GEN-V 454 clearance issues

R

rwmorrisiii

Member
Hey Guys,

I have been coaching my brother in law thru a rebuild of a GEN-V 454 and we ran into an odd issue using a set of Speed Pro forged pistons. The crank is for sure a 4" stroke GEV-V crank, the rods are rebuilt and are the original 6.135" factory units. The pistons are the correct compression height for the total combo. But... The OD of the crank counterweight is hitting the skirt of those pistons as it nears BDC. #1 installed and worked fine but when he put in #2 it won't make it all the way around. This is tricky for me as I'm not standing there watching this happen but from all the facetime video and photos it looks like the skirts are just a touch too long to clear that crank vs maybe an earlier MARK-IV style BBC.

My question to you all is has anyone heard of this? Experienced this? Or knows how to take the easiest route to correct it? I'm thinking he can just have the crank OD of the counterweights turned down and then the machine shop can re-run the balance job with the existing bob-weights. It does appear that there's different pistons listed for the 1991 and up motors but they are all the factory cast flat top or slight dish units. Hopefully my description can communicate the issue he's seeing and hopefully someone has seen this before! Ah they joys of building motors.... Sometimes the demons pop up when you least expect them.

Cheers,

Robert Morris
 
Welcome to the forum Robert !

Well I'm not the one to help you with this problem, but surely Grumpy will be along tonight or tomorrow and shed some light on the problem. Can your BIL join the forum and post some pics so when Grumpy gets around to checking out your/his problem he will be able to provide a much better answer. Pics provide SO MUCH MORE info !
 
Indycars said:
Welcome to the forum Robert !

Well I'm not the one to help you with this problem, but surely Grumpy will be along tonight or tomorrow and shed some light on the problem. Can your BIL join the forum and post some pics so when Grumpy gets around to checking out your/his problem he will be able to provide a much better answer. Pics provide SO MUCH MORE info !
Click to expand...
Hey Rick,

Possibly? I can ask him if he can join along but I can also see if he can snap a few kodak's for me. It's a rather simple interference issue but we just need to know what path to take to get out of it. I'm sure that a more "slick" performance style forged piston, JE, SRP, Venolia, Etc would clear by a country mile with their reduced skirts but these SpeedPro's are kinda chunky. While this is a good engine I don't think it needs a set of $600~$800 pistons in it. Ha!!! But then again maybe it does? LMAO.... Thanks for the response and I look forward to others as they come along.

Cheers,

Robert M.
 
pictures would be helpful, and I may be thinking about this wrong,
but is there any posibility the pistons been installed 180 degrees out, or spun so the piston, is 180 degrees out, from its intended location?
 
Hey Grumpy,

I don't believe the pistons are in wrong but I will have him check again to be sure. Here's a few pics of what he's dealing with. The one photo indicates where the counterweight is hitting the skirt. The other shows the #1 slug installed in the correct orientation and him rough checking the deck clearance.

~RM
deckclearance.jpginterferance.jpg
 
Yeah it looks funny but the rods were all rebuilt and should be straight as an arrow. I had a good chat with the guys at SCAT this AM regarding their replacement crank and it sounds like they have turned down the OD of their counterweights and assured me it will clear with a standard rod and piston. I have some photos of the factory counterweights as well and they are really rough, "as cast" vs what you would normally see. I'm really thinking it's just a rare case of a little too long of a skirt on the piston and a rough "un machined" counterweight on the crank. More news soon....
 
Crappy cast counterweights! Took delivery on a new SCAT replacement crank for that series of BBC and everything fits perfectly. Now for a quick rebalance spin using the existing BOB-Weights and this engine can go together for the final time. Thanks to everyone for the comments and help.
 
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