Another low budget 360 build

[woods]

I have a 70 Dart swinger that I'm doing a full drivetrain swap from slant 6, 904 and 7 1/4 a 360, 727 and 8 3/4.
I will be going through and rebuilding everything as I go so the budget will be a little tight.
The engine is a 76 truck 360 with just over 100,000 miles on it with fresh stock rebuilt 3769974 heads.
Pulled the heads and checked the cylinders this last weekend. I was surprised to see that the cylinders look very good with hardly any ridge on the stock bore. I will remove the ridge this weekend and measure the cylinders.
My goal is to build the engine to get the best performance while running on 87 octane.
The build plans are H405CP pistons,
gasket match and clean up the porting on the heads and heavier valve springs,
Shave the heads a little more and use Mr Gasket .028 head gaskets.
factory 360 4 barrel intake with a Holley 650,
Hooker headers and 2 1/2 duals with an X pipe.
The cam is where I have questions. The two that I like are Comp Cams XE268 and Lunati Voodoo 60403 pushing towards the 60403. Other 2 options are XE262 and 60402
Can I get away with using the stock non adjustable stamped rocker assembly with the above cams? Will the heads do OK with the high lift of the 60403 in stock form? what would be a good valve spring for these heads?
My future plans are to possibly replace the heads with a set of closed chamber 2.02 heads and airgap intake in the next year or 2
Thanks in advance for all of the help.
Ken

 

[skep419]

Depending on the converter and gears I'd go with the smaller cam. I wouldn't recommend those head gaskets either. Felpro blues are worth the loss on compression. Just my 2cents

 

[woods]

Depending on the converter and gears I'd go with the smaller cam. I wouldn't recommend those head gaskets either. Felpro blues are worth the loss on compression. Just my 2cents

My goal is to get the compression ratio to 9 to 1 with the open chamber heads.
Gears will be 3.23 with a shure grip and looking at a 2400-2600 stall with a hd rebuild on the 727 and shift kit.

 

[needsaresto]

Big stroke in that 360. Could pick up a few h.p on the cheap with oil control,get a windage tray. Big strokes wrap the crank in oil when winding rpm. Not sure what rpm a windage tray would come into effect? It may be more of a race thing than a street car thing.

 

[woods]

Big stroke in that 360. Could pick up a few h.p on the cheap with oil control,get a windage tray. Big strokes wrap the crank in oil when winding rpm. Not sure what rpm a windage tray would come into effect? It may be more of a race thing than a street car thing.

Good idea. Doesn't hurt to run it

 

[70aarcuda]

I have run those Mr Gasket 1121G heads gaskets on a 11 to 1 360 for over 8 yrs now....look in signature below for a 71 Dart...

and got them on another 360....

 

[IQ52]

I have run those Mr Gasket 1121G heads gaskets on a 11 to 1 360 for over 8 yrs now....look in signature below for a 71 Dart...

and got them on another 360....

I too am running them.......on a 601 HP 360 stroker.

 

[woods]

Thanks,
I plan on staying with the 1121Gs
I was originally planning on going with the 60402 cam but all I read on the 403 cam sounded much better. But I don't think I can run it with stock valve train and the 402 may actually be better with the lower compression

 

[skep419]

I too am running them.......on a 601 HP 360 stroker.

I had a problem with them sealing on my 360. Couldn't see anything wrong with the gaskets. Put on the felpros and problem was solved.

Could have been user error but after I had issues I read a summit review where someone had the same issue.

 

[woods]

One more thing is I would be surprised if I put more than 2500 miles per year on this car

 

[woods]

I had a problem with them sealing on my 360. Couldn't see anything wrong with the gaskets. Put on the felpros and problem was solved.

Could have been user error but after I had issues I read a summit review where someone had the same issue.

Good to know. I don't plan on decking the block so hopefully I don't have any issues.

 

[273]

If the goal is too run it on 87 gas 9:1 might be pushing it and the closed chamber mod down the road will definitely be too much.

Why not do the 2.02 valve swap now with a 70 degree cut and open the bowls to match now ? Don't need closed chamber heads especially if your not building in any quench.

Id go with the smaller cam other than that everything seems like a good choice.

 

[woods]

If the goal is too run it on 87 gas 9:1 might be pushing it and the closed chamber mod down the road will definitely be too much.

Why not do the 2.02 valve swap now with a 70 degree cut and open the bowls to match now ? Don't need closed chamber heads especially if your not building in any quench.

Id go with the smaller cam other than that everything seems like a good choice.

I'm looking into the cost of going up to 2.02 intakes. First place quoted $350 to cut the seats and surface the heads.
I will shop around some.

