360 Queries

[dodgedart360]

I'm new here. I am building a 2dr Valiant ( Australian ) into a Dodge Dart clone.
Question: Which 360 do I use?
a. An early 360 '71, '72 etc - can be bored out more, bigger cubes.
b. A later 360 '78 or '79 - I believe these had a roller cam? and a better combuston chamber.
c. A magnum 360 - roller cam, better combuston chambers but are they really worth it for my intended use?
I will be using this vehicle for cruising, no racing, however it must develop respectful HP to keep local V8's at a distance. I don't know anybody here in Australia who has done any serious work on these motors other than rebuilding up mainly standard motors with mild cams.
I will be fitting extractors, 4 barrel Rochestor and electronic ignition, need help on a street inlet manifold. I don't have any cam preference. A 4 or 5 speed manual gearbox will transmit the power. It will be running on pump gas
I hear that these motors are externally balanced, can they be internally balanced? I will be having the heads mildly ported and manifolds matched. Is there a higher capacity oil pump? Is there a heavy duty water pump available or is it worth adapting a late model pump complete with serpentine belt?
I'm not interested in a crate motor, I have a friend who will be bringing back several cars soon and he has said that I can load a few goodies in with them including a used rebuildable motor, he has a contact for "cut outs" but wants to know what I want.
Most of my questions arise because I have read a few articles in American magazines but they have only left me with more questions.

[DartGT66]

I think all hte LA 360's are about equal as starting points. Like in any mopar blocks, the wall thicknesses vary, according to some sources the early blocks had thicker cylinder walls because they used 340 water jackets. Don't know wether this is true or not, because I have seen several different years for the "last good blocks", and I think they didn't convert it on the new years eve either? A hydraulic roller cam came in, I think 1989 with the "high swirl" heads, but unlike teh 318 high swirls, the 360 heads had open chambers similar to the older engines. The exhaust ports have way better shape, and the intake ports have way bigger pushrod bulge restrcting the port. Those heads are also prone to crack, I've heard. I wouldn' pay much attention to the roller, or on roller; for high performance you have to change everything in the valve gear anyway, and you can get retrofit roller lifters for the older blocks too. All 360's are balanced externally from the factory, you can balance them internally using ehavy metal, but it's pretty expensive. I would just have it rebalanced externally with the flywheel & damper. As far as the intake goes, don't really know good intake maniforlds for a spread bore carb. Maybe a M1 single plane would work? I would just use a RPM intake and a squre bore carb.

[rumblefish360]

I can understand your confused state. Good thing your not doing an early Ford due to there constant changes. YIKES!

But, here it goes. Start with any 360 block and keep the overbore to the min. The extra cubes from boreing it out larger do not mean squat! It actuall means thinner cylinder walls that could flex more and cause a poor ring seal. Thats less power.
If you can get a roller cam engine, that would be great to use with a roller cam. Swapping a Hyd. or Solid cam is just a bolt in deal with corrected pushrod length and push rod ends to match the rocker and proper rockers to match the type of cam used. (Though mechanical rockers can be used with Hyd. cams, well keep it simple for now.)

On the heads, the newer the model, the better off you'll be. The skinnier ports add velocity for a beetr mixing of air and fuel. This adds toque and HP. Magnum heads are best in this area but the rocker gear is different than the older heads/engines. There are several upgrades for the Magnum heads for more serious HP if need be. This is not really the case for the older heads. There upgrades are better stock replacements. IE: Harder stiffer shafts and rocker up grades.
The Magnum chanbers and the 308 series heads have closed chambers for better flame travel and overall combustion.
These benifits add power and torque as well as mileage to the engine.
The older heads can be made to perform well, but it takes more work.
IMO, better to start off with a better head, Magnum or not, and go from there.

Best bet for performance;

A dual plane intake and moderate cam/compresion and carb for great throttle response, easy driving and ease of fuel costs.

A 9.0-1 engine can use our 93 octane, no problem with mild cam choices.
Cam choice is a sticky one, but you can get a great head start with a match up of the cams cruise range in RPM's to match to the cars intended cruise range and intended use.

