I put together this engine this spring. I got a little over 100 miles on it and then the 700r4 died...I then put in a th350
.
I Got the car all back together on Thursday. I drove it around a bit - about 50 miles or so at the most. The tranny shifts well and the cars seems somewhat strong on the top end but....I am pulling the engine out tomorrow.

Something is wrong at the bottom end of the powerband. Under 3000rpm the car is a dog. It sputters and bogs and revs up quite slow. Above 3000, the engine smooths out and pulls pretty hard. I've had a couple of guys helping me out and they figure its valvetrain related. It could be that a few lifters are bad and that once the oil pressure is up at high RPMs they smarten up and don't collapse at mid-lift...I don't know.

Or maybe the valvesprings aren't quite right.... they are 1.450" OD Hydraulic Dual Valve Spring, 120 lbs. on seat, .550" maximum lift.

I want to pull the cam out and check it out and pull the oil pan and double check for crank endplay. Better safe than sorry.

Or maybe a lobe on the cam is wiped...I am not sure. Time for a solid cam?

Good times.

 

Doesn't sound like anything valve realted to me. Above all, it's not any of that stuff about "collapsed" lifters. That just pure fantasy-land.

Sounds more to me like a carb tuning issue.

Try swapping another carb onto it, just for test purposes.

 

I agree with RB, try swapping on another carb that you know works correctly and can be tuned correctly.

 

Yeah, you don't check crank end-play for a low-RPM driveability problem. That's nothing but a left turn off the pavement and down the dirt road, past the end, and into the weeds. Actually, more like into the forest and off the cliff into a lake.

Instead of inventing bizarre one-of-a-kind "explanations" for tuning issues, try tuning it first. You might save yourself an untold amount of trouble and grief and expense.

About any Holley square-flange carb ought to go on without too much fuss. If you can find one of your friends that's got one that's know to work good and get him to where he's not in such a hurry to dig into your short block, try substituting it on there. Or, just apply normal carb tuning techniques to your Demon, and dial it in.

Forget all the rest of that drivel; it's just that, drivel. If your friends insist, nod knowingly, smile condescendingly, don't say a word, and then ignore them and use comon sense instead.

 

You had a regular Qjet before and it worked pretty well right? Why not (temporarily) swap it on and see what happens?

If I get my new carb soon, your welcome to try it out too. Its a vac secondary 750 Holley.

Whats the ignition curve like? Stock smogger GM HEI curve, or did you change the springs/weights/both?

BTW - did you ever get the oil pressure sender fixed?

 

As RB said its probabily a Carb tuning issue. But just to put your mind at ease you can remove the valve covers and crank the motor over and watch the valves. If a cam lobe is pooched you'll notice it in the valve ( rocker movement.) if they appear ok and the valve train is quiet, put all that to bed.
the carb probabily swallowed some dirt. (Fuel system) tear it down and clean all the passages and blow them out with compressed air. mke sure all the right parts are in the carb.
(jets , air bleeds etc) I'm not real familiar with Demon carbs so can't recommend a tuning starting point. if it was a holley would be different.

What is your ignition timing settings? ( initial, total, advance curve)
What is the stall speed of the converter?
What plugs are u using ? what do they look like.?

 

Just out of curiosity what size stall and gears are you running. Because the XE274 is not exactly a low end cam. If you dont have at least a 2400 or so stall and at least 3.55 gears its gonna be pretty sluggish up until it gets into its powerband. I could defenetly see it stalling and sputttering with the stock stall and gears numerically lower than 3.55. I know I may be pointing out the obvious but no one else mentioned it.

 

EDIT - nevermind

 

When I broke my 10 bolt I run 2.73's with the T5 for a month or so and it was a real dog with this cam. Was hard to get it going from a stop. Plus the TH350 has a higher first gear than the 700r4 which won't help, unless you have the right gears and stall. What gears do you have now? Should have 3.42's at a minimum prolly, and 3.73's would be that much better.

 

I guess I didn't post the complete story on this board before...

My rockers keep backing off (3rd time), I am struggling to get 10" of vaccuum on a similar setup to others who get 15"+ of vaccuum and the three cylinders that I had a compression tester into read 150, 125, 110.

The carb has been jetted several times and I have tried different shooters. It may not be optimum, but should run well as we put it on a friends 12s car in place of his 750 Holley and ran pretty much the identical mph. Also tried a different distributor yesterday with very little or no improvement.

I may still be a little soft on the new converter, but thats not what is causing the big stutter.

The cam should allow the engine to make lots of torque even in the 2000 rpm range. The new converter should flash to at least 3000rpm.

I also tried another distributor with little to no difference. One distributor had 22 initial and 36 total in by 3k and the other 12 initial with 38 total in by 2800.

