360 Build advice

[74desertduster]

Thanks to everyone for the advice.

I am going to have a 360 built for my 74 Duster very soon and need some advice.

It will be an older 360, probably from the 70's. Not sure of the heads yet but I am guessing they will be stock 360 heads from the mid 1970's.

I want some performance but it will be a driver too so not anything wild...but I would like a nice strong street setup.

Looking for Piston, cam and intake advice.

It will be going in a 74 Duster, 727 Trans and 8 1/4 rear with 2.73's in it.

Thanks,

Brian

 

[70aarcuda]

pistons kb107 is the best deal...light, raises compression.

intake.....hard to beat eddy air gap....

 

[goldduster318]

Do you have your heart set on using the 70's heads? Magnum heads are cheap compression and have better combustion chambers. I built a nice strong 360 setup that is as follows:

77 360 w/stock replacement 8:1 pistons (bought it that way)
Magnum Heads with R/T Springs & Retainers
Summit K6901 218/228 @.050 cam with .470/.470 lift at the valve with the magnum 1.6 rockers
Summit 7.650" hollow conversion pushrods for the magnum conversion
Edelbrock RPM Air Gap intake for magnum heads #7577
Holley 600 Vacuum Secondary Carb
Stock replacement electronic ignition
1 5/8" headers

Its a strong runner. I have a 4-speed and its stupid easy to lay rubber with it, yet it idles pretty smooth at 800rpm.

You'd pick up a lot of performance by going to 3.23's or 3.55's

 

[74desertduster]

Am waiting for more engine/head details and will post shortly...

 

[rumblefish360]

Looks like that the bigest performance issue will be the rear gears. And, IF you want to keep them for mileage purposes, they will limit your cam size.
If money is in limted supply, let it be known upfront. This way crazy advice on more expensive parts will be left out. Stock heads can go far.

 

[74desertduster]

Money is in short supply...so am looking at maybe an upgrade in Pistons over stock...and for sure cam and intake...rear end will have to stay for now....I'm just glad I have a 727 in place....

Not sure what my heads are and am waiting for that info...

thanks!

 

[rumblefish360]

With stock gears, I would stick with a OE 4bbl. intake and heads, with a performance valve job. K6901 Summit cam (As above) and headers. Mill the heads a bit for more compresion if the OE block and pistons are fine. Otherwise, the KB107's are a bit high of a ratio with a small cam. You could use them with a thicker Fel-Pro head gasket @ .054 -.055 thick for reasonable compression with this small cam.
This gasket and unmilled heads will have you right around 9.5-1 compression ratio.

 

[74desertduster]

The engine is going to be gone through anyway so I have a chance at different Pistons. Not sure how much more expensive the kb107's are compared to stock pistons.

I was planning on buying the intake because the 318 I have as an exchange core has a stock 4 bbl intake from a late 70's...casting is 4095080...not sure if it is good or not but it has EGR on it so that's bad to me...

Thanks

 

[rumblefish360]

The KB107's sell for under $200 at summit/jegs.

A EGR valve is not a bad thing. It has a bad rap as a emissions part and while it is, what it does is introduce exhaust gas back into the engine at cruise speeds. At wide open throtle, it closes and blocks the exhaust gas from re-entering the engine. The inert gas doesn't hurt performance at cruise and the inert gas allows for more timing advance.

So now you know, is it really that bad?
If it makes you happy, leave it on the intake and simply dont hook it up, it'll remain closed.

Go into the plenum and take out the floor jet, purchase a plug and plug it up. Weld the other floor jet closed.

The OE 4bbl. intakes are not a bad performer at all. And since money is an issue, save yourself $200+ dollors on the intake and reuse that money on someting else.

On the price of pistons, don't take this the wrong way, but I have to be blunt like a balling ball, stop bitchin about a few bucks on piston price. Penny pinching on slugs but spending 200 plus on a intake is backwards thinking. You can change a intake easy and quick, not the case with pistons.

 

[curts73]

i have a 71 360 in my duster it is a truck motor and has factory flat top pistons. i put alow buck summit cam in and did a port clean up and gasket match with the summit port and polish kit. i am happy with the power i have, it would be nice to have more but a budget is a budget.and the guys are right about the rear end i had 307 gears originally and now i have 321's and could not believe the difference.

