Flywheel and crank mismatched bolt holes

Takis M.

Supporter
Guys,
Hit my first issue in my build (which at moment is limited to engine assembly as chassis and parts not due until later this year).
I found that only 5 of the 6 flywheel bolt holes line up with the crank.
Do I need a new flywheel or can anything be done to my current arrangement to make it safely usable (bearing in mind engine is planned to have just under 500hp mated today a ZFQ transaxle)???
 

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Takis M.

Supporter
I seem to have accidentally posted this query twice. My apologies. If an administrator could delete the one without the photo attached (the other one) I would appreciate it. Thank you.
 

Paul Hendrickx

Supporter
Hi,
look at this , picked this up one day on the net, don't know if accurate or not, but could be a start somewhere
it's about crankshaft pre 85 and after 85 with new positions for the holes and bolts
Paul
 

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Brian Magee

Supporter
There is one hole in the crankshaft offset so that the flywheel will only fit in one place to ensure the balance stays correct. The unused hole at eight o'clock looks like it is off set. maybe it just needs moving round.

Brian.
 

Brian Kissel

Lifetime Supporter
And, as Mike P said in your other post " use ARP bolts", and the proper washers. The bolts you have in there currently are cheap hardware store grade 5 bolts.

Regards Brian
 

Takis M.

Supporter
Thanks Brian - that is very important as you and Mike P say. I had noted the bolts. Quality is second to none. I will have correct ARP bolts and proper washers.
 

Takis M.

Supporter
tried it every which way (including lose) and still doesn’t quite all line up. One hole still remains just a fraction off. I could possible tighten it all down but risk stripping.....have ordered ARP bolts in case they may help.
 

Howard Jones

Supporter
Brian and/or Chris is correct. OR........Take your questionable flywheel to a engine machine shop and compare it to a known correct ford flywheel if you don't have access to a known correct one yourself. If it is new then it is possible that it was drilled incorrectly.

Do not force it into place!!!!!! no matter how "close" it is. It may be completely wrong for the application including a totally mismatched balance. You must be sure of this as a mis balanced flywheel with shake that engine apart very rapidly and ruin a lot of those expensive pieces. All of those bolts must drop in the hole dead on and tighten down finger tight without any more torque that that. Then it is correct. Really, I'm not kidding.

As far as balance goes. Do yourself a favor and have the entire rotating assembly balanced as a unit including the clutch pressure plate and crank damper.
 
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Takis M.

Supporter
Howard, I am doing exactly that. I have the complete rotating assembly ready to go for balancing. The balancing shop advised me to double check on the fitment of the flywheel and crank because they had seen a few for GT40’s that did not line up. Unfortunately, I may just be adding one more to that statistic. I am using good quality parts whcih i have researched with the help of various engine shops both in the UK and US (in fact all my parts except for the flywheel and 28oz harmonic balancer came from the US). I am not going to compromise on quality of parts or work. Just need to work this out......with your help I am sure I will, it’ll just mean another small setback and time delay.
Thank you for your help here.
 

Mike Pass

Supporter
In actual fact the flywheel and crank drive each other by friction. The bolts would not hold them together. They are there to provide the clamping force. On some race engines we used to lap them together with valve grinding paste to ensure a good contact.
If you have a 28oz flywheel the offset bolt hole ensures that the balance weight is in the correct location to offset the out of balance crank. A very small deviation will be taken up by the final balance job. The bolts should be able to be run easily by hand. As the threaded holes in the crank go through use thread sealer.
Cheers
Mike
 
Guys,
Hit my first issue in my build (which at moment is limited to engine assembly as chassis and parts not due until later this year).
I found that only 5 of the 6 flywheel bolt holes line up with the crank.
Do I need a new flywheel or can anything be done to my current arrangement to make it safely usable (bearing in mind engine is planned to have just under 500hp mated today a ZFQ transaxle)???
As Chris said earlier , in the photo you supplied you have the flywheel on back to front, that side with your name on it should face to front of crank/engine and the 2 threaded holes in the low machined area are for a weight to bolt to if its 28 or 50 oz balance factor.
 

Takis M.

Supporter
Hi Jac, Yep I get that. I have tried it every which way. I took the photo at the end of all the attempts and didn‘t have the patience to flip it round again. Tolerances are far higher than stock for these parts and as the difference is only slight I will send it out to my engine shop for balancing and have them look at it. I didn’t want to force it and risk stripping the crank thread. Thanks again to all. I should have more info end of next week.....
 
Well -- the FW has an offset hole and appears the crank doesn't ? So, what's the crank from ??
Most SBF cranks have 3" pcd 7/16" unf 60 60 60 60 56 64 degrees looking at the crank
Maybe a modified small big end journal Chev crank ?
Now we're curious
 

Takis M.

Supporter
Chris, the crank is a SCAT 331 stroker, brand new from SCAT in the US. Having said that I will double check the serial number of the crank tonight just in case. I had not thought that the crank might be the cause for concern. Thanks Chris. will revert tonight....
 
Hi,
look at this , picked this up one day on the net, don't know if accurate or not, but could be a start somewhere
it's about crankshaft pre 85 and after 85 with new positions for the holes and bolts
Paul
I would check those drawings out Paul, the one with larger center hole & dowel appears to be for later SBC with 1 piece seal, other one without provision for dowel might be SBF, but not sure without being able to measure .
 
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