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Smallblock 360 cylinder head questions
#541577
11/30/09 11:44 PM
11/30/09 11:44 PM
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Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
1swingin
OP
mopar
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OP
mopar
Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
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I have posted many questions on here and got my dart into the tens with all of your help. Thanks guys! Now iam swiming in uncharterd water and i dont know anything about small blocks. I have a fresh early 70s smallblock with a recent stock rebuild. It has stock 340 j heads,rpm intake and a 340 cam. It runs great but i cant leave anything alone! I picked up a 11 in. 2800 stall converter and an old school mp 484 cam. Heres my delema. Iam at about 9.1 compression and thats not enough for that cam. So magnum heads,right? That means rockers,poshrods,headbollts,money,money,money! Iam trying to get to 10 to 1 on the cheep. I can get a set of low mileage magnum heads for free but what else would i need?(pushrods,rockers,etc.)and will they outflow the js? I could just deck the hell out of the js but thats not the right way to do it and will probably give me more problems with geometry. Any suggestions? Should i just throw the cam in and go with it? Iam trying to get mid to low 13s out of a 70 cuda. I got a fresh 727 w/2800 stall,4,10s, dual plane rpm,eddy 750. I will spray it if i have to! Thanks for the help boys! 
"I aint here on buisness baby,Iam only here for fun"
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Re: Smallblock 360 cylinder head questions
[Re: 1swingin]
#541579
12/01/09 12:05 AM
12/01/09 12:05 AM
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Joined: Jan 2005
Posts: 12,478
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,478
Kalispell Mt.
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With a stock bottom end 72 360 and the thin .028 mopar head gaskets my 360 is 9.0 compression exactly. I am running magunm heads and actually CCd everything out. It wasa really bad the way it came from the factory  I have an M1 single plane intake a comp XE268 cam and even with the 2.76 gears has some nice bottom end punch but I still have the stock spring in it for break in and have not had it over 4000 yet. I also only have a 2000 stall converter. You will have a slightle bigger cam but also more gear and converter so it should not be a too much of a slouch. The magnum heads flow better volume and quality OOTB than a J head and have WAY better chambers, 10 valve cover bolts, machined valve cover rails, no water in the exhaust bolt holes, no heat crossover, 1.6 rockers, 2 lbs lighter and most of them have less wear because they were in EFI engines instead of carbed motors that allowed raw fuel into the oil and wears out the guides. I think you should just throw together what you have, magnum heads mopar cam 4.10 gears 2800 converter RPM intake and with the chassis sorted properly (not hard to do at that power leval) you should easily run low 13s 
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Smallblock 360 cylinder head questions
[Re: 1swingin]
#541580
12/01/09 12:09 AM
12/01/09 12:09 AM
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Joined: Jan 2005
Posts: 12,478
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,478
Kalispell Mt.
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I think only one head bolt needs to be changed. Your lifters in the motor should have PR oiling already, it is hard to find one that does not have PR oiling any more. Rockers are a JY away. I may even have an extra set I would part with cheap, I will look tommorow.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Smallblock 360 cylinder head questions
[Re: HotRodDave]
#541581
12/01/09 12:31 AM
12/01/09 12:31 AM
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Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
1swingin
OP
mopar
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OP
mopar
Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
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I thought the intake bolts were straight up and down and the early ones are angled. Let me run this one past you guys. I grab the low mileage heads,rockers,pushrods from the low mileage 318 magnum my buddy has,take a die grinder to massage the bolt holes on my intake,use the magnum head bolts and let her rip! will the magnum boltdown rockers work? what pushrods should i use, the early ones or the magnum ones? There is someone selling a whole setup on parts for sale but he wont budge on the price! Iam a bigblock guy but i have been knocked off by alot of smallblock cars so i know they can run!!!
"I aint here on buisness baby,Iam only here for fun"
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Re: Smallblock 360 cylinder head questions
[Re: 1swingin]
#541582
12/01/09 12:47 AM
12/01/09 12:47 AM
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Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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stock pushrods from magnum wont work...too short.
stock pushrods from LA 360 wont work...no pushrod oiling...
double check the lifters to make sure they will oil thru the pushrod...
magnum heads have vertical intake bolts..
LA heads are at angle...
Tony
70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Smallblock 360 cylinder head questions
[Re: 1swingin]
#541584
12/01/09 12:58 AM
12/01/09 12:58 AM
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Joined: Dec 2007
Posts: 486
IL
knyech1
mopar
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mopar
Joined: Dec 2007
Posts: 486
IL
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I agree with HRD about the throwin together what you have with 4.10s. I had a duster basically stock 318 (smaller hyd cam) with 3.91s and 26in cheap radial tire ran 14.2 in the quarter.
As far as the pushrods and intake bolts: the bolts are straight up not angled on magnum heads. Pushrods: well the magnum engines oil up the pushrods, and what I was going to do (since I WAS thinking about a magnum head conversion) was take the lifters out of a motor (roller) put a roller cam in it, buy some chevy roller rockers (way cheap it's worth it) and have the heads re-tapped for that size studs (forgot what size sorry), and pray that the pushrods fit that came out of the same motor I got the lifters from. Mopar Performance makes a conversion kit, uses Jeep roller lifters. Hopefully this helps you.
