GM 454 power/MPG issues

[Gary - K7GLD]

Guess I'm just an analog guy in a digital world, but I'll take simple, tried and true over gee-wizmo gizmos any day.

:-laf:-laf:-laf





YUP - I LOVE the power of my modded '02 24 valve - but feel compelled to carry a spare VP-44, ECM, PCM, APPS, and LP - PLUS all the necessary tools to replace them if necessary out here in the boonies where I live because of the established weakness and failure rates of those critical components - and the resulting difficulties and delays in obtaining replacements...



NEVER had those issues with the earlier purely mechanical stuff - the new stuff is neat and powerful in itself - but come with a PRICE - and SOMETIMES, that "price" sure seems stiff...

 

[RVTRKN]

I stand behind what I said "modern GM is Crap" the 426 HEMI Dominated Stock Car racing including Chevy. (notice I didn't write NASCAR) Everyone has thier own opinion and I can respect that.



As far as a 360 Magnum goes, pulling 12K GCWR on grades will beat the 454 in a pull up a grade with the same weight, but the 454 will pull more and more easier over the 12K, but watch the fuel gage drop as you climb. My 360 got 18MPG the 454 no mater what you are doing or as fast as your doing it will get no better than 10MPG. I'm not a fan of the new HEMI but would love an SRT V10/V8 in any chrysler product.

 

[GCroyle]

I can see this turning into a series of posts from Gary about how he squeezed every ounce of energy out of the venerable 454, can't wait to watch his analytical mind explore what can be done with his and Arlene's new toy.



Best of luck my friend enjoy the camping and the challenge, you have some really interesting leads so far.



Me I got this crazy bug to look at Airstreams, just cause my truck is silver that silver bullet would look great behind it. Tents are my favorite though.



Happy trails to the camping and RV crowd!

 

[Gary - K7GLD]

I can see this turning into a series of posts from Gary about how he squeezed every ounce of energy out of the venerable 454, can't wait to watch his analytical mind explore what can be done with his and Arlene's new toy.



Best of luck my friend enjoy the camping and the challenge, you have some really interesting leads so far.



Me I got this crazy bug to look at Airstreams, just cause my truck is silver that silver bullet would look great behind it. Tents are my favorite though.



Happy trails to the camping and RV crowd!

:-laf:-laf:-laf



Thanks for the input, Gary - and the challenge to refine the abilities of the 454 IS interesting to an old hotrodder like me - but the basic age of the MH itself, as well as the sorta limited actual use and mileage we're likely to put on it create a pretty tough limit on practicality. I can see better mufflers, or total exhaust system, tho the exhaust manifolds and size pipe already there would seem to limit increases available from that source. The carb and distributor refinements are quite do-able, but I need a good source (Summit perhaps?) for items needed to get started - either a complete RV developed drop-in distributor/Carb, or the smaller parts to mod what I already have.



Even if I *double* the MPG, it's still pretty low for serious or long-distance travels - but if I could get something like that AND significantly improved power, THAT would be VERY attractive...



Efforts on the MH so far have been a full wash and paste wax job - like polishing a BARN! And installed new Bilstein front shocks and steering stabilizer. Totally rewired the headlights - separate relays for hi/low beams, all 10 gauge wire direct to batteries, all soldered and shrink-wrapped connections - GREAT lights now! We have a replacement refrigeration unit coming for the weak Norcold refrigerator - will install that in the next week or 2. Also totally resealed the roof - it was pretty good, but wanted it better, came out very nice!



Here's a shot from our first outing to the local lake CG with the MH:



#ad




BY the way, when are you gonna be headed over our way again - I owe you a lunch or supper!



.

 

[RVTRKN]

I can't imagine my (departed) 98 1500 5. 9 (360) magnum out performing any 454 that could still crank up and run. If it truly was a magnum, my third grade cap pistol was a howitzer. Mark

Sorry, I missed this post. Your 360 was the same but the exhaust and some minor differences were not. The 94 2500HD (and there was a difference) 360 gasser had better breathing capability. I don't remember the differences because I gave my shop manual away when I sold it, but I can't forget the 3" exhaust it had.



Gary - K7GLD, I hope you enjoy your MH and wish you the best, please keep us posted on the performance of it and what mod's you do.

 

[SRath]

That's a nice rig, Gary. Our friends have one very similar with a 454. They use it to pull a fairly large motocross trailer full of bikes, tools, etc. and that baby rips! Something is definitely not right with your's, judging by your posts. 454's are great motors. (and Nopower 360's aren't, RVTRKN )

If you give the guys here at Skip White's a call and tell them what you need, I'm betting they can either set this distributor up with the right advance curve or tell you how to do it yourself. Check out the features, power, and price on this baby: SBC BBC 350 383 CHEVY SUPER 65K HEI DISTRIBUTOR 6500-GY:eBay Motors (item 370246194892 end time Aug-26-09 07:16:05 PDT)

I bought some aluminum heads for our Camaro project motor from them and they treated me right. I'll also be buying one of these distributors.

These guys build solid Chevy motors. They are a machine shop and racers. I'm sure they know how to build a motor for a tow vehicle/RV, too. Pick their brains for some engine ideas while you have them on the phone. They can out-do even an edelbrock package and I have not found better prices on go-fast stuff anywhere.

 

[Gary - K7GLD]

If you give the guys here at Skip White's a call and tell them what you need, I'm betting they can either set this distributor up with the right advance curve or tell you how to do it yourself. Check out the features, power, and price on this baby: SBC BBC 350 383 CHEVY SUPER 65K HEI DISTRIBUTOR 6500-GY:eBay Motors (item 370246194892 end time Aug-26-09 07:16:05 PDT)

That looks great - and so does the PRICE!



