After all the little bugs, water temp, rockers coming loose, push rods breaking, header gaskets leaking, the motor finally decided to give up and spin a bearing or something to that effect. Loud banging noise and it's not the rockers again. I got to fix an oil leak (oil pan) so I guess it all works out to some extent. It ran for a few months and maybe 400 miles. Definitely not worth the time, money, and effort put in. It'll be a long time before it gets re-built, no more funding at this time. It was fun to drive for the short time I drove it and when the time comes to re-build, those dual quads and rockers are history.

 

I'm sorry to hear about your engine . When you do have the finances to rebuild it please create a thread showing us what your doing with it. John

 

That really stinks! Did you do the engine, did you have it done, or did it come like that. I do hope you get her on the road again. Sorry to hear about this....

 

That was a pretty hot build wasn't it?

 

I'll sure post what I find. I built it, the machine work was done by the previous owner or who he had do it. I bought the parts and put it together so I may have goofed up. I wasn't afraid to run it hard and hope I didn't do it too soon. It screamed above 3,000 rpm which makes sense with the cam and converter in it and after installing the 3.91 posi, it was crazy.
Maybe just maybe it won't be so bad, it made noise, I may have exaggerated the loud banging, it sounded kind of like the a rocker was loose but louder. The rockers checked out. I'll just have to pull it apart and go from there. The oil pan leaks and or rear seal, so I need to fix that anyway.
It should be hotter when I do get to put it together. Torker, 850 Holley, and HS 1:7 rockers.

 

Depending on the rest of your combo upon reassembly, you might want to rethink the Torker, and/or the 850 Holley.

Done 2 in the last year, stay with a 750 or so with the Torker or the 850 with a Performer, even with the 3.91

Jmo.

 

Sorry to here your troubles. I hope you have a chance to salvage your hard work. Let us know.

Maybe its a small issue...fingers crossed.

 

Here's some pics of the left side. The noise was coming from #1 and it looks like #1 was contacting the head at the top of the piston. This may have just started hence the noise. #3 piston looks like crap, carbon build up. Looking at the headers, #3 & #5 are gray, #1 & #7 black. Wasn't burning evenly.

 

wow sorry for your bad luck could have it been a blown head gasket looks like a break by the water jacket hole. Is the number 1 rod okay something had to cause the slap.

 

Pics of the other bank. What is all that copper colored stuff on the pistons? This engine doesn't have a bunch of time on it. #4 piston like the one opposite has the carbon on it. Must have something to do with the heat crossover plugs I put in that over time got smaller and didn't do what they were suppose to do. I also ran mostly off the rear carb, I guess the engine was running rich?

 

The center two pipes of the header you show look lean to me, other than that, it doesn't look to bad. Maybe a bit rich in some cylinders, but nothing extreme, but I know nothing about what to expect from those dual carb setups.

- Eric

 

Looks like you spun #1 rod bearing. Piston made contact with the head.

Gene

 

That's my guess.
Eric-the only thing to expect from a dual quad setup is what you see. They're really a whole lot more for show than go.

 

Yeah, glad to hear you say it .

If you do the math for two 600cfm carbs, then a 455 would have to turn about 8,000 RPM (with an optimistic 100% of the displacement cycled every revolution) to use their capacity.

For two 800cfm carbs, well, that number would be a whole lot of revs...

- Eric

 

All I know is my "more show than go" setup had nothing to do what happened. Mine had plenty of go. I may have to keep the intake and downgrade to 500 cfm's which will be better than the 750's. Math or no math, it'll go!

 

Yeah, and not to get into a back-and-forth about it, because your motor made plenty of power, and the carb setup had nothing to do with the failure, but you'd need at least 9,500 RPM to use those 1,500cfm of capacity, and as you can see from the mixture variations in your cylinders, you trade off a certain amount of evenness of distribution, as well as trading low-throttle control and consistency, for that extra capacity that you can't use.

