for all the 406 owners - Team Camaro Tech
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post #1 of 17 (permalink) Old Oct 13th, 09, 12:25 AM Thread Starter
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for all the 406 owners

I have a stock bottom end with dish pistons, 202 160 with 74cc chambers IRON HEADS ,edelbrock air gap intake, hei, 1.6 procomp roller rockers arms, Saturday Night Special Camshaft; RPM 2800-6400; Adv.Dur. 284 Int./290 Exh.; Valve Lift .480 Int./.494 Exh.; Lobe Angle 106 deg., holley 750 dp carb with 50cc accelerator pumps, procomp gear drive, msd 6al box, th-350, 373's posi 10 bolt.

im currently running my timing at 30 initial, hei has been re-curved to add little to nothing. I have the vacuum advance pluged, carb pluged. the runs really good, but i feel like im leaving something on the table. feels like it should be faster...

can someone give me some more insight as to how my timing and set-up sounds to you? should i be adding more timing?
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post #2 of 17 (permalink) Old Oct 13th, 09, 01:13 AM
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Re: for all the 406 owners

shave heads .020 -.025//swap dished for flattops//get a smaller cam.

You dont have enough compression and/or cylinder PSI to move the amount of air the engine would be able to move if it was 10.5:1 or at least close. Never built a 406 with less than 190PSI in all the cylinders and at least 10.25:1 (so that it would run on methane, dont ask why stupid friends experiment)

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post #3 of 17 (permalink) Old Oct 13th, 09, 03:41 AM
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Re: for all the 406 owners

On my first 406 I had a 280H (230 @ .050,.486 I/E) Compcam and 9.5:1... int timing was 12 and total was 36.

68 Camaro~LSx ~all motor
1.54 60'--6.95 @ 98.45 660'--10.96 @ 121.53
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post #4 of 17 (permalink) Old Oct 13th, 09, 11:39 AM Thread Starter
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Re: for all the 406 owners

or should i just run two shot nos?
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post #5 of 17 (permalink) Old Oct 13th, 09, 12:02 PM
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Re: for all the 406 owners

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Originally Posted by wayne33 View Post
or should i just run two shot nos?
NOS is hard on parts, unless you have a steel crank & forged pistons I wouldn't do it. My engine builder said "Every time I take apart a NOS engine everything is coated with something that looks like rust." I have never run NOS so I can't comment on that.


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post #6 of 17 (permalink) Old Oct 13th, 09, 01:29 PM
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Re: for all the 406 owners

Quote:
Originally Posted by wayne33 View Post
I have a stock bottom end with dish pistons, 202 160 with 74cc chambers IRON HEADS ,edelbrock air gap intake, hei, 1.6 procomp roller rockers arms, Saturday Night Special Camshaft; RPM 2800-6400; Adv.Dur. 284 Int./290 Exh.; Valve Lift .480 Int./.494 Exh.; Lobe Angle 106 deg., holley 750 dp carb with 50cc accelerator pumps, procomp gear drive, msd 6al box, th-350, 373's posi 10 bolt.

im currently running my timing at 30 initial, hei has been re-curved to add little to nothing. I have the vacuum advance pluged, carb pluged. the runs really good, but i feel like im leaving something on the table. feels like it should be faster...

can someone give me some more insight as to how my timing and set-up sounds to you? should i be adding more timing?
I'd run more like 35*-36* with those heads, but watch out for detonation. I think timing alone will help the seat of the pants feel a good amount.

Honestly though the cam/heads/compression are not an ideal match, those heads are going to be a choke point on that motor (are you saying they are a factory type iron head?) and the cam's RPM range will never really get a chance. With my first set of heads on my 406 it would be all done by about 5800rpm, that was with heavily ported SR torquers.
The RPM range and duration of that cam are not a great match with a lower compression motor and low RPM potential heads, so that's going to hurt you no matter what. But you should be able to dial it in and make some decent power down low.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #7 of 17 (permalink) Old Oct 13th, 09, 01:37 PM
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Re: for all the 406 owners

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Originally Posted by wayne33 View Post
or should i just run two shot nos?
Your motor is not ready for nitrous, you won't see the gains you should and more than likely will hurt it, with stock parts on the bottom end, especially with 2 systems..

Contrary to popular belief nitrous does not fix everything....
That coming from a pretty long time nitrous guy.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #8 of 17 (permalink) Old Oct 13th, 09, 01:55 PM Thread Starter
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Re: for all the 406 owners

So i was also thinking of taking my heads to my friends shop and let him do a stage 3 port. Or will it just be a better idea to look into some better heads? he told me he would port them for 200...
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post #9 of 17 (permalink) Old Oct 13th, 09, 02:19 PM
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Re: for all the 406 owners

30 degrees initial? Then recurved to what? No vacuum advance? Lots of stuff there I'd do differently.

