1g rods with 2g crank PLEASE help

[black97spyder]

Okay so about 3 months ago when i was in the middle of buying parts for my engine rebuild I came across a unused set of forged Wiesco 8:1 and scat H beam rods for $450 online.... The guy said that they were for a 7 bolt, standard bore and ready for install!! So i made a road trip and went and inspected them and they looked great! Jus minute surface rust patches Here and there on the rods so i bought them.... First off, they ended up being .020 overbore so i Thought no big deal, I'll just bore my block and go on with the install. So i bored my block and found out the guy I got them from Had 3 out of 4 rods turned around backwards. Once again dumb me Thought no big deal, so i turned them around so the bearing tangs were facing the correct way. Being that i Thought I had everything ready for my build to begin, I went ahead and put my ARP main studs in and dropped my crank in...... Now I started to put the pistons in, compressed the rings and stuck the first one in to find out that my rods are too wide for my 7 bolt block!!! .... So I found out once again the guy I bought them from deceived me yet again and they were 6 bolt rods Not 7 bolt rods

Situation is that i am now broke otherwise I would just buy a set of 7 bolt rods and sell the 6 bolt ones

Is there any problems that anyone can forsee me running into by simply swapping the rods to 7 bolt rods? Are the wrist pin sizes the same between 6 bolt and 7 bolts? I'm trying to solve this massive headache as easy and cost friendly as possible.. What options could I do to make the 6 bolt rods work with my 7 bolt crank??

ALL would be greatly appreciated! Thanks, Matt

 

[arrowhead]

You dont seem to have much confidence in your machine shop, side clearance of rods is done every day and is a very common and simple procedure it is not something that the life of the engine depended on it and would bring you problems later on.

This would only entail a little more grinding, yes that is what we call it, as a matter of fact this should be done to every rod just to clean small nicks and dents.

I will try to upload a picture of a rod grinding machine later, although it can be acomplish with other types of equipment.

 

[black97spyder]

Some pictures would be great arrowhead!!! How Exactly Should my machine shop go about the resizing of the rods?? This is his first 4g63 engine. He's never touched one before so he keeps asking me questions on What to do??? despite all that I do have confidence in my local machine shop as he helped me with the machine work on my 550 horse camaro.

What he first suggested was resizing the rods like you and several others have suggested as well.. the only thing I doubt is that he has the right equipment for the job .. I also know a guy who's interested in my pistons and rods in the future so i could sell those and at least get my $$ back out of them.

I got some extra money loaned to me last night for the all the things I'd have to buy. When I got my 6 bolt setup that I didn't know was 6 bolt at the time, the only thing i wanted different was higher compression and now I have a chance to go that route....

 

[BogusSVO]

There are several machines that can do the job, he may need an attachment bushing made tho.

A wet segment stone surfacer, a flywheel grinder, even an old brake lathe would work.

 

[black97spyder]

Hmmm Alright. Thanks BogusSVO!!! What steps would he take on one of those machines? It'd b my luck that the machine shop would resize them and something would go wrong. Then I'd b stuck doing more custom work, which is what Im trying to avoid for now altogether! Thanks for all the helps guys!! It's making me feel a tad better about my headache of a problem!

 

[BogusSVO]

Take the rods and crank, and a used stock rod to the machine shop.

They will need to measure width of the crank throw, and the old stock rod, then figure want is needed for rod side clearance.

Then evenly and flush cut the rod down, then champher the rod.

Its not all that hard to do, just time consuming and tedious.

The set up has to be accurate, and parallel

 

[black97spyder]

Thank you soo much Bogus!!!!! I will take an old rod down to the machine shop and see What they think locally and if he's even able to do it!

Thank you soo much Bogus!!!! I will take my used stock rods to the local machine shop and see what he thinks!

Sorry about the double post. My smartphone is acting up

Sorry about the double post. My smartphone is acting up

 

[slo2spool]

I would have to say you are wrong, a typical automotive machine shop can cut them down, if they wanted to.

I know I could. On 2 different machines, on one machine 2 different ways.

I have done the procedure before, but it is not common to do.

The "Blanchard Machine" is found in machine shops, just a smaller version, one being a wet segment stone grinder, commonly used for surfacing heads and blocks
Another would be a flywheel grinder.



MJ, Sorry, grinding would work work with the proper set up, it would be slow going though.

I only say blanchard grinding because it is what gets done on certain pieces of stock before machining...but of course I machine MUCH larger things. And I have been in a couple machine shops for engine building and haven't seen anything I would really use. Besides, every part I've machined that has been blanchard ground before hand has always held super tight tolerances, not that 90% of the people on this forum know what blanchard grinding is.

 

[black97spyder]

Well I'll admit that I'm one of those people who doesn't know what a blanchard grinding is . I've been around a lot of mechanics and engine building but I havent had to do any special work to make things work properly.

I have a full Manley assembly coming within the next week! Forged Manley 9.5:1 compression with Manley rods that hold 175 horse per rod!!

Anybody have any ideas on roughly about how much compression I'll be pushing with just the head and block resurfaced and a Mitsubishi MLS head gasket??

 

[BogusSVO]

Now way to tell what your compression will be with out some more info.

What is the thickness of your head? or the CC of the combustion chamber

What is the piston to deck clearance?

What is volume of the dish in the pistons?

 

[black97spyder]

I will have all of that info late next week when I get the 9.5:1's in the mail and install them! Then I will be able measure piston to deck height and see if the pistons even have a dish, I think they will b flat top, Not dished Though bumps that Had 10:1 or 10.5:1 would be awesome!!!

I will also have the machine shop volume test my head to see what CC the combustion chamber is

 

[BogusSVO]

http://www.dsmtuners.com/forums/articles-engine-fuel/341621-how-cc-combustion-chamber.html

http://www.dsmtuners.com/forums/cyl...heck-piston-deck-clearance.html#post152107571

http://www.dsmtuners.com/forums/articles-parts-feedback-reviews/458346-manley-piston-inspection.html

Also save a few bucks, stall the build for a week or two if you have to, and have the rotating assembly balanced.

The engine will just be smoother.

 

[black97spyder]

It was already balanced with my previous rotating assembly (the 6 bolt one that wouldn't work) and Is now $100 wasted because I had to get new pistons and rods :/ but I guess I can save back up again and take the crank back out of the block for another balance job!

You have been tons if help BogusSVO!! Thank you so much!! I will get back with you when i get the pistons and rods installed in the motor and have you double check my compression ratio when i get my numbers.

 

[BogusSVO]

Well the crank is still balanced, 4cyl cranks do not use a bob weight, like V6 V8 cranks do.

So you just have to balance the rods and pistons.
Most of this should apply to you.

http://www.dsmtuners.com/forums/cylinder-head-short-block/342138-how-fix-balance-hang-pistons.html

 

[black97spyder]

Alright awesome! I can weight match the rods and pistons with a paint scale at my work (oriellys) and then do a lil touch up work to get the weights the same!

Yet again you've came through, thanks bogus!!