Engine Rebuild Wish List

[tmsnyder]

I believe they do. The cam specified above is probably it. At the time, Jim Bounds was kind of secretive on the specs of that cam and asked customers to not share the cam card, but I'm sure he's relaxed his stance on that by now.

Yes the cam Sailorman referred to is Kryptonite cam according to Jim Bounds. Its the 'smallest' 455 olds cam that Comp makes. There is a flat tappet version too.

The roller version, plus low compression rebuild pistons (compression height lowered to account for a decked block) plus my stock deck height block resulted in a pretty mild cranking pressure iirc, about 120-130 psi. I would have liked more although that pressure is right in line with the workhorse tall deck BBC engines in the topkick/Kodiak trucks. Good for burning the least expensive gas and doing work continuously!

 

[Tom Katzenberger]

I just spoke with Jim Bounds and he said that his video with the cam specs has disappeared. He did say:

"Drew Koba provided those roller cam specs to Comp from the cam he and his friend designed at Crane before they closed up in Daytona. Very similar to the flat tappet 42-214-10 first cam we designed."

He was referring to COMP Cams and he mentioned that I should look it up in Comp Cams website and he seems to remember that the number 413 is somewhere the model number.

This is it!

Here are some of the specs.

Jim confirmed that this is the cam in my engine. It was specifically designed for roller rocker.

I don't know if a FiTech technician will use this information to tune my COOP 455's FiTech 50001 In-Line Frame Mount Fuel System but it's worth a shot.

Maybe it is a "Hot Rod".

Sailor man Thank you and Carl,

I'm going to forward this to my engine builder as I am rebuilding a Ford 300 now and have my hands in too much at this time. This is a big help.

Take care,
Tom K.

 

[Kendra]

My 455 has the internal specs SailorMan described. JimB 2016 rebuild.
When it reaches 100k (half way there) I'll be aiming for the same if available.
Plenty of power, nice sounding idle, never pings at any elevation or temperature.

 

[Tom Katzenberger]

Did the Comp Cam Xtreme Energy Cam 42-413-11 work well with the Morel Roller Lifters? Does anyone have the part number for the Morel lifters? Did the Morel Lifters need to be ground down or modified?

Thanks again,
Tom K.

 

[LarryW]

Tom,
The last tech session that Dick P did for GMCMI was at the Corunna rally. IIRC he did a session on engine rebuilding. When asked about roller cams, he did not think that roller cams in yesteryear Olds engines was a good idea for several reasons. He questioned longevity primarily because they were developed aftermarket and did not have the technical expertise and testing that GM put into that kind of modification/change in the BB engines we use. The difference between the roller lifters and flat tappet lifters is significant. The roller lifters have more parts to wear out, so questioned the hardness of those rollers and how they would last on the ramp designs. He stated that the flat tappet lifters were a proven item over many millions of miles. Flat tappet lifter against a flat tappet cam has a point contact. The point contact of a roller lifter is even smaller and more severe potentially leading to more wear, especially if that roller stops rolling. He made that same point on roller tipped rocker arms. His experience with roller tips is that they do not continue to roll and found many roller tips with wear in only one spot of the roller tip indicating that they stopped rolling.

After listening to Dick, and thinking about it for some time, I think for the little that would be gained, (if anything) and knowing that flat tappet has been designed into so many big and small block engines, that until a long term proven roller cam and lifters is offered for my Cadillac, I'm good with the flat tappet system. It is important to note that replacement cam and lifters should come from a known on shore brands. In addition, oil brands known to resist wear are imperative for engine break-in and longevity. All JMHO.

