Eer sicne i got my motor rnning, is seems that it isn't producing as much power as i expected. I've heard about some ppl using domes and loosing CRAZY amounts of power because of the flame travel, but that was on a 14.5:1 motor, so it sounds like the dome was simply insane.

What sparked my concern, was a few weeks ago, i raced a 99 pickup on the high way. He had a few things but didnt tell me what, but i know he atleast as longtubes, some muffler, and dumps. EW went 5 times and 3 of them we were even, 1 i pulled him by about 1 ft, and 1 he pulled me by 1 ft. Now, my motor is supposed to be right around 450 hp at the crank, according to desktop dyno, and virtual engine dyno, but there isn't really a part that factors in if there is a huge dome.

Now when i got my domes,( 11cc SRP domes), they already had a small cut( 5/8" x 1/2" x 3/16" deep) in the dome for the spark plug, but i went ahead and and made it a little deeper, wider, and longer and took out roughly 1-1.5 cc's, but when i put the motor together, i noticed the spark plug still pointed ( like this \--) at the dome with only about 40*-45* from perpendicular, now i would think that that would disrupt the spark travel quite abit, and i'm already hurt cuase of my 70's smog heads, with their beautiful trapizoid shaped open chambers.

So, is there a huge percentage of power lost from bad flame travel or is it somewhat minimal when done right?

 

11cc domes? those are little! I wouldn't worry about that...in the BB world 43cc are big, 11cc are small...so I'd say 11cc on SB are also small....desktop dyno gives you the ultimate number, aka perfect tune, and no detonation....be carefull when you pick your heads in that program, if you use stock heads even ported I would go with the lowest heads on there or 2nd lowest....either way it's not your domes...its something else

 

Smog heads and domes don't work really well. The Smog heads burn horrible to begin with and the domes don't help but they are ot the problem the chambers are.

How much timing does that thing need? I would imagine you could throw a good amount at it.

Bret

 

well, i;m actually not sure, i think, but it had been reading around 55-60 before i advanced my cam timing 2*, but we thought it was just a fluke some where. You think i'm really running that much timing? Is it time for the ported 220cc proactions?

 

55 is about what a Top Fueler runs, it shouldn't be that high. Get out a timing light and check it again.

Bret

 

well, we used 2 timiong lights. One crappy one that just flashes, and then this bad *** snap-on one that had a dial and the guy that helped me with it had to set the light @ ~ 55* to get it to show on the timing tab, and when he set it to 35*, it ran like CCCRRRAAAAPPPP!!!!!!, back fires when i reved it a bit, NO low end power AT ALL, so then i put it back to where it was before (~55*). He then took apart my distributer, and did something to it, and then we tried, it ran a little bit better, but still read crazy timing, so he thought it was because of my timing gears. Well hopefully next week i should have it running again with a week with a double roller chain, and then we'll see if that changed anything. And what would make the timing read that high??, i mean when it was at that high timing, it ran OK, like it had decent driving torque, and if i got it tuned right and the wheather didn't change to much, i could get it to pull somewhat nice, being a 4200 lb truck and all, but i know that the timing marks were lined up correctly.

 

55 degrees advance?!

What sort of valve timing does your cam have and what type
of fuel are you running?

I would think on pump gas and relatively high static compression,
the timing should be optimal between 34-40 degrees.

It almost seems like there is a phasing issue with the distributor
or the rotor?

Just a few thoughts...

 

Well said,

Something is wrong there. Maybe the vaccum advance is screwed up or the timing curve is euchred. 55 degs is just plain wrong.

Bret

 

well, my distributer has already been gone through by my machine shop, charged me $25 to do what ever he did. You think i need a new distributer? Say ...... an MSD Billet Distributer?

 

Is this the original 30 year old distributor?

I changed mine out recently and it did wonders for timing.
Check for slack in the drive gear and bearings.

IMHO, I would spend a few bucks and replace everything
from the cap down.

 

Make sure that you have the proper timing marks to match the engine and balancer..There are quite a few small block locations..

If you run lets say for simplicity, late model cover with a aluminum acessory bracket the mark may be behind the water pump..The balancer will look the same but the marks may not line up..Same goes for those cheapie chrome indicators that you can buy from trans dapt..

as for the snap on timing light..On mine i have buttons but i sure its the same..You want to adjust the **** (in my case the readout) till the mark meets the 0 degree mark on the timing tab and balancer..Then you can just read the dial or screen to get your total or base timing..

Disconnect the vaccum advance completely and check to see if it is not jamming up inside the dist..Pull off the cap and work it back and forth with your fingers...It should hit the rest built into the mechanism with a puch of a finger..

 

I would leave the vacuum of totally. I don't know anyone using
vacuum advance.

Aren't those mechanisms a little 'sluggish' to begin with?

 

the distrubuter is an accel HEI replacement with an accel super coil. The timging tab is on the drives side and fits close to the balancer and i'm assuming its on there right, cause the guy at the machine chop didn't say anything when he was using his timing gun on it. Also, the timing mark shows up on the opposite side of the balanancer.

 

About the only way to know for sure if your timing marks are lined up properly, is to get the #1 piston on TDC on the compression stroke and see if the marks line up.

 

AAHHH HAA!!!!! There it be's. Wrong timing tab. Now back to the power issue. So does it sound like my chambers are the cuplrit of the the loss power? or do you think it might be the little things ( plugs, plug wires, 3.07 rear gears so it just feels slow, mechanical seconcary carb tuning,) I think i'm getting to dislike carbs now...