- Eric

 

I ran mostly off the rear carb so I guess that's the reason for the uneveness. Good to know. If I use the manifold again I'll be putting 500 CFM carbs on and run them in tandem.

 

I would think the 2 - 500 cfm's would do really well. However, wouldn't it be more economical to rejet the 2 you have???

 

Never thought of that. I'll have to look into it, I'm definitely on a tight budget.

 

Sorry to hear about engine problems, hope you can get things squared away. If piston hit head you will want to pull that rod and check it and bearings. Also see that others will not repeat the trouble. I have 2 carter 500's on an offy manifold on a 425. Looks great and seemed to run very well but I am not sure of HP gains or loss over a single 4bbl. It was just a matter of choice. Linkage worked both primarys together and secondarys opened simultaneously as well.

 

That sucks Dan, I'm sorry to hear this happened. I hope you can get her running again...just nudge the wife into your corner by taking her out to dinner a couple times haha!

 

It's funny cause I haven't told her yet, she sees it as a big waste of money and after dropping 5-6k recently only to tell her that it broke and will be another 1k to get it going again, not good. I'll get it running again but not anytime soon. I guess the smart thing to do is start selling the extra motors / parts I got laying around to help fund this. Got to have one of two cars running at least.

 

When the piston hit the head, you are going to check and see if it still has ring clearance. Make sure it did not mash down on the ring. In order to do it right , you should replace the one rod for sure and make sure it did not damage the rod next to it. Also I would recommend that you resize the other rods. If you have the TRW/Speed-pro pistons, when you have the block honed, make sure you have at least .005 piston to cyl wall clearance.

Gene

 

Thanks for the info. This is going to cost more than I had hoped.

 

Not trying to add to the cost total, but if you're going to stick with the dual-quad setup, I highly suggest getting the correct tool to synchronize them. It's going to be something along these lines:

http://www.summitracing.com/parts/EDL-4025

I've been searching for a little bit to try and find the correct one for the 4-barrel application, but not having the greatest luck. Maybe someone else here can suggest where to get the specific one you'll need for your carbs.

Having the specific model numbers of them would possibly help as well. I remember learning how to tune multi-carb setups on the old BMW inline 6 engines back in the mid 90's while working with one of the best carb guys I ever knew out in Denver. Lost track of where he ended up after I moved back to Ohio eventually, but man... he knew how to make those cars scream! twin 2-barrels on an inline 6 running on split manifolds so each carb ran 3 cylinders.

I remember one guy had a dual-quad custom setup on a built engine, and it was scary fast after a proper tune. Basically, you should balance the airflow at idle to make sure each of them is working in synch with the other, or you wind up with the balancing issues like you're seeing inside your combustion chambers.

There's some other good principles found here:

http://www.thecarburetorshop.com/Dual1barrelcarbs.htm

(those guys may be a good contact on where to get the correct tool)

http://www.aircooled.net/gnrlsite/re...s/dualcarb.htm

(Good overall information on what exact steps you'll want to go through)

http://www.cuda-challenger.com/cc/in...?topic=68383.0

There's a good picture in this thread of an adaptor someone made for the uni-syn balancing tool. Something along those lines may be the cheapest option.

http://www.chevyhiperformance.com/ho...ual/index.html

Good article here on overall setup (yeah, I know it's for chevies, but the theory is the same. The iron/aluminum doesn't know what's stamped into it...)

Just trying to help out. I've worked on quite a few multi-carb setups back in the day, but never dual-quads. Always wanted to play with such a beast.

Which specific manifold are you running? I might want to play around with a setup once I get a good running 425 under my right foot again.

-Jeff

 

... The Porsche dual Webers were always fun to synchronize as well - the equivalent of six fully independent carburetors, one for each cylinder. As you say, get 'em set up right, and man would they scream!

- Eric

 

#1 rod bearing spun. Doesn't look like any other damage. Caught it early if that's possible. Should be an easy fix. Why it spun is the question.

