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 super 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 3.10 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

I like the set up , I think the cam with the specs you listed look great in a hydraulic flatt tappet , but i think it could stand a bit more duration 240 -246 @ .050 .. being its a soild.. AND since you want 6000 rpm comfortably.
DO they make a performer rpm for a spreadbore?
You have 1500. dollar heads ,and a you are asking about a cast crank!! GO AHEAD A GET A 4340!!

nice combo..

I don't think you can get the 20 mpg unless you get the cruise RPM down. With the 3.10 gears you will be at about 23-2400 RPM on the hwy at 60. You may have to drop down to the 2.73 rr gears. I would also think about going with a little smaller duration cam for mileage since you have good flowing heads. I like the Crower 00320 at 230/236 @ .050" on 112LSA and run a 1.6 rocker on the intake. I also agree that you should go with the forged crank since you are spending a lot on the other components.

You're not going to get 20 mpg out of it.... 17-18 on the highway is probably about the best you'll be able to do.

I had a 400 with a Comp 282S and then later a XE274 and a XR282HR, and it got about that same mileage with all of those cams. TRW dished pistons (the smallest dish), 186 heads. Stock block, stock 400 rods with SPS bolts, stock main bolts (new), it ran about 145,000 miles and is still sitting in my garage in runnable condition. It was low 10s CR, maybe 10.2-10.4:1 range. Performance Distributors DUI ignition. A T-5 (.73:1 OD) and 3.73 gears for a while, then 3.23 for a while, then back to 3.73. Didn't make a whole lot of difference to the gas mileage. I was running a Holley 6211 spreadbore 800 CFM carb. I didn't have a suitable Q-Jet core; but I suspect that if I did (7029201 or 9202) it would have run near about the same.

Yes, "they" do make a Performer RPM for spreadbore.... can't exactly recall who "they" are, but it might be the mfr of the Performer RPM.... ;) I think "they" call it the Perf RPM Q-Jet.

I think the rest of your build is pretty reasonable, no parts just stick out as "wrong", except for all that 4-bolt main stuff. Totally unnecessary for what you're working on. You sure don't need a $600 crank. The cast steel one is entirely adequate. You're not setting a real high goal in terms of stress on the bottom end, so you'd do best not to overspend on that. Stock stuff would even do fine, if the rod bolts were upgraded. The only mismatch in your combo is your rear gear. It's simply too low to work well with that much cam in that small of a motor. The motor will be drastically inefficient at RPMs below 2200 or so; very bad for gas mileage. You might actually get better mileage with a higher gear. 3.31, 3.42 or 3.55 would probably be better choices.

You don't need 1¾" headers. 1-5/8" would do fine. I was running Edelbrock TES on my motor, which is a mix of 1½" and 1-5/8". The smaller headers will give you more low end torque and better gas mileage, at the expense of top-end HP; most likely it's a trade-off worth making.

That's more cam than you really need. Remember, there's no such thing as too much cam, only not enough motor. That's not really enough motor, in that setup, to use that much cam. Drop the cam back at least one step (6° @ .050), or maybe 2 steps (12°). You'll be ALOT happier with slightly too little cam for the motor, than slightly too little motor for the cam.

One thing that NEEDS to be said and that is that IF you match your heads to your cam and cr. RIGHT, you can make big power easy with a smaller cam!!!

This is how the late, great John L. did it, imho!!

And doing so help's the mpg!!

All this info is on the Boards, either here, Little Brothers (Team Camaro) site or SGCOG so please do some searching to find it.

pdq67

First off, if you only plan on maxing at 6 grand, a 2-bolt will be more than sufficient. Go with a big Q-Jet. Change the rearend gears to 3:73's, and with everything else you've listed I think you'll be fine as far as busting 12's, but probably slightly off of the 20 mph goal.

You might look at the Lunati 401A3LUN, it is 272/282 at .020, 238/248 at .050, .485"/.503" gross valve lift, and 112 LSA. If you wish, you can run 1.6s for more lift. It goes all year on 1 valve lashing, and will give years of daily driving life. I've recommended it for 26 years.......

UDHarold

I went through a learning curve doing my 406,and found a few things you may need to keep in mind. The larger the motor,the bigger the cam needs to be. Most cam catalogs give rpm ranges for 350's.If you're looking to see power in the 6000 range running a 383,you may need to pick a cam that says it pulls to 6500 or so. My first cam in the 406 was a Comp XE 274,which ranged to 6000 in the catalog,and their tech line also recommended it. I found the idle silky smooth and top end was only around 5500. It would turn higher,but the power dropped sharply at 5500. I ended up flattening a lobe and replaced it with the Comp XE 284/1,60 rockers. Much better pull to 6000,and would turn to 6500 or so.(240/246@.050 duration)

On the first round with the Comp XE-274, I found the stock cooling system to be insufficiant,had to install a Griffen 31x19 aluminum radiator. More power means more heat. Stock would cool it for about 20 minutes,then the temps would slowly rise till overheating. Now it stays at 190.

On the second round,while recurving the distributer,I made repeated runs from ground zero to 90 mph or so,and found fuel starvation with my Q-Jet. I replaced the pump with a Holley 130 gph mechanical pump,and the problem persisted. I then baught a Holley 3310,slapped it on and was able to turn 6500 rpms with no problem. The intake I had was an RPM Q-Jet,which is drilled for both spread bore,and square bore carbs. This combination idled at 650 in gear,fenders shaking and got 16 mpg commuting 400 miles a week to work.

I then discovered a bent pushrod,decided to tear down the motor and try a solid Isky Z-35,and Vic Jr intake. The last combination had tons of low end torque,in fact too much for my P295 50's to handle on a hard launch. I decided to shift the torque curve up to bleed off some low end,and gain some topend rpms. I got it back together and ran it a month before blowing my tranny. Idle is now 1000-1200,top end pulls to 7000 and will rev higher. Overall not bad,but with 10 inches of vacuum at idle,power brakes are not reliable. They do work,but you need to test them prior to actually stopping.

Anyway, I thaugh I'd share some of my experiences. May help guide you in the direction you want to go. I realize everyone's "perfect combination" may not be "perfect for everyone".

Thanks for the replies folks.

First for the rear gear, my current setup gives me a 9.42 first gear final drive ratio which is basically equivilant to a Muncie with a 3.73 rear gear. So I am happy with the current 3.10 rear gear. And yes my cruise RPM at 60 is 2300 right now.

As for the cam I would rather gain 20 ft-lb @ 3000 and give up 15 ft-lb at peak. A flatter, wider curve would make Autocrossing and Road track much easier. Harold, I had several people that are running the 401A6LUN suggest that to me. But the 401A3LUN looks like an interesting selection. Does Lunati have a master catalog of the UD grinds on the web somewhere???

As for the 4340 vs. cast steel crank, I see you point about $1500 head, so another $400 on the crank isn't allot. The main reason for that is this plan has been evolving for the last 2 months and the original plan was much more expensive and I have been scaling back with time to a more reasonable cost level. And so I have been staring at this list for a long time and that is why I need a few fresh sets of eyes looking at it. I am checking with SCAT to get their recommendations. And I was hoping that Wolfplace might put in his $.02.

Yes Edelbrock offers a Performer RPM model #7104.

pdq, what is SGCOG??? I have been searching for a while now, but I am not familiar with that one.

Thanks for the feedback.