340B5

Re: Small Block help and ?s - 10/27/13 02:01 PM

Quote:

I'm with the other guys, you need to do a compression and leak down test before you go any further.

Thats a good looking car!

Check Vacuum too while its together.

Posted By: j.mcconnell

Re: Small Block help and ?s - 10/27/13 02:21 PM

It has 0 vacuum at idle but increases if revved in neutral

Posted By: B1MAXX

Re: Small Block help and ?s - 10/27/13 02:39 PM

240 at .050 is a big cam for a 340, what is the lash set at? You better get a better vacuum guage 0 vacuum, no run.

Posted By: B1MAXX

Re: Small Block help and ?s - 10/27/13 02:48 PM

what is the gearing and converter specs?

Posted By: J_BODY

Re: Small Block help and ?s - 10/27/13 04:33 PM

Hate to say it, but I'm thinking that "second guessing" is going to eat at you until you tear the timing cover off and go through the degreeing motions again.... a couple of times.

Posted By: j.mcconnell

Re: Small Block help and ?s - 10/27/13 04:40 PM

Yea I already have the gasket set so I'll rip it apart next weekend.

I'll also track down a compression tester and see what it says.

Thanks and I'll report back on Friday

Posted By: kingdust

Re: Small Block help and ?s - 10/28/13 02:52 AM

when you degreed the cam how close was it to the specs on the cam card? if it wasn't close that should have clued you in as to being off. I would take the cover off also and double check everything. even if you didn't degree the cam that thing should run good with the cam installed strait up. I always use a yellow paint marker on the dots so their easy to see. good luck. mark.

Posted By: viperblue72

Re: Small Block help and ?s - 10/29/13 04:53 AM

I ran 72/82 jetting with that same carb on a 408 with 13in vacuum at idle. 77 seems really high.
I agree with everyoe here. Cam timing, and or make sure the cam break in worked out alright. Check your valve preload.

Posted By: j.mcconnell

Re: Small Block help and ?s - 11/02/13 06:07 PM

169 to 173psi across all the cylinders, fairly warm and throttle open. What do you guys think?

Posted By: cudadoug

Re: Small Block help and ?s - 11/02/13 06:21 PM

Cam timing is what I think.

240 is a little long for a mild 340. I would TRIPLE CHECK the cam WITH A DEGREE WHEEL to ensure it's where it's supposed to be. Having said that, even then I would advance it a couple of degrees to build some bottom end.

In fact, if you wanted to do a quickie you COULD just advance it 2 degrees from it's at and try it. But as long as the cover is off...I'd want to do it right.

By the way, NICE Duster!

Posted By: j.mcconnell

Re: Small Block help and ?s - 11/02/13 08:27 PM

Ok, front cover is off and it appears the cam is at 4deg advanced as is. Here is the full cam card
XE284H Cam Card

Any advice from here? I won't get to mess with it again until next weekend.

Thanks

Posted By: Hot 340

Re: Small Block help and ?s - 11/02/13 08:56 PM

Quote:

Ok, front cover is off and it appears the cam is at 4deg advanced as is. Here is the full cam card
XE284H Cam Card

Any advice from here? I won't get to mess with it again until next weekend.

Thanks

How did you determine it is 4 degrees advanced? Did you use a piston stop and degree wheel? If not, you are whistling dixie.

Posted By: 5spdcuda

Re: Small Block help and ?s - 11/02/13 10:42 PM

Something is clearly out of wack. Double checking the cam is where I would start. My 360 is very similar to your 340, other than the fact that I have 25 more cubes. I used to run the same 284 cam you have [ presently 285 XEHL series ] with approximately one point [ 9.7 : 1 ] less static compression and Indybrock heads. I can blow the tires off from a roll in 1st. gear. FWIW my old 284 cam was one whole tooth off when we degreed it. As near as I can recall we wound up running it at 104.5*. I run 32* total advance all in by 2,000 rpm and 18* initial. My carb is a 3310 with 68 primaries and 76 secondaries on an RPM Air Gap manifold. Good luck, it should run really well when you find & fix the problem.

Posted By: cudadoug

Re: Small Block help and ?s - 11/03/13 04:19 AM

Quote:

Ok, front cover is off and it appears the cam is at 4deg advanced as is. Here is the full cam card
XE284H Cam Card

Any advice from here? I won't get to mess with it again until next weekend.

Thanks

Only way to know for sure is to check it with the proper tools/method. I've seen cams that were off, cranks off and twice aftermarket timing gears that had the dots off as well.

Posted By: j.mcconnell

Re: Small Block help and ?s - 11/10/13 11:48 PM

Got ahold of a degree wheel and checked the ICL twice today and got 107.5 both times. Cam card calls for 106 and I'm already in the 4 degree advanced keyway in my timing set.

Should I buy a new crank key and advance it more?

Posted By: Hot 340

Re: Small Block help and ?s - 11/11/13 12:16 AM

I would put it in at 101 or 102.

Posted By: SSDart

Re: Small Block help and ?s - 11/11/13 12:32 AM

Quote:

Got ahold of a degree wheel and checked the ICL twice today and got 107.5 both times. Cam card calls for 106 and I'm already in the 4 degree advanced keyway in my timing set.

Should I buy a new crank key and advance it more?

