400 Refresh
When I said "at for below 8.0:1", I meant if I'm running 91 octane all day.
I would love to run 87 Octane since these old beasts are 8000 lbs dry, and are about as fuel efficient as driving a barn down the highway, in the wind, uphill, in the snow...
After searching through the info above, I'm looking for a DCR calculator that'll give me a decent estimate of what I'll end up at. Just for kicks, not to be taken as gospel. I agree that 8.0:1 with my build would require that everything lines up perfectly and goes according to plan... after selecting the appropriate parts to get there.
So far, here's the numbers I'm using for the DCR calculation:
- Comp Cams 260H - Intake Valve Closes @ 56 ABDC
- Assume 78cc head (not sure how much will be milled at this point) - I'm using the original 2V open chamber truck heads that will have a full rebuild
- Stroke length (stock): 4.000"
- Bore (0.030 over): 4.030"
- Rod Length (stock): 6.580"
- Assumed Static Compression: 9.2:1 (based on the text on Tim's website)
- Boost = 0
- Elevation = 1893 ft (where I live)
Using this DCR calculator, I get a DCR of 7.45:1.
Again, this is highly theoretical, and everything HAS to be 100% dead on to achieve 7.45:1 with what I've used as inputs to the DCR calculator. So what I actually get will be lower than 7.45:1.
Any comments on this?
This a chart I found, it seems to be accurate with my build. I'm running a 8.27 DCR with alloy heads, so subtract that from 8.27 and I get 7.77. I get by on 91 octane, but at 199 engine temp I start to get a very slight fluttering ping at part throttle. I can take a turn or two out of the vacuum advance on the dizzy to get rid of it, but its just showing I'm right on the edge as far as dcr and octane goes. wish I could find a chart that has a lower octane fuel.
This a chart I found, it seems to be accurate with my build. I'm running a 8.27 DCR with alloy heads, so subtract that from 8.27 and I get 7.77. I get by on 91 octane, but at 199 engine temp I start to get a very slight fluttering ping at part throttle. I can take a turn or two out of the vacuum advance on the dizzy to get rid of it, but its just showing I'm right on the edge as far as dcr and octane goes. wish I could find a chart that has a lower octane fuel.
Let me put my engineer's hat on for a minute
. I don't think we need a chart that shows the lower octane ratios.This is an assumption, and a big one at that... but the relationship between the fuel octane and the DCR is linear. Extremely linear in fact.
Therefore, we can recreate the formula's for all three temperatures on your chart you posted and calculate the maximum allowable DCR to run say 87 octane.
Simple algebra and knowledge of graphs. Hey look mom! I'm useful! LOL.
Here's a bunch of info on DCR/Octane: http://garage.grumpysperformance.com...on-ratio.2718/
Ford Trucks for Ford Truck Enthusiasts
More reading for me too!
I might be able to convince my shop to change its mind (slightly) on a few things with my build, but at this point in time, I believe he's made a couple of parts orders to get everything ready for when Tim's pistons arrive.
We had originally thought of using stock pistons with the 252H cam... until I found out about Tim's pistons and wanted a little more mmph by selecting a better cam too.
The plans for this build is:
1) Reliability (make this build last as long as humanly possible - I'm 27 now and I want to still own the truck when I'm 97 lol)
2) Weekend warrior with the occasionally being upgraded to daily driver on those nice summer weeks.
Occasional towing, and weekend use like fishing or 2-4 hour road trips. This will not be a show truck, and definitely won't be a trailer queen. It'll be driven, but not beaten on.
I should also mention it won't be use for those extreme activities either. No mudding, no hunting, no climbing, no real back-country use unless there's a decent road lol.
- All the torque I could muster
- Roughly 300 hp - 350 hp
- Remain streetable and drivable
- Good fuel mileage, not a total pig at the pump
Just talked to the shop and the motor won't be ready until December. Huge bummer........
So much for a Fall start-up and break-in...
So I turn to you guys. What are my options?
It'll be -30 Celsius by the time the motor is back. Do I leave the engine sit on a stand until Spring? Do I attempt the first 500 km break-in period before parking it?
I don't plan on driving this sucker in the winter, but it will have block heaters in it.