I emailed them, will see what reply I get - thanks.

 

[SRath]

There's nothing like a dyno session to dial in a great advance curve, but an experienced engine tuner/builder can sure get you close. When you check for vacuum leaks, be sure to check your transmission modulator, too.

Yeah, for the price they are selling those ready-to-run distributors, you can't even begin to do the same things to your old one. Heck, a no-name cap, rotor, and coil would cost more.

 

[Gary - K7GLD]

Regardless of their reply as to re-curving one for my application, I'll probably buy one just on general principles - sure can't hurt!



I remember a past case with one of my GM vehicles, where the advance diaphragm was apparently torn - no advance, vacuum leak - and poorly running engine...

 

[DValentine]

If I am not mistaken I believe that 88 was the first year for the truck to get a roller cam. As mentioned before, a cam would help you out. Heads too. I gather you don't want to spend a bunch on this project, but a cam in a Chevy is a lot easier than a cam in a Cummins.

Dave

 

[GCroyle]

Gary, that's a great looking rig and a nice spot to camp at. Good luck on the challange. My travel plans do not have a NW trip right now, but things can pop up, I'll keep you posted.



I thought it would have been a van body with an add on camper, that's a nice one.

 

[steved]

I have been told by friends of mine, who build 454s for their 4x4 toys, that there is sometimes insufficient oiling with the cam in the 454 and that the cam tends to wear the lobes off prematurely. Obviously, less lobe is less lift, and less breathing.

We had a 1987 3500 stake body at the drilling company I worked back in 98... it ate the cam lobes with less than 100k on the clock (those were hard miles though)...

Take that for what its worth...

 

[Gary - K7GLD]

Well, the Carb guy SRath pointed me to didn't figure much advantage in going into the Quadrajet, since it was just newly rebuilt - I bought one of the fancy and VERY reasonably priced distributors pointed to further above - will wait a bit before deciding what or where to dig in next, engine wise. MH goes to shop Wednesday for transmission service, and I went ahead and ordered new Bilsteins for the rear of the MH, since my impression on the short drive I took was that the front ones helped.



I'm pretty convinced that gains are available if the timing could be advanced - but as far as I can see. it's virtually IMPOSSIBLE to check timing in a conventional manner - the front of the engine is totally covered by the dashboard overhang, and the fan shroud finishes off THAT avenue - must be some other way to do it - will check over on IRV2, and get ideas, unless some here have been down that road, and can pass me a clue...

 

[SnoKing]

Set the motor to tdc and mark new timing marks on the bottom of the motor. They make a tape that you can install on the crank pulley and then make a new pointer.



SNOKING

 

[fox]

I have been told by friends of mine, who build 454s for their 4x4 toys, that there is sometimes insufficient oiling with the cam in the 454 and that the cam tends to wear the lobes off prematurely. Obviously, less lobe is less lift, and less breathing.



We had a 1987 3500 stake body at the drilling company I worked back in 98... it ate the cam lobes with less than 100k on the clock (those were hard miles though)...



Take that for what its worth...

THe chevy V-8's oil the cam ok. That was an oil quality problem, in my opinion.

There will be many more flat tappet/cam motors die from this , as modern oils have less of a certain additive that helps lube these high friction points.

The bigger motors ussually have heavy/bigger valves that require stronger valve springs, so this adds to the issue.

 

[Gary - K7GLD]

Fortunately, found the lower timing mark/pointer - turns out that visibility is good from below, looking up from behind the front crossmember...



Just need a light with LOooooong leads - or the helper mentioned above...

 

[SnoKing]

Score one for Chris! SNOKING

 

[Gary - K7GLD]

ONE thing mentioned from another forum over in IRV2, was that when using that timing index on the bottom side of the engine, the timing light should be attached to #5 plug instead of #1 - anyone heard that one?

 

[steved]

THe chevy V-8's oil the cam ok. That was an oil quality problem, in my opinion.

There will be many more flat tappet/cam motors die from this , as modern oils have less of a certain additive that helps lube these high friction points.

The bigger motors ussually have heavy/bigger valves that require stronger valve springs, so this adds to the issue.

I was only relaying what I was told...



When the 87 finally got "tired", the local GMC dealer simply replaced the OE cam with another OE cam. There was nothing wrong with the bottom end of the engine, the reason they diagnosed it as the cam. It was very gutless... so if timing doesn't help, might look at that possibility.



The power difference was VERY noticeable afterwards. And again, it was nothing more than an OE cam swap... not an aftermarket cam, but a OE GM cam from a local GMC dealer.

 

[BDaugherty]

A cam swap and/or mild head work will really help a 454. They make peak torque at a very low RPM which sounds great, but it really isn't. When you are pulling a grade, you have usually downshifted causing the engine to wind up into a RPM range where it doesn't make its best power. The easiest thing to do is to help the engine breath a little better. All the smog stuff sure doesn't help matters.



A torque converter lockup switch will help a lot. If you lock the t/c in 2nd on long hills, you will keep a lot of heat out of the cooling system and you won't loose as much power to the t/c.



Make sure your air cleaner is pulling cold air from outside the engine compartment. Verify that the flapper valve in the intake tube is shutting off the hot air from the heat riser piping on the manifold.



You can experiment with using 89 octane fuel instead of 87. In some cases, the computer will allow you to run more timing which will give you more power and economy. You will have to experiment to see if it's worth it, but you may get enough increase to offset the additional cost.



A Duramax torque converter is the hot towing setup for a TH400. It's got a stronger clutch, lower stall speed, and you may be able to pick up a cheap used one from someone who upgraded.