[Rich33]

Originally Posted by rumblefish360

The Magnum chanbers and the 308 series heads have closed chambers for better flame travel and overall combustion.

The 308 heads are open chambers. It's the 302 heads (and magnums) that have closed chambers.

[dodgedart360]

Thanks for the info, I noticed that there are a couple of other queries started at about same time as mine, I am reading those as well.
I had heard that the early 360 blocks had the 340 water jacket casting, so maybe an option for more cubes? The heads are where I am still confused, X or J or later style? As I am only using for cruising, no drag racing, I don't need max porting or flow but I still would like to keep the MOPAR brand in front. I will be fitting quality rockers and push rods, std rockers with their poor stampings would defeat any effort to maxamize efficient cam timing. Would 1.6 be better or stick with 1.5 ratio.
Intended rpm would be between 1800 to 5500/6000, I was thinking a dual plane manifold as was suggested with a Q jet Rochester carby, there are very few options/parts for the Thermo Quad here.
Can the later serpintine belted water pump be used on early blocks or is there an alignment problem?

[rumblefish360]

If you use a serpintine set up from a MAgnum, you'll need all the parts from it. Theres is also a issue on the front timing cover being thicker than a Magnum engine I believe. Due to the cam snout being shorter.
Any head preped will do well. Use a Magnum head if you can.

[Ray Bell]

As for heads, with a bit of work you can do something different and fit those from a 318 Poly...

There's a guy in Melbourne has done this to a 360 already.

[dodger1]

Judging from what you said, you might as well try and source a complete 89-92 truck 360 to be added to your pal's container. You'll get the roller cam, late 308 heads, and still be able to bolt on pretty much any LA-style accessory such as a Weiand spread-bore or stock (but not too shabby) Chrysler iron 4-barrel manifold. Forget about the cyl. wall thickness. As rumble says it aint worth the extra cubes. As for internal balance, only if you decide to go the stroker route (which isn't a bad idea if you want displacement - think 408 ). Otherwise it's too expensive.. Enjoy!!

[dodgedart360]

What sort of money are the '89 - '92 Truck motors ( suitable for rebuilding )? What would an early 360 ( non roller ) be worth or are they too hard to find? Will carby manifolds fit the truck motors? I think based on info I have received here that I will keep the over bore to a min. possibly .030 - .040 max.
360's are very low compression so what is a good piston that will push the comp. ratio up to low 9's with min. head and block surfacing? Is Felpro a good gasket to use? I have heard that most MOPAR head gaskets are opened up for the 340 bore and you can loose a little of comp. ratio due to this?
On the Summit site they advertise an inlet manifold under their own brand, does this perform better or should I go for RPM or Edelbrock or ????, keeping in mind this is for the street. I still haven't settled on a cam but am looking at one with around 450 lift, definitly under 500, possibly 260 duration. My engine man will make the final choice based on info as he understands all this better than me.

[chryslerman71]

Originally Posted by dodgedart360

I'm new here. I am building a 2dr Valiant ( Australian ) into a Dodge Dart clone.
Question: Which 360 do I use?
a. An early 360 '71, '72 etc - can be bored out more, bigger cubes.
b. A later 360 '78 or '79 - I believe these had a roller cam? and a better combuston chamber.
c. A magnum 360 - roller cam, better combuston chambers but are they really worth it for my intended use?
I will be using this vehicle for cruising, no racing, however it must develop respectful HP to keep local V8's at a distance. I don't know anybody here in Australia who has done any serious work on these motors other than rebuilding up mainly standard motors with mild cams.
I will be fitting extractors, 4 barrel Rochestor and electronic ignition, need help on a street inlet manifold. I don't have any cam preference. A 4 or 5 speed manual gearbox will transmit the power. It will be running on pump gas
I hear that these motors are externally balanced, can they be internally balanced? I will be having the heads mildly ported and manifolds matched. Is there a higher capacity oil pump? Is there a heavy duty water pump available or is it worth adapting a late model pump complete with serpentine belt?
I'm not interested in a crate motor, I have a friend who will be bringing back several cars soon and he has said that I can load a few goodies in with them including a used rebuildable motor, he has a contact for "cut outs" but wants to know what I want.
Most of my questions arise because I have read a few articles in American magazines but they have only left me with more questions.

