1975 360 bottom end power

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sorry guys I should have been more clear. It came with the Performer rpm cam in it. I suspect a lot of the bottom end power (or lack there of) is resulting from this cam. it picks up very quickly from 50 - 100 mph but doesn't have that low end power.
 
canadian duster said:
sorry guys I should have been more clear. It came with the Performer rpm cam in it. I suspect a lot of the bottom end power (or lack there of) is resulting from this cam. it picks up very quickly from 50 - 100 mph but doesn't have that low end power.
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Where is the cam set at? If it's advanced, that would move the torque curve up in the powerband.

The cam I'm installing can be advanced, but I am choosing to install it straight up to give me a broader torque curve.
 
Bomber,I know you are a smart guy, but I fail to see your Cordoba point. I'm not the cleverest guy, but I think you missed post #1. He's looking for more starting-line get up and go. Not one single mod you listed will help with that,with the exception of the TC and gears,which has already been mentioned.

The 360s biggest claim to infamy is it's mediocre compression ratio.And IMHO, until that is addressed, all the mods you do to it will be sub-optimum.Band-aids and crutches I call 'em. Sure with the go-fasts,the mid-range can pick up a tad, and the top-end might be a tad less sensitive to lack of compression. But without compression, the NA-engine will always be, soft on the bottom, and sub-optimum everywhere else.
So, on the OP's budget, how does a TC and gears compare to a set of pistons,and in the big picture of things (not quarter-miling), which will offer the most satisfaction in the long run?
TC and gears offer a quick improvement in get-upNgo. The TC has a great seat-of the-pants effect. But once you get into top gear they are done.The engine has to get you down the track and through the traps. Over the years those band-aids will cost you money at every fill up, and the engine longevity will suffer, and so will cruising comfort.
Now, how about the compression boost? Well firstly, the engine will make more torque, and more power.Then,it will return more mpg's, and it will be more responsive to throttle inputs.And then again; instead of requiring race gears and a 2800TC to affect a good "get-up-N-go", it might do quite well on 3.2s and 2600TC, or 3.5s and 2400. Less band-aid, less crutch. In the big picture, of SBM street driving, high compression has a big smile written on it.And finally, every single mod, stacked onto the optimized compression, will return a higher performance increase than the same mod on the low cr. That's got ear-to-ear grin, money in the bank, satisfaction, stamped aaall over it.

I've stacked stuff on LC-SBMs, before. Never again. Since I learned about Dcr, which never got mentioned before about 15years ago,it made a firm believer out of me. Before that, most of us just slapped stuff together in the hopes that it would work, or we hired someone else to do it and hoped he knew how to make it work. When I built my 360 in 99 there were no online Dcr-calculators. I had to work out every single combo longhand, using trigonometry and algebra, and there were no published Dcr targets. I was fully prepared to have to put water-injection on my combo, cuz everyone said 11.2 was too much for pump-gas. Turns out I coulda put even more compression into it.
Every building needs a firm foundation. A house built on a soft ground,will not stand for long.
 
IMO change that cam first. I have the Comp Xtreme energy and even though mine is probably bigger than what you need(284/296) it still maintained a great low end even on my low compression 318( I am building a 9.75 SCR 318 anyway). You could go with the Comp XE 268 that a lot of people seem to recommend.

Torque converter can help a lot as well, as long as you get one setup for your application.

What is your rear end gear ratio? Moving from 2.xx to 3.23/3.55 will help a lot.

Cylinder heads: Be careful in this area, larger combustion cambers will lower your compression and decrease low end, so will increasing the runners and valves themselves. So IMO don't mess with changing cylinder heads unless you know the combustion chambers are smaller and need more compression.

Long tube headers should in theory improve things across the board, but are a PITA to install, and on my nearly stock 318 did next to nothing...(seat of the pants and track), but most likely much better gains depending on the cam.

Ignition timing: A little more timing will help, could start with a better than stock distributor.

Intake and Carb: What do you have here? I think the stock 360 4 barrel stuff should be pretty good for low end, maybe even midrange.
 
Some updates I have:

Intake - performer rpm
Carb - edelbrock 600cfm (4053 I believe)
Timing 0 set at ~ 12
Idle: 900-1000 rpm
Cam - Performer RPM
DURATION AS ADVERTISEDINTAKE: 308°EXHAUST: 318°DURATION @ .050INTAKE: 234°EXHAUST: 244°LIFT @ CAM (Lobe)INTAKE: 0.325"EXHAUST: 0.34"LIFT @ VALVEINTAKE: 0.488"EXHAUST: 0.51"LOBE SEPERATION: 112°INTAKE CENTERLINE: 107°IDLE VAC @ 1000 RPM: 10"
 
canadian duster said:
Timing 0 set at ~ 12
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That's the timing at idle... not even close.