Anyways....my girlfiend and I yanked the motor out on Monday and today I pulled the rotating assembly out. Here is what I found:

1. The incorrect rod bearings were used. The crank should have been only used with chamfered bearings. The rod bearings are now cut/rounded resulting in small particles everywhere.

2. The #4 cam bearing has a large, deep, rough mark in it. The cam was tough to get out and it wouldn’t go back in.

3. The #1 main bearing has lost is crush due to particles floating around.

4. The low compression on was likely caused by rings line up on 4 cylinders (3, 4, 7, and 8 ).

5. Cylinder # 4 was porous and pitted badly. Several cylinders had significant amounts of rust in them.

6. The rings on cylinders #5 and #7 are rusty.

7. The oil pump is cut up from material in the oil.

8. Only half of the rod bolts had assembly lube on them, the other half had none which would lead to inaccurate torque readings.

Needless to say I am quite impressed with the quality of the machine shops work. I guess I'll see what they say tomorrow.


EDIT: The short was put together at the machine shop in May and was fired about 10 days after.

 

.......................
















...ouch.




Sorry to hear that man, thats a real bummer, but at least your not spending more time trying to figure out whats wrong.

 

They built it right? Give em hell and get another one built right... by them or someone else, but it should be on them.

 

Paid the shop a visit...
The owner was at the front desk, when he asked how it was going, I said not good and started to explain some of the problems...He didn't seem overly willing to help but told me to walk back to the machine shop and talk with the guys that assembled the short block. He also said that I'll have to bring it in on Monday morning as he is leaving on holidays after that.

Went back and talked to the guys in the back. They seemed surprised at first and then sort of rationalized the items (ie. converter could have ballooned taking out the thrust bearing and then all of the other bearings, fuel wash, detonation....that the assembly lube wears off, that rings sometimes just line up but they always stagger them). I told them I'll bring it in on Monday morning and we'll go through it together so they can see what they think happened. Didn't sound very promising though as error didn't seem like it was high on their list of possibilites.

 

Sounds to me like they are wanting to make excuses for a poor assembly. What are the chances of all those things happening at the same time? This is when you MAKE error high on their list of possibilities.

 

What shop was this?

 

Thane's / Prarie Engine

 

And Legal action high on your list of possibilities if they won't fix it at their cost. before you take it in for them to look at I'd document what you've found wrong ( pictures are good). So is haveing another qualified auto machinist look it over at your house.

 

UPDATE

Took everything to the shop yesterday to go over with them.

Here is what happened in response to my issues posted earlier:
1. The incorrect rod bearings were used. The crank should have been only used with chamfered bearings. The rod bearings are now cut/rounded resulting in small particles everywhere.
"Yeah, those aren't the right bearings. They sent us the wrong bearnings in the kit." I don't think it was a kit as the parts were chosen individually. Either way, thats either their suppliers problem or their problem.

2. The #4 cam bearing has a large, deep, rough mark in it. The cam was tough to get out and it wouldn’t go back in.
"The oil must have been so full of fuel that it lost all lubrication properties."

3. The #1 main bearing has lost is crush due to particles floating around.
"Due to the timing chain at the front of the engine, the #1 bearing sees the most wear."

4. The low compression on was likely caused by rings line up on 4 cylinders (3, 4, 7, and 8 ).
"We staggered the rings - rings just sometimes line up and then sort themselves back out."

5. Cylinder # 4 was porous and pitted badly. Several cylinders had significant amounts of rust in them.
"The black streaks are normal water marks, and the rust is normal on engne that sits for a few days at a time - our Cascar motor would look the same if we tore it down right now."

6. The rings on cylinders #5 and #7 are rusty.
From the 5.

7. The oil pump is cut up from material in the oil.
"The oil pump looks fine inside...just needs a good cleaning."

8. Only half of the rod bolts had assembly lube on them, the other half had none which would lead to inaccurate torque readings.
"Completely normal...we see that on a lot of motors that get taken apart."

I asked what the warranty policy was and he told me that he'd have to talk to the owner and see what he figured. He'd also phone the manufacturer of the cam bearings to see if they've had any issues. I was told that they'd get ahold of me after lunch (Monday).

I heard nothing yesterday or this morning so went in after lunch today. The owner had just left so I left a message to call me back.

He called back today and told me "all your going to get out of me is bearings." I told him that I thought that was awful poor and told him that I'd be by shortly to pick up my stuff.

