[h=5]Recently I had Ken from Everyday Performance build a 800 CFM Q jet for a Caddy 500 engine that a friend on mine owns.[/h] On the engine dyno today the engine put down 425 HP at 4400 RPM and 560 ft of TQ at 3000 RPM. This is just a mild rebuild on a 500 engine with ported iron heads, RV camshaft, backed by a NV4500 5 sped trans and all going in a tow truck . I just wanted to show people that the Q jet can make some great numbers!
I few years ago we sent a 1978 Pontiac Q-jet to a customer who had his engine dyno'd by a shop catering mostly to the "Chevy" crowd. The engine was a 455 Pontiac with 290cfm aluminum heads, 10.5 to1 compression, and 236/245/112 hydraulic roller camshaft. It was topped with a ported RPM intake. The dyno shop chuckled at the owner when they noticed the Q-jet sitting on the big 455, and commented that they wouldn't make much power and would have to install one of their "dyno" Holley carbs if they really wanted to see what the engine could do. The 455 cranked out 552hp and 604 torque on the first pull. The engines owner said that the dyno shop operator and employees were dialling 911 and heading for the exits!.......Cliff
That is a cool story!!! As an update on this Caddy 500 it made 585 foot pounds at 3000 RPM and 430 HP, just a mild iron headed engine going in a tow truck with manual trans 6 speed and 4.56 gears. Should haul plenty of old cars and trucks back to my freinds farm!:TU:
I'm down with that! Looking at the Pure Stock results from Stanton this year, I counted 43 cars running in the 13's or better on Q-Jets (and I forgot to include 4 429's!). Both Rick Mahoney's Pure Stock Firebird RAII and Cliff's pump gas Ventura are running mid 11's So the point is for most of us - if we're not running those numbers, it not because of any limitations of the Q-Jet.
Another pretty cool story comes from down South, from the owner of a 1970 454 powered Chevelle. The owner contacted our shop, wanting to build a "stealth" engine, which means keeping the stock heads and "crappy" flat stock iron intake, and Q-jet. Several local Chevy "guru's" told the owner the intake and q-jet wouldn't work. I recommended stroking the 454 and raising the compression, and spec's out a custom hydraulic roller cam for it. The carb and distributor came here for custom tuning. The engine went to a local dyno facility when completed, which catered to Chevy's, and once again they laughed at the q-jet sitting on the stock intake. They told the owner that they had never once seen that deal work, and recommended going to a high rise intake and big Holley carb before any testing was done. The engine roared to life and cranked out over 500hp and 600ft lbs torque. So much for the "crappy" iron intake, carb and distributor not being up to par for big power. As far as "limitations" with the Q-jet, I don't know where this is? I have customers running into the 9's with N/A engines, some use one "small" 750cfm Q-jet. One in particular has a 67 Camaro powered by a 355cid engine with iron heads, and runs mid-9's, legal Super Stocker. I've been at this deal for decades now, and continue to see folks dumping their factory carbs and intake manifolds, on 15 second rides (or slower), just to guzzle more gas and go slower than the stock parts. My own car uses a stock intake, recalibrated stock Q-jet, and stock HEI distributor. I have to retard the timing 4 degrees and short shift at 5000rpm's to stay roll bar legal, in hot/humid weather. I even stay with a tight converter and 3.42 gears, and the car still easily runs under the roll bar rule in full street trim. http://www.youtube.com/watch?v=6zVdoLR-VzM ......Cliff
I really appreciate all the effort you have put in to help us be succesfull with the Q jets carbs! Do you have more info on the 355 Camaro? I am always eager to hear people's tricks to run fast with small cubes! I do know of three Buick 350 powered cars running 11s in the quarter mile with Q jets, stock intakes etc....
I lost contact with the owner a few years ago after he was involved in a serious car accident. From what I remember, his engine was professionally built (big bucks), and spun it really high rpm's. I did the carb here, set up for legal Super Stock racing. We don't really cater much to the Super Stock crowd. There is more money to be made in restoration work, and it's much easier. We still do a few race units every year, which include circle track racing. With the q-jet there are two obstacles to cover. Steps to keep the carb full on hard runs, and venting on really fast cars. It's easy once you've got those two items covered......IMHO.....Cliff
I have a #7042240 1972 BBB q-jet, on a 1966 Q-jet nailhead manifold 425 .030 ported polished heads , ported exhaust manifold, and ported intake ala Gesseler style, the custom Isky cam is a 270 int dur 280 ex dur .469 int lit and .496 ex lift wth a 110 LC . What kind of set up to the carb( stock rebuild) should be done to compliment this combo. Your expertise is very much appreciated.
Im anxious to get my Q-Jet back on my 350 after Ken redid it for me:TU: I honestly believe the 750 vacuum secondary Holley was holding me back, even with the lightest spring, the secondaries aren't fully open till 6750 rpm! WTH:eek2:
Snake - some of the bigger decisions on Q-Jet calibration are going to be based on what kind of vacuum the engine pulls at idle. Cliff's book give some great baseline build stats for 3 stages of tune in increasing "badassedness" from one to the next. We'll see what he has to say here, but if you don't have the book I'd really suggest you pick it up if even just for reference or further tuning once you settle on a baseline. I can tell you how I built mine (750 and 800 CFMs, there might even be a thread on it) , but my cam is stock, and I haven't done any porting beyond the manifold.
Snake, the baseplate is different width and will require a spacer for the fast idle adjuster to clear the intake. The nailhead doesn't need any extra air bypass, it tends to not like that extra air for a good idle.
I used a 76-79 M4M for my 800 and found it has the proper width for clearance, but yeah, if your using a 68(?) - 74 carb Mark is right. I took pics some time ago and there is a thread on that.....
1/2" to get fast idle adjuster high enough. It will fit without spacer if you don't need a choke and remove all of the components.
wait i grinded a spot, if your looking at the front of the carb and maifold its on the left hand side, i remember grinding an area with the carb attatched for clearence ,
It's a coating that is sprayed and baked on to withstand heat up to 1200 f , has the same look as polished aluminum, reduces heat temps , on exhaust manifolds there is also a thermal barrier sprayed on the inside to reduce heat and cause scavaging effect , they spray headers for other companies there. The place is called Engineered applications in Vernon Ca. I take manifold and exhaust manifolds cost $240 but I had to port , Polish grind and smooth the outside for a better look before I sent them in.
