Making 300+ with a 360 is easy.
360 Mild Build Questions
- Thread starter KCBones
- Start date
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Babyblue66
Cool dude
I recently built a 8.8 to 1 360 with a Hughes cam and a performer intake with no modifications. 2.02, 1.60 valves and some pocket porting. Nothing special. Made 354 hp 388 lbs on the dyno.
Freshen yours with a good valve job. A mild cam and you'll easily make 300hp. Figure out the compression ratio and pick a cam. It's not complicated, though some people make it so.
Freshen yours with a good valve job. A mild cam and you'll easily make 300hp. Figure out the compression ratio and pick a cam. It's not complicated, though some people make it so.
I used motor oil on used heads to get an idea of the chamber size. It doesn't poor out quite as fast past non sealing valves.
Go for it. Nothing better than firing up and engine you built for the first time, except maybe the first drive after breaking it in to find out what its got.
@273 has posted a good video where you can copy what you see.
The bug question(s) is;
What size rear end and gears do you have now?
Size tires?
Who or manual transmission?
If automatic, is a torque converter change something you can afford or want to do?
Have you figured out what compression the engine is?
Is it the original engine?
Answer these questions or your just flying blind.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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IMO;
I think you ought to have the bores checked with a dial-bore guage. You can't see taper nor out of round, but your rings will ; and if the rings get to sliding around in the grooves,the engine will soon begin to lose cylinder pressure, which, at 8/1 Scr and with a longer-that-stock intake duration, is gonna make for a lazy bottom end.
BTW
A one thousanth change in bore size equates to over three thousandths change in ring gap. If you set your gaps tight at the top, they will be even tighter at the bottom.
I think you ought to have the bores checked with a dial-bore guage. You can't see taper nor out of round, but your rings will ; and if the rings get to sliding around in the grooves,the engine will soon begin to lose cylinder pressure, which, at 8/1 Scr and with a longer-that-stock intake duration, is gonna make for a lazy bottom end.
BTW
A one thousanth change in bore size equates to over three thousandths change in ring gap. If you set your gaps tight at the top, they will be even tighter at the bottom.
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That J head is probably a U head with half the U either machined off or mis cast. Lots of them are like that. If it's the same casting number, the head is the same.
Yeah like with a dead cylinder.
If you only have one cylinder head, it would make it tougher. LOL
I like that youtube 273 posted up. The 360 with a mild cam, 4 barrel and headers will make 300 hp all day long. The XE250H is similar in lift and dur at .050 as a 340 cam. Close... I think comp says that 250H cam ranges to about 4800 and this one pulled a little past that point.
Put a larger cam in it like a 268 voodoo or XE268 and it will make a bit more ponies... and still be easier to tune and drive on the street. Even with a stock converter. Notice how tight the TQ was at the bottom of the pull, you'll never notice that difference.
As the guy pointed out with headers, the benefit isn't necessarily peak delta, it's the improvement throughout the range. The delta in the 2500-3500 area means the vehicle accelerates faster, plus when tuned correctly MPG increases with headers from that efficiency.
And that youtube also supports my contention that the old 340 dyno derby build with stock heads/rockers, air gap, headers and a XE268h cam made 391hp... sure it did! This 360 with more cubed, touched up heads and closer to true 1.5 rockers didn't make that 391hp number. HMMMMM....
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.....and yet when you say "300HP" people shrug it off. .......and those are the ones who've never felt an honest 300HP in a car capable of putting every bit of it to the ground. It's a fun place to be in a light street car.
KCBones
Well-Known Member
I appreciate all the input, differing opinions, and suggestions. Like I said, it's a first build...sort of a science project for my own enjoyment. I had some Christmas money from my wife so I ordered a dial bore gauge, a 100 ml burette (1 ml = 1 cc, sometimes metric makes a little sense), a stand for it, a plexiglass CC plate, and a set of cylinder head stands. I plan to strip the engine down to the block, start taking and recording some measurements, and I'll cc the heads. I spoke to my local auto machine shop and he said they can hot tank the block and heads, check the block and crank, bore it if necessary, and help me out with what I need to order for about $500.00. I'm sure if I need anything done to the heads, such as hardened valve seats or cut for bigger intake valves, that will be extra. I plan to use the existing cast crank with new bearings if everything checks out, put new pistons in it (KB or Sealed Power Hypereutectic), and use the stock rods, maybe with some upgraded rod bolts. I'm not sure about the cam yet, I'd like something with a somewhat lumpy idle. The intent is to use some headers I have and a full dual exhaust. I'll dial a lot of this stuff in with my local machine shop, they do a lot of performance engines and a lot of Mopar stuff. For the heads, I also got a porting abrasive kit to knock off some of the casting flash and maybe check out some YouTube videos on some very basic porting. I was also considering some stainless intake and exhaust valves. I hope to end up in the 9.0 to 9.5:1 compression ratio. I will probably also look at gasket matching the intake just because it's an intake I already have and may look at upgrading in the future so I figured it would be fun to play with this one a little bit.
