GEARMAN69

Yep I found similar one light one medium

1BOSS83

What did your total timing and curve end up coming out to?

olds 307 and 403

One light and one medium is what Crane recommends in their kit. I would also consider an adjustable vacuum advance if your not running one, 30 degrees is a lot of extra advance for 9.3 to 1.

Fun71

Here' what I had in my tune up database:

Timing Parameters 11/09/2003
Factory weights/center plate installed
Weights stamped 139, plate stamped 446

Locked advance plate
Set total timing to 36 degrees
Initial measured 20 degrees
Mechanical advance = 16 degrees

Set total to 38 degrees, Initial at 22 degrees
One light and one medium spring - total in at 1800 RPM
Two medium springs - total in at 2200 RPM
Vacuum advance connected
Idle set to 800 RPM in Neutral, 650 RPM in Drive
Vacuum = 16 in Hg @ 800 RPM; 18 in Hg @ 1400 RPM

cutlassefi

Explain please.

79T/A

I installed the cam neither advanced or retarded. It degreed perfect.

joe_padavano

Actually, it degreed straight up. Whether or not that is "perfect" for your application and combo with this particular grind is a different question.

80 Rocket

You can degree a cam perfect for any spec you wish to degree it at given you have enough adjustable settings. Just curious as to why you would want to degree it at the LSA which is what you apparently did. Where exactly did you degree the cam in reference to the LSA?

cutlassefi

That cam was supposed to be installed with some advance to it per the cam card. Just sayin.

79T/A

I didn't see anywhere on the cam card where it said to install it advanced. It had 4 degrees built in to it already. How much should I have advanced it?

cutlassefi

Well that's why a few of us here aren't confident it was done correctly. If you really did it the right way you should be able to say "Guys it's in on a 106icl" or whatever. The fact that you can't tell us where it is leaves some doubt. That cam most likely should've been installed at just that, a 106icl.

79T/A

I went back and checked my notes and we used the intake center line method and it degreed at a 106 intake center line.

olds 307 and 403

Fun71, are those weights/bar special to bring the timing all in so soon? On multiple HEI distributors, 3000 rpm was the quickest all the timing would come in, no matter what springs were used. If the cam is where it should be and the air fuel ratio is good, then timing and maybe opening the secondary air door more is all that is left for gains as is.

79T/A

I changed my distributor springs to one light, one medium and it's made a world of difference in how this car runs. I haven't used a dial back light yet to see where my total timing is but I can tell the car has a considerable gain in power. I'm sure there is still more in it, I've got a stage 2 smi carb being built so I would think that's going to help also.

Fun71

Those are the factory weights and center bar; only the springs were changed. Distributor was from a 78-79 403 engine.

I think it's odd that light springs didn't allow full advance below 3000. The weights fly out due to inertia/mass/centrifugal force or whatever you want to call it, and the springs counter that force. If you remove the springs entirely, the weights should move to their maximum at very low (idle) RPM unless something is adding friction or somehow restricting movement of the advance plate. Lower spring force should directly correlate to lower RPM for maximum advance movement.

olds 307 and 403

I agree, they should have advanced sooner. I used Crane's, Accel and Mr Gaskets springs in 3 different HEI. One had an advance curve like a points distributor. Then there is the issue of adding extra timing at over 4000 rpm, so I went with the Mallory Breakerless distributor.

MrEarl

Does anyone know whatever happened with this case. Cam installed improperly or what? Scary, very scary.

MrEarl

Appears I found the answer to my question.


>"403 bored .030 7a heads milled .015, 2" intake 1.625 exhaust valves. Erson Viking cam 222/222 @ .050, 476/476 lift, 110 lsa. It runs good, I was dissapointed when I dynod it but that was before my custom built carb and before I recurved the distributor, I'm pretty happy with it overall."<

From his updated thread...

https://classicoldsmobile.com/forums...erence-102444/

as I am about to embark on a similar build, I was relieved to hear of the somewhat happy ending

69CSHC

I view modification gains in a different fashion. I like to look how far something has come from base. A mint 403 In a late 70s Trans Am factory, untouched, would be lucky to see 150 HP on a wheel dyno. So 79T/As 200 HP from essentially exhaust mods followed by another 50 HP gain from a cam swap etc. Is great in my opinion. 250 HP to the wheels is around 300 HP at the flywheel net. VS an engine born with 185 HP flywheel net.

Now I don't know how the build was sold to him... or his initial expectations etc. But I think he did great and I'm glad it got even better.

P.S. Mr Earl I hope it worked out well for you as well. And moderators, etc, sorry for bringing back a thread from never never land. Just felt it may help others with similar wants or issues to see this from a different perspective.