Big increase in power in my 1977 403ci engine

[david j. forjan]

Hey everyone. This is an FYI post only. No questions. This info may be very helpful to others because a genius mechanic increased my horsepower
considerably; very considerably. And he did this without any new parts. It's quite amazing actually. But it's true. I now have ALOT more power
from my 403ci engine. Here's what he did (keep in mind this guy restores and services race cars). First he changed the arrangement/hookup of the
vacuum hoses. He didn't add any, he just rerouted them. He said "Dave I want to connect the vacuum hoses the way we used to connect them. The other
mechanic connected them the way people do nowadays. If you want I'll re-route them and you'll get more horsepower". And I did, just by him hooking
up the vacuum hoses differently. I don't know how he changed them, but maybe one of you reading this post will understand and explain.

The second thing he did is adjust my timing differently. This was a wild experience. He had me start the engine, with the emergency brake on, and
told me to hold down tight on the foot brakes, and put the transmission in drive. Then HE revved the engine with the throttle in the engine
compartment, and revved it really really high. I had all I could handle just standing on the brakes to keep the motorhome from lunging forward.
Picture this, he's revving the engine all the way up, while it's in Drive, the emergency brake on, me all but standing on the foot brakes, so the
motorhome is trying so hard to lunge forward, but it can't, and with all these opposing forces fighting each other, the motorhome started shaking -
violently. I almost lost it once and the motorhome almost got away from me the thing was trying so hard to go forward. And at this point of maximum
forces, THAT'S when he set the timing.

I'm not a mechanic so I don't understand all that's involved. The mechanic before him was a young guy and he tuned and timed the engine when he put
in new plugs and wires. Rick, the genius (he's about 55), changed the vacuum hoses and set the timing as I described above - and sure enough I have
alot more power from that 403ci engine now.

Maybe all this is common knowledge and you all will understand what I've said. But this was all new to me and I have alot alot more power now. Even
sounds different. Almost like a jet engine.

FYI to those who understand or want to understand. I look forward to comments from all you experienced folks out there.

Be well. Thanks for listening
david
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[chris tyler]

What he was doing was a version of power timing- an other words advsncing the timing under load until it pings or power drops.

Ive seen it done this way. However, its VERY dangerous to do- and there is no way Id try it on a 12k# vehicle with marginal brakes.

A much better method involve setting the timing based on driving performance- which is sometimes difficult to quantify.

Not sure how he routed the vac advance, but probably bypassed the TCS switch. Vac advance is more about cruising and idle.Personnaly, I prefer spark
ported vac advance rather than full time, and an adjustable cannister to see what it likes under cruise

If he advanced the distributor, he increased both the initial and total timing. Unless you limit the centifigul advance mechanism.

What I have found is that most engines like more initial advance while limiting the total, and quickening the advance curve with lighter springs.But
it is VERY easy to get lost if you dont know what you are doing

There are more than one ways to skin a cat {11 per Mr Spock, as I recall] and the bottom line is, if the setting work for you great. But you should
probably use a dail back to zero type timing light and record the inital and total with the vac advance disconected so that you can get back to those
settings in the future. However, my prediction is that when you drive it on a hot day uphill, its going to ping if not detonate after setting it this
way.
--
76 Glenbrook

 

[david j. forjan]

Hey Chris. Thanks for the insights. Too complicated for me but others will understand. And I'll report back when I go up a big hill on a hot day.
Be well.
david
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[john r. lebetski]

Both things he did had to do with timing. Vacuum and initial. I hope you don't need new engine mounts now. You may also experience "hot start" issues
if he over did it. Better to set on a road course, adjust and drive more etc til you narrow the tuning window until you are just bellow ping threshold
in ALL conditions. If he set at WOT where vac drops, you will have pinging at part throttle tip in where loads are high along with still having vac
signal to the advance pot adding advance.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[david j. forjan]

Sorry but I almost forgot one important point. Rick used one criteria to cement his decision on the timing position. Keep in mind we went through
that revving/braking/shaking experience several times. And each time we stopped he used as his final criteria how quick the engine starter turned
over the engine. He decided it was just right when the engine starter turned over the engine INSTANTANEOUSLY. No hesitation, no delay. Once there
was absolute no delay in starting the engine, not even a nanosecond, he was satisfied.
In case this help understand.
david
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[Matt Colie]

What rick did was just about exactly how we determine spark advance in an engine test lab. The real problem is that manufacturing variations mean
that one setting will not be good for every engine.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[dave king]

I wonder how much Manny cringed when he heard what this guy did. I'd bet the tranny fluid
temps were sky high. If Manny reads this would you choose to comment?
I've read that really HOT tranny fluid has a VERY short life, like in minutes
--
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada

 

[john r. lebetski]

This is the equivalent of using "Locked Rotor Amp Draw" to determine how many Amps a running air conditioner compressor actually draws. A range of
driving conditions is way more accurate. The final setting should be just a slight hint of ping in maybe one of the RPM/load conditions and not the
others.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Ken H.]

