360 build

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A-BOMB360 said:
that overheating hubub is from the chevrolet camp. mostly anything over .030 over on those chev smallblocks you'll have problems. the 400 is EPIC for that. nevermind just the steam ports in the head. but yah generally .060 on a 360 is no problem.
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Oh yes,I remember distinctly a ride in my buddies mid 80's malibu that had a mild 400.He made a full throttle pass up Scott road hill in Surrey.Anyone who knows this hill knows it's quite steep,maybe better than a 10% grade. Anyways,there was steam jetting out of the breather after we pulled over. He cracked the heads...

The chev smallblock is a very light,thin casting.

Funny thing is I could hammer on that 318 all day long and never a problem.

Funny thing is the car was a dog.My 318 74 Duster beat the pants off it all day long with just a 4bbl,cam and duals.Still had ex manifolds too..I always seemed to have at least 2 car lengths on him,lol!

Ashton go to Mancini and have a look at the mopar performance engines that are discounted.Theres lots to look at.

http://chucker54.stores.yahoo.net/smblensh.html
 
thanks for the great help moper. ill be asking more questions as soon as i talk with my engine guy
 
Ashton,

I ran a low compression 360 in my 68 originally. I built it when I was 17 with limited funds. Like I alluded to in an earlier post, it was a cheapy Pep Boys rebuild. 7.823 to 1 compression, X heads, 508 MP hydraulic cam, stock pushrods and rockers, torker intake and 750 dp Holley. I had it in my Dart with a 3500 stall ,low gear 904, and a 4.56 geared sure grip 8 3/4. It made 297 at the rear wheels in street trim. The car ran 12 ohs at 110 in a 3200 pound car. If I had do it all over again I would cut the heads and increase the compression and I would not change the pistons. Leave it and put some cut heads on it and put a good cam in it and you wont be disappointed. I ran this motor for years with no problems. Good luck.
 
Are you sure it doesnt already have them? Did you get a longblock or shortblock? Sorry...lol Forgot....
 
They would be fine. But keep in mind you gain compression, but it's a very small port. So without some work, even the 340/460 intakes are a severe port mismatch and the engine will run out of steam pretty quick in terms of rpm. I think you would do better with a set of EQ Magnums.
 
how much more compression? im aiming for 9.0-9.5. What is necessary to make the intake work? This is my first engine (obviously), and my dads not a car guy, but he is into woodworking.
 
ashton1024 said:
how much more compression? im aiming for 9.0-9.5. What is necessary to make the intake work? This is my first engine (obviously), and my dads not a car guy, but he is into woodworking.
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Iron magnums are good for a max of 10:1 on pump gas. Because of a double quench chamber and a fast flame front they like lots of quench.About .034 should do it They also like a single pattern cam as the exhaust really needs no extra help from the cam.It's almost too good. In many cases guys run stock 1.6 ratio rocker on the intake and a 1.5 on the exhaust to try to maintain flow balance at 75%. I would use a magnum pattern eddy air gap as the magnum has no heat crossover and the intake will run very cool.The other option is to drill and tap the mags for la intakes.Then you have the best of both worlds available.
 
well..i got a great deal on a set of j heads from J-MacsMopars. Theyll be sent to the machine shop next week to be cleaned up. Wheres the best place to buy hardened valve seats? And could i port these myself? (im 15)
 
ashton1024 said:
well..i got a great deal on a set of j heads from J-MacsMopars. Theyll be sent to the machine shop next week to be cleaned up. Wheres the best place to buy hardened valve seats? And could i port these myself? (im 15)
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If thier going on a 318 no port work is needed.The ports are more than enough stock.However the chambers are large too and the head should be cut,otherwise compression will be no better than 7.5:1-8:1 with 360 heads.What year are they? They may already have induction hardened seats.

If these are jy heads be prepared to spend some bucks freshening them up.
 
not to be a smarta**, but there going on a 360 hence the thread titled "360 build". there 71 heads, so they dont have hardened seats. My machinist charges $60 for valve job+cleanup and $8 each for valve guide repair
 
Some may dissagree with me, but I wouldn't worry about the hardened seats. Unless you have a work truck or drive it for 100k, they'll last a long time.
My old job we built many performance engines, and unless the seats were damaged we didn't add hardened seats. The boss had engines he built years ago and they never had a problem.
 
For this build, I wouldnt put seats in it. With the 340/360 chambers and the short as built, you will have a true compression around 7.5:1. Use the MP thin head gaskets or it will be less than that. On the up side, piston to valve clearance is pretty good even with no valve reliefs. Have a valve job done and have the intake valves back cut as part of the valve job. It's a little extra $$ but will help out flow without touching the ports. I agree with what was said... dont port them.
 
Babyblue66 said:
Some may dissagree with me, but I wouldn't worry about the hardened seats. Unless you have a work truck or drive it for 100k, they'll last a long time.
My old job we built many performance engines, and unless the seats were damaged we didn't add hardened seats. The boss had engines he built years ago and they never had a problem.
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my sentiments as well....
 
ashton1024 said:
not to be a smarta**, but there going on a 360 hence the thread titled "360 build". there 71 heads, so they dont have hardened seats. My machinist charges $60 for valve job+cleanup and $8 each for valve guide repair
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Dont worry about it. Im famous for forgetting what the heck Im talking about in the middle of a conversation,lol. Sounds like your machinist is reasonable unlike the friggin bandits here in Canada.In fact I'll probably seek a good trustworthy machinist in Spokane.

Sounds like you got a deal on the heads. I would still have them cut...
 
any hp estimates? or cam suggestions. ive been looking at changing to a flat top piston, whats the benefit of having higher compression?
 
350 h.p is an easy build for a stock headed 360. You dont need to port the heads at this level.

9- 9.5:1 for compression,keep the cam under .500 lift and under 230 ish duration. Good exhaust like headers and duals. If you were to do any porting I'd match the ports and concentrate on the exhaust.
 
While more compression does help,it has to be matched to the ports ability to breath,the chamber design,fuel being used,cam being used etc.More compression will give an increase of tq and h.p across the entire power band but the rest of the components must match.You could make well over 600 h.p with twin turbo's and 8:1 compression. But you can also make 600 h.p by virtue of big cid and lots of compression

For example it does no good to install an rv grind cam in a 16:1 race hemi.The rv cam doesnt help in an 8:1 turbo engine either.
But the rv cam works nicely in an 8 or 9 to 1 motor that needs lots of torque down low. A mismatch will result in a poorly performing engine that is sluggish.No amount of tuning will help it.Lets say you decided to ignore my advise and go with 7.5 or 8:1 and a biggish .480 lift cam. While the engine will run and probably drive O.K,it will have weak low end tq. And you will be leaving h.p and tq on the table across the entire rpm range.More compression does come with a price. Pinging due to crap fuel or too much timing advance can be hard on an engine. Be sure to polish everything in the combustion chamber to prevent hotspots

I'd say you will be looking at closer to 400 h.p with 9.5 compression and a well matched cam.

You can still use the pistons you have. Just have the block cut to square everything and shave the heads to reduce the chamber volume. You will also need to have the intake side of the heads shaved to match and have a good seal.

For your engine go no higher than .480 lift. You need to look around and do some reading,learn some about cams,compression,heads etc. Do you have any books?
 
i asked for some books for christmas. I know i need a small cam-i think the comp cam xe256h would work for me. Does anybody have sound clips of this cam?
 
I dont know how crazy you can go with this. I would ask what internals are used in it. Price is right and free shipping and no core charge so not all bad.
 
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