[wanab5150]

I ran my sled up and down Highway 80 this afternoon in 95 degree weather. I cannot distinguish any difference between the #70 and #73 Roush jetting and the #71/ #74 jetting I tried yesterday. I’m thinking the very, very, slight surge I described might have just been the crappy pavement on 80. Bumping along on 17 inch donuts combined with the aerodynamics of a brick at speed with even a slight breeze could produce the feeling of a light surge. So, I’ll chalk it up to that that theory.

For now I’ll drive it this way for a couple of hundred miles and report back. I think I’m very close if not right on. Tom

CONTINUE IF YOU ARE NOT BORED.

I drove to Smeding Engines in Rancho Cordova and talked to Unki Kim, manager and assistant engine Guru. Still searching for the universal knowledge of carburetors and jetting, I ended up getting the full tour of the shop including the dyno room, build room, and storage area where six engines sat ready for shipping. I was there for about an hour and was treated like a diplomat. For what reason, I don’t know. Was he just a nice guy? Was he was bored? Does he just love his work? ……I think it was the latter. Well, very nice guy too!

Unki pulled three different carb brands from the back room and described the differences in each, eventually stating my Holly 770 should still be jetted correctly and if it runs flawless and doesn’t overheat then he would not recommend changing to any of the cool iron sitting on the counter. Now I have a trifecta of answers from Roush, Holly, and now Smeding stating the jetting should not have changed with the addition of larger exhausts.

The three trick carbs he showed me were a Holly 4500 series 750cfm HP, the second was a Speed Demon 750cfm and the third was a Quick Fuel Technologies 750cfm double Pumper with red anodized metering blocks and base plate all made out of some special high grade “un-obtanium”. All 3 of the carbs sell for about $500 to $600.

The Quick Fuel carb looked like “MAN JEWELRY”, and I wanted one. If I could just get him to say it produced more HP than my 770 it was a done deal. He wouldn’t! I tried the direct approach….”Could I get another 10 HP out of it?” “Possibly, but maybe not, he said “. My Visa card was burning a hole in my hand. Christ, what do I have to say to get him to take my money?

Unki said if my Holly 770 was working correctly with no issues it may not be worth the money or set up time to switch. The performance difference would probably be negligible and at $500 for MABEY five HP it just wasn’t worth it. He said come back and see him if I had an issue with my Holly and he would help me out. But, from what I was describing, my Holly was set up better than most.

The myth of any major HP gains were also dispelled when we discussed the Holly’s (and others) air horns where the choke butterfly’s are located. I’ve heard rumors these deflect air as it enters the carb throat and because the Demons and 4500 HP Holly’s have a smooth bore entry with no air horn or other obstruction, more Horse power will be on tap. Unki said if you don’t run an air cleaner you may gain a few if any, because the air cleaner already re-directs the air downward in most cases and therefore changes the airflow before it even enters the carb. If no air cleaner is used or a velocity stack is used instead, then maybe it would matter, but not enough to be concerned about.

Most of the high performance /race carbs allow for easy air bleed adjustments and changes where street carbs usually have fixed air bleeds. There are also usually less vacuum ports and lack of the choke horn I discussed above. Generally, Unki said, it’s adjustability that differentiates between high performance carbs and street performance carbs. At wide open throttle, a 750cfm hole is a 750cfm hole! What matters is the fuel /air ratio, which is the jetting.

I asked about going to an 870cfm or maybe a 1000 cfm carb as I have read some Cobra guys are running them, and swearing by them. He said in a drag race scenario the Roush 427 could handle the carb but on the street you’re going to lose all the “drivability” and furthermore all the torque will drop as a result of the huge intake. He said you have to choose WHAT KIND of power you want as opposed to how much power you want. If I wanted 600 HP and 400 lbs of torque go with the 1000cfm and live with the crappy street manners. If I stay with the Holly 770 I might have ONLY the 550 HP but I gain the torque back and the good manners for the street. ….It seems the carb Rouse put on the motor is a good choice!

I was impressed with Unki’s knowledge and the shop itself. The Smeding engines are remarkably similar to Roush engines in Cubic inches and off the shelf parts. As strange as it may seem, the Roush 427R engines are made from Dart Sportsman blocks, “H” beam rods, 10 to 10.5 compression ratios, AFR 205 heads, 1.6 Rollers, Edelbrock, and Holly carbs. Roush parts? Smeding uses mostly the same components with their own cam spec, Quick Fuel or your choice of carbs, and choice of ignitions. The biggest differences are price …..Roush $15,995 (mine) and Smeding $9,995. The Smeding engine posts 560HP and 560TQ. It’s no surprise that their 427 is called a “Smeding 427 Cobra”.

I am happy as a pig in Sh@! with my Roush, but I think I may be swayed if I decide to build another sled. For $6000 I think I could find an engraver to scratch “Roush” onto the look alike valve covers.
Smeding is in Rancho Cordova, Ca. 1(916)638-0899