Stabbing a smaller cam in 454, need your opinion

[rebelrouser]

Not a guru by any means, but there is very reasonably priced engine software that can calculate timing curves for what ever fuel you are running taking into account your cam, compression etc. I have had good success in using a distributor machine to modify the distributor to match the computer generated timing curve, and it fixes all these issues. I have also used these types of programs when using EFI and boosted engines to calculate a curve under boost and using those numbers to set up the timing maps and again it seems top work very good. If you don't have a distributor machine, check the timing at 500 rpm increments and plot the curve on a piece of paper. I use performance trends software, but I am sure there are many others. I just fixed a ford with a 351 Cleveland with the same issues you are having, about an hour on the distributor machine and all is good.

Hey rebel, do you have a link to that software you speak of? I'm interested for sure.

TIA

http://www.performancetrends.com/Engine-Simulation.htm I use the standard 3.4 version, never tried the pro version for the extra money.

[Machtuck]

I have it at 22 degrees initial as it seems to like it. No bent pushrods. Just an incessant lifter tap. About a year ago, i went a bit too far on the pedal (7000 rpms and valve float) with this hyd roller cam and lifters. Afterwards, i heard the tapping and believed that i collapsed the lifter. It cleared up the next day and was fine. Now it’s back. Maybe dirt but I’m guessing it’s not. Can I rebuild the said lifter and how? Maybe diassasemble and just clean. Outside looks good. No roller or wheel damage. They are Howards Max effort retro-fit.

The reason why i post this is I’m looking to do some real long trips to Florida and was trying to tame this 454 a bit. I guess in the grand scheme of things, this voodoo cam is relatively tame anyways. But the 8mpg is killing any effort to take this thing past church. Currently running an 800 double pumper.

Think i will take all your advise: fix/ replace lifter, keep the voodoo, and put the stage 2 quadrajet back on. Dial in reasonable base timing, connect the vac adv, leave the overdrive And 3:42. Good plugs,gas and cooling. Seemed to ping going up these Tennessee hills. Yes, can do better to tune this out.

Was wondering if any of you take your cars long distance and do you do it with agressive cams?

Thanks again for all of your inputs again. It’s really appreciated.

[RevTheory]

I don't recall if it's been mentioned but it might like those grades better with the distributor hooked to manifold vacuum, assuming it isn't already.

[JoePorting]

I'd just bring back the timing 4 degrees to 32 total and see how it runs. I always found 36 degrees as being too much.

[gmrocket]

What's your cranking psi?

Do you know what it was before with the crane?

[gmrocket]

..

[F-BIRD'88]

Re: 7000 rpm. Why do people buy a hyd roller cam setup when they want the performance of a solid roller cam setup.?
There is nothing wrong with the initial timing set.

The holley carb likely needs fine tweeking to dial in the idle off idle/ cruise fuel metering to get it right.
This can get rid of the detonation and also improve the fuel mileage. A afr guage can help here.
First eliminate all vacuum leaks.

Does it only knock while climbing hills?
What rpm, gear (OD?), throttle position?
May need a simple power valve swap.

A eddy 650 avs2 carb will likely outperform the holley on this car for what matters, mpg etc.

[F-BIRD'88]

If mileage is the real goal then a much smaller hyd roller cam can help. With 3.42 and OD a cam in the range of the cam used in the GMPP 454 HO crate motor is good.
211-230@.050”. 112 .510-.540 You can google that to see.

Efficientcy in OD wants a small cam. It will also run quieter. The car will still GLH and run a strong 12 sec et with traction.

Dial in the carb. Add cold air ducting. Fix the fuel distribution issue.

[Machtuck]

It will ping sometimes at partial throttle inputs above 70 degree F.

I didn’t mean to shift that high. Inadvertent.

I have that GM 454/425hp billet roller cam sitting on my shelf.

211/230. .540 lift. 112.

I would gladly put this cam in but again, would this be too much cylinder pressure and if so, should I remove the shim gasket and put .039 gasket?

Don’t know what my current cylinder pressure is.

