4.300 - 6.700 0r 6.800 rods for truck engine ??

TravisRice March 5th 2010, 10:52 pm

I am using this in a D9TE truck block with a set of D3 heads that I purchased off of Jones. So this will be a 9.0 :1 - 9.5:1 build with a .030- .040 overbore. Which will be more beneficial for piston skirt wear and scuffing?? Looking to build a 75,000 to 100,000 mile engine.

Thanks,
Travis

schmitty March 5th 2010, 11:52 pm

I seriously doubt at the end of the day that it will amount to a hill of beans either way. Very Happy

jbozzelle March 6th 2010, 12:32 am

I would think with the D9 block it really won't matter. I'd run the 6.8 in a D1 though. I'd say whichever rod you find a good deal on first.

jones March 6th 2010, 12:36 am

From my past little experiance I'd let your piston selection make the choice for you. That is if you are wanting to go with an "off the shelf" piston.

LivermoreDave March 6th 2010, 2:27 pm

My first concern would be the crankshaft centerline to deck dimension. Assuming the crankshaft has (excuse me Embarassed

) BBC journal width and diameter your rod selection should be plentiful. Unless you option piston pin diameter, a piston that makes up the remainder of the distance (block's crank C/L to deck - 6.7" or 6.8" rod - 2.15" - piston depth @ TDC = piston CD .... I think!) and has a popular ring package (bore dia. & ring width) should work.

There are two (2) ways to figure cost IMO. If the dimensions you seek can't be exacted (is that a word?), which would consume the least from your wallet? Removing material from the block's deck or from the piston. IMO, with an application (I assume daily driving &/or towing) as yours, keep quench tight, compression ratio near 9.1:1 (cast iron head), 9.5:1 to 10.1:1 ( pale

) (alloy head) and a good ignition timing curve and rate you will be a happy camper and enjoy the use of less expensive pump gas .... I think!

Oh, you did ask of piston wear! As others have replied, the difference in piston skirt loading offered of the different rod lengths you mention will probably be non-existent.

Just another $0.02!
Dave.

TravisRice March 6th 2010, 6:41 pm

Thanks for the input guys. After a little more research I have found out that the 4.300 / 6.800 combo will require a oil ring support rail , which means the oil ring is in the wrist pin groove, had not really thought about that. So I will probably go with the 6.700 rod deal, that shows no oil ring support rail needed. With a 26cc dish, 94 cc heads and shooting for zero deck with a .041 head gasket looks like 9.0:1 is achevable. Worst case would be to look for a .038 gasket which I think Ford racing offered a few years back, but I am unsure of the bore diameter which could mean a wash if it turns out to be a 4.600 deal.

Dave you are right on key with what I am looking to do. 67 F-250 2wd with a E40D conversion............. should pull my trailer nicely.

Travis

LivermoreDave March 7th 2010, 8:04 am

Travis I did a "Tow Project" several years ago, the ingredients were a lot less than your recipe. The Ford 385 Series engine displacement is 466 cubic inches with D or C something heads that received exhaust port and bowl work along with a 1.72" valve. The intake side, except for a bit of "deburring" remained in stock form. The camshaft's duration measured 210*(IN) and 218*(EX) @ .050" lift. An Edelbrock Performer 460 intake manifold with a 450 CFM Holley. Compression was near 9.1:1, the distributor was modified for a nice amount of advance at a rate the engine could agree with. My application is a 1982 F-150 2WD, C6 and 2.75:1 ring & pinion.

On the other end of the spectrum, it was simply amazing how the engine would accelerate the 5000 lb. plus vehicle! During the search for a ring & pinion combination that the engine liked, I started at 3.25:1. It would accelerate with a moderate automobile and top speed was scary! I changed ring & pinions three (3) times before discovering a ratio that offered the engine a bit of labor!

Sorry for the rambling, so let me get to the point! My project, as mentioned above, tows great! I believe I could bend the ball Shocked

if so desired! With your combination, you may tear the hitch from the frame, if your not careful! Surprised

Good luck and happy motoring.
Dave.

TravisRice March 7th 2010, 11:00 am

Dave,
With all the mountains I have to travel over torque is the main goal of the build. Realistically I would probably only put 50,000 to 60,000 miles on this truck in the rest of my lifetime. I want it to pull a 10,000lb trailer with out ruing the piss out of it.

LivermoreDave March 7th 2010, 7:25 pm

Travis sounds as you have throughly thought out your project! It should be a "Torque Monster". Good luck and keep us informed. Charlie was on the phone with me after visiting with you. We talked about the hills in your area. I told him not to run off the road, they would never find him!

Dave.

The Pope March 7th 2010, 9:00 pm

O.K. you two!

I see where it appers that Dave knows what gear you (Travis) is running, care to let the rest of us know? Suspect

TravisRice March 7th 2010, 9:57 pm

4.10's with the E40D, and a 265 / 75 R16 10ply radial. Right now the truck is a 352 2V AT C-6 with 4.10's, gets 14.5 mpg empty and runs as fast up hilll as it will down. ........... Shocked

75mph top speed.

Travis

Diggindeeper March 7th 2010, 10:06 pm

One thing you may want to consider is if you think you might want to swap out the 4.3 arm and put in a 4.5 in the future... you'd have the correct pistons if you ran a 4.3/6.8 and went to 4.5/6.7

with 4.10's, e4 and those tires you'll run around 2000rpm @ 70 mph. (in lockup) iirc.

