Reasonable priced rockers suggestions

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AJ/FormS said:
OP
Is this on a stock 8/1 engine? Maybe a 360? How do you find the take-off punch?
That's a nice torquey cam, I had a similar one. But on an 8/1 engine, the bottom might still be a lil lazy . The cure is more compression,a lot more. And generally that requires either pistons or machine work. The latter will require different length pushrods again. If you're thinking along those lines, then it might be cheaper.....in the long-run.... to get the adjustable pushrods, and then you are set. Plus, you can set your lifter preload anywhere you want.
Those 1110 springs will rev to 7000 with about 1/2 turn preload. Not that,that cam will make power up there,but sometimes it's just fun to go there.
To make the most of that cam, the Scr needs to be up near 9.8, but it may need premium gas when you stand on it; 9.6 should be safe. The difference in torque from idle to maybe 3000 will be phenomenal. And of course with more compression comes more power. Some say as much as 8% per point, in which case, on a 280 hp engine, 1.8 points could mean; 40 hp. Personally, I don't build engines, but I have heard that half that is easy so the 9.8 over 8/1 is worth between 20 and 40hp on a 280 hp 360.
So if you're already up there, or if you already have a TC close to 3000; then just put me on ignore.

And BTW, have you checked to see if your heads will accept the .506/.518 lift?
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i POSTED A REPLY BELOW THISES COMMENTS BUT FUEL IS A PROBLEM, NO DOUBT sHE WAS RATTLING BEFORE.....
 
SgtLee511 said:
10.5 COMPRESSION 340 BALANCED 340 BUILT AND GARAGED SINCE THE EARLY 90'S, 3000 STALL, EDDY AIRGAP, 800CFM EDDY, WAS A MP 484 PURPLESHAFT, THEN CHANGED TO A COMP VERSION OF THE MP CAM, YES THIS MAY BE MORE CAM THAN I NEED, IVE BEEN BUILDING A ROADRUNNER 383 RESTORATION, I HAD TO STOP ON IT TO GET THIS CAR BACK TO THE SHOWS, SO MY MONEY IS IN SHORT SUPPLY, RIGHT NOW I NEED TO GET HER GOING, AND YES I HAVE SOME CONCERNS ABOUT THE CAM, BUT CANT CHANGE IT OUT AT THIS POINT. IVE HAD THIS CAR SINCE 1982, MY FIRST CAR LOVE OF MY LIFE, AND HAVE SOME CONCERNS ABOUT THE CAM, I DIDNT REALIZE WHAT I ORDERED, TOO BUSY BUILDING THE 383....HERE I AM...NEED TO MAKE IT WORK, BUT WONT BE REVING IT HIGH, 52 YEAR OLD COP.....
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That cam will be fine.
 
So you say this combo has already been running at one time, and it rattles, As in detonation rattle?

I would kindof expect that on a TRUE 10.5 Scr 340. But if the 340 is just a stock HO item with no machining of decks or heads, then premium fuel might cure it, and/or a slightly delayed or reduced timing.
But if the engine was optimized for the 284/484 and drag-racing.........then you may be in trouble. The ICA of your current cam is about 60*( I'm guessing cuz Hughes doesn't publish seat-to-seats, and when the do, they are measured differently than the "norm"), and the purple was about 66*. On a lower compression engine this would not have been a problem. But on an optimized for a 284/484 this might be pushing the limit, as you have discovered.
With the 3000TC, and for your application; you might be able to stay out of detonation with one of,or a combination of, the following, and in no particular order; a cooler running engine, cold air intake,delayed power-timing,smaller carb,reduced engine loading,reduced power-timing,running rich,retarded cam timing,and thicker head gaskets.
Low engine loading could be a more performance oriented rear gear, or a trans with a lower first gear; but this is getting extreme.
Cooler running is not running a 160 stat which may accomplish what you want, but at the expense of engine life and probably power. No,cooler running is ensuring that the cooling system can actually keep the temp at or near the selected thermostat rating.
I run a 195 stat, but the engine runs a rock solid 205. That's what you need, a spread of not much more than 10 degrees from the minimum to the maximum. Your engine might be fine with a 180*, if you can get it to run a maximum of 190, etcetera.
Cold air can make a world of a difference. An intake like an AirGap is a divorced from the valley design, and helps a lot.
Detonation is nothing more than uncontrolled burning in the chamber,usually because the chamber is too hot for the available fuel, and is most effectively reduced or controlled by lowering the chamber temperature. The first line of defense is always the compression ratio, and in this case probably the cheapest.....with thicker head gaskets.That cam really wants 9.8 or a tad less.
#1)The Wallace calculator spits the following out, for the current combo;
Static compression ratio of 10.5:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 8.62:1 .
Your dynamic cranking pressure is 176.10 PSI.
V/P (Volume to Pressure Index) is 143
These numbers,in bold, are usually reserved for aluminum heads.
My 367 runs a bit over that with aluminum heads , and is quite happy with 87E10
#2) This is about where you want to be, same combo as above but with reduced compression
Static compression ratio of 9.8:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 8.06:1 .
Your dynamic cranking pressure is 161.44 PSI.
V/P (Volume to Pressure Index) is 134
V/P Index Calculation
 
