SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: bshaw on October 16, 2017, 07:16:13 PM

Title: How much compression
Post by: bshaw on October 16, 2017, 07:16:13 PM: .042 head gasket
Ported c8 heads with bigger valves
22cc dished hyper speed pro pistons
Stock rods stock stroke stock d1 blocks deck height
Haven't made a cam choice yet because I don't know what compression I'm at but I was thinking a 224/234 duration at 50 with 550/553 lift 110 lobe separation. If anyone could tell me what ball park compression I'm in would help a lot I'm taking a wild guess at 9.5:1

Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Title: Re: How much compression
Post by: angermgmt on October 16, 2017, 07:42:15 PM: What's your bore size?

Sent from my iPhone using SoCal Jet Boats
Title: Re: How much compression
Post by: bshaw on October 16, 2017, 07:45:14 PM: Can't believe I missed that, 4.390

Sent from my iPhone using SoCal Jet Boats
Title: Re: How much compression
Post by: mach1_557 on October 16, 2017, 09:19:46 PM: 10.124 compression ratio
Title: Re: How much compression
Post by: mach1_557 on October 16, 2017, 09:21:06 PM: That's if it's zero decked
Title: Re: How much compression
Post by: angermgmt on October 16, 2017, 09:48:05 PM: Agreed. That's what I have.

Sent from my iPhone using SoCal Jet Boats
Title: Re: How much compression
Post by: bshaw on October 16, 2017, 11:19:08 PM: Anyone have an idea of what A good spec Cam would be? Really don't want a mild cam I want something aggressive that's going to make the highest numbers possible with the parts I have

Sent from my iPhone using SoCal Jet Boats
Title: Re: How much compression
Post by: bshaw on October 17, 2017, 04:31:47 AM: Also I think c8 heads are 77cc is most castings aren't they?

Sent from my iPhone using SoCal Jet Boats
Title: Re: How much compression
Post by: angermgmt on October 17, 2017, 07:15:07 AM: Go to the comp cam website. They have a few marine options depending on your impeller size.

Sent from my iPhone using SoCal Jet Boats
Title: Re: How much compression
Post by: LakesOnly on October 18, 2017, 09:05:49 AM: Quote from: bshaw on October 16, 2017, 07:16:13 PM
.042 head gasket
Ported c8 heads with bigger valves
22cc dished hyper speed pro pistons
Stock rods stock stroke stock d1 blocks deck height
Haven't made a cam choice yet because I don't know what compression I'm at but I was thinking a 224/234 duration at 50 with 550/553 lift 110 lobe separation. If anyone could tell me what ball park compression I'm in would help a lot I'm taking a wild guess at 9.5:1
If you're certain about the parts specs of your engine combo, then your estimated compression ratio is about right, maybe 9.6:1.

I've done countless large valve D0VE head swaps to OEM 460 Marine short blocks without issue, but once the block is decked and/or the cam is changed all bets are off. Under such circumstances your OEM replacement pistons might not have valve reliefs that can accommodate your big valve heads. Incidentally, based on that cam's valve lift I hope the valve guides have been cut down on the valve train side of the C8VE heads.
Title: Re: How much compression
Post by: bshaw on October 18, 2017, 01:16:25 PM: I just bought this last night not sure if the lift is too much that the valves won't fit the pistons reliefs

Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Title: Re: How much compression
Post by: bshaw on October 18, 2017, 01:18:25 PM: Ive got Manley dual springs and guide plates with 7/16 studs I'm pretty sure

Sent from my iPhone using SoCal Jet Boats
Title: Re: How much compression
Post by: bshaw on October 18, 2017, 02:43:22 PM: Here's the pistons best picture I've got at the moment to show the reliefs

Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Title: Re: How much compression
Post by: bshaw on October 19, 2017, 09:54:07 AM: My bad, crower springs and Manley guides. Not sure if this helps but still wondering if that cam will work with these heads

Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Title: Re: How much compression
Post by: mash on it on October 20, 2017, 11:01:39 AM: Quote from: bshaw on October 16, 2017, 07:16:13 PM
.042 head gasket
Ported c8 heads with bigger valves
22cc dished hyper speed pro pistons
Stock rods stock stroke stock d1 blocks deck height
Haven't made a cam choice yet because I don't know what compression I'm at but I was thinking a 224/234 duration at 50 with 550/553 lift 110 lobe separation. If anyone could tell me what ball park compression I'm in would help a lot I'm taking a wild guess at 9.5:1

Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)

I'd go with a lil more duration, and a bit more lift.

Comp cams cl 34_336-4. 292 adv. duration, .560/.560 lift, 244/244 @ .050".

I had this cam in a 454. (292AH), With headers. 9.25:1 compression ratio, and a single plane intake, 750 Holley.

Pulled an 'A' impeller to 52-5300 rpm, about 500 hp.

Maybe Paul/Lakes Only will chime in, I'm not a Ford guy.

Hope this helps..

Dan'l
Title: Re: How much compression
Post by: bshaw on October 20, 2017, 01:27:33 PM: I'm just not sure that with the lift of the cam I got, wether valves will hit the pistons because if clearance and or the geometry will be off in the valvetrain due to the seals or retainers being too tall or short

Sent from my iPhone using SoCal Jet Boats