Looking to make some more power, welcoming ideas/advice

[GRTfast]

I have a big block in my scratch built rod.

specs are:

0.030 over 454. 2 bolt main
forged crank, H beam rods
comp cams "Thumpr" hydraulic roller (I know, I know..)
https://www.compcams.com/thumpr-227-241 ... 6-454.html
Federal Mogul forged pistons
9.5:1
Brodix bb2 race rite rectangular port heads
RPM air gap with divider filled in (improved low RPM cruising manners, light bucking was an issue, probably from the amount of overlap the cam has)
QFT 1050 w/mechanical secondaries
1 7/8 headers into 3.5 collectors, primary tubes ~28 inches (kinda short, necessary for my space constraints)
HEI, 22 initial, 40 all in at 2800, 10 degrees vacuum advance

It makes right at 500 crank HP at 5600 RPM and 532 Tq at 4200 RPM on the dyno, then falls on it's face hard.

The car is 2600 lbs, M23 autogear 4 speed, mustang cobra 3.27 rear end.

I am getting the itch to bump the power up, while maintaining the drive-ability it currently has. Trying not to break the bank.

Ideas?

[mt-engines]

its out of cam.. needs more cam
also needs more intake.

[dannobee]

Have Mike spec you a cam.

[econo racer]

Those heads are pretty big for such low compression and low rpm.

[GRTfast]

Yeah I realize the motor is pretty mismatched. I’ve considered different heads to get the compression up a bit, and a different cam.

What is a safe compression number for Florida heat and pump gas? 10:1, 10.5:1?

With the right hydraulic roller, what could I expect to make HP wise if I kept the rest of my combo the same? What about if I picked “better” suited heads?

[econo racer]

A good set of oval ports and 10-1 compression is good.

[GRTfast]

A good set of oval ports and 10-1 compression is good.

What I’m getting at though is, say I do a different set of heads and a cam. At its root, it’s still a street build with tall-ish gearing so it needs to behave low end and mid range. Can I expect to get another 100hp and retain the low range mannerisms, or possibly even improve them if the cam has less overlap?

[bobmc]

valve spring issues might be limiting your rpm, try shimming? I would keep the heads and spend that money on stroker crank and pistons

[GRTfast]

valve spring issues might be limiting your rpm, try shimming? I would keep the heads and spend that money on stroker crank and pistons

The valve springs are the ones that came with the Brodix heads, they are a bit overkill. The cam is advertised to top out at 5500, I don't think I am losing comtrol of the valves.

Basically a more direct way to ask my question is, will the right cam yield appreciable benefits without changing the rest of my setup? If not, what else needs to be changed? What kind of power can I expect to gain from just a cam swap, and from a cam swap with a little more compression and heads better suited to Hydraulic roller street cam RPM ranges?

[Little Mouse]

You dont have one of those monster size bore engine. Cant see any reason with aluminum head you cant run 10.5 compression. Far as I know the thumper cams have silly amount of exhaust duration split. Were me I would get rid of the HEI dist, most overrated thing since teenage nuki.. Up the compression and put a better cam with all the lift you can throw at it with those big heads. Ya if you can spend the money a good set of aftermarket oval port heads like AFR would certainly be better for what your trying to do.

[bobmc]

what are the gear ratio's in that trans? what rpm are you cruising at now? vacuum at cruise?

[GRTfast]

what are the gear ratio's in that trans? what rpm are you cruising at now? vacuum at cruise?

1st 2.994
2nd 2.043
3rd 1.468
4th 1.0


lowest RPM I will cruise is about 1800, it gets a little unstable below that. Not sure about cruise vacuum.

[mt-engines]

Yeah I realize the motor is pretty mismatched. I’ve considered different heads to get the compression up a bit, and a different cam.

What is a safe compression number for Florida heat and pump gas? 10:1, 10.5:1?

With the right hydraulic roller, what could I expect to make HP wise if I kept the rest of my combo the same? What about if I picked “better” suited heads?

the heads are fine. you would be better off spending the 3k on stroking it and throwing a 3.55 gear at it. you want power, build it bigger or spin it more. why lug the engine and expect performance.

[mt-engines]

You dont have one of those monster size bore engine. Cant see any reason with aluminum head you cant run 10.5 compression. Far as I know the thumper cams have silly amount of exhaust duration split. Were me I would get rid of the HEI dist, most overrated thing since teenage nuki.. Up the compression and put a better cam with all the lift you can throw at it with those big heads. Ya if you can spend the money a good set of aftermarket oval port heads like AFR would certainly be better for what your trying to do.

have you ever owned a pair of AFR heads or are you just one of the bandwagon types?

why would he buy a new set of heads, when his exact combo with stock heads would yield the same power?

whats wrong with an HEI? Why is it so overrated?

even stroking it wont help the top end part because of the intake manifold. put a single plane on it. Or rework the Dual plane.

[CamKing]

Basically a more direct way to ask my question is, will the right cam yield appreciable benefits without changing the rest of my setup?

Yes. That cam is way off.
You need more Intake Duration, more Valve Lift, and a wider LSA

If you want to use the springs that cam with the head, I recommend:
Cam# BBC, HR73353-75348-110
233/240 @.050"
.353"/.348" Lobe Lift
.600"/.591" Valve Lift
110 LSA

If you can change springs, to handle more lift, I recommend:
Cam# BBC, HR73389-75375-110
236/241 @.050"
.389"/.375" Lobe Lift
.661"/.637" Valve Lift
110 LSA