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AJ/FormS said:
So you say this combo has already been running at one time, and it rattles, As in detonation rattle?

I would kindof expect that on a TRUE 10.5 Scr 340. But if the 340 is just a stock HO item with no machining of decks or heads, then premium fuel might cure it, and/or a slightly delayed or reduced timing.
But if the engine was optimized for the 284/484 and drag-racing.........then you may be in trouble. The ICA of your current cam is about 60*( I'm guessing cuz Hughes doesn't publish seat-to-seats, and when the do, they are measured differently than the "norm"), and the purple was about 66*. On a lower compression engine this would not have been a problem. But on an optimized for a 284/484 this might be pushing the limit, as you have discovered.
With the 3000TC, and for your application; you might be able to stay out of detonation with one of,or a combination of, the following, and in no particular order; a cooler running engine, cold air intake,delayed power-timing,smaller carb,reduced engine loading,reduced power-timing,running rich,retarded cam timing,and thicker head gaskets.
Low engine loading could be a more performance oriented rear gear, or a trans with a lower first gear; but this is getting extreme.
Cooler running is not running a 160 stat which may accomplish what you want, but at the expense of engine life and probably power. No,cooler running is ensuring that the cooling system can actually keep the temp at or near the selected thermostat rating.
I run a 195 stat, but the engine runs a rock solid 205. That's what you need, a spread of not much more than 10 degrees from the minimum to the maximum. Your engine might be fine with a 180*, if you can get it to run a maximum of 190, etcetera.
Cold air can make a world of a difference. An intake like an AirGap is a divorced from the valley design, and helps a lot.
Detonation is nothing more than uncontrolled burning in the chamber,usually because the chamber is too hot for the available fuel, and is most effectively reduced or controlled by lowering the chamber temperature. The first line of defense is always the compression ratio, and in this case probably the cheapest.....with thicker head gaskets.That cam really wants 9.8 or a tad less.
The Wallace calculator spits the following out;
Static compression ratio of 10.5:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 8.62:1 .
Your dynamic cranking pressure is 176.10 PSI.
V/P (Volume to Pressure Index) is 143
These numbers,in bold, are usually reserved for aluminum heads.
My 367 runs a bit over that with aluminum heads , and is quite happy with 87E10
This is about where you want to be
Static compression ratio of 9.8:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 8.06:1 .
Your dynamic cranking pressure is 161.44 PSI.
V/P (Volume to Pressure Index) is 134
V/P Index Calculation
Click to expand...
 
SgtLee511 said:
Too much detonation on the mp purpleshaft
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Well in that case you're fubarred. The smaller cam with the earlier closing intake will only make it worse. There is no cure except to reduce your compression.
Here is what the 284 looked like with an ICA of 66*
Static compression ratio of 10.5:1.
Effective stroke is 2.52 inches.
Your dynamic compression ratio is 8.22:1 .
Your dynamic cranking pressure is 165.61 PSI.
V/P (Volume to Pressure Index) is 128
The emboldened numbers are borderline for the best pump gas.