I'm in victoria too mate.If you want a good 360 built try pavtec racing in high street lalor.They built my 360 a couple of years ago and I was very happy with their workmanship.The car ran a 11.5 down the quarter.

[MrChemist]

Felpro makes good gaskets; I would use Felpro part number 1008 for your head gasket. I have been abusing...I mean, using their gaskets for over 10 years and never had a problem. For the intake manifold, Edelbrock performer RPM Air-gap is probably the best you can get for a street car. As far as pistons, if you don’t plan on beating on the motor (nitrous or high horse power/RPM) you can go cheap with hypereutectic pistons. The exact part number I can’t help you with unless you know what heads you will be using (deck height would be nice too).

[peg leg]

to check deck height dimensions before doing any machine work. Some of the late 70 blocks are infamous for off-square decks. One I tried to use was 0.030 out of square on one side, and was worthless. The other had the center main cap drilled at a slant and would not accept studs. Ended up with a new Magnum block.
For heads, look at the new R/T heads from Mopar. They are closed chamber without the exhaust port and runner restrictions, and flow well. The chambers are heart shaped and cc at 60.
I'm using a Comp 20-225-4 cam, Rhoads lifters (non roller) and KB pistons for about 9.5:1.
It is not menacing the streets here yet, but I think I'll be happy when it's running and the body is finished!

Ron

[platboy]

Originally Posted by chryslerman71

I'm in victoria too mate.If you want a good 360 built try pavtec racing in high street lalor.They built my 360 a couple of years ago and I was very happy with their workmanship.The car ran a 11.5 down the quarter.

I was happy with them too... until I found two pistons put on backwards, and none of the rods in their right bores according to the factory stampings. That's pretty simple stuff to mess up, and annoying when you're paying top dollar. The rest of the machining etc was okay though.
Cheers, J.

[rumblefish360]

Will carby manifolds fit the truck motors?

Car and truck engine are the same. Theres no difference.

360's are very low compression so what is a good piston that will push the comp. ratio up to low 9's with min. head and block surfacing?

MrChemist hit it on the head. Once you have your engine block machined with overbore and sqaured up. Your half way there. Then the heads come into play. You'll need to know how many cc's the chambers are when the head is done and ready to bolt on.

Is Felpro a good gasket to use? I have heard that most MOPAR head gaskets are opened up for the 340 bore and you can loose a little of comp. ratio due to this?

Yes, yes and yes BUT, most gasket manufactures do a general stamping and thats that. You can get custom gaskets from Cometic for a few bucks more and are race and road proven excellent. Also, a 4.100 gasket on a 4.030 bore isn't going to be a big power loser for you. But it should be calulated in to the equation.

On the Summit site they advertise an inlet manifold under their own brand, does this perform better or should I go for RPM or Edelbrock or ????,

I *THINK* the Summit brand intake is a Profesinal (sp) Products part. I have not heard or read of anyone useing it yet. However, I have used the RPM and it is just a great part. Most excellent for street or street strip duty.
A stock head, for the most part, will flow well until .500 lift. The problem with stock heads are the poor flowing exhaust ports. To help get around this problem, use a split duration cam. The longer exhaust duration will help power, extend RPM a few hundred and help bring a good balance to the engines breathing.
Check out Comp cams and Crane cams.

[dodgedart360]

Thanks Chryslerman71, I will be using Peter Orger Engine Services of Bayswater, outer eastern area. I have had many engines machined by him, he only employs tradesmen and his work is definetly top shelf and not over the top pricing ( slightly dearer that the johnny come lately's though ). Peter and Lindsay have a wealth of experience with modified engines and will listern to what you want and advise.