Dropping back to 32 degrees a good idea.

[travis]

I think that would be a much more appropriate cam for your application.

Consider that 3.42’s x 0.67OD = 2.29 effective rear gear ratio. You’re pulling a heavy car at very low rpms at highway speed in high gear...well outside where your current cam is efficient.

Tighter quench is better for detonation resistance.

I would seriously consider getting a compression tester...they are cheap...and see where you are at. Back the timing down, run good gas, make sure you have no vacuum leaks, etc. You could easily see a 75% gain in highway fuel economy with that 454/425hp roller cam.

[midnightbluS10]

75% gain in fuel economy? So he could go from 12 to 20+ mpg with that cam? That seems proposterous.

Edit: maybe not if going from 8mpg to 14. That seems much more sensible.

[F-BIRD'88]

No the cylinder pressire will not be too high with that cam. (If the real cr is 9.8:1). If I had it and wanted better mileage, I'd use it.

Carb idle/ off idle circuit needs work. May just need a idle air bleed tweek. IFR tweek.

Does it ping with the qjet on it? Can be good if the carb adapter is right. (Divided type).

That milder cam will want a different spark curve.

[F-BIRD'88]

You are the guy that the Edelbrock 650 AVS2 carb is intended for.
You do need to get the vacuum advance system working.

[GARY C]

I have it at 22 degrees initial as it seems to like it. No bent pushrods. Just an incessant lifter tap. About a year ago, i went a bit too far on the pedal (7000 rpms and valve float) with this hyd roller cam and lifters. Afterwards, i heard the tapping and believed that i collapsed the lifter. It cleared up the next day and was fine. Now it’s back. Maybe dirt but I’m guessing it’s not. Can I rebuild the said lifter and how? Maybe diassasemble and just clean. Outside looks good. No roller or wheel damage. They are Howards Max effort retro-fit.

The reason why i post this is I’m looking to do some real long trips to Florida and was trying to tame this 454 a bit. I guess in the grand scheme of things, this voodoo cam is relatively tame anyways. But the 8mpg is killing any effort to take this thing past church. Currently running an 800 double pumper.

Think i will take all your advise: fix/ replace lifter, keep the voodoo, and put the stage 2 quadrajet back on. Dial in reasonable base timing, connect the vac adv, leave the overdrive And 3:42. Good plugs,gas and cooling. Seemed to ping going up these Tennessee hills. Yes, can do better to tune this out.

Was wondering if any of you take your cars long distance and do you do it with agressive cams?

Thanks again for all of your inputs again. It’s really appreciated.

You mentioned running A/C, that is enough load to drop about 2 mpg and add a lot of heat to the cooling system.

The only iron head combo I could share did not run A/C but was an SBC at 10.4 compression with an XE 262/218 on a 110 wit .508 lift with 1.65 rockers, it had a little over 200 cranking psi and pulled 16" of vac.

167cc runner with 2.05 valve and 67cc D shaped combustion chamber straight plug like a factory head, I will post a picture.

I ran a medium and light spring combo in the distributer with an adjustable vac advance hooked to full vac so it mimicked the modern day LS timing curv and pulled timing out under throttle load and then slowly added it as rpm increased.

I set the total to 36 and then hooked up and dialed in the vac advance to achieve max vacuum at idle (this my cause you to have to readjust carb settings to get it to idle back down) this put me at 20 total and 40 part throttle, if i encountered a situation that caused ping (Texas summer conditions) I would pull over and back out the vac pod a 1/4 turn and then go back and retry the hill to make sure it was dialed in, even though It fixed the part throttle issue it barely effected the idle timing and vacuum.

This had an Air Gap intake and a Holley 780 VS carb with stock jetting.

[GARY C]

Here is the car and engine, 79 Elcamino, t350 trans, 2000 converter, 2.73 or 2.56 rear gear (don't remember) 28" tire, built as sleeper to haul material, loaded about 4000 lbs 100 or so mile round trip.

Tried 2 different intakes, Stealth and the Air Gap with and with out divider gap blocked off as well as a 850, 830 and 780 carb.