Well there is a cure, called race gas lol.
 
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At a true 10.5Scr and say a bore of 4.06, your total chamber size is 74.1 cc
To get to 9.8Scr, you need a total chamber size of 80cc
Because your particular chambers seem to be fussy,and because of your stated usage, you might want to reduce your Scr a tad further to say 9.6, and that requires a total Chamber volume of 82cc.
It's a long way from 74.1 to 82.
You need either; a thicker gasket, or,to machine off the tops of those pistons.
8cc is .037 or so more gasket.

Or you could put in a specialty cam with a later closing intake, yet a similar at .050.
I think they call them Thumprs or Whiplash. This will reduce your cylinder pressure, perhaps , no.....I don't think there is one to bleed off 15psi;that's a lot. Lemmee go look. No those won't work either.
#3) You'll need a custom cam with a very wide LSA and a moderate duration; something like a 276/114 with an ICA of 68*
Static compression ratio of 10.5:1.
Effective stroke is 2.47 inches.
Your dynamic compression ratio is 8.08:1 .
Your dynamic cranking pressure is 161.96 PSI.
V/P (Volume to Pressure Index) is 124
Yeah that's getting closer....
#4) Or, and I like this one, put an MP292/108 in there at 70* ICA
Static compression ratio of 10.5:1.
Effective stroke is 2.43 inches.
Your dynamic compression ratio is 7.96:1 .
Your dynamic cranking pressure is 158.84 PSI.
V/P (Volume to Pressure Index) is 120
There ya go; that will work with your 3000TC and sound real nasty, and burn pumpgas all day long.
The penalty with that combo is the VP. Notice the 292 is down at 120, about what a stock 318 makes. Go back to combo #1, and see the current VP is 143. this would normally be a big problem, but with your 3000TC should be tolerable with 3.55s or better.Another bugaboo with this cam is that the power doesn't even start until in the mid 4000s and is still pulling hard deep into the 6000s, not exactly street-friendly,IMO.

So once again, it really boils down to fixing the compression .
 
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There certainly IS another cure besides reducing compression.

Run race gas. A mixture of five gallons to the rest super will probably suffice.
 
If you want to make the new cam a little more street friendly install it about four degrees advanced. That will move its sweet spot down a bit in the rpm range.
 
Uuuuh... his problem appears to be detonation... and advancing the cam will make it worse. Retard it is more like what is needed. Looking at the cam specs posted the cam has 4-5 degrees of ground-in advance already, so some retard may be in order.

But I would first:
- Examine the ignition advance and look at back off of that. I would expect that to be a good cure. BTDT on a true 10.2 SCR engine with mild cam; worked fine on pump gas. OP what is your initial (or base) timing?
- Next would be thicker head gaskets....
 
nm9stheham said:
Uuuuh... his problem appears to be detonation... and advancing the cam will make it worse. Retard it is more like what is needed. Looking at the cam specs posted the cam has 4-5 degrees of ground-in advance already, so some retard may be in order.

But I would first:
- Examine the ignition advance and look at back off of that. I would expect that to be a good cure. BTDT on a true 10.2 SCR engine with mild cam; worked fine on pump gas. OP what is your initial (or base) timing?
- Next would be thicker head gaskets....
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If I'm not mistaken that engine has not been fired yet...
 
SgtLee511 said:
Too much detonation on the mp purpleshaft
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What timing specs were You running?
What heads are these again?
Before buying pushrods, consider custom thickness head gaskets, depending on the quench/squish situation. You may be able to make it to safety with them.................
 
Krooser said:
If I'm not mistaken that engine has not been fired yet...
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It's a bit hard to follow but the engine has been running for limited miles over a lot of years and has been setting for a while.

Sgt Lee, just a dumb question: Is perchance the gas you are running on some old gas, or old gas diluted with some fresh gas? I ask, as crappy old gas will tend to knock a LOT. Just diluting it with fresh usually won't be adequate. ALL of the old crap gas has to come out....

Also, is your premium pump gas a 93 octane or a 91 octane?

I'll go back to the ignition timing. We (and perhaps the OP) don't know what we're working with here.
 
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