My 318 build...opinions

[lomchivok]

Hi guys and gals,

Looking for opinions on my already completed installed and running build.

1968 318 in a 68 Barracuda notch with 904 and 8 3/4 323 suregrip stock converter...about 1700 stall??

Here's the build

318 bored .040 over. KB forged 1.81 CH pistons floating pins.

Block decked and pistons .003 in the hole with .040 head gasket.

360 rods on a forged crank.

Heads are Hughes PN# HUG 20301A Indy/RHS LA/X, 62 CC closed chambers with 1.920 and 1.620 valves off the shelf with no port work and stock rockers off the original heads.

Eddy air gap manifold with a Holley 4150 650 cfm carb #3 power valve.

Cam is a Comp XE268H. Closest I could get is 105.5 intake centerline on the degree wheel with a cloyes double roller with a chain tensioner.

Pertronix Flame Thrower Distributor.

Ceramic coated headers with H pipe.

Issues:
Low vacuum...idle 16"Hg...in gear idle 10-11" HG. Doesn't like ported vacuum. Compensated with a crane adjustable can with stop, on manifold vacuum allowing 6* advance at idle. Base timing is 18* BTDC with a base and VA total at idle of 24* BTDC. (Idles much better now). Mechanical is all it at 3000 with stops set at 35* total base and mechanical.

It actually gets 15.95 MPG freeway on 90 ethanol free real gasoline if I don't use the loud pedal. No detonation.

It likes to run hot in traffic... extreme I've seen is 210*. Haven't steam cleaned the engine compartment yet with a lifted the radiator cap.

What do you think my compression ratio and HP would be with this setup?

Would I do better with a lower/ higher base timing and changing the VA can stop to keep me at 24* idle timing and keeping the total mechanical and base at 35-36* all in with the stops.

It's a strong motor but it just feels like I'm leaving something on the bench...maybe it's that 360 sitting over there that I decided against in favor of the matching numbers 318.

 

[Bad Sport]

Issues:
Low vacuum...idle 16"Hg...in gear idle 10-11" HG.

Have you tried dialing in the 'in gear' vacuum, with the car in gear?

Mechanical is all it at 3000 with stops set at 35* total base and mechanical.

Might shoot for 2500 all in.

It likes to run hot in traffic... extreme I've seen is 210*. Haven't steam cleaned the engine compartment yet with a lifted the radiator cap.

210* isn't hot IMO, but it does bear watching.

I'm no expert, but it sounds like a decent combo.

 

[nm9stheham]

CR works out to around 9.5-9.6:1; that's a pretty good spot for a street motor.

When you say it feels like it is leaving something.... is this at certain RPM's or under certain driving conditions?

 

[lomchivok]

210* isn't hot IMO, but it does bear watching.

I'm no expert, but it sounds like a decent combo.

I just installed the VA can yesterday late. Here in a few minutes I'm going to take it to the shop and dial in the idle vacuum as you said.
I did try the lighter springs for all in @ 2500 but noticed surge and that the weights tended to not fully return to Zero but that was before the new VA Can where the idle needed to be 1075 out of gear to keep it running in gear and when the A/C pump kicked in.
Maybe I'll try a combo of 1 copper and 1 silver spring to see what that does for me.

Thanks for the response

 

[lomchivok]

CR works out to around 9.5-9.6:1; that's a pretty good spot for a street motor.

When you say it feels like it is leaving something.... is this at certain RPM's or under certain driving conditions?

I don't have a tach in it yet but I would guess at about 4500 it starts to fall off. Reviewing the torque specs they say max torque is at about 4000 rpm so that may be all I am feeling.

 

[Bad Sport]

I don't have a tach in it yet but I would guess at about 4500 it starts to fall off. Reviewing the torque specs they say max torque is at about 4000 rpm so that may be all I am feeling.

I have a step down HE268H in my mild 318, and it pulls pretty good to 6000 and starts to fall off around 6200/6300.

Stock long block with a Weiand 8007 Dual Plane intake and a 600 CFM street/strip carb from Summit.

 

[prostreeter9]

Hey guys:

Not to steal your tread, but I'm in the process of going through mine right now and this is the first time I've heard of someone using the 360 rods. Can you tell what you are gaining by doing this? Are they longer?

Jon

 

[lomchivok]

Hey guys:

Not to steal your tread, but I'm in the process of going through mine right now and this is the first time I've heard of someone using the 360 rods. Can you tell what you are gaining by doing this? Are they longer?

Jon

Not longer just stronger but do add to rotating weight. i also had them machined for floating wrist pins.

 

[Lelo Dart]

I was just thinking....... What about your valve springs?

I don't have a tach in it yet but I would guess at about 4500 it starts to fall off. Reviewing the torque specs they say max torque is at about 4000 rpm so that may be all I am feeling.

Could be valve float if your springs aren't up to the job. I have pretty much the same set up except 302 heads and don't get any of that all the way up to the rev limiter (5500rpm).

 

[lomchivok]

I was just thinking....... What about your valve springs?

Could be valve float if your springs aren't up to the job. I have pretty much the same set up except 302 heads and don't get any of that all the way up to the rev limiter (5500rpm).

Turned out to be a broken spring and a dislodged stop on the mechanical advance that jammed the weights too far open. I checked the timing curve after initial installation and it was all good. One 10 min power run after install was all it took to break the spring and jam things up. Today I mixed a light and medium spring and brought it in to 36* all in at 2400 rpm and it pulls HARD all the way up to what I figure is 6 grand...I really need a tach.
(Edit) Actually the weights weren't advancing enough due to the stop jammed and the broken part of the spring had fallen near the gap of the ignitor...After the fix it's all good...for now.

 

[Bad Sport]

I really need a tach

Yup.