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Later head (71) on a 65 slant
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Author:  65cuda [ Wed Jan 13, 2010 3:27 pm ]
Post subject:  Later head (71) on a 65 slant
I am takeing out a 71 /6 .
I have a 65 slant six i want to put in the 71. is it worth it to use the 71 head or just run the 65.
I am also debating if i should try to drill out the crank hole or switch the crank from the 71.

my goal is to make a daily driver and be: #1 dependable, #2 MPG then #3 performance. i have a super six setup and electronic ign.
i don't mind taking the head to the shop and getting it rebuilt or shaved.
does the 71 have the hardend valve seats?
while i have it out i am going to change the freeze plugs to brass and i have a gasket kit ready.
the 65 is suppose to be low miles and the 71 is high miles. thats the reason for the parts swap.
anybody have suggestions???
Author:  Joshie225 [ Wed Jan 13, 2010 3:53 pm ]
Post subject: 
I would assess the condition of both engines before doing anything else. I have a 46k mile 225 in my '67 Valiant with significant cylinder bore wear. The car was apparently subjected to a lot of short trips and the power valve was assembled wrong so the mixture was always rich. This is just one example of how a low mileage engine can be worn more than a higher mileage engine. My Dakota has over 4.5 times the mileage on the odometer than on my Valiant, but it uses much less oil and has better compression.

For both engines: Do a compression test and a leakdown test if you can. Compare the cold and hot oil pressure. Check for timing chain stretch too.

Either head will need hard exhaust valve seats, but the '71 head will have the improved combustion chamber. If you pull the head measure the piston deck height and the combustion chamber volume. You may be surprised at how low the true compression ratio actually is. Of course a low compression ratio will hurt both your economy and power goals.
Author:  65cuda [ Wed Jan 13, 2010 4:31 pm ]
Post subject: 
well the 65 is already out. i bought it because i thought it would be a easy swap. then i found out about the crank hole size change in 68. the 71 is almost out. i did have it running a little before i started taking it apart. i couldn't really tell much about it. i will need to measure how far down in the hole they are. there was a cheap rering kit on ebay a while back but they must have sold out.
so has anybody tried drilling out the hole in the crank. ???
Author:  Joshie225 [ Wed Jan 13, 2010 5:24 pm ]
Post subject: 
You don't drill that hole in the crank for the torque converter. You put the crank in a big lathe and bore the hole. Dutra had this done not too long ago.
Author:  65cuda [ Wed Jan 13, 2010 5:34 pm ]
Post subject: 
well crap!! i guess i will swap the crank out of the 71 block and put it in the 65. maybe find me a rering kit while i am at it.
Author:  Joshie225 [ Wed Jan 13, 2010 5:37 pm ]
Post subject: 
Quote:
well crap!! i guess i will swap the crank out of the 71 block and put it in the 65. maybe find me a rering kit while i am at it.
I still don't think this is necessarily the best course of action. Newer isn't always better. Inspect and measure carefully. Make sure what you're doing really is of benefit.
Author:  65cuda [ Wed Jan 13, 2010 7:44 pm ]
Post subject: 
I do wish that i had a chance to drive both of them. Then i would have an ideal of which was the best. but one thing for sure is the 65 crank isn't going to mate with my 70s 904. guess i will just look inside both and measure what i can.
where is the best place to get a rering kit?
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