 

[crackedback]

The difference between a 262/268 and the 402/403 are so small it's not worth discussing, IMO.

Run the 60403 as long as valve springs aren't an issue and it will be fine. A 403 or 268 are about the limit for stock style rockers.

Either build it to quench or get the head away from the piston.

 

[woods]

Either build it to quench or get the head away from the piston.

Not quite following you
I will probably keep the open chamber heads if I go bigger on the intakes and am happy with how the engine runs
My concern with the 403 cam is the 513 exhaust lift With a stock head and non adjustable rockers.

 

[crackedback]

You won't be getting 513 lift with a stock rocker and crappy pushrod angles.

Most SB stock rockers are in the 1.40-1.45 ratio. Deduct about 4% for the poor pushrod angle.

You'll likely have something in the .470 range is my guess

 

[woods]

You won't be getting 513 lift with a stock rocker and crappy pushrod angles.

Most SB stock rockers are in the 1.40-1.45 ratio. Deduct about 4% for the poor pushrod angle.

You'll likely have something in the .470 range is my guess

Didn't think there would be that much loss with the stocks
How accurate are the factory adjustable?

 

[moper]

I think either Comp is fine. The Lunatis recommend dual valve springs that require head work so if the heads are not going to the shop, I'd skip them. I have an '87 360 in my truck. All stock long block with the XE262, 901-16 springs, the MP windage tray, recurved distributor, MSD, Performer intake and Edelbrock carb, and cheapo headers. I did not rebuild anything, block's never been out of the chassis. It's a great all around package and pulls like a freight train off idle. I pull a car trailer and plow an 8' blade uphill when it snows with it. With the better pistons I'd go with the XE268 and the 901-16s. The stock rockers will work, but you will need to measure for, and order, custom pushrods to get the right preload so be prepared for that.

 

[rumblefish360]

You won't be getting 513 lift with a stock rocker and crappy pushrod angles.

Most SB stock rockers are in the 1.40-1.45 ratio.

You'll likely have something in the .470 range is my guess

I don't think he will loose that much lift but it will be close. LMAO

Didn't think there would be that much loss with the stocks
How accurate are the factory adjustable?

About that same as the stamped consider also that there old worn high mileage parts.

Not quite following you.

What he was saying is ether;

Build the engine with quench or don't.

Quench is the described as the very tight clearance between the top of the piston and the bottom of the cylinder head. This can best be seen or imagined when a flat top piston is at zero deck height, (dead even with the deck of the block) and the head gasket is thin, (think .045 or less & less is better)
And the cylinder heads flat spot is over the piston. Think Edelbrock heads and there small chamber. A lot of the head is a flat area.
That flat area over the piston is the quench area.

OR

Move the piston down the cylinder (AKA Low compression slugs) or move the head up, as in thick gaskets. This prevents detonation.

A good quench engine doesn't have this issue of detonation if used correctly.

 

[woods]

Build the engine with quench or don't.

Quench is the described as the very tight clearance between the top of the piston and the bottom of the cylinder head. This can best be seen or imagined when a flat top piston is at zero deck height, (dead even with the deck of the block) and the head gasket is thin, (think .045 or less & less is better)
And the cylinder heads flat spot is over the piston. Think Edelbrock heads and there small chamber. A lot of the head is a flat area.
That flat area over the piston is the quench area.

OR

Move the piston down the cylinder (AKA Low compression slugs) or move the head up, as in thick gaskets. This prevents detonation.

A good quench engine doesn't have this issue of detonation if used correctly.[/QUOTE]


so would I be better off with H405cp pistons and a thicker head gasket or even stock cast with thinner gaskets? would there be much of a difference in performance?
So how do you achieve quench with open chamber heads without running high octane fuel?
I was originally looking at running higher compression with H116cp pistons. Could I get away with these and open chamber heads using the other components listed above and run 89 or 91 octane fuel?
I'm very mechanical but get stumped on calculating stuff like this.
I just want to build a good running reliable engine that has enough power to play with when I want to.
Thanks for your time

 

[rumblefish360]

so would I be better off with H405cp pistons and a thicker head gasket or even stock cast with thinner gaskets?

This question answered last.

would there be much of a difference in performance?

It would take a side by side test to allow you to feel the difference and a track to see the slip times. It would be small but very much there.

So how do you achieve quench with open chamber heads without running high octane fuel?

Odd looking pistons. Quench pad on one side, deep dish on the other.

I was originally looking at running higher compression with H116cp pistons. Could I get away with these and open chamber heads using the other components listed above and run 89 or 91 octane fuel?

Not 89. 91 if your careful.

