Input on my set up

[Chris_69_SS]

Hi Cliff,

I bought your book from Summit - Thanks for writing such a great piece for us Qjet-O-Philes in training! 

I wanted to get a kit from you for my Qjet so I can start playing with it (esp. gaskets and any other parts that would stand up better to todays fuels). 

Below I layout my carb details as well the rest of my set up for you to comment on, should you have the time of course.

Carb: 17057584 (smi stage 2 build that is 3 yrs old)
Current specs: 43 rod (43k)  /  CE sec. rods / 76 Primary Jets / .130" needle & seat / has provision forexternally adjusting APT
Some Stuff I have on hand: Edelbrock Power Piston spring assortment, .Edelbrock .145" viton needle & seat assy,  .545" G hangar,  Hi- Perf Edelbrock acc. pump plunger & spring.

Combo this Q-jet is bolted to:
1969 Chevelle.
454 cu. in.
.030" over / 10.5 compression
Ported GM iron oval port heads - 049 castings (flow 290+ on the good intake runner - supported over 600hp in my last motor).
Cast Iron GM Qjet intake - stock, no porting or gasket matching
Exhaust manifolds - stock, no porting or gasket matching
Crane Hydraulic flat tappet.  284 / .228 / .544" / 112
Mechanical fuel pump - Edelbrock performer RPM --into stock repro fuel filter before carb.
3/8" fuel line front to back.  Has return line.
Pertronix ignition under stock distributor.
Dyno said 450 hp & 530 TQ (peak tq @ 2300 rpm)... this was with dyno headers and dyno elec fuel pump.
M20 4 speed transmission (2.52 1st gear)
3.08 posi   
Full 2.5" mandrel bent exhaust exiting stock location.

---> Any suggestions on the tune in the carb? 

---> I'd also like to get a couple of sets of gaskets from you.  Can you confirm price & availability?

---> p.s. what are your thoughts on the filter pictured below on my engine - This is the stock look/mounting but think it may be restrictive?  Car actually runs out of steam at 5,000 rpm and I feel it should pull pretty hard to 6,000.  I was thinking of removing this and adding a hi-perf unit near the tank (hidden) - maybe this: http://www.summitracing.com/parts/hly-162-551/overview/.   

---> *Either way, can I take the filter out of the carb body?  Seems redundant to run this with the inline one as well....OR will this be good enough?

---> Have any experience on porting exhaust manifolds?  Is it even worth it with my combo?

[TommyK]

Not Cliff obviously, but...

With stock exhaust manifolds and intake that cam is doing exactly what it is supposed to do. Make massive torque low in the rpm range. I think 450 hp at 5000 is doing quite well given the restrictions noted above. A performer rpm intake and a set of headers will definitely extend the rpm range but at the expense of some torque down low. I don't think that cam will be making power at 6000 rpm even with the aforementioned changes. 5600-5800 maybe.

I think what you have is a great combo for a street car. It must pull like a freight train from right off idle.

Nice car.

[Cliff Ruggles]

Agreed, not enough camshaft to support the CID and head flow.  I've tested 230 @ .050" cams around 280-285 seat to seat timing and they are DONE by 5000rpm's on engines that size.

I know the cam manufacturers tell us they will make power much higher, but they don't build and dyno engines, they just produce cams and throw out "generous" specs with them, to help sell more product.

A few years back, we were on the dyno with my own 455 engine, using aluminum KRE heads, and did some cam testing.

We were running a Crower factory duplicate of the RAIV cam, 231/240 @ .050, 304/314/113 LSA, .520/.520" (1.65 rocker arms).  It made 494hp at 5600rpm's, 567tq at 3800.

We bought a custom Comp cam with their XTQ lobes (best at that time).  It had less seat timing, but 10 degrees more .050" duration.  240/248/112 LSA, with .560" lift.  Comp tells us that the "modern" lobe profiles will make more power everywhere.

We LOST 10hp and 24ft lbs torque, engine was DONE at 5200rpm's.  My first lesson in "modern" cam profiles.

We then ordered a custom ground hydraulic roller cam, 230/242/112, with .361" lobes, 282/287 seat to seat timing.  The HR made about 4 more HP than the "old" Crower cam, and another 8ft lbs torque, done at 5400rpm's.

I made a few additional changes, and some additional tuning and ended up getting 514hp/587tq from the big roller cam. 

At the track the roller cam took my car from a best ever 11.64 at 116mph to 11.52 @ 118mph.  Over $1000 for about a tenth in ET and 2mph.  Not sure most folks would consider that gain worth the expense, but I really liked the roller cam, and have not went back to flat cams in any of my engines since........Cliff

[Chris_69_SS]

Thanks to you both for the replies.

Cliff - can you advise what I should order for gaskets?  I`d like to have some on hand for when I start playing with the carb.

Lastly, don`t want you all to think I built this set up for racing or being anything other that a fun street car that LOOKS original to the casual observer.  Been low 11s @ 121 with this car (same heads on it now) and was tired of driving it on the street set up as such so I changed direction....  car is a ton of fun on the street esp. with the 3.08s that I feel are perfect for the set up.

[Cliff Ruggles]

That carb is most likely a large MAB model.  It will need large jets and small metering rods for what you are doing.  I prefer to install small airbleeds in them and recalibrate with smaller jets/rods.

The Edelbrock accl pump is junk, get one of our pumps instead.

I'd upgrade to our high flow .135" needle/seat assembly as well.

The SR kits have both, and all the gaskets and small parts, etc.....Cliff