 

[tmsnyder]

Tom,
The last tech session that Dick P did for GMCMI was at the Corunna rally. IIRC he did a session on engine rebuilding. When asked about roller cams, he did not think that roller cams in yesteryear Olds engines was a good idea for several reasons. He questioned longevity primarily because they were developed aftermarket and did not have the technical expertise and testing that GM put into that kind of modification/change in the BB engines we use. The difference between the roller lifters and flat tappet lifters is significant. The roller lifters have more parts to wear out, so questioned the hardness of those rollers and how they would last on the ramp designs. He stated that the flat tappet lifters were a proven item over many millions of miles. Flat tappet lifter against a flat tappet cam has a point contact. The point contact of a roller lifter is even smaller and more severe potentially leading to more wear, especially if that roller stops rolling. He made that same point on roller tipped rocker arms. His experience with roller tips is that they do not continue to roll and found many roller tips with wear in only one spot of the roller tip indicating that they stopped rolling.

After listening to Dick, and thinking about it for some time, I think for the little that would be gained, (if anything) and knowing that flat tappet has been designed into so many big and small block engines, that until a long term proven roller cam and lifters is offered for my Cadillac, I'm good with the flat tappet system. It is important to note that replacement cam and lifters should come from a known on shore brands. In addition, oil brands known to resist wear are imperative for engine break-in and longevity. All JMHO.

Was that the GMCMI that Barry Owens rebuilt the engine over 3 sessions and ran it on the final day? Pretty sure it was b/c that was the first one my wife and I attended iirc. I remember that Barry said that about the cam.

I built mine as a full roller engine, and having done that I agree with what you said as long as you could guarantee that the cam won't 'wipe a lobe' . These days, it seems like finding such a cam isn't a given anymore. The engine I took out has a flat tappet cam, and if it looks and measures 'good' I'm going to put it back in the engine when I rebuild it. A known good cam and set of lifters is about as close to a guarantee as you can get so I would just put the used cam back in the engine.

The roller cam doubles the cost of the rebuild: in addition to the camshaft, Morel roller lifters flipped around so they clear the concave intake on the 455, a cam button to keep the cam from walking around, composite distributor gear from BOP Engineering b/c the billet cam will eat the stock gear, valve springs to accommodate the higher lift (if you want to retain the rotators, I found Howards has a single spring they recommend for their flat tappet cams which will accommodate the lift and apply correct forces), rocker stud kit, pushrod guides, custom Smith Brothers low oil flow pushrods, Scorpion roller rockers with locking nuts, thick molded rubber around steel valve cover gaskets to make room for the rockers ..... it adds up!! $$$

If I were to do it again, I would have Comp grind me a roller cam that more closely matched the stock cam. Low lift and long opening and closing ramps so it's gentle on the lifters, springs, and valves and would work with the stock valve springs and rockers.

 

[mech0001]

I considered roller cam, roller lifters, etc when I rebuilt my motor.

The bottom line to me is a realistic assessment of mileage you will driving.
80K to 100K is what I would expect from one of these engines if correctly rebuilt. I would include balancing with that.

Though they would probably run longer, I would expect piston wear to become a factor as significant as cam/lobe wear after 100K.

So, how many miles are expecting to put on it, then? I drove mine across the US and back, 7000 - 8000 miles total. Might do it again (then again, might not due to fuel costs), plus some shorter trips. At an optimistic guess I'll put 30K on it. It will be barely half worn at that point. As mentioned frequently, these coaches are OLD! So many places to allocate money/time before a roller setup the way I see it.

 

[sailor man]

Sailor man Thank you and Carl,

I'm going to forward this to my engine builder as I am rebuilding a Ford 300 now and have my hands in too much at this time. This is a big help.

Take care,
Tom K.

I know that I have posted this before on other threads, but I am doing again because some of you reading this thread may not have seen it before.

The best source that I have found that deals with a comparison of various motor, loads, gear ratio and speeds is in a GMCWS technical seminar on 10/10/2006. I think that it was mostly written by Chuck Botts with some commentary by Jim Kanomate and Grandpa Billy.
http://www.gmcws.org/Tech/Final_Drive_Ratios.pdf
SO far it is the only comparison that includes a GMC COOP 455 motor. It is limited somewhat because it does not include any data from fuel injection or switch pitch torque converters. I think that it is a vary interesting read even though it is 17 years old.
I am interested in your opinions after you read it.

