Search found 39 matches

by Tom68
Mon Feb 08, 2021 5:30 pm
Forum: Propane Forum
Topic: More Air Flow for a Model 425 on a 327 SBC
Replies: 66
Views: 1062

Re: More Air Flow for a Model 425 on a 327 SBC

P.S. ring seal takes several forms, you can have blowby without having cylinder wall oil overcoming yhe rings.

Is it a small journal with valley breathers ?
by Tom68
Mon Feb 08, 2021 5:28 pm
Forum: Propane Forum
Topic: More Air Flow for a Model 425 on a 327 SBC
Replies: 66
Views: 1062

Re: More Air Flow for a Model 425 on a 327 SBC

Dears, Thanks for your comments, My camaro is a 6 cyl original, V8 327 was built end of the eighties (all papers available) with a cam etc and I have the car for 20 years... Maybe i ran 15 k miles since then... I doubt this engine never saw a lot of miles on it...Just took out the timing cover out ...
by Tom68
Fri Feb 05, 2021 3:10 am
Forum: Propane Forum
Topic: More Air Flow for a Model 425 on a 327 SBC
Replies: 66
Views: 1062

Re: More Air Flow for a Model 425 on a 327 SBC

Please Tom can you explain your though behind your wording? FYI I see oil deposits everywhere on the intake parts of the engine, getting more and more thick deposits until the valves bowls. Yesterday I spent 2 hours cleaning 1 head with tar solvent and a light brass brush, all the cleaning job is a...
by Tom68
Fri Feb 05, 2021 2:02 am
Forum: Propane Forum
Topic: More Air Flow for a Model 425 on a 327 SBC
Replies: 66
Views: 1062

Re: More Air Flow for a Model 425 on a 327 SBC

Marc wrote:
Thu Feb 04, 2021 3:05 am

I have a bad PCV valve. I already noticed oil being sucked too much by this valves, and oil on the throttle blades when dismantling engine....
More likely you've got a pressurised crankcase from poor piston ring seal.
by Tom68
Wed Dec 30, 2020 12:03 am
Forum: Propane Forum
Topic: More Air Flow for a Model 425 on a 327 SBC
Replies: 66
Views: 1062

Re: More Air Flow for a Model 425 on a 327 SBC

Marc the 327 will be lacking up top as you've found with a 425, you don't state what Holley base you have it on but even a 600 base will outflow a 425 by way more than the implied 175 cfm deficit, actual deficit probably closer to 200+cfm.. Great size engine for factory heads etc that were available...
by Tom68
Sat Apr 04, 2020 11:53 pm
Forum: Propane Forum
Topic: Propane Tuning AFR and Lamda
Replies: 10
Views: 1915

Re: Propane Tuning AFR and Lamda

Sold all my cars etc when retired a while back Spent a lot time on Data logger dialing in SB chev. With a single 425 found lean out started about 4400/4500 then got more serious around the 4900/5000. In practice, passing a large cattle truck (they are long in NZ) maybe doing 80/90km/h , the whole m...
by Tom68
Sat Mar 28, 2020 7:20 pm
Forum: Propane Forum
Topic: Lean out at WOT. Fine at 3/4 throttle
Replies: 18
Views: 2674

Re: Lean out at WOT. Fine at 3/4 throttle

The high pressure lines are all copper-tubing. Both tanks are connected together in the trunk. I've fueled up the car yesterday and I'm noticing (as always), the car has some more power. But still everytime I depress the throttle-pedal fully, the AFR goes very lean after about a second orso. Everyt...
by Tom68
Wed Mar 18, 2020 2:07 am
Forum: Propane Forum
Topic: mkiv 454 big block and impco300 mixer too small?
Replies: 7
Views: 2442

Re: mkiv 454 big block and impco300 mixer too small?

thanks C3H8 thats a clear explenation. I also found this website, I could have found myself...since its a simple calculation as you stated https://www.widman.biz/English/Calculators/CFM.html Tom68 I have a air-gap dual plane ready to be swapped on. They told me that a single plane big intake would ...
by Tom68
Mon Mar 16, 2020 1:18 am
Forum: Propane Forum
Topic: mkiv 454 big block and impco300 mixer too small?
Replies: 7
Views: 2442

Re: mkiv 454 big block and impco300 mixer too small?

As advised you'll be able to trim the af ratio. That cams no baby for a stocker, you're running a baby mixer with a half decent cam. Cams costing you low rev power, the mid range and up is limited by your low horsepower mixer. A top end manifold with a mid range cam and a bottom end mixer, missing o...
by Tom68
Sun Mar 15, 2020 5:18 am
Forum: Propane Forum
Topic: Dual carbs with propane?
Replies: 26
Views: 9992

Re: Dual carbs with propane?

I did a compression test a few months ago. I remember all cylinders were 120 or 115. I forgot to hold the throttle open when I did it and I live at 4000 ft, so actual numbers are probably quite a bit higher. The engine still delivers good mileage and power and doesn't smoke or make any weird noises...
by Tom68
Thu Mar 12, 2020 3:46 am
Forum: Propane Forum
Topic: Dual carbs with propane?
Replies: 26
Views: 9992

Re: Dual carbs with propane?

Wouldn't the cam-induced-egr theory only work with a horribly restricted exhaust? Any sort of free-flowing exhaust system should provide enough of a reduction of pumping losses to offset any mileage benefit of egr Gas flows to lowest pressure, that's why the oil getting into your inlet tract gets b...
by Tom68
Wed Mar 11, 2020 2:27 am
Forum: Propane Forum
Topic: Dual carbs with propane?
Replies: 26
Views: 9992

Re: Dual carbs with propane?

I thought about the mile-a-more but was scared off my its 108 lobe center. I was reading another post on here on how propane doesnt like tight cams as it tends to suck the intake charge out the exhaust . It probably makes more power, but I drive this truck 60 miles a day so mileage is important. I ...
by Tom68
Tue Mar 10, 2020 3:30 am
Forum: Propane Forum
Topic: Dual carbs with propane?
Replies: 26
Views: 9992

Re: Dual carbs with propane?

For reference, my cam is a isky 256. 450/450, 202@.050 and 112 lobe sep. I just looked that up and I think you have lobe separation (LSA) and Lobe Centreline Angle (LCA) mixed up. In all honesty I think the MILE-A-MOR or the Turbocycle-A are better alternatives. Why? Mile-a-mor is a single pattern ...
by Tom68
Mon Mar 09, 2020 6:13 pm
Forum: Propane Forum
Topic: Dual carbs with propane?
Replies: 26
Views: 9992

Re: Dual carbs with propane?

For reference, my cam is a isky 256. 450/450, 202@.050 and 112 lobe sep. I think a important thing to remember with mileage is that its more about the whole truck than the engine. Replacing the 9 in axles with 8.8s and the granny 4 speeds with the mazda 5 speeds im sure helped with mileage. the bul...
by Tom68
Sat Mar 07, 2020 5:03 am
Forum: Propane Forum
Topic: Dual carbs with propane?
Replies: 26
Views: 9992

Re: Dual carbs with propane?

Im RV cammed and computer free, so I dont have those restricting me. Seems like the consensus is a single mixer for propane. I know the old school GM inline guys swear by dual or triple carbs for their sixes, and thats what got me thinking about it, but they dont have the benefit of dealing with pe...