Set it to 36 degrees mechanical at 3000 (with the vaccum advance plugged). Then let the initial fall where it falls,..probably from 15-20 degrees. Then hook up your vacuum advance to manifold vacuum. Using vacuum advance will give you better off idle performance, better mileage, and a cooler running engine. At cruise, your engine will want from 50-55 degrees total advance, mechanical + vacuum.

Also, I don't know how you guys can start a car with 30 degrees initial without getting kickback. Makes me ask if the harmonic mark and timing pointer are mismatched. Which would compound your timing problems. Might check.

Lastly, bigger cam and smaller heads is almost always a recipe for disappointment. Can you swing some aftermarket heads that will feed the 406 like she needs?
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post #10 of 17 (permalink) Old Oct 13th, 09, 02:44 PM
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Re: for all the 406 owners

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Originally Posted by wayne33 View Post
So i was also thinking of taking my heads to my friends shop and let him do a stage 3 port. Or will it just be a better idea to look into some better heads? he told me he would port them for 200...
What heads are they? No amount of port work is going to make those heads ideal for your motor if they are a factory iron head. Save your pennies and get a decent set of aftermarket heads.
Be careful not to spend a fortune on the top end though if the bottom end is stock and especially if it's not fresh, you need to look at the motor as an entire package, go to far in one area and it will bite you in the other.

You can definitely optimize what you have though, give us some more details and someone can give you a better answer how to do that though. Motors take thought to assemble properly but it'll be worth it when your done

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #11 of 17 (permalink) Old Oct 13th, 09, 02:48 PM
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Re: for all the 406 owners

Quote:
Originally Posted by 68rs406 View Post
I'd run more like 35*-36* with those heads, but watch out for detonation. I think timing alone will help the seat of the pants feel a good amount.

Honestly though the cam/heads/compression are not an ideal match, those heads are going to be a choke point on that motor (are you saying they are a factory type iron head?) and the cam's RPM range will never really get a chance. With my first set of heads on my 406 it would be all done by about 5800rpm, that was with heavily ported SR torquers.
The RPM range and duration of that cam are not a great match with a lower compression motor and low RPM potential heads, so that's going to hurt you no matter what. But you should be able to dial it in and make some decent power down low.

By the way, to clarify I was talking about 36* total timing, I see you had said initial, did you really mean initial? If so whats the total?

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #12 of 17 (permalink) Old Oct 13th, 09, 11:20 PM
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Re: for all the 406 owners

performer RPM heads would work but for the performance, Id just bite the bullet and get AFR 195's.

Iron heads need about 4 or 5 more sizes up in jet size to run right and wont with your current combo. Get the 64cc angle plug AFR 195's. They will last any SBC you have from now on. Last set uyoull buy...

JMHO of course.

AE2(AW) Harley Moody, USNavy
"Master-at-Arms" for the CDWJB!!
November 26th, 2008 was my last day to serve my country as a member of the World's Greatest Navy.
Thanks Chief.
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post #13 of 17 (permalink) Old Oct 14th, 09, 12:16 AM
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Re: for all the 406 owners

I ran a 406 in my best friends car with similar components about 9 years ago. It had stock open chamber heads with 2.02 valves. In a 3350lbs 69 it ran 7.30s in the 1/8th. There is nothing wrong with what you are running. As long as the pockets behind the valves are blended and the state of tune is close it should make great power, by no means should it be lazy. If so something is out to lunch.

68 RS, 16mpg, 3200lbs, 355ci, 9.6:1, Ported Kemper Perfomance, production 441s, 76cc, 2.02 1.60. Hyd flat tappet XE274,RPM Performer,750 Holley, 1 5/8 tubes, 2.5 Dynomax full exhaust. 3500, 400TH, 3.73s, caltracs, NA [email protected] 1.62 60ft DA 1400ft.
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post #14 of 17 (permalink) Old Oct 14th, 09, 12:26 AM Thread Starter
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wayne
 
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Re: for all the 406 owners

here are some more details on the motor and heads...
the motor is flesh just did first oil change has a little over 600 miles on parts.. the heads are [FONT=Arial]Casting number is 3998993 76 cc heads they have had a three angle valve job,decked,and new z28 .550 lift springs.they are 1.60 exh and 2.02 int valves.. i sure the shop said that i was running 30 initial timing and i was going back to dyno/ tune car..due to the timing we had thats why we did us vaccum advance.. they curved the distributor to put no more than 3 degrees in..
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post #15 of 17 (permalink) Old Oct 14th, 09, 03:48 AM
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Re: for all the 406 owners

With the 280H cam,9.5:1 compression,and home ported GM 400 heads I ran 13.2 @ 102... Torque out the yingyang
200cc Protopline Iron Lightnings was the only change (smaller cc chamber upped comp. to 10.2:1) and went 12.3 @ 110

8 mph and .9 faster in the 1320'....approx 100hp jump using better heads.

68 Camaro~LSx ~all motor
1.54 60'--6.95 @ 98.45 660'--10.96 @ 121.53
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