maniehau

Hi everyone.

So, I just finished a build with a machine shop (well respected) down in Tucson, Arizona.
The specs are:

350 +.030
stock crank/rods with ARP bolts
Canton pan
SFI balancer/flexplate
Balanced lower end - ARP main studs
Speed Pro forged flat tops (-.008 +/- .002) in the hole
.041 head gaskets
Lunati hyd. 233/241 Voodoo cam - comp cams lifters .522/.539 lift
Harland Sharp 1.6:1 roller rockers on 7/16 studs
Cloyes true roller chain
MSD ignition and Pro Billet distributor
#4 heads 2.07/1.65 valves - bowls opened up with light porting
Edelbrock performer RPM intake manifold
Quick Fuel 750 Q dp carb
Headman street headers

The combo was just tuned on the dyno with 12.5:1 on average AFR
I'm going to pick it up for the W30 this week.

Shop says the HP/TQ are 386FT-lbs @3800 with fairly flat torque curve and HP at 382@ 5300.

I'm curious if this is reasonable or if there is something more that we can get out of this build fairly cheaply.
I know nothing is cheap, but with approx 7-8K in the build including assembly, dyno time etc. I was hoping for around 415hp to reach my goals.

Thanks,

Maniehau

olds 307 and 403

What is the actual compression ratio? Were the crossovers in the heads filled? I would have thought 400 HP/TQ would have been hit and I assume what you are looking for. Good luck on your quest.

maniehau

The heads were not filled. The shop would not do it. They used the block off plates for the intake but that is all they would do. Shops are getting really hard to find these days.
The actual compression ratio as calculated is 10.67.

maniehau

I'm wondering if its the carb. For the 750 Q brawler they said they needed to go down to 70/76 jets and below 3500-4000 the car was rich but achieved 12.5 at WOT.
Its now off the dyno and not sure when it could have a time slot again (shop time is ridiculous with demand) but 385hp is not going to reach the goal of running a 12.5 with a 3400 lb. car.

70sgeek

Mark (CutlassEFI) built me a 350 roller cam motor a few months back of roughly 385 hp / 400 tq at 9.5:1 CR - the build was on a '69 block with 7a heads and HS 1.6 roller rockers. Also with a QF but a 780 CFM atop an Edelbrock 7111 intake. if I recall correctly without going back into my docs, he used Mahle 4.100 10cc forged pistons and Molnar forged connecting rods, filled and mildly ported the heads and installed the cam 4* advanced. Cam is a Comp Cams custom Hyd roller, .576 / .573 cam (again based on my immediately available partial cursory notes).

He used a nodular crank which I believe was turned 10/10. Pertronix Ignitor II ignition and a SCAT balancer - the motor was neutral-balanced.

on his dyno, it peaked just above 400 hp and at approx 404 tq at its respective torque peak. Ultimately the dial-in figures are approx 385 and a hair under 400 respectively. I run the motor through Thornton shortie headers and a 2.25" dual exhaust (no 'H' pipe)

So though my outline is largely incomplete for needed info comparison, seems to me at least your figures are possibly within range if my build is any barometer.

coppercutlass

I ran that same combo and ran it to 6300 rpm

maniehau

Thanks for the barometer guys! I really appreciate it. I'm guessing that the power figures are quite comparable then.

Copper~ I actually built this combo after watching more than likely too many of your videos. I'm hoping to have some fun, learn, tinker, improve with this little 79 HO I have. The ultimate goal is to walk the line between what is theoretically possible (calculators have the car at 12.4 best at 6200 through the lights) and what I can do with all of my human error.

Before I go pick the motor up though and start the install, I am curious if there is something obvious that I am not seeing. My gut is telling me the carb is wrong due to the significant changes in jet sizes. I am though on a budget, so if its $1000 for minuscule benefit - I cannot justify the expense. I sincerely appreciate advice.

Thank you. Maniehau

coppercutlass

I ran a 750 DP on my combo with a 1 inch spacer. I had set the timing to be all in before 3000 rpm. I did run the lifter preload at 1/4 turn. That helped it alot. I didn't do the 1/2 or 3/4

cutlassefi

Yes it’s a little light.
BUT, lots of variables. Dyno calibration, O2 accuracy(on mine I find I get the best power at 12.8-13.0) and so on.
70sgeek actually made 422/430 with headers like yours, and nearly stock heads(2.00/1.62). Filled but no other work. And while he had more lift, he had more than 10* LESS duration, and a full point LESS compression. 10.7:1 is stretching it a bit on pump gas in my experience.

And I’ll bet the Brawler cost you at least 10, maybe more if you bought it in the last 8-10 months. Jetting is dependent on a lot of things, first the metering blocks that are in it, and how strong the signal is at the booster for starters. I don’t use those anymore, they’ve become very inconsistent. Scott’s (70sgeek) used a QF, but the Hot Rod series. Better carb.
Lastly we don’t know how well the machine work was or wasn’t done. I’ve posted how mine is done, different than probably 98% of how others do it.
385 isn’t terrible, but maybe more tweaking might have gotten you closer to your goal. Only you and your Dyno guy know that😉.

maniehau

Hi Mark,

I was hoping you would comment. What carb do you think I should use? I can always pick up a better carb and take it down to the shop. I didn't realize the brawlers were having issues. I did purchase it within the past year.

cutlassefi

I’d bet you’d pick up some with either an SS, Hot Rod series, or especially the best, a Black Diamond. I’d also lean it a bit up top.
Lastly Scott’s used a solid roller lifter on a hyd roller cam. That’s worth another 10+ as well. More stable valve control.
But I would’ve thought 400+ would have been doable with your combo. You have plenty of compression and a fair amount of cam.

maniehau

Thanks Mark, your knowledge is very much appreciated. While I most likely won't be tearing into the motor a wideband and a black diamond carb is more than doable. Thank you sir.

DR_DAN

12.5 is too fat . Try to get it at 13.0

Bernhard

Personally I would not be worried about trying to squeeze more hp out of the engine until you have the engine in the car and sorted out. What does the rest of the drive line look like?
The $1000 might be better spent on drive line or fuel system up grades than chasing the last few HP.
Good Luck.

olds 307 and 403

Yep, the stock TH350 and spindly 7.5 rear end will blow to pieces behind that power.

maniehau

Currently shopping for a good TH350. I have a converter already left over for a past project (Hughes 3500) I really need to use. Rear has been upgraded already to an 8.5 sourced from an 86 442. I upgraded the axles, differential and gears. Differential is a Detroit locker and gears are 3.90's.

I'm trying to figure out (just because I don't know) if the stock shifter cable/bracket will work on any BOP TH350 or do I need to use the stock transmission and have it upgraded accordingly?

The shifter in this car is a big deal to me preserving. It needs more power than 170ish hp it was born with, but I don't want to deviate too much from its identity (shifter,wheels,paint)