The Chevrolet P-30 Chassis Owners' Manual says in its transmission appendix
that stalled torque converter will heat the ATF at a rate of 1*F per
second. It also recommends a maximum temperature of ATF at the torque
converter output of 350*F, and states that at 300*F, parts begin to warp
and seals to melt.

Considering that the ATF was probably at 150*F at the start of the
exercise, 200 seconds of mistreatment should reach the maximum outlet
temperature. Since the coach was not moving, the ATF cooler probably
wasn't reducing the temperature much before returning the fluid to the
transmission, meaning the limit should be 300*F, reducing that to 150
seconds.

At 300*, ATF has a service life of about 1500 miles.

I think I'll use another method.

Ken H.

> I wonder how much Manny cringed when he heard what this guy did. I'd bet
> the tranny fluid
> temps were sky high. If Manny reads this would you choose to comment?
> I've read that really HOT tranny fluid has a VERY short life, like in
> minutes
> --
>

 

[david j. forjan]

Thank you all for the insights. I think I'll change the transmission fluid. Love you guys. Be well.
david
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[mike sadlon]

I too tuned my engine that way. The shuttering was probably the trans plates slipping.

Mine ran great after the power tune!

And after the 120 miles that the trans lived, the new trans that my wife picked up at Ken's works great also.

Mike

 

[david j. forjan]

FWIW. My transmission is just fine. I've probably driven 1500 miles since Rick set the timing this way. Transmission is as strong if not stronger
than ever. Maybe, just maybe, Rick, who builds and restores and repairs show cars and race cars in El Paso TX, knows what he's doing. Have to
consider that.
Thanks for all your posts folks.
david
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[Ken H.]

David,

Frequently posts here receive a lot of feedback that's not necessarily
critical, but could easily be taken as such. Yours is one of those.

Some, perhaps many, or even most, of us here understand the procedure that
Rick used to set your timing. But just telling how he did it doesn't really
"cover all the bases". I'm sure that in the back of Rick's mind were a
number of factors to consider that were not obvious to many of the
readers. Among them was probably the dramatic ATF temperature rise being
generated (he may have been "watching the clock" without telling anyone).
And the potential for disaster if brakes slipped (he may have even
positioned you in a clear area without mentioning why). And perhaps other
factors no one among us has thought of.

Frequently someone of us will try to divulge such background information
for the benefit of those who may not recognize it. That is, without meaning
to be critical, many of us sometimes make comments just to be sure that
everyone's aware of non-obvious considerations. Hopefully, doing so will
prevent bad consequences for the uninitiated.

I know of people who refuse to post here because they've been "insulted" by
such comments, even though they're really a part of the extreme value of
this forum: Broad knowledge and experience are shared freely without
"finger pointing". It's rare that anyone is really chastised here, 'tho'
it may sometimes seem so.

Ken "Learning something new every day" H.

On Mon, Jun 5, 2017 at 12:41 PM, David J. Forjan
wrote:

> ​...
> Maybe, just maybe, Rick, who builds and restores and repairs show cars
> and race cars in El Paso TX, knows what he's doing. Have to
> ​
> consider that.
> ​
>
​...

 

[david j. forjan]

Thanks Ken, I appreciate your point and I live by it. My previous post was not meant to be sarcastic, although now I can see it could have been taken
that way. My point was that, despite people's concerns and opinions, valid ones to be sure, that somehow Rick made this work, and for the benefit of
everyone, to point out maybe it's possible, and as such, there's a tremendous benefit. I have lots more horse power now. Lots. And from a 403ci.
And it was worth making my point, helpfully not to offend anyone. I don't take criticism or advice negatively, not for a long time. I posted this
topic for the benefit of discussion and education, for me and others if they can learn too. I also try to learn every day, being open to everyone's
opinions and advice, otherwise I would have remained as stupid as the day I was born.

Thank you for your wisdom in raising this issue. And if you follow my posts you'll see I am always grateful for people taking the time and educating
me and others with their experience.

