[disco_hillbilly]

I had a junkyard 460 that I did the wrong thing with - which is to say a quick and dirty hone, re-ring, and re-bearing. It lasted about 50k in my daily driven 70 Torino until I lost oil pressure cruising on the highway a week ago. I took it apart from under the car and most of the rod bearings were hammered pretty bad. I think #1 spun as it had a weird deformity and major discoloration although it seemed as if the bearing was in the right place idk.

Anyway, I'm kind of pinching pennies at the moment until I get a project done and sold, so I'm wondering if I can put some parts together that I have on the shelf and have something to cruise around for a while, but I think I will be really pushing it as far as compression ratio goes. 91 octane is the best in this area and it gets really hot in the summer.

Fresh 20 over d1ve block, new cam bearings and align hone.
Fresh d0ve heads with comp 924-16 springs
New sealed power h612p +12cc pistons
Stock rods (I think I have enough to make a good set)
Stock crank I will take to have ground
Roller rockers
Edelbrock performer intake
Holley vac sec 750
Points dizzy curved by mad porter to ~16 initial/34 total with a quick all-in

Comp Xe274h or lunati 31605 cam

With those pistons and heads I would be at 10.34:1 static compression. The block is at stock deck height so the quench will not be ideal.
With the XE274h with straight up timing I would be at 8.35:1 dcr
With the 31605 with straight up timing I would be at 9.15:1 dcr. I think maybe there is something about cam overlap and detonation that I don't understand because I always hear this cam can be run with high static compression ratio.
I could run either cam with retarded timing for a more favorable dcr but I've bumped into the limit of my knowledge again and I'm unsure if that's either necessary or a good idea

I can deal with bad street manners it's a 4 speed car with manual everything and 3.70 gears.

Thanks in advance for any input and sorry for the long post

 

[disco_hillbilly]

I got a good reply in PM which brought up some great points. Some additional info that may be relevant that that gentleman brought up:

• My distributor does have a vacuum advance on it. It is one of the adjustable ones. I forget what the range is on it.
• I believe my d0ve heads have received a 3 angle valve job with the std size but it was years ago and my memory is a little hazy. They are currently assembled on the shelf but I will go pull a couple of valves and see. I'm also looking into doing the home porting thing per mad porter for especially the exhaust side. Def willing to put in the elbow grease.

 

[disco_hillbilly]

Cam card for the 31605 since it's been out of circulation for a while

 

[pedal2themetal45]

HI,
That is a good size cam. I'm not sure but I don't think the Dove heads Don't have the exhaust bump that is usually ground out on porting of the exhaust..

good luck take care be safe
tim

 

[disco_hillbilly]

Realized I misunderstood the cam specs and that Comp gives the cam timing info in valve lift @ 0.006 while Lunati gives it at .050. I was thinking it was weird looking at the intake close point on the bigger cam vs the smaller one.

I think the dynamic compression ratio on the Lunati should actually be 8.27:1 which seems doable as long as I get it tuned right. And I can still keep retarding the cam 4* in the back pocket just in case.

 

[The Mad Porter]

CC your pistons' dishes.
The 612's and 3157 silvolites typically cc at 15.
I just had 3 checked randomly and 15 to 15.5 cc's.


Your DCR using the @ .050" closing figures +15* as inputted on the UEM calculator should be less than 8.7 to 1 for iron heads and questionable quench / squish. 8.5 would be fine.

Understand that DCR is primarily a measure of operational or dynamic c/r at lower rpm or when throttled.
High DCR is problematic more so in working / heavily loaded engines.
Performance combinations not so much.
Highest VE is typically found at peak torque.

If at any point your engine achieves 90, 100 or say 105% VE your actual running Dynamic compression at that point is your measured static c/r x VE %.

Compression Ratio Calculator | UEM Pistons

uempistons.com

Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine

 

[disco_hillbilly]

CC your pistons' dishes.
The 612's and 3157 silvolites typically cc at 15.
I just had 3 checked randomly and 15 to 15.5 cc's.

Will do. Have some syringes laying around for my elderly cat's medicine that will help. I suppose I should do the same for the heads while I'm at it.

Your DCR using the @ .050" closing figures +15* as inputted on the UEM calculator should be less than 8.7 to 1 for iron heads and questionable quench / squish. 8.5 would be fine.

I think we're looking good on this now that I understand it better. Especially if the piston dish is larger than advertised. Might actually turn out okay-ish performance wise although I wish I had had the block decked way back when.

Understand that DCR is primarily a measure of operational or dynamic c/r at lower rpm or when throttled.
High DCR is problematic more so in working / heavily loaded engines.
Performance combinations not so much.
Highest VE is typically found at peak torque.

If at any point your engine achieves 90, 100 or say 105% VE your actual running Dynamic compression at that point is your measured static c/r x VE %.

Compression Ratio Calculator | UEM Pistons

uempistons.com

Thanks I really appreciate this info. It's been a challenge for me to find out about his kind of stuff.

 

[pedal2themetal45]

HI,
You can't just squirt some fluid into the chambers and expect to get a correct measurement. fluid well dome before it runs off. you well need to seal it flat then have a small hole in it to except the syringe and fill from there..

good luck take care be safe
tim

 

[19Fo79rdF250$]

I had a junkyard 460 that I did the wrong thing with - which is to say a quick and dirty hone, re-ring, and re-bearing. It lasted about 50k in my daily driven 70 Torino until I lost oil pressure cruising on the highway a week ago. I took it apart from under the car and most of the rod bearings were hammered pretty bad. I think #1 spun as it had a weird deformity and major discoloration although it seemed as if the bearing was in the right place idk.

Anyway, I'm kind of pinching pennies at the moment until I get a project done and sold, so I'm wondering if I can put some parts together that I have on the shelf and have something to cruise around for a while, but I think I will be really pushing it as far as compression ratio goes. 91 octane is the best in this area and it gets really hot in the summer.

Fresh 20 over d1ve block, new cam bearings and align hone.
Fresh d0ve heads with comp 924-16 springs
New sealed power h612p +12cc pistons
Stock rods (I think I have enough to make a good set)
Stock crank I will take to have ground
Roller rockers
Edelbrock performer intake
Holley vac sec 750
Points dizzy curved by mad porter to ~16 initial/34 total with a quick all-in

Comp Xe274h or lunati 31605 cam

With those pistons and heads I would be at 10.34:1 static compression. The block is at stock deck height so the quench will not be ideal.
With the XE274h with straight up timing I would be at 8.35:1 dcr
With the 31605 with straight up timing I would be at 9.15:1 dcr. I think maybe there is something about cam overlap and detonation that I don't understand because I always hear this cam can be run with high static compression ratio.
I could run either cam with retarded timing for a more favorable dcr but I've bumped into the limit of my knowledge again and I'm unsure if that's either necessary or a good idea

I can deal with bad street manners it's a 4 speed car with manual everything and 3.70 gears.

Thanks in advance for any input and sorry for the long post

Use the XE274H cam. It matches the flow of those heads much better. The other cam has way too much lift and duration. You'll need dual spring valve springs.