Someone asked about auto/manual trans, rear end, gears, tire size, etc... I don't know about much of that yet. I picked up an A833 4-speed out of a '69 340 Dart and found a good bellhousing to go with it. I need a bunch more parts for the 4-speed conversion. I have a line on an 8-3/4 A-body rear end but haven't got it yet. If I can get my hands on that, it's an open rear but a friend has a sure grip with 3.55 gears he said he would sell me. My Dart is a 318 / 904 Torqueflite auto with a 7.25 rear end. My original plan was to reuse all of that until the 4-speed kind of fell in my lap and I found the 360 core. Then everything changed. Wheels and tire size seem like a way off decision at this point but I've always been a fan of regular old Cragar S/S rims, old school. Tire size will depend on what I can cram in the rear wheel wells. Fronts will be a bit skinnier. I like the original MM1 Bronze paint and may even put the black vinyl roof back on it, that could go either way.
For now, though, it's all about some rust repair and an engine/trans rebuild and swap. I hope it can look as good as some I've seen in this forum but I really just want a good, fun driver.
Any additional comments and suggestions are always appreciated. Once I get rolling, I'll start a new thread and upload some pictures as I go, maybe some of you can warn me before I screw something up.
Someone asked about auto/manual trans, rear end, gears, tire size, etc... I don't know about much of that yet. I picked up an A833 4-speed out of a '69 340 Dart and found a good bellhousing to go with it. I need a bunch more parts for the 4-speed conversion. I have a line on an 8-3/4 A-body rear end but haven't got it yet. If I can get my hands on that, it's an open rear but a friend has a sure grip with 3.55 gears he said he would sell me. My Dart is a 318 / 904 Torqueflite auto with a 7.25 rear end. My original plan was to reuse all of that until the 4-speed kind of fell in my lap and I found the 360 core. Then everything changed. Wheels and tire size seem like a way off decision at this point but I've always been a fan of regular old Cragar S/S rims, old school. Tire size will depend on what I can cram in the rear wheel wells. Fronts will be a bit skinnier. I like the original MM1 Bronze paint and may even put the black vinyl roof back on it, that could go either way.
For now, though, it's all about some rust repair and an engine/trans rebuild and swap. I hope it can look as good as some I've seen in this forum but I really just want a good, fun driver.
Any additional comments and suggestions are always appreciated. Once I get rolling, I'll start a new thread and upload some pictures as I go, maybe some of you can warn me before I screw something up.
If you are using the factory 360 pistons you'll be lucky to get 8-1. However all is not lost. Be conservitive with the cam if this is your route. The compressin is so low with stock pistons that 5 cc would barely matter. I bult a 360 years ago. Brush hone with a Summit rering, bearing, timing chain and cam kit. Like [email protected]" Lapped the valves with lapping componnd and a drill. TQ, stock TQ intake, stock truck manifolds. Stock pistons, slight bore wear. Just made sure the ring gap was big enough at the bottm. As get got larger up the bore. It actually ran pretty damn good. Done many higher end builds a swell. Just shows what you can build with low $. Better comression is the first big step in building a 360 that runs well. Built another. 9.5-1 actual, Crane 214/224 .464, .471, Performer RPM, headers, Holley 750, 4.10 gear, 904 stock converter. It would click off 12.90's in a 67 Baracuda.
Doug
Doug
Low compression... get a cam cut on a 106-108 LSA and install it at 100-102. That will change the way it runs a lot.
Put a lot of cams bigger than should be in "truck" 360's a long time ago. Ran good that way.
Surface the head if possible and a thin head gasket might help boost static compression a bit.
Put a lot of cams bigger than should be in "truck" 360's a long time ago. Ran good that way.
Surface the head if possible and a thin head gasket might help boost static compression a bit.
Babyblue66
Cool dude
I used speed pro H405C pistons. Came out to 8.8 or so. They were $135.00 new from an e-Bay vendor. Very close to stock weight. It wouldn't have even needed balancing it was so close on the balancer. That was using 1971 heads with 66cc chambers and fel pro gasket.
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