Engine Critique Requested – Street/Track 383 Solid flat tappet combo.

[airrj]

I am looking for input on my engine plan for my ’72. The car is a street driver; not exactly a daily driver, but more than a weekend and car show cruiser. Also it will see some track time; I have been autocrossing it and I have plans to run some open track days and the occasional rip down the ¼ mile. None of which will be for serious competition only for my entertainment. My original goal for the car was to run a 12 second quarter (12.99 or better) and get 20 mpg. These are not set in stone, and I am assuming that the 20 mpg is more in jeopardy than the 12 second goal.

The car is an average weight ’72, not loaded with options and such, but it will not be significantly equipped with supper lightweight parts either. The drive train is a Richmond 5-speed with a 3.04 first and a 1:1 fifth gear, with a Ford 9 inch 3.25 rear gear. And the rear tire will be about 26.5” tall. The car also has manual brakes so there will be no specific engine vacuum requirements.

Ok on to the motor. Here is my current ideas:

350 4-bolt block with steel main caps installed and ARP studs, zero deck
SCAT 383 Series 9000 internal balance crank
SCAT Pro Comp I-beam 6.0” rods with 7/16 bolts
SRP Flat top forged piston, 403 grams
Canton 15-250 road race 7 quart pan
Solid flat tappet cam in the 236 I / 242 E @ .050 and .500 to .530 range
AFR Eliminator Street 195 heads ~.040” quench height
Edelbrock Performer RPM intake
Q-Jet carb
Reasonable quality ignition system, MSD 6 system or equivalent
CR will end up in the 10.25 range with a DCR in the 8.25 range
All of the supporting parts Valvetrain, oiling system, etc. will be the appropriate type/quality.

I will want this engine to survive at moderately high RPM for a good duration of time. 6000 RPM would be a reasonable upper limit. This combo looks like it should be in the 430 hp range with 475 ft-lbs. range with good torque across the entire band.

Some of my questions:
Straight 4 bolt block with steel caps, will this survive? I have a 4-bolt block all cleaned and ready so I am hoping to use that. If I had a 2 bolt I would go right to the splayed bolt caps.

Is the SCAT Series 9000 crank durable enough? Or do I need to step up to a 4340 crank?

And specific suggestion on cam specs? Solid flat tappet my level of compromise between cost vs. power. I like the extra torque over a hyd. and the cost to step up to a roller is just too great for me. I am willing to spend the extra money for a custom grind.

Headers, size suggestions? Stainless Works makes a nice 1 ¾” set, but I don’t know any lengths or collector sizes.

Any recommendation for a balancer? I have no personal experience with any of the latest aftermarket balancers. I have an e-mail into SCAT to get their recommendation.

General comments/questions/suggestions for my plans. Anyone have any combos that are close?

I know that the Q-Jet kind of stands out in the combo, but I am a Q-Jet fan from long ago. I believe this is a key to my mileage and streetablilty goals. And I have seen some strong street cars running well with a Q-Jet. I am willing to try it and try to get it dialed in, and I am not afraid to switch over to an HP Holley or equivalent if the Q-Jet doesn’t work out.

My biggest question is the cam specifics. I plan to dial in the CR and DCR when I nail down a cam spec. I will talk to some cam companies soon but I would like your ideas.

Happy Holidays

[ProdigyCustoms.com]

I would ease the compression up. With upper 10:1 compression you could have a 500HP combo. Is that RPM intake a Airgap? Are you serious with the quadrjet? Are you a super stock tuner? I bet the carb kills more then 50HP. Crank and block are fine, I have done 500HP with cast cranks and 2 bolt junk 1980s blocks, LOL!

As for the cam specs, that is about right for those heads. But your cuttinf yourself real short at 430HP unless you are factoring in the negative effect of the Q jet

[JEFFTATE]

It's funny, I was thinking of an engine similar to that.
I would probably use a Demon carb.
I haven't heard much negative comments on them.
The extra mileage of the Quadrajet looks good on paper , but you may not put enough miles on it to notice the extra mileage in your wallet.
I too am a Quadrajet fan. I think they are the best Street carb designed, but the Demon will outperform the Quadrajet by far and the gas mileage is not that much different.
JMO

[boosted6]

I recently had a Olds cutlass with a Edelbrock performer RPM intake with a Holley carb on it and it ran like crap! It had no low end. Everyone I talked to said to find a good Q-jet and put that on. I ended up selling the car before I done the swap but a good working Q-jet would work great. Hence the words: (good working)..

[zbugger]

Heh.... I may be the only one here telling you to keep the Q-Jet. It's not usually as bad as some people say, but that's because they can be difficult to tune correctly. The small primaries will help with mileage a lot. I noticed better mileage with a Q-Jet than with my two barrel. Tuning the secondaries will be where you get all your power. There's a few guys out there that have been successful out at the strip with them. Most factory Q-Jets are rated at around 650 cfm or so, but I have an Edelbrock #1903 that's rated at 795 cfm. It could help you in this case. The only thing I'd see changeable about your combo is the rear gear. You may wind up better of performance wise with a 3.50-3.73 gear, but that would kill your mileage quite a bit.

[airrj]

Thanks Guys.

I plan on allot of trips with this car and so 8,000 a year isn't out of the question. I would really like to try to make the Q-Jet work and I am sure that it will be down on power from that, but I have a very good carb to start with and I am willing to swap out the carb for a race day if I find the Q-Jet to be too far off. My carb is from a mid-'90's 454 boat engine with 0 hours on it. I don't have the numbers from it with me.

I was mostly looking for suggestions on the cam/head combo. And the short block. And I have had many people tell me that I should step up to a 3.50-3.75 gear. I don't see that. My first gear final drive is 9.46:1 right now. If my 383 has the low end torque that I am shooting for I am guessing that my traction will be limited already with that gear. Am I too far off on that idea? Right now cruise RPM is 2200 @ 60mph.

Thanks.
R.J.

[USAZR1]

I'm building a 385" sbc similar to what you're doing. However,I'm using a late model roller block. Have considered the AFR's but will probably buy a pair of Brodix 1K 200's. Like you,I kinda want to keep my Quadrajet carb and was planning to send it off for a total performance rebuild. If not,I'll probably run a Holley 770 Avenger or 750dp.
Your gearing looks to be fine with that combo. I'm running a D&D T56/Fab 9 w/4.11 cogs.