Low compression 360 cam suggestions

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petethekiller

petethekiller

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Hey all, I have a fresh remanufactured 1978 360 short block that I want to use to build a budget hot rod motor for my 75 d100. It has .040 cast dished pistons so I am not expecting much for compression. I will be using a set of speedmaster heads and air gap intake.... I would love to have rev happy engine that has great mid range power.... Idle quality is not important (choppy s good but not required). My budget will have me stay with a Flat tapped cam... Please offer your suggestions

thanks
 
Isky 280 Mega cam. 'Rev happy'. I presume that means will get into the higher rpm range. That will mean a rough/lopey idle. If you do not want another failure, find some factory lifters & have them re-faced.
 
Best. Compared to...what? The cam I suggested has 0.040" more lift & modest advertised duration.
 
I put the summit 6900 in the exact same spec 360 40 thou over dished piston motor back in 2012 when I built my motor and put on an edelbrock manifold and a summit 650 vacuum secondary carb and use factory exhaust manifolds with a single 2.5 inch exhaust with a single muffler ( I hate noisy droning exhaust on long drives) and run a 2.92:1 diff with 14 inch rims and 215/65 tyres
I get reasonable economy on the open road around 25 mpg and while not the quickest off the mark it is not a snail either, I built it as a cruiser not a racer
 
petethekiller said:
Hey all, I have a fresh remanufactured 1978 360 short block that I want to use to build a budget hot rod motor for my 75 d100. It has .040 cast dished pistons so I am not expecting much for compression. I will be using a set of speedmaster heads and air gap intake.... I would love to have rev happy engine that has great mid range power.... Idle quality is not important (choppy s good but not required). My budget will have me stay with a Flat tapped cam... Please offer your suggestions

thanks
Click to expand...
Here's a video on a mild low cr 360 from 225 hp 2bbl to 387 hp 4bbl cam etc.. and few steps in between. Worth a watch.

 
It's really up to you, people could make arguments from stock to fairly wild.
I'd be shopping for around 215-225 intake duration on a 110 ish LSA with something like a .475-.500+ lift.
 
Seems like nowadays when it comes to SBM FT cams…….. there’s what you’d like…….. and what you can actually get.
Which are often not one in the same.
 
And odds are, when you killed the other flat tappet cam, it wasn't the cams fault. Its almost always in MY experience, improperly ground lifter faces
 
PRH said:
Seems like nowadays when it comes to SBM FT cams…….. there’s what you’d like…….. and what you can actually get.
Which are often not one in the same.
Click to expand...
Have you seen when you order a cam, get it, check it, and its not what you ordered?
 
ValiantRacing said:
Have you seen when you order a cam, get it, check it, and its not what you ordered?
Click to expand...

Are you asking if the cam is boxed wrong(part number on cam and box don’t agree), or the part number is not what you ordered?

Or the measured specs are not correct for the number on the cam?

I don’t recall having any of those scenarios play out.

Edit- I take that back……..
I had a SBC roller cam that was pretty far off the advertised specs.
It also didn’t really match any of that suppliers other catalog cam specs.
Cam was an off the shelf grind with the part number stamped right on it.

I was discussing it with a customer who also had a cam from this supplier. I urged him to measure his cam…….which he did……and it was also pretty far from the advertised specs.

I’m remembering a couple of others…..
One was a cam from a friends Pontiac stocker…….there was an issue with all the exhaust lobes not getting finished correctly.
Another was a lift rule oval track cam for a SBC where the exhaust lobes didn’t measure what the lobe master sheet called for.
There was the typical “that’s impossible” talk from the grinder, but in the end, it turned out that the lobe master had been made wrong.
 
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petethekiller said:
I will be using a set of speedmaster heads
Click to expand...
petethekiller said:
It has .040 cast dished pistons so I am not expecting much for compression.
Click to expand...
petethekiller said:
budget hot rod motor for my 75 d100.
Click to expand...
petethekiller said:
that has great mid range power
Click to expand...


and what do you expect the Scr to come in at?
and just how heavy is that D100?
With what rear gears/what trans.

It seems to me that you are looking for a miracle.
If it's mid-range torque you want, yur gonna need Pressure. But yur also gonna need the rpm to be at the road-speed that you want it to be at.
If it's power you want, yur gonna need all the usual go-fast stuff, including a hi-stall TC; and then the lack of compression won't hurt as much.
Rev happy will depend on what gears the beast is hooked to. Say like 2.94s will go from 1800stall @ zero mph to ~5400@60mph still in first gear.... with 29s. Not exactly rev-happy, if it takes 3 minutes., lol. If peak torque hits at 4000, that would be about 44mph, so, you'll have a bit of wait until the engine gets up on the cam. In other words;
for lack of torque, you need a higher stall to find where the power is, and you'll need to change the rear gear so you can use TWO transmission gears to get to 60 mph. Of course, that means no more hiway cruising with a 3-speed auto.
Ok so, have you priced a new TC and gears, installed?
How does that compare to a proper zero-deck block with flat-tops, and small closed-chamber heads? It doesn't take much to get a 360 up to in the range of 10.7 to 11/1, which you can then parlay to pressure from 175 to 195. as compared to ~120 and less, with the current combo, and some of the recommended cams.
And then you can run a serious cam, and smoke the tires, maybe, all the way to 60 mph. From there you can fine tune the rpm to the speed you need it to be at.