 

[74desertduster]

Thanks for all the good advice....so to sum up...go with the kb107's and use the stock intake and use the K6901 cam?

Thanks!

 

[rumblefish360]

Thanks for all the good advice....so to sum up...go with the kb107's and use the stock intake and use the K6901 cam?

Thanks!

That's the route I'd take. Curtis gave you a good thumbs up on his low buck/compression build and goldduster318's build is a very good one for the street. His only difference was the Magnum heads which your budget will not yet allow, but may later.

I went to the KN on line compres. caulc. The ratio with the thicker gasket, and it resulted in 9.4 or slightly better. The gaskets bore size I didn't know, so I played around with a few bore sizes and it varied little. Between 9.4-1 - 9.5-1.

 

[340sFastback]

I think you would be happy with kb107s and cleaned up heads. And if you want to swap on some better heads later you will be good to go.

 

[74desertduster]

This is what I am planning based on your inputs...

kb 107 Pistons
Summit K6901 Cam
Stock 4 bbl intake
Stock 360 heads
Dual exhaust (in place), switch to headers when I can


Down the road I would like to get gears in the 3.23 or so range....will this setup still be good?

Thanks to all!

Brian

 

[goldduster318]

yes, 3.23's are fine.

 

[rumblefish360]

Agreed, it'll be fine.

 

[green1]

The KB107's sell for under $200 at summit/jegs.

A EGR valve is not a bad thing. It has a bad rap as a emissions part and while it is, what it does is introduce exhaust gas back into the engine at cruise speeds. At wide open throtle, it closes and blocks the exhaust gas from re-entering the engine. The inert gas doesn't hurt performance at cruise and the inert gas allows for more timing advance.

So now you know, is it really that bad?
If it makes you happy, leave it on the intake and simply dont hook it up, it'll remain closed.

Go into the plenum and take out the floor jet, purchase a plug and plug it up. Weld the other floor jet closed.

The OE 4bbl. intakes are not a bad performer at all. And since money is an issue, save yourself $200+ dollors on the intake and reuse that money on someting else.

On the price of pistons, don't take this the wrong way, but I have to be blunt like a balling ball, stop bitchin about a few bucks on piston price. Penny pinching on slugs but spending 200 plus on a intake is backwards thinking. You can change a intake easy and quick, not the case with pistons.

Can you expand further on the egr? This is new.

 

[rumblefish360]

Can you expand further on the egr? This is new.

What would you like to know or understand better?

 

[green1]

How does inert gas allow more timing?

 

[TheDemonator]

Magnum heads can be had on the cheap if you keep your eye out for them. Check with your local machine shops, if you have any near you... or check regularly at places like craigslist.

I picked up a pair of rebuilt magnum heads with upgraded springs and a 3 angle valve job locally from craigslist for $100.

I realize that the price I paid is more the exception than the rule... but my point is that they are out there to be had!

I built my 360 using the magnum heads, a comp cams 268H cam, and the KB pistons, an air gap intake and a 670 street avenger carb... it is a torque monster, and a sweet street engine.

Running it through an 833OD transmission and a 3.91 rear gear... a screamer on the street (using the first 3 gears), and good mileage on the highway too. (in OD)

Good luck on your build!

 

[rumblefish360]

How does inert gas allow more timing?

Don't know/can't remember, remember readiing this several times via different publications. I remember reaing the gas is inert, low in amount since the holes in the intake are small and controlable by you if you want to run a smaller jet or close them off. There a NPT tapping.

 

[74desertduster]

Yeah...I am talking my time because I want to make sure I don't rush into something and then be unhappy with the results. Just taking inputs and have been talking to a couple engine houses in Phoenix...nothing much here in Tucson.

Brian

 

[74desertduster]

Will my 318 Torque Converter be OK on the 360 if I buy one of the B&M Flexplates I have seen discussed?

Thanks!

 

[goldduster318]

Will my 318 Torque Converter be OK on the 360 if I buy one of the B&M Flexplates I have seen discussed?

Thanks!

Yeah, it will work

 

[74desertduster]

Sorry for all the questions....should I use 360 exhaust manifolds until I can get headers or go with my 318 manifolds? Will the 360 manifolds match with my current exhaust...same physical size as the 318's? Thanks!