My fear is crashing into someone and losing the truck permanently in the icy/cold Canadian north winter.
Just talked to the shop and the motor won't be ready until December. Huge bummer........
So much for a Fall start-up and break-in...
So I turn to you guys. What are my options?
It'll be -30 Celsius by the time the motor is back. Do I leave the engine sit on a stand until Spring? Do I attempt the first 500 km break-in period before parking it?
I don't plan on driving this sucker in the winter, but it will have block heaters in it.
My fear is crashing into someone and losing the truck permanently in the icy/cold Canadian north winter.
So I take it that no initial start-up and the first 500 kms is equal given the lack of responses? lol
Knowing you're chomping at the bit to get her runnin' and your builder threw you a curve ball, I would do everything possible to the vehicle - clean/pain the engine compartment, new vacuum lines, electrical wiring, brakes squared away, trans in good shape, etc, etc - until all you're doing is waiting to drop in the engine and ready to roll.
Actually, I would would break her in as soon as you get the engine....you're bound to have some nice days, and the initial brake in won't take more than 45 minutes. During that time you could take notes on what to do to "fine tune" her. If she's runnin' good, leave the break-in oil in and take her for a quick spin....shifting from second to third (at a fat RPM) and then backing off the gas --- letting the engine's compression slow her down. Do that a few times...it'll seat the rings faster.
Laving in the break-in oil after initial fire up, you say? Yeupp! It's good for about 300 miles - ~ 482.7 Km. Or if you want to change the oil right away, wait 'till the engine's cooled down a bit before you throw Dino oil with the additive in. Don't put cold oil into a hot engine! And, the valve springs need a few heat/cool off cycles to be happy....I'm presupposing you're running new valve springs, keepers and retainers with the new cam, yes?
Coolant....If you're positive about the engine's workmanship being done right, you could break her in with 50/50 water and antifreeze....just be sure about the head gaskets being on correctly and the thermostat is working as it should.
Take her out and do the engine compression slow down a few more times then drive her like you stole her. During the coming lousy winter months, you can play with her a bit more.....the block heaters are a nice touch as are some little portable electric heaters placed on the deck and under the bonnet....Concrete blankies always help if you can get 'em.
Knowing you're chomping at the bit to get her runnin' and your builder threw you a curve ball, I would do everything possible to the vehicle - clean/pain the engine compartment, new vacuum lines, electrical wiring, brakes squared away, trans in good shape, etc, etc - until all you're doing is waiting to drop in the engine and ready to roll.
I was operating under the assumption that the oil would need to be changed immediately just to make sure there's no issues or metal flakes with the cam scrub / cam break-in.
Dino oil? Additive? Do you mean more engine break-in oil + some sort of additive?
I'm assuming that the engine needs at least 500km on break-in oil in order to be happy. After that, I'm also assuming I can make the switch to something else + a zinc additive (if zinc additive is required).
I've got a heated garage to work in (for now) until my relatives start throwing a hissy fit... but they know the motor won't be back until December.
From what I've read online, the break-in process sounds scary & intimidating.. but from those I keep talking to, the online stuff I've been led to believe is wayyyyyy overkill.
Using purely break-in oil for the first 5,000 kms is what I keep seeing... changing it at 500, 1000, 2000, and 5000... That's like $500 just in oil!!!! I keep getting told it's way way overkill and things should be seated and good within the first 500km if I do it correctly.
EDIT:
Thanks for sticking around my thread everyone. Its days like these that you guys give me some confidence with this whole motor rebuild.
Absolutely...won't hurt a thing and it'll save you a few bucks...especially if you're using something like Joe Gibbs Driven BR 30 for break-in oil.
Just what break-in oil are you planning to use, if I may ask?
Tiny metal flakes/shiny stuff? Well, you're gonna get those, even after many miles on her, albeit diminishing in nature. Why do you think you run a good oil filter in the first place? Don't skimp on the oil filter here!
Dino oil? Additive? Do you mean more engine break-in oil + some sort of additive?

EDIT:
Thanks for sticking around my thread everyone. Its days like these that you guys give me some confidence with this whole motor rebuild.