Rad Post #370, 3/12/24 on pg #19 on

 

[GMC Cruse]

I wonder how the GMC COOP 455 motor by Jasper compares to the Coop 455 motor by Drew Koba with the Comp Cams cam.

 

[sailor man]

I wonder how the GMC COOP 455 motor by Jasper compares to the Coop 455 motor by Drew Koba with the Comp Cams cam.

I know that there were some problems with the first engines that Jasper built, but they got better. I think that you would have to ask Jim Bounds about who was the best. If you are a "Ranch hand" you can call him.

I am pretty sure the Drew built mine.

I did once speak to Drew about building one for me before the COOP folded. He said that he would only build them for Jim.

So far, I can find no information on the performance of a COOP 455 with a carb vs on with fuel injection.

We do have data from Chuck Botts comparing his COOP 455 with card vs GMC stock 455 engines.

 

[sailor man]

Sailor man Thank you and Carl,

I'm going to forward this to my engine builder as I am rebuilding a Ford 300 now and have my hands in too much at this time. This is a big help.

Take care,
Tom K.

There are a few other things that Jim Bounds did in the COOP 455 engines. It would be a good idea for you to search for Jim Bound's videos on his COOP 455.

In addition, there are videos on how his tested them and broke them in and how he added FiTech fuel injection. He installed the engine on an old Mercedes convertible that still has the Mercedes engine in it. He has the COOP 455 power the rear wheels, tested i=them in the shop and then took the test car on the road.

 

[tmsnyder]

I know that I have posted this before on other threads, but I am doing again because some of you reading this thread may not have seen it before.

The best source that I have found that deals with a comparison of various motor, loads, gear ratio and speeds is in a GMCWS technical seminar on 10/10/2006. I think that it was mostly written by Chuck Botts with some commentary by Jim Kanomate and Grandpa Billy.
http://www.gmcws.org/Tech/Final_Drive_Ratios.pdf
SO far it is the only comparison that includes a GMC COOP 455 motor. It is limited somewhat because it does not include any data from fuel injection or switch pitch torque converters. I think that it is a vary interesting read even though it is 17 years old.
I am interested in your opinions after you read it.

Rad Post #370, 3/12/24 on pg #19 on

I have read it several times, and I'm sorry, I know it's just me but I having trouble getting past units of vacuum of 'negative inches of mercury' (so it's positive pressure??) and graphs with a bunch of lines with no legend. I get so tied up with the nonsensical presentation of the 'results' that I have no faith in the presentation. Plus it seems like they are just trying to sell their engine at the time.

Couple take aways for me though:

Many coaches are driving around very much out of tune. I can believe that. After 50 years with a carburetor and distributor that's not surprising at all and a great place for everyone to focus their energy in the hunt for a long living engine and reasonable power and fuel economy.

And the weight of our coaches is all over the map. I can believe that too as mine is on the lighter side after eliminating many heavy items, replacing with lighter weight items. That's why I hate to see the coach weigh-ins not offered at GMCMI lately. That info is so valuable.

One tid-bit in the article: "The Coop motor was developed to use 85-octanegasoline with an 8.75 Compression ratio (165 psi). " That's very interesting. 8.75 is interesting b/c there is no piston offered at that ratio. Did they deck the block, use an 8.5 piston and a thin head gasket perhaps? Maybe someone more knowledgeable could figure that out. I don't know how one could arrive at 8.75 if they started with a 10:1 piston. And 165psi cranking pressure is super interesting! That's right in line with the Alan Gold video I posted where he shoots for 160-180 on street engines. Seems pretty high for our coaches but with FI you could make it work without run-on at shutdown and by controlling pre-ignition with a knock sensor. Good way to get good fuel economy and power.

 

[tmsnyder]

Tom, how was the surgery?