Thanks. David
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[david j. forjan]

Just one point of reference about horsepower. If anyone has driven over St. Augustin pass, going from White Sands Missile Base over the Organ
Mountains to Organ and Las Cruces, NM you can appreciate this. Before Rick set the timing his way, I had to go over that pass in 1st gear. Now I can
climb that pass and go over in 2nd gear. A rise of 1800 ft. in

 

[Keith V]

I'm glad you got your timing better.

Just to be my usual doubtful self I'm of the thought that your increase is getting the engine back to where it should be. It's unlikely that your engine is performing significantly above design and likely that is used to be poorly tuned and running significantly below design. The change from below design to par or slightly above design definitely does occur , but it's very hard to exceed design by much.

a good total timing / distributor recurve would also get you there. It's 6 of one 1/2 dozen of the other. with the total timing being the more deterministic of the two.

nothing beats a well running engine.

________________________________
From: Gmclist on behalf of David J.Forjan
Sent: Tuesday, June 6, 2017 10:39:38 AM
To: gmclist
Subject: Re: [GMCnet] Big increase in power in my 1977 403ci engine

Just one point of reference about horsepower. If anyone has driven over St. Augustin pass, going from White Sands Missile Base over the Organ
Mountains to Organ and Las Cruces, NM you can appreciate this. Before Rick set the timing his way, I had to go over that pass in 1st gear. Now I can
climb that pass and go over in 2nd gear. A rise of 1800 ft. in

 

[robert mueller]

Keith,

I was thinking the same thing. Being the pedantic bugger that I am I would
have liked Rick to set up the engine as per the MM, let Dave drive it and
assess the HP. THEN work his magic.

Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Keith V
Sent: Wednesday, June 7, 2017 3:08 AM
To: gmclist
Subject: Re: [GMCnet] Big increase in power in my 1977 403ci engine

I'm glad you got your timing better.

Just to be my usual doubtful self I'm of the thought that your increase is
getting the engine back to where it should be. It's unlikely that your
engine is performing significantly above design and likely that is used to
be poorly tuned and running significantly below design. The change from
below design to par or slightly above design definitely does occur , but
it's very hard to exceed design by much.

a good total timing / distributor recurve would also get you there. It's 6
of one 1/2 dozen of the other. with the total timing being the more
deterministic of the two.

nothing beats a well running engine.

________________________________

 

[david j. forjan]

You're right Keith, nothing beats a well running engine. I must also add, belatedly, that I had the engine tuned and timed (new plugs and wires and
distributor) by a professional mechanic before Rick performed his magic (and drove it that way for a couple thousand miles). As for getting more out
of a design, doesn't dual exhaust or quad exhaust or headers or turbocharging get more out of the original design? Significantly more too? Granted
that those are new parts added on, but also keep in mind that Rick makes race cars perform better, getting more out of those engines. As for just
changing the timing, even I can see conceptually what Rick did. He made the engine run best at the point of higher performance; higher RPMs. So when
the RPMs are higher, that's the sweet spot of the timing setting (excuse my layman's description). Surprisingly to me, the engine still performs just
fine at lower RPMs. And I also get better gas mileage, as he said I would (~11mpg vs.~10mpg - 10% savings on my gasoline bills). As for the proof of
the pudding, going up a big mountain in 2nd gear vs. 1st gear is a significant improvement no? With no additional parts.
Personally, I think what Rick did is stunning. And I don't say that because of any ego-trip.
thanks to all of you for your opinions. Be well.
david
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[david j. forjan]

I must add one more thing. I just realized that no one asked for Rick's phone number to pick his brain directly and specifically about why his
approach works. And I forgot to so I'll provide that now, albeit belatedly, sorry Rick. He's Rick Peterson of Show 'N Go in El Paso at 9660 Dyer St.
(915) 821-7278.
Be well.
david
--
David J. Forjan, 1977 403 26' Palm Beach, glad to have the 3.70 Final Drive and pork chop for level front end, Tularosa New Mexico

 

[mike sadlon]

One of the coolest things I got to do was build a spark curve for a new motor on a dyno. Hours of holding the motor at an RPM while timing was
adjusted at 500 rpm intervals Cool stuff!

I set my timing by the light, and I could tell it wasn't right. Wrong pointer, slipped balancer don't know. I have power timed 100's of boat motors
and a whole bunch of car motors. That's easy to do in a boat, under load lift the hatch and have at it. Boat motors run on a linear load curve like
dynos do to engines. Motors at light load can take a lot more timing and should have it for mileage.

My point was most have no idea of the condition of there transmissions, and as others said, it can be tough on them.

Mike

Ken, I love your response!