I went right over and loaded everything onto the truck. After it was all on I went over to talk to the owner. I asked why he was giving me bearings and nothing else. He responded "I'll admit that we assembled the engine with the wrong bearings but that's not what killed this motor....it had nothing to do with it....fuel wash and detonation killed this motor." I let him know I wasn't very impressed with the fact that he'd only replace the incorrect parts and wouldn't offer any other recourse (ie. labour paid for to assemble the engine with the incorrect bearings). He told me that "hey, if you knew anything about racing, you'd know that there is never, ever any warranty on anything with performance attached to it" (I thought the insult was a nice touch!). I opened my bill and read to him " Warranty on parts & labor is 1 year or 20,000 km whichever comes first." Warranty work has to be performed in our shop & cannot exceed the original cost of repair." He said that warranty statement isn't applicable because this is a performance application and there is never any warranty on performance applications. He told me that he was firm and that I'd have to sue him but "you can take me to court but I know that without a doubt I'll win."

I said that I couldn't believe that he wasn't prepared to do anything else, even clean my parts and he then offered to clean up my things. I just said to order my bearings and that I'd be back for them.

There was more said but that summarizes the converstion.

 

I'll be sure NOT to be doing any business with them

But.... if the warranty statement doesn't say anything about 'performance parts' then its assumed that it could be applied to anything they build... I think you could probably get him on that one

 

I'd be talking to a lawyer, I think this would go in your favor from the way things sound. I think he was trying to intimidate you to MAKE YOU FEEL like you wouldn't win. Of course, I'd try and get a full refund of all parts and labor and court/lawyer costs of course, not another engine done by them. That's a pretty sad business right there.

 

I agree completely. Its like someone trying to talk all big and bad to scare you out of a fight but in all actuality you would kick there a$$. I would defenetly speak to a lawyer.Good Luck man.

 

Like I said before, if it comes down to getting a lawyer, I can recommend two of the best in town.

 

That really is messed up. You can most likely get him on this, though. Like Air_Adam said, if there is no place on the statement that says performance is void of warranty, then they have no argument. That's why companies always make sure to put that kind of junk on disclaimers. If you accept the bearings though, he may be able to say that you agreed to have that as compensation and could get out of legal action. Don't know.

How do you distinguish performance from normal applications in a machine shop, anyway?

 

Not sure how a main bearing would lose crush due to particles in the oil. Clearance, yes; crush, no.

Last Friday there was a conversation in the pits about warranty work. And, we're talking drag racing engines here. There was no question when something was put together wrong, it should be made right - regardless of use, and regardless of the cost to repair vs. the cost of work originally done. This was coming from people who work in/run shops.

One guy related advice he was given a couple of decades ago: As a shop owner, you either need to be small enough that you can oversee everything that goes on in the shop, or you need to be big enough to be able to eat the cost when something isn't done correctly. The problems come when you're in between.

Sounds like this shop is in between.

 

The builder already willingly admitted to installing the wrong bearings even thou he know full well they were the wrong ones. ( tat way the motor was sure to come back busted and he could get you for 2nd build. he's a crook. He owes you a full Quality rebuild or your money back. Where did fuel wash and detonation come into this?
does the motor show signs of detonation? (crushed ring lands, over heated spark plugs, burned ground electrode, cracked porceliens, blown head gaskets.)

Fuel wash will not hurt the bearings like you've described. A two stroke motor is lubed by mostly fuel with some oil mixed in. far more fuel than any possible fuel wash condition. They seem to run fine.
ALl desiel motors end up with fuel wash. they seem to last a long time. All motors that run on Methanol get "fuel wash" in the oil, tons of it and water. Seem to run fine.
Water/antifreeze is a different story. Piston rings do not ever line them selves up and then correct them selves, even in nascar motors He's dreaming.
Here in Ontario a mechanic or engine rebuilder who provides service to the pubic for any engine used on the road has to warranty parts and workmanship for 90days.
Check your local (provincial) laws. And stick to your guns. get a good lawyer.
I;ve been building, driving, racing "performance cars", with "performance engines" for probabily longer than the shop owner and surly the kids that work for him have been alive.
He's full of S*(&T) ...
Ya you can bust a rod by over reving it and smash a piston ring land by detonating the hell out of it but a motor build is either right or its not.
Did you save the engine oil and filter? It's strong evidence. Can be tested by a lab for fuel, etc etc metal etc...

 

As far as the legal side of it:

A-the warranty statement does not specifically exclude your motor does not qualify for the warranty (doesn't even imply its excluded)

B-even if it was excluded the fact that wrong bearings were used could be argued as gross negligence on the part of the shop (which would negate any disclaimers, like his attempt at convincing you about some industrywide 'no warranty on performance' schtik), and getting something so basic (especially for an engine shop!) wrong casts considerable doubt on the quality of their whole operation.

HTH, good luck. I do find the alarming slide in quality of service almost everywhere lately, well, pretty alarming.