I would leave the cam.... Is your fuel getting hot from anywhere? Did you check your timing mark on tour damper?

Posted By: j.mcconnell

Re: Small Block help and ?s - 11/11/13 01:05 AM

Fuel is a 1/2in line return system and the closest it get to any heat source is ~6in away at the mufflers so it shouldn't be getting hot. Ive never checked, but the balancer is new. I'm going to put a decal on it when it goes back together.

I'm starting to think the cam is a little rowdy for the rest of the combo.

Posted By: SSDart

Re: Small Block help and ?s - 11/11/13 01:13 AM

Quote:

Fuel is a 1/2in line return system and the closest it get to any heat source is ~6in away at the mufflers so it shouldn't be getting hot. Ive never checked, but the balancer is new. I'm going to put a decal on it when it goes back together.

I'm starting to think the cam is a little rowdy for the rest of the combo.

That is a big cam......... you will need a real loose converter... is it an 8 inch?

Posted By: kingdust

Re: Small Block help and ?s - 11/11/13 02:41 AM

what is the convertor stall and what gears are you running? cam card says 3000 recommended and I would run a 391/410 gear. 107.5 isn't a big deal but I personally would retard it 2 degrees.

Posted By: j.mcconnell

Re: Small Block help and ?s - 11/11/13 03:56 AM

3.91 gear and what should be a 3500-3600 stall 9" PTC converter. It's never ran well enough to test the converter. 325 drag radial (28in) tire

I'm going to throw a 4 degree cam key at it and put a new tape on the balancer. I may get one more weekend before it gets cold.

Posted By: SSDart

Re: Small Block help and ?s - 11/12/13 01:01 AM

Quote:

3.91 gear and what should be a 3500-3600 stall 9" PTC converter. It's never ran well enough to test the converter. 325 drag radial (28in) tire

I'm going to throw a 4 degree cam key at it and put a new tape on the balancer. I may get one more weekend before it gets cold.

I'm not that big on advancing cams much. But in your case it is the cheapest fix. A cam with 10deg less duration on the intake would work better in straight up.

Posted By: Hot 340

Re: Small Block help and ?s - 11/12/13 01:27 AM

Its just my opinion but I dont think the cam is all that big. Bullet made me a custom 251/255 for my stock stroke 360 and the car is heavy with the same compression as the op's. But every time ive had a cam made for a stock stroke combo the cam grinder always told me to advance it..and not one time was it over 104. Op would be doing himself a favor to call the cam company himself and get their opinion.

Posted By: SSDart

Re: Small Block help and ?s - 11/12/13 02:11 AM

Quote:

Its just my opinion but I dont think the cam is all that big. Bullet made me a custom 251/255 for my stock stroke 360 and the car is heavy with the same compression as the op's. But every time ive had a cam made for a stock stroke combo the cam grinder always told me to advance it..and not one time was it over 104. Op would be doing himself a favor to call the cam company himself and get their opinion.

Hot It really depends on the converter in this case...... Problem when asking the cam company is....are talking to someone who even has a clue... You need to find someone good at specing cams.. You find the people leading in this area are not advancing the cams like was once done.... But in this case, he should advance the cam if all else fails......

Posted By: Hot 340

Re: Small Block help and ?s - 11/12/13 02:27 AM

Both cam companies were Cam Motion and Bullet, and they are well respected..and their advice is recent. But I agree the converter is an issue. But all the more reason I would advance it. If I paid for a 9 inch converter that only flashed 3k, it would be back in the mail.

hopefully the op can get it figured out enough to really test the converter as well.

Posted By: ademon

Re: Small Block help and ?s - 11/12/13 06:09 AM

Bigger issue is the 0" vacuum at idle and the puffing out the breathers. That cam is not that big and should pull around 6" at least at a 850 rpm idle. I would fix that up before I spend $600 on a converter. Make sure your balancer is at 0 at TDC. Then add the timing tape, set initial at 18 to 20 degrees then make sure your primary throttle blades are not open to far allowing fuel to dribble out of the boosters at idle

Posted By: j.mcconnell

Re: Small Block help and ?s - 11/12/13 02:05 PM

I also got a new vacuum gauge this past weekend I I will take another reading once it's all back together. I'll also get some video of the breathers puffing. Hopefully the rings just haven't seated well because it was running so bad

Thanks guys

Posted By: j.mcconnell

Re: Small Block help and ?s - 11/24/13 12:03 AM

Cam is in at 101.5 and she runs great! 6-7in of vacuum at idle now. It also really like the increased timing at idle. 55 degree day and she fired right up after sitting for 2 weeks, something it has never done.

Only problem I had was a rubber muffler hanger that broke on the test drive

. I got it off the road and pulled the muffler off and drove it home.

Thanks dudes.

Posted By: 5spdcuda

Re: Small Block help and ?s - 11/24/13 12:17 AM

Glad to hear you got it running closer to your expectations.

Posted By: SSDart

Re: Small Block help and ?s - 11/24/13 07:09 AM

Quote:

Cam is in at 101.5 and she runs great! 6-7in of vacuum at idle now. It also really like the increased timing at idle. 55 degree day and she fired right up after sitting for 2 weeks, something it has never done.

Only problem I had was a rubber muffler hanger that broke on the test drive . I got it off the road and pulled the muffler off and drove it home.

Thanks dudes.