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I have a late ‘68 455 that was rebuilt 12 years ago. I have very little info on what went into the engine. I’ve been told it has a Thumpr cam. No idea about any other internals. It has an Edlebrock Performer intake. I heard it run several times back in 2009. It was in someone else’s project car that he never finished. It was given to me and is currently sitting in my 65 GTO project that had no motor.
As a newbie, I’m curious if you guys think I need to tear it down and verify what’s in it before proceeding. Like I said above, I know the motor ran. It was never put on the road. It was always garaged. It still rotates freely.
I was considering at least replacing the Thumpr cam with something more appropriate for street cruising. Thanks in advance.
I guess it depends on how confident you are in the quality of the machine work. Do you have any idea of what was done and by who? What are your goals with the car?
If the engine is out of the car, pull the oil pan and inspect the bearings. While it’s not very accurate, plastic gauge will give you an idea on bearing clearance. I would prefer the clearances to be on the loose side of tolerance, but most shops machine things with a Chevy mindset.
Build the short block correctly. As long as the bottom end is done right and stays together, you can always upgrade the top end.
Just my opinion, but gaskets are cheap. Take the water pump and front cover off and see if there are any identifying marks on the cam. "Thumper" is a relative term and you may find the cam is not too aggressive for what you want out of the engine. Make sure it is degreed properly while the front is apart and repair as necessary. Take the pan off and check the bearings, if it was never in a car, they should be like new. Plasti-gauge should give you a good idea of the bearing clearances like mentioned. You can get a small bore camera and stick it through a spark plug hole to find if the pistons have info on them. If they are something desirable, leave them there. You could possibly know everything about this engine for $100 or so.
Just my opinion, but gaskets are cheap. Take the water pump and front cover off and see if there are any identifying marks on the cam. "Thumper" is a relative term and you may find the cam is not too aggressive for what you want out of the engine. Make sure it is degreed properly while the front is apart and repair as necessary. Take the pan off and check the bearings, if it was never in a car, they should be like new. Plasti-gauge should give you a good idea of the bearing clearances like mentioned. You can get a small bore camera and stick it through a spark plug hole to find if the pistons have info on them. If they are something desirable, leave them there. You could possibly know everything about this engine for $100 or so.
Thanks for the advice. I'll probably do just that. I was thinking of swapping out the front accessory drive anyway. I don't currently have the brackets for air conditioning or power steering and plan to equip the car as such. The GTO was a factory A/C car anyway.
January 19th, 2021, 05:01 PM
