Factory roller 360 and 308 head questions.

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65deuce

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Great forum you guys have.
After putting together a warmed over Slant for my 69 dart, I’ve decided that I went the wrong way…Ahh I coulda’ had a V-8.

So I bought a 360 out of a 1990 B350 Van. It’s a factory roller engine, with 308 heads.

Everything is at the machine shop right now, they’re doing the normal stuff .030 bore, .010/.010 on the crank, and all the hot tanking.
They magna fluxed & bead blasted the heads and have given them a clean bill of health, I’m having them install Milodon Stainless 2.02/1.60’s. Heres what I’m considering for the build:

Stock roller block
Stock crank and rods
.030 Speed Pro H116CP Hypereutectics
9.5-10:1 compression
308 heads as cast w 2.02/1.60
Comp XE274HR, XE280HR or XE286HR (I’m leaning towards the 280)
PRW Shaft Style Full Roller rockers
Performer Air Gap

Can you guys shed some light on a couple concerns?
What is the chamber volume on a 308 head?
Can I expect any problem using factory lifters with one of these cams?
Which of the listed cams suits this combo best?
Any guesses on power output?
What type of tranny was in that van?
Has anyone used an automatic overdrive in a 69 A-Body?
 
65deuce said:
Can you guys shed some light on a couple concerns?
What is the chamber volume on a 308 head?
Can I expect any problem using factory lifters with one of these cams?
Which of the listed cams suits this combo best?
Any guesses on power output?
What type of tranny was in that van?
Has anyone used an automatic overdrive in a 69 A-Body?
Click to expand...


Chambers will be around 68 to 70ccs.

Im not sure about the roller lifter but I cant see a problem with it ?

Choosing the cam depends on gearing and converter and what your looking for the motor to do.

I would say around 400 to 450hp depending on how well the machine work is done and what cam you choose.

The van probably had a 727 in it

The a500 and 518 over drives require fabrication to the floors and cross member to fit.
 
For a moment I considered going with magnum heads, but didn't want to get into the pushrod and lifter change-over. Will the 308 heads support powere levels to 450 HP?
 
I think you'll need some port work to see 450hp with the 308 heads, Even the Magnums will need some help at least in the bowls.

The magnums will work with just about any lifter, most have the oil hole all ready.
Just cross check the part number with AMC lifters, If its the same number your good to go as amcs all oil through the push rods.

Most likely you will need a new set of push rods anyways, after the block and heads are decked, Non factory head gaskets and a different cam (base circle) your geometry will need to be measured anyways.

Magnums will need pedestal mount rockers (aka chevy rockers)

and a Magnum intake.
 
I have a set but they are the 547 or something like that. They were from MP and have no air hole in the exhaust ports and 2.02 valves.

My heads were 69cc before I had them milled .030. That made them 63cc.

I am with you about the newer rocker arms. I believe the shafts are better for higher rpms. Just get the iron adjustable rocker arms and push rods.

I am very happy my 318 has them.
 
dodge freak said:
I have a set but they are the 547 or something like that. They were from MP and have no air hole in the exhaust ports and 2.02 valves.

My heads were 69cc before I had them milled .030. That made them 63cc.

I am with you about the newer rocker arms. I believe the shafts are better for higher rpms. Just get the iron adjustable rocker arms and push rods.

I am very happy my 318 has them.
Click to expand...

The other heads you have may be 576 heads. They are non-emissions, over-the-counter only replacement versions of the 308. They were available from bare 1.88" intake valve castings to ported, milled assemblies from Mopar after the 308's were used up. Aside from the "air hole", I haven't seen any other differences from the 308's.

They make good power with the right combo. Exhaust ports are more efficient than older 340/360 heads. Which heads, between the newer and older shaft-style versions, are better is debatable. My engine builder has run pretty fast in IHRA Stock with 308's and he recently built a very similar engine for me, but using older heads. It will be a while before we have a better idea how each works for our application. But the newer heads should make more torque.

The best thing you can do for small block heads is bowl work and blending in that area.

I'd check with Comp Cams about using OEM lifters. But I would guess that their versions would work better. (Anti pump-up) Springs too.
 
1.92 intake vale and a bowl hog and blend would work much better with those heads- keep the velocity up. and don't blend too much in the are next to the valve guides or you hit water - and $1000 is p-----d away.
unless you are going to spend $800-1000 for a convertor, go with the XE274, the bottom end torque will be better and very little Hp difference.
The stock mopar lifters will work too.
need anything elase - pm me.
 
Yeah thats the number. I should have took a few pictures of them before I bolted them on.

I don't believe they are any different than the 308 expect for those air holes on the bottom of the ports.

It cam with 2.02 so I used them. Muscle Motors did the milling and bowl hog them. Eric over there thought the newer high swirl 308-576 were BETER than the J's and X heads, thats what he told me and I got them before talking to him.

I love E-bay....sometimes :-D
 
I'm going to pick up the block, crank and one piston and rod assembly tommorrow and mock up the rotating assembly. I wanna check deck height and get an idea of what to deck to make it zero (or close). Is 10:1 too much for street? I use 93 octane in all of my performance toys already.
 
Depends on the camshaft. The bigger the grind, the more compression it can take.

I do know on speedtalk, were pro racers chat, on some of their "street" motors, they claim to be able to use 12 to 13-1 compression. But then their "street" cams are 250 @ .050
 
My motor is 9.8:1 with a some what small XE268 and runs on pump gas.
 
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