455 Dyno'd today & I am horrified!!

After a 20 minute 2500 rpm breakin run for the cam and lifters and then a oil & filter change and then 2 low timing pulls to confirm that the rods stay in block its high time for 34 degrees of timing and getting the fine tuning show on the road!

Let me guess your paying this shop by the hour, or have they given you a package price I hope?

And as posted doing pulls with way backed down timing on a non NOS motor will skyrocket the Exh temps above the tolerated safe max, and even more so if the motor is trying to pump out thru Exh Manifolds!

I question what that shops reasoning is for doing such?

 

I was only there when I dropped the new timing chain off. The standard size was too loose.

They did a test fit to make sure the chain had the right tension so to speak. They took the #1 piston to the top (flush with the block), & they mentioned 0*. Not sure if they looked for the "dot" or if they changed the position after I left.

Kyle

 

I have a 462 stock intake and stock stage 1 heads with the same cam. 409.7 hp and 514.8 torque with 36 degrees total timing.
Good Luck with your engine.

 

My engine guy has said the dyno will make you very happy or very sad.

 

Thanks for all the suggestions guys.

I’m going to get on the case & get to the bottom of this issue!

Kyle

 

26* break in. They are full of something and blowing smoke up your skirt. Sounds like they do not know Buicks.

 

If it's a break in pull they likely weren't going full throttle. It is possible to run the engine on the dyno with out beating it half to death. Quit pulling your hair out and wait for the power runs.

 

THIS^^^^^^

 

watching this thread with interest

 

I don't even know where to begin on this one...

When someone asks me where the cam is, I reply with the Intake lobe center-line.. If I get a funny look from that reply, then I translate that to "4* advanced" or whatever it is. If I asked someone that, and they replied with "it's in at zero" I would assume 2 things

1. They don't understand what I am asking... or
   
2. They installed the chain "dot to dot"

You never want to run any motor, much less a brand new one, with the timing retarded.. as was mentioned, that puts way too much heat in the cylinder heads and exhaust.

I will do a flat tappet cam break in at 30*, but never less, and never do any type of WOT pull at less than that. Unless you have some special circumstance on a high compression engine with oxygenated race fuel or something.. but that is unusual..

After initial cam break in (3300 crank revolutions, or about 15 minutes at around 2000 rpm), then the engine is allowed to cool off for a few minutes.. at that point in time we set the timing conservatively (for a 10-1 compression street BBB that is 32*), and do a cruise test... the dyno is set in steady state mode, and tested at 30-60 and 90 HP outputs at part throttle, to analyze how the part throttle system in working on the primary side of the carb. That test simulates driving it down the road, under various conditions and speeds. If it needs to be adjusted, we do that, and re-test until we get the proper A/F ratios.

Then comes the check out WOT pull.. it's just shorter in rpm, typically if it's a 6000 rpm motor, we pull it about 800 rpm less than peak.

After that comes the full throttle, full rpm tests.. as long as we are in the correct ranges on the A/F ratios, that test is repeated 3 times, with waiting periods of about 5 minutes in between, for cool down. Fans are blowing on each side of the engine, pointed at the block/oil pan area.

On the third WOT pull, the numbers should repeat, which means the rings have fully seated.

After that, we tune with fuel and timing to achieve the best numbers, and then maybe play with a carb spacer or two.

A complete dyno session, which results with the motor fully broken in, is typically 8-12 pulls, and if it has a carb and distributor, is easily accomplished in 4 hours total, including setup and tear down time. Cost is $495.00 EFI stuff, and chasing any problems may take longer and cost more.

$800 to "break your motor in" is highway robbery.

All testing on "pump gas motors" should be performed with a 50-50 mix of 110 race fuel and pump premo, to add a safety margin against detonation during tuning.

This is a procedure that has been refined by my dyno guy, who just celebrated his 10,000th engine dyno'ed. He has dynoed well over 100 BBB's for me. The video that Larry posted is his engine, at my dyno shop, after we built it for him.

JW

 

26 degrees advanced, while conservative, is not going to hurt a thing. It's a stock build. With the way the factory timed distributors you'd be lucky to see 26 degrees!

With out knowing what the intentions of the shop was with that pull or what their break in procedure is, we can't comment on what they are doing and what we think they are doing wrong.


A 10 minute conversation and 3 questions to the builder is worth more than this thread will ever be.

And, honest to god, do you think the builder would accept 140 as the final number? Clearly their is a miscommunication going on somewhere.

 

Well it being a holiday weekend & watching this thread, I sent them an email stating how the distributor & carb are set up for this motor.

I also told them where I want them to start with timing & sent a picture of the cam to degree it properly if not done so. If they have any questions to call or email me.

I have a feeling when they saw the numbers, they knew something was amiss & that maybe something was wrong.

Kyle

 

The 140 number is what I saw on their computer screen after the pull.

If I remember correctly, the computer screen may’ve said “corrected numbers”.

Kyle

 

Shoo!! Got email back today.

387hp 490lb. ft. with their carb & 34*.

So now have to figure out what’s going on with my carb. Seems like my secondaries aren’t opening.

Kyle

 

Glad it worked out well for you.

 

Thanks for all of the help & suggestions guys.

Think I’ll gain anymore once I get the Q-Jet squared away?

What’s a good loss percentage to go by to get a rough guesstimate of RWHP?

I’ve always gone by the 20% adage. I have a TH350(for now) & 3.42 rear with TruTrac limited slip.

Thanks again,

Kyle

 

You'll gain some horse power and torque with the TH 350 you won't need a TH 400 and less you raced the hell out of it. Back in the 80s and build a 73 455 from LeSabre cost me 50 bucks, in my parents garage just Honed the cylinders New rings and bearings didn't even gap the rings KB 118 cam , stage one carburetor and fuel pump. The transmission went bad in my 71 Skylark custom I had a 70 custom I thought it had a turbo 350 I put it in the car and I found out it was a powerglide I would shift that 455 at 60 miles an hour. I eventually put a 350 behind it and she ran 1367 at 101.5 just use first and second gear would finally shift into third going through the lights Used to have a great time even though the alternator belt come off all the time I should've used a deep pulley on the alternator I was a kid didn't know no better.

 

Simply ask them when they degreed the cam where did they install the intake centerline at? You want that number to match the cam card