Dyno numbers. Seems pretty low. 340

[MoparRocks]

So anyone that's been in the electrical forum knows I just finished a pretty major overhaul on my 71. Whole new wiring harness, converted to a MSD ready to run pro billet distributor, MSD streetfire ignition, MSD wires, plugs, carb spacer, the whole nine yards.

Once it was all done I took it to a local shop for a Dyno tune session to get it all dialed in. Of course the shop found some other issues while it was there. Harmonic damper was shot and the timing was totally out of whack because of it. So that got replaced.

Anyway, it was all done and I picked it up today. Best pull was
182.3 HP @ 3,750 RPM and 282.2 ft lbs @ 3,200 RPM.

I kinda feel like something may be up with the trans too. It's seriously bogging off the line. I went to punch it from a stop light and it really bogged down before kicking up. I also had to manually drop the trans in to first driving up the hill to my house.

So what's everyone's thoughts on what I should look at to improve the off the line issues?

Oddly enough, I feel like it had more oomph before I did all this work to it.

[cdr]

something or somethings is wrong.

[c00nhunterjoe]

Peak hp at 3700 rpm? Something is broke. What are the FULL specs on the engine build to start. Then what was the timing set at. What jets are in the carb, what carb is it? Was fuel lressure verified and what was it.

[alfaitalia]

Last time I saw a curve like that the engine was running quite seriously lean.....just a thought.

[MoparRocks]

Yeah something is definitely off.

I have no idea what's inside the engine. I know it had a top end rebuild before I bought it. Don't know what cam is in it. It has an Edelbrock intake, Edelbrock carb (still need to pull the numbers and figure out which one and how many CFM). Not sure what jets are in it or if he ended up changing them during tuning.

It did have some issues when I took it in. I realized I know little about carb tuning and timing. When I first fired it up after all the work it was running super rich. I could smell it. Plugs were black, etc. I got it dialed in enough to take it in for a dyno tune. Made it over there, when he took it for a test run before puttting it on the dyno it stalled as he came back into the lot. Put it on the dyno, it died again. So after some time and work they found the old two piece balanced was shot and way out of spec on the timing marks. So new balancer was put in. Then he got it running reliably and did the dyno tune. To be fair, it's not stalling anymore and it is running well. It just has no balls.

I looked over the paperwork and I don't see the timing settings noted anywhere so I'll have to put a light on it and see what he set it at. Other than the bogging issues and lack of power everything else looked decent. Idle is around 800 RPMs, oil pressure looked good, etc. it ran at about 190 on the freeway and a little over 200 on surface streets. It did climb up to about 230 coming up the hill to my house, and again I had to drop the auto in to 1st manually to get it to move going up the hill. When I first turned the corner I had the pedal down pretty good and it was just barely chugging along, even when I floored it.

During the rebuild I added
MSD streetfire ignition
MSD ready to run distributor
MSD streetfire wires
Edelbrock 1" 4 hole carb spacer (it had hot start issues before)
I added a fuel filter between the pump and carb, previously it had a filter before the pump. Now has 2.
Installed a set of Purple horny mufflers straight to the flanges on the manifold. No other exhaust past that.

[HPP]

IMO, you haven't done a rebuild or overhaul. You bolted on some goodies that will generate nominal, if any, increases. All the ignition would do is make the starting and idling more consistent and in my experience, is no more powerful than a well set up stock system.

Not knowing whats inside the engine is a huge deficit to have. So is having a rebuilt top end, IMO. Typically engine parts wear together. While the PO may have done some analysis,or maybe not and he just went with what his buddy told him, rebuilding the top end could have been everything from simply replacing valve seals to a true rebuild with new guides, seat, etc. Typically rebuilding just the heads tightens up the top and now blows all the crap(and performance) out the bottom end and it still lacks power. I suspect that is what you have here.

For now, you could try dialing in more timing. Turn it up until the valves rattle, then back off several degrees. Turn off and restart. If its hard to start, back off a few more degrees.  That will be as good as it gets for ignition.  Ask you dyno buddy if they made any changes in the carb. This will let you know where you are or may need to go. Also, did they have a sniffer up the pipe when testing? If so, this will direct you which way to go with carb tuning. If not, its going to be reading plugs and experimenting unless you want to get an emissions test, which will tell us the same thing. You might also do a compression test on all cylinders just to see where you are at. This will give you an indication of cylinder health and hole to hole variation.

