Teardown and Rebuild

[Royal Squire]

My Dad used to drive Ford(cummins powered) school buses. The schools mechanic always told the drivers " if it's too cold to go outside with no clothes on, plug those buses in"

[CSM]

I think injectors make a big difference with droplet size, but CR  (compression ratio) makes more difference. 

H.o. trucks should start best,  but Tylers truck will have a slight disadvantage with marine pistons. 

Another disadvantage tyler has is his big cam.  I have not run the numbers,  but I think that the dynamic compression at low rpm is pretty low.

[diesel4life]

5 minutes ago, Royal Squire said:

My Dad used to drive Ford(cummins powered) school buses. The schools mechanic always told the drivers " if it's too cold to go outside with no clothes on, plug those buses in"

Cummins recommends plugging in at 0*F and colder. It surely doesn't hurt to plug them in in warmer temps (except for the wallet) 

I generally plug in once it dips down into the single digits unless I'm at work, then I plug in pretty much all the time during the winter months LOL. 

[TFaoro]

Mine is great when I let the grids kick in, but if I don't it starts rough. Heck sometimes it gives a hickup at 60* (no grids) and blows white smoke until some heat builds up. I'm not worried though. She always starts!

 

[AH64ID]

Is the marine engine bowl size larger than pickup pistons? The marine Pistons in my CR have the same size bowls but my compression is slightly lower due to protrusion differences. I should be around 16.8:1  

I would think that a slightly larger cam would help as that is more air being compressed which should acheive a higher pressure and temperature. 

 

 

[TFaoro]

The lift shouldn't make a difference at cranking speed, but the timing should. I don't know what the time difference is for the intake valve closing

[Mopar1973Man]

36 minutes ago, diesel4life said:

Cummins recommends plugging in at 0*F and colder. It surely doesn't hurt to plug them in in warmer temps (except for the wallet) 

I generally plug in once it dips down into the single digits unless I'm at work, then I plug in pretty much all the time during the winter months LOL. 

The only time mine doesn't get plugged in if outside is when there is no electricity to plug into. Darn "Current Bushes" don't work very good up here in the middle of winter. Typically I make sure to get it at least parked in a unheated shop which is typically above freezing not but much though.

[CSM]

27 minutes ago, AH64ID said:

I would think that a slightly larger cam would help as that is more air being compressed which should acheive a higher pressure and temperature. 

 

To get specific numbers, I need the degrees ATDC the intake valve closes.  I can't seem to find the cam info stock on the Hamilton 188/220, but assuming about 4-5 degrees of overlap I get the following.  I doubt 4.5 deg is anywhere close to right.  I based it of half the overlap-45/2.   

Static compression ratio of 16.3:1.
Effective stroke is 4.71 inches.
Your dynamic compression ratio is 15.07:1 .
Your dynamic cranking pressure is 353.71 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 15.07 :1.
V/P (Volume to Pressure Index) is 381

Calculator used. http://wallaceracing.com/dynamic-cr.php

In all honesty though, it has been so long since I got into the nitty gritty of cams, I really don't remember much!  T-56 Allisons don't have Cams dangit!  

[AH64ID]

I have the info on my 178/208 at home so I would guess Tyler has it on the 188/208. 

[CSM]

It would be interesting to compare to a stock cam. 

[AH64ID]

IIRC there is very little, if any, overlap on my cam. The colt stage 1 I rad did have a bit thou. 

Interesting enough the dynamic compression ratio doesn't include valve lift/duration into account. 

I wonder if you could find the stock cam specs. 

Edited November 9, 2015 by AH64ID

[Mopar1973Man]

Interesting not on that page...

Dynamic Cranking Pressure: (at 150 rpm starter rpm) Note=> after 7 to 10 needle pulses on a hi-quality Compression Tester

The slower the cranking RPM, the lower the cranking psi The faster the cranking RPM, the higher the cranking psi

The poorer the Piston Ring seal, the lower the cranking psi

The poorer the Valve Seat (and guide) seal, the lower the cranking psi

In addition, aluminum Blocks may show lower cranking psi

Also Engine should be between 140 F to 180 F temperature for Tests

The compression tester's needle should swing over to 90+ or more psi on the 1st Pulse this indicates great Hone Job, Valve Guides, and Valve Job

[TFaoro]

New track bar bushing installed. No signs of even trying to death wobble

Got the new gauge in tonight.... turns out I was making 60psi until BOOM

Edited November 12, 2015 by TFaoro

[BBHD]

Bummer! But at least you know what kind of boost your making instead of guessing off a bad gauge. Did you paint your intake horn?

[Mopar1973Man]

Time for silicone boots and fresh clamps.

[dripley]

Do the clamps actually wear out?

[TFaoro]

8 hours ago, BBHD said:

Bummer! But at least you know what kind of boost your making instead of guessing off a bad gauge. Did you paint your intake horn?

No... those are under the hood LED's. It happened around 10:30pm on the highway.

7 hours ago, Mopar1973Man said:

Time for silicone boots and fresh clamps.

These are very thick boots. I haven't counted the plies but they are definitely thicker than the vulcan ones I have sitting in a box over here. Clamp was fine. I just cranked it down, hammered the hell out of it again and it didn't move!

[Me78569]

care to part ways with your vulcan boots?

 

 

 

[JOHNFAK]

It's always exciting when something let's go at that high psi 

[notlimah]

wow! built cummins probs! haha