That engine will want at least 20* and fix the mechanical to hit your total number. The low end will increase a LOT!!!!

A side benefit will be a much cleaner idle as well.
 
Does thing thing barely idle? If that cam is really what you have, then that cam looks waaay out of line with the rest of the engine.. Several steps above a 268 and not even remotely like the Crower Baja Beast cam that Abodybomber referred to for his 360 with good torque. I'd run compression numbers first then if they are low, I'd pull that cam 1st thing, and put in something reasonable.

BTW, how do you use this car? Daily driver? Pure drag racing? Street drags? A lot of the combo that is best depends on your use. It will help everyone (especially YOU) to state your purpose for this car/engine.
 
I have the box from the PO that put the cam in and it matches up. It idles better now but still not great. I Will advance further and look at results.

This car will be street drags and driving around town. wont be drag racing at all.
 
Your intake and carb seem decent, unless the carb isn't tuned very well.

I am not sure how the 75 distributors are, I switched from points to a Mopar Performance distributor which is probably similar to the 75 except maybe for the mechanical advance. You need to set the initial at 18-20 then check the total mechanical to see where your at.

And again, get a better cam... :)
 
This will sound stupid but how are you accurate to 20 initial timing? I assume your using a different timing light than mine as the marks on the block only go +10 to -10
 
search "hillbilly timing tape"

I use a 35 year old inductive basic timing light. Never need any new fancy stuff.
 
canadian duster said:
This will sound stupid but how are you accurate to 20 initial timing? I assume your using a different timing light than mine as the marks on the block only go +10 to -10
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You can use that timing scale on the block (timing cover actually) as a scale to make more marks on the crankshaft than the one that is there.
1. Set the original crank timing mark to 0 on the timing cover.
2. Make a new mark on the crank lined up with the 10 ATDC mark on the timing cover. (10 degrees CW from the original crank timing mark.) This new mark will be your new 10 degree BTDC mark when it lines up with the 0 mark on the timing cover.
3. Move the original crank timing mark to 10 BTDC on the timing cover (move it CCW).
4. Make a 2nd new mark on the crank lined at 10 ATDC on the timing cover. (20 degrees CW from the original crank timing mark.) This will be your new 20 degree BTDC mark when it lines up with the 0 mark on the timing cover.
5. You can keep moving the crank another 10 degree to the left (CCW) and making new marks on the crank at 10 degreee intervals for 30, 40 and 50.

Or, just buy a stick-on timing tape for the crank damper!
 
I never said you can't improve low end torque but only was pointing out a stock engine has most of the right things to build low end torque. And actually pointed out to start with to check the health of the engine and to tune the engine for the basics. And pointed out exhaust and cam to build a boost in torque and hp plus gears which made a night and day difference with my cousins duster he went frim 3.23 to 3.91. And with compression the original OP never said anything about tearing in to the shortblock and adding compression is a little extreme for someone looking for a little more off the line power and I did cover it with the suggestion of EQ which will give him more flow and CR than with his head choice. And even though CR will help going more than 9:1 is gonna be hard with pumped gas and will help but ain't gonna set the world on fire with performance. So yes tuning and some mods will get the results he wants as long he doesn't have a sick engine to start with.


Edit-I see now with that engine combo and with no gears and stall why your engine seemed sick to me.

I'd go with the EQ heads and a lesser cam plus gears and stall.
 
I would first and foremost check to see if the mark on the balancer is true.
 
Lots of stupid ideas here spending your money. The smart thing is to optimize what you have FIRST, then decide if you want more. Get what you have tuned correctly and go from there. Tuning is FREE.
 
fishmens67 said:
at least 4.10 and 3000 stall. a weak shortblock will not support the rpm cam.
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tuning will help a bunch, in the end your combo will be headed here or a cam change.
you can add all the timing it will take, and still no lowend grunt
 
crackedback said:
search "hillbilly timing tape"

I use a 35 year old inductive basic timing light. Never need any new fancy stuff.
Click to expand...

Hell Ron, my old Penske is not even inductive LMAO

$_1.JPG
 
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