After that, come back here and we can guide you through the next changes that may be possible.

[MoparRocks]

Ok. Just put a timing light to it and it looks like at idle I have about 9 degrees before TDC. At speed I'm seeing 20 degrees before TDC. Isn't that pretty low for a Mopar?

Also, carb is an Edelbrock 1408. 600 CFM from a quick google check on the model number.

[MoparRocks]

Ok. So the timing was way the hell off. Put a vac gauge to it and was only getting 14hgc. Well below the green zone on the gauge. I just gave it more timing until the gauge hit green. Sounds way better and is idling much smoother.

[69wannabe]

I would start the initial timing at 15 BTDC and see how it goes from there. Without knowing any engine spec's would you say it's pretty much stock? Smooth idle, vacuum gauge close to 20 maybe. You said you are still running manifold's and not headers, honestly in stock form with a 727 behind it that 340 wouldn't make much more than 200hp at the rear wheels just guessing. The 727 transmission really robs the power going to the rear wheel's from what I have been told since it's such a heavy duty transmission, don't know how much truth there is to that. From messing with engine's most of my life if you want to make HP numbers you got to make major changes, good cam, performance intake, headers, better flowing heads, better compression pistons. A good ignition system is great and necessary but not really going to make any more HP. Thing about an engine is you don't know what's in there unless you have it built or build it yourself with a specific recipe.....

[firefighter3931]

Ok. Just put a timing light to it and it looks like at idle I have about 9 degrees before TDC. At speed I'm seeing 20 degrees before TDC. Isn't that pretty low for a Mopar?

Also, carb is an Edelbrock 1408. 600 CFM from a quick google check on the model number.

The power is down because the timing curve is fubarred. 

Most open chamber Chryslers like 36-38* total timing and at least 14-15* at idle. With a hotter build you need to dial in more base timing to improve throttle response. That being said....a distributor with an adjustable mechanical advance goes a long way towards fine tuning the ignition curve. 

With total timing in the 20* BTDC range it's no wonder the power numbers were so anemic ! 

Try and map out the timing curve in 300 rpm increments starting at idle. Record the rpm and timing until the timing stops advancing and report back with those numbers. We'll be able to see what the timing curve looks like and suggest improvements. 


Ron

[PRH]

Before I got too carried away with timing changes, I would verify the TDC mark is in the right location on the replacement damper.

Does that distributor have vacuum advance?
If so, you'll want that disconnected to set your total timing.

After verifying the damper is correct, my starting point would be 34deg total advance, all in around 2500-3000rpm(this would be for no vacuum advance).

[MoparRocks]

Well I drove it to work this morning. Timing changes made a big difference and it ran great. Now I have a new issue. Looks like either the parking brake or the rear drums are locking up. I came to a stop and was wafted in white smoke. When I got to work and got out I found smoke wafting from both rear tires. Checked the wheels and they are hot as hell. Gonna try and shove a screwdriver thru the access port and kick the auto adjusters loose to drive it home. Just ordered everything to rebuild the rear drums. 

[PRH]

If they were dragging when the car was on the dyno ....... That would certainly impact the hp numbers.

[MoparRocks]

Turns out it was the parking brake sticking. I had set it to check the transmission fluid level the other day and I guess it got stuck.  So I don't think they were dragging on the dyno. I managed to get it freed up by applying and releasing it a few times. The drive home was perfect. Did a nice burn out leaving the parking lot at work, got some front end lift when leaving a stop light, and I made it up the hill to my house with the trans in drive with no issues. So yeah, I think the timing was just completely out of whack and way too low. I should note the Dyno shop i took it to does a lot of Mustangs, but they had a nice GTO in the shop when I went in and they do work on other classic muscle cars. Guess he doesn't actually know Mopars very well.

[c00nhunterjoe]

Timing is timing, regardless of ford chevy or dodge.