I'm very mechanical but get stumped on calculating stuff like this.
I just want to build a good running reliable engine that has enough power to play with when I want to.
Thanks for your time

Completely understand. I went through a lot of trial and error before the internet was invented.

MoPar used to sell a head shim. This was .100 thick and designed to be intalled inbetween the head and block to lower compression for todays crappier fuels and run a lower octane. It takes away all quench. Not so good for power but it did allow you to at least drive your car. Very helpful for those nasty 13-1 & 11-1 iron headed engines of yesteryear.

so would I be better off with H405cp pistons and a thicker head gasket or even stock cast with thinner gaskets?

The H405cp is a bit lower of a ratio. You will need to do the math on exactly where it sits in the cylinder bore and how many cc's the head is, gasket thickness and it's bore size. Once you know all the specs, you can go here; Compression Ratio Calculator - Wallace Racing and calulate the compression ratio.
Iron head and small cam = 8.0-1, moderate to big-ish cam, 9.50-1 MAX

As for the H116cp slugs, this is what I am doing.

You can run the H116CP with a .038 gasket and moderate cam if your also going with a higher stall converter and gear. Currently, I have this set up going on now but with a thick MLS gasket @ .075 to reduce detonation problems with small cams. (reduced to 9.94-1) Later, the head gasket will be replaced with a .036 (10.90-1 before head milling) and a healthier cam, ([email protected] to [email protected]) 4.10's instead of 3.55's, more converter.
(.030 = 11.07-1, .027 = 11.16-1 )
Notice the lower compression with the smaller cam. While I would like lower, it willwork with an aluminum head and 93 octane. It's cutting close. These ratio's are possible with aluminum heads. Reduce your ratio by 1 point min. with iron heads. Quench or not.

 

[woods]

I know the block has a stock deck height. I don't think they would vary throughout the years.
Not sure how accurate of a measurement I would get with dish pistons that are still in it
Hopefully I can get away with a bottle brush hone on the cylinders and not have to bore
And the open chamber heads were rebuilt and probably lightly surfaced. not sure how to check the volume.
Not sure what the quoted CCs of an untouched open chamber head is. I found 65cc in my searches. would that out of the box specs or is that considered what it would be with maximum allowed after surfacing?

I was looking at this to get an idea to what would be expected. I assume their rating is with standard .045 gasket.
Mopar TRW Forged Pistons Speed Pro Forged Piston Hypereutectic Sets
This is the spec's of the H405CP piston
Bore (in):4.000 in.

Bore (mm):101.600mm

Piston Style:Flat top, with four valve reliefs

Piston Material:Hypereutectic aluminum

Compression Distance (in):1.576 in.

Piston Head Volume (cc):+10.00cc
Not sure if this helps or maybe I am rambling. Could have been the excess of coffee this morning

 

[nm9stheham]

I actually worked out the numbers... The H405CP pistons are about .050" in the hole for a standard LA block and have 10 cc's worth of valve reliefs so are not high compression by any means. (BTW< the compression height is 1.675".) The OP's combo works out to 8.6 static CR with 72 cc head chambers, and 8.9 static CR with heads shaved to 68 cc chambers. Both of these numbers are with the .028" head gaskets.(I would not expect 65 cc open chambers; that is probably an NHRA minimum spec.)

Dynamic CR's will be 7.1 and 7.3 respectively with the Lunati 60402 cam. I can't see where the OP has anything to worry about with detonation at these levels and regular fuel and the mid 2000 rpm range stall TC.

Later on with closed chamber heads, there will be no effective quench with these pistons so that anti-detonation aid is out if the H405CP's are used. 63 cc closed chamber heads would push DCR to 7.7 with that cam so still has some margin against detonation although a cam change may be in order then, or aluminum heads would pretty much proof it against any such problems.

BTW, OP, I use the Pat Kelley calculator if you want to plug in numbers and see these results on your own.

 

[woods]

I want to thank for all of the help with this project. Didn't think it would take so much more thought lol.
Think I will stay with the current plan of H405CP, go with the 60402 cam, 901-16 springs.
Check into going to 2.02 on the intake valves and shaving a little more off the heads.
Would it help any to advance the cam 4 or keep at 0

 

[nm9stheham]

These cams come with 4 degrees ground-in advance. You can tell by comparing the LSA (lobe separation angle) to the ICL (intake centerline angle). All that gets factored into the computations in the Pat Kelley calculator once the data is entered correctly, so it is in the numbers I listed for you.

If you want a hair more low end torque, then advance the cam a coupla more degrees.

And, as an FYI, cutting .006" off the head lowers the open chamber volume by about 1 cc. So shaving .030" off would get you around 5 cc less chamber volume. I would expect that head cut to end up with around 68-ish cc range chambers for the larger open chamber head.