If you want I have the stock rockers, stock pushrods still, if you want that stuff just pay me for shipping it is just sitting here. The stock rockers will work on those heads, but IIRC the magnum heads block off the oil passages on an LA block so you HAVE TO make sure you get lifters and pushrods that oil the same way a magnum does.
knyech1-
'71 Sassy Grass Demon 340/904. Pump gas, 1.61 60ft, 7.439 1/8 @ 95mph, 11.824 1/4 @ 111mph
"Not too bad for a pump gas 340, full of used parts and hillbilly ported stock heads." - V.B.
'03 2500 5.9L HO 6-spd on 35's. 395hp/755ft-lb at tires.
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Re: Smallblock 360 cylinder head questions
[Re: knyech1]
#541585
12/01/09 01:19 AM
12/01/09 01:19 AM
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Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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unless the 318 block is a "roller motor" you can not use the stock magnum roller lifters...
no place to bolt on spider to hold down the dogbones that hold the roller lifters in place..
retro lifters are pretty expensive.
magnum use 5/16 studs.....hughes and compcams sells kits to install roller rockers without doing any drilling...
Tony
70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Smallblock 360 cylinder head questions
[Re: knyech1]
#541587
12/01/09 01:36 AM
12/01/09 01:36 AM
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Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
1swingin
OP
mopar
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OP
mopar
Joined: Nov 2007
Posts: 521
somewhereintheswampsofjersey
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Someone is selling a complete magnum head setup with bigger ports,adj,rockers,bigger valves,proper angled intaks bolts,pushrods,etc. everything to do the swap for 900 bucks. on smallblock parts for sale. Should i just sell a kidney and buy that?
"I aint here on buisness baby,Iam only here for fun"
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Re: Smallblock 360 cylinder head questions
[Re: 1swingin]
#541588
12/01/09 09:06 AM
12/01/09 09:06 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
I thought the intake bolts were straight up and down and the early ones are angled. Let me run this one past you guys. I grab the low mileage heads,rockers,pushrods from the low mileage 318 magnum my buddy has,take a die grinder to massage the bolt holes on my intake,use the magnum head bolts and let her rip! will the magnum boltdown rockers work? what pushrods should i use, the early ones or the magnum ones? There is someone selling a whole setup on parts for sale but he wont budge on the price! Iam a bigblock guy but i have been knocked off by alot of smallblock cars so i know they can run!!!
pushrods, you'll need to get a length checking pushrod, and see how long you need for a flat tappet, and then order the right length hollow rods from summit stock pushrods will be ~.7" too short because of the roller lifters. 7.625-7.65" should be in the ballpark. intake, you can try that, not sure how good it will work. LA intake bolts are 83 degrees from the face of the head, magnums are 45. that's a lot of angle to make up. you may have sealing issues. you can make a jig out of some angle iron & black pipe on an LA head to redrill the magnums, or use a mill. I did mine on a mill, setting it up at the proper angle (7 degrees from vertical) and using an LA intake gasket to double check my positioning. or just buy a magnum specific intake.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Smallblock 360 cylinder head questions
[Re: S/ST 3040]
#541591
12/01/09 09:41 AM
12/01/09 09:41 AM
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Joined: Jun 2009
Posts: 705
Michigan
Hemiroid
super stock
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super stock
Joined: Jun 2009
Posts: 705
Michigan
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Quote:
That seems like an awful lot of trouble for a point of compression.
Keep the kidney and mill the heads. 
 I wouldn't even worry about milling the heads.
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Re: Smallblock 360 cylinder head questions
[Re: HotRodDave]
#541596
12/01/09 11:08 PM
12/01/09 11:08 PM
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Joined: Oct 2008
Posts: 492
South Jersey, NJ
DragDart360
mopar
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mopar
Joined: Oct 2008
Posts: 492
South Jersey, NJ
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Quote:
With a stock type rebuild and unmilled heads he is at an advertised 9 to 1 compression and in actuallity he is more like 8 to one. Milling the heads that much also requires milling the intake or the intake face of the head, milling the head that much will take away a lot of your valve cover gasket surface, milling the intake means you will have a hard time ever selling that intake and if you ever want to swap intakes you will have to get your new intake milled also. Sounds like a lot of work for 1 point compression any way you look at it
.030-.050 off the head is not very much gasket area. I have heads that were milled .030 off the block mating surface and used 3 different intakes without milling either mating surface head or intake, no leaks.
If you mill the intake mating surface of the head any intake will fit. Why would you want to mill the intake instead?
70 Dart Swinger, 2850 lbs
SB 408, Bullet roller 264/268 @50 .636 SSDS stage 2 Edelbrock heads, 1 7/8 Headmans, 1050 dominator by Dom, 9.867 @ 133
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