 

time to break out the micrometers. I've tried replacing bearings that have spun before. Sometimes it works, sometimes not. I know they make some odd sized bearings. Like +.001 +.002 +.003 Get some good measurements and get the correct one if possible/needed.

-Jeff

 

Will do. I assume the bearings had too much clearance. Thanks for the other info on the carbs. I attached a pic of my setup.

 

Had a similar situation, my crank was bent. Thats how I got it back from the machine shop so I guess it is possible to turn a bent crank. I pulled all the rods and had the big ends trued. Had the crank straightened and turned again and all new bearings. It is still running fine.

 

Pic of the bearing. I'm so cramped in my garage now.

 

You can't put a bearing in the rod and stick it back in. It WILL spin again. You need to tear it all down, turn the crank, re-size that rod,(if possible) And get all new bearings. You can cheat and re-use the mains if they are clean, also the rings if you keep them in the same hole. Don't forget to hot tank the block to clean all the debris from the oil galley's, and make sure the oil pump is clean.
When you spin a bearing crap goes everywhere.
Gene

 

My crankshaft is out of limits so is trash now. I got another 455 crank to use. Will bring it to get turned along with the rods. The rings will be reused and all new bearings installed. Every thing has been torn down and will get the block cleaned. Just wish I knew why it spun in the first place.

 

Any idea what your clearances were?

 

The rods were around .0025 and mains .003
Another lesson learned is to actually keep the paper that numbers were written on. I could just measure it out again to be sure which is probably a good idea.

 

When you say the crank is trash, what was the size of the last grind. .030 on the rods I have done a bunch of times for a grand ma type driver and even .040 a few times. Granted, I don't really like doing that, but some times you have to do what you have to do.
When they sized the rods , did they make them minimum bore size for good bearing crush, and then grind the crank to size for clearance? Also did they do the same for the mains?
If not, that is probably why the spun bearing.

Gene

 

The last grind was .010 and I believe it would take .040 to fix. Not sure how the rods were sized. It was done before I got the pieces. What I did was measure the journals for the rods and mains. Then I measured the rod and main bores. I subtracted the ideal clearance from difference and that left me roughly the bearing size of .010. The crush you mentioned, is that making the rod bores roughly .005 smaller? I forgot about the standard bearing thickness in the equation.

I attached some pics of the bearings, not sure what normal wear looks like. The #6 bearing has a perfect groove in it, copper color, but the crank showed nothing out of the ordinary. Also pic of rod and crank.

 

What he was referring to regarding bearing crush. I know how it works, but it's a bit difficult to explain in text w/o the parts to look at. I found a good definition here:

Bearing Crush
When journal bearings are assembled, each insert installed either in a semi-circular bore in the block (or rod), or a similar area of a bearing cap. When assembled into the cap and the bore section of the block, the ends of the inserts stick out slightly. When the cap is put in position, the ends of the bearing inserts butt up against one another before the cap actually seats against the block. In this position, the inside diameter of the bearing will be slightly greater when measured between the centers of the inserts than when measured between the two ends of either insert. The difference between these two diameters is the bearing crush. The crush is removed when the main cap bolts or connecting rod cap bolts are torqued.

Off this website:

http://www.imperialclub.com/Repair/Engine/terms.htm

There's also some really good info here on bearings:

http://www.underhoodservice.com/Arti...ech_Talk_.aspx

-Jeff

 

Looks to me like you had a nick in the rod journal on #6. Then you get trash thru everything. Hard to tell which came first though.
Check the rod big ends real carfully not only for size but for taper and or barrel size bores. When you have limited contact between the bearing shell and rod you get hot spots. The bearings grab the crank and away you go.

 

I'm going to have everything sized resized check rechecked next go around. I just did a quick check of rod clearances and they varied from .001 to .008. I wish I had my original numbers. I used .130 for a .010 bearing in my calculations.