TravisRice March 7th 2010, 10:14 pm

Only thing with the 4.300 / 6.800 is that the oil ring pack is in the wrist pin area requiring the oil support rail for the ring pack. Worried about oil consuption when it gets a few miles on it. Never built a mild 385 engine before, kind of new to me.

Travis

DaveMcLain March 8th 2010, 2:39 pm

An advantage of running a shorter rod in this application is that it'll allow the piston to be taller and a little more massive. This will allow it to better handle the heat produced in a hard working low compression truck application that's pulling a heavy load and it will allow you to spread out the ring pack a little bit more.

Several years ago I did a 505 Chevy for a customer's truck application and it ran and worked great. Later he had me use the same engine for his mud racer and we just upped the compression, changed the cam and did some head work. The undersides of the pistons that I removed from the engine were very caramel colored underneath nearly down to the wrist pin bore. They were not collapsed or heat damaged in any way but you could see that they had been worked hard. Even the top of the rod had the caramel coloring from the heat and oil....

TravisRice March 8th 2010, 6:22 pm

Dave,
Glad you chimed in. Is there anything else I should consider about a build like this before purchasing pistons?? I was looking at the probe 26CC dish SRS series #13599. About everything I have purchased so far is used with the exception of the pistons, camshaft and camshaft related accesories. The cylinder heads are fresh and never run, crank used, still searching for some rods, etc..

Thanks in advance,
Travis

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DaveMcLain March 8th 2010, 6:54 pm

I think something like that would be a good choice. I would use that Scat I beam rod too, they are inexpensive yet nice quality.

I'd love to find a set of those Ford wheels for my '79 1 Ton.

TravisRice March 8th 2010, 7:02 pm

Dave,

I will keep a look out for a set for you. This set looked abit rough when i bought them ,with the clearcoat pealing and scratched up. I took some inexpensive aerosal paint stripper, tal strip actually and sprayed the wheels hosed them off with water and they looked like a million bucks. I really did not have to do any polishing , I just did them to basically get rid of the water spots and put some protectant on them. I like Wenol aluminum polish for the wheels also.

Travis

DaveMcLain March 8th 2010, 8:10 pm

Someone in town has a really nice Ford pickup with a set of those and I think it's about a '96 model. I'm assuming that they are 16 inch and that they will fit over the calipers on the front of my pickup.

TravisRice March 8th 2010, 9:00 pm

Dave,
Think they came on 92-97 models. newer than that they are metric pattern. I have another friend who has them on his 66 long bed chevy 2wd, they look real good on there. We converted the centers over to newer chevrolets and they look factory on it also. Should fit over your brakes with no problem. Think they are 16X7's if my memory serves me correctly.

Travis

jones March 8th 2010, 9:12 pm

That's a sweet looking truck! Nice little cream puff!!

OldRedFord March 8th 2010, 9:20 pm

TravisRice wrote:Thanks for the input guys. After a little more research I have found out that the 4.300 / 6.800 combo will require a oil ring support rail , which means the oil ring is in the wrist pin groove, had not really thought about that. So I will probably go with the 6.700 rod deal, that shows no oil ring support rail needed. With a 26cc dish, 94 cc heads and shooting for zero deck with a .041 head gasket looks like 9.0:1 is achevable. Worst case would be to look for a .038 gasket which I think Ford racing offered a few years back, but I am unsure of the bore diameter which could mean a wash if it turns out to be a 4.600 deal.

Dave you are right on key with what I am looking to do. 67 F-250 2wd with a E40D conversion............. should pull my trailer nicely.

Travis

What pistons are you going to use? Wondering for future reference.

Brian_Eyler March 8th 2010, 9:34 pm

Travis, Truck looks great with those wheels - that's going to look badass pulling the Galaxie. Watch those Probe pistons - I believe those are the same ones I have in my 532. Nothing wrong with them other than I'm pretty sure mine were only a 22cc dish - not 26cc like advertised. If you look at their other dished piston on the webpage, it's 22 cc - I believe both of them are only 22cc. I ended up milling a little more out of mine to get down to 11:1 to run pump gas.

TravisRice March 9th 2010, 6:37 pm

jones wrote:That's a sweet looking truck! Nice little cream puff!!

4.300 - 6.700 0r 6.800 rods for truck engine ?? 042

TravisRice March 9th 2010, 6:42 pm

Brian_Eyler wrote:Travis, Truck looks great with those wheels - that's going to look badass pulling the Galaxie. Watch those Probe pistons - I believe those are the same ones I have in my 532. Nothing wrong with them other than I'm pretty sure mine were only a 22cc dish - not 26cc like advertised. If you look at their other dished piston on the webpage, it's 22 cc - I believe both of them are only 22cc. I ended up milling a little more out of mine to get down to 11:1 to run pump gas.

Thanks Brian. Did the math both ways, 9.0:1 with 26cc and 9.2:1 with 22cc. I think it will be fine either way.

DaveMcLain March 9th 2010, 6:47 pm

That is really a nice looking truck. According to the speedometer you shouldn't drive it over 70mph.

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4.300 - 6.700 0r 6.800 rods for truck engine ??

4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Tow, Tow, Tow away!

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

They go uppity up, the go downdy down!

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??

Re: 4.300 - 6.700 0r 6.800 rods for truck engine ??