Ok now, the thing is this,
at 120 psi yur 360 will be a turtle on the rev-happy-in-Neutral, scale.
Whereas, at say 185psi, a good number IMO, it will hit the rev-limiter with authority.
Yes, you will, need a rev-limiter even with an automatic, cuz that engine, without the recommended oiling mods, will not make many trips past 6000 before it starts throwing rod bearings.

You can skip all this foolishness, and just put the stock top-end and cam back on/in it, but with a 4bbl, and I would still run a free-flowing exhaust, (headers preferred), and stall the beast at about 2800. Then, maybe later, get some gears.
IIRC the factory cam is about 252/262/112 Peak power might be around 4500 rpm, but with the big-port heads, and a 112Lsa, that should pull to 5000 in your application. With 2.94s and 29s that comes to about 56mph @5000 still in first gear. and cruizing, 65=about 2300. Give her the timing she needs and lean her out, and see what happens.
These are my opinions.

Yur gonna do what you want anyway, so ......
Let the flaming commence. I ain't coming back.
 
AJ/FormS said:
and what do you expect the Scr to come in at?
and just how heavy is that D100?
With what rear gears/what trans.

It seems to me that you are looking for a miracle.
If it's mid-range torque you want, yur gonna need Pressure. But yur also gonna need the rpm to be at the road-speed that you want it to be at.
If it's power you want, yur gonna need all the usual go-fast stuff, including a hi-stall TC; and then the lack of compression won't hurt as much.
Rev happy will depend on what gears the beast is hooked to. Say like 2.94s will go from 1800stall @ zero mph to ~5400@60mph still in first gear.... with 29s. Not exactly rev-happy, if it takes 3 minutes., lol. If peak torque hits at 4000, that would be about 44mph, so, you'll have a bit of wait until the engine gets up on the cam. In other words;
for lack of torque, you need a higher stall to find where the power is, and you'll need to change the rear gear so you can use TWO transmission gears to get to 60 mph. Of course, that means no more hiway cruising with a 3-speed auto.
Ok so, have you priced a new TC and gears, installed?
How does that compare to a proper zero-deck block with flat-tops, and small closed-chamber heads? It doesn't take much to get a 360 up to in the range of 10.7 to 11/1, which you can then parlay to pressure from 175 to 195. as compared to ~120 and less, with the current combo, and some of the recommended cams.
And then you can run a serious cam, and smoke the tires, maybe, all the way to 60 mph. From there you can fine tune the rpm to the speed you need it to be at.

Ok now, the thing is this,
at 120 psi yur 360 will be a turtle on the rev-happy-in-Neutral, scale.
Whereas, at say 185psi, a good number IMO, it will hit the rev-limiter with authority.
Yes, you will, need a rev-limiter even with an automatic, cuz that engine, without the recommended oiling mods, will not make many trips past 6000 before it starts throwing rod bearings.

You can skip all this foolishness, and just put the stock top-end and cam back on/in it, but with a 4bbl, and I would still run a free-flowing exhaust, (headers preferred), and stall the beast at about 2800. Then, maybe later, get some gears.
IIRC the factory cam is about 252/262/112 Peak power might be around 4500 rpm, but with the big-port heads, and a 112Lsa, that should pull to 5000 in your application. With 2.94s and 29s that comes to about 56mph @5000 still in first gear. and cruizing, 65=about 2300. Give her the timing she needs and lean her out, and see what happens.
These are my opinions.

Yur gonna do what you want anyway, so ......
Let the flaming commence. I ain't coming back.
Click to expand...
Here's the dyno result's to that video in post 12, Where is the supposed loss of torque over stock 2bbl low cr 360 ? (1. Final Baseline in Blue is like 340 lbs-ft peak) every single mod (including both cams xe256h and xe268h) is making about 50 lbs-ft over stock at 2500 rpms and almost making a 100 lbs-ft at peaks, look at all that extra power from 2500, possibly 2000 rpms and up to 5500 + rpm.

1743744574694.jpeg


 
AJ/FormS said:
If peak torque hits at 4000, that would be about 44mph, so, you'll have a bit of wait until the engine gets up on the cam. In other words;
Click to expand...
Notice that xe268h cam makes peak torque at 4000 rpm but also notice it makes way more torque practically everywhere by a huge margin than the stock 360?
Just cause it peaks at 4000 rpms doesn't mean it don't make useful torque at lower rpms also.
 
273 said:
Notice that xe268h cam makes peak torque at 4000 rpm but also notice it makes way more torque practically everywhere by a huge margin than the stock 360?
Just cause it peaks at 4000 rpms doesn't mean it don't make useful torque at lower rpms also.
Click to expand...
pfft! you get outta here with your facts and figures and ****, man!

i think the only thing AJ hates more than 318's are 360 2bbls
 
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