cleveland and modified heads

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   My 351 cleveland has modified heads (not sure why previous owner had this setup, didnt find out until i took heads off). To date i have not found any info as to wether this has any advantages or disadvantages, but i have read that the heads are interchangeable. Any of you guys have any insight?

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JavierV Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 15-May-2012 Location: New Mexico Status: Offline Points: 118	Post Options Post Reply Quote JavierV Report Post Thanks(0) Quote Reply Topic: cleveland and modified heads Posted: 30-May-2012 at 2:20AM
	My 351 cleveland has modified heads (not sure why previous owner had this setup, didnt find out until i took heads off). To date i have not found any info as to wether this has any advantages or disadvantages, but i have read that the heads are interchangeable. Any of you guys have any insight?

Rockatansky Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072	Post Options Post Reply Quote Rockatansky Report Post Thanks(0) Quote Reply Posted: 30-May-2012 at 9:40PM
	what is the casting code, D5xx... do they have an 'M' in the corners? if they are truly Modified heads that would mean that they came on a 351M engine produced beginning in 1975, thus the D5 casting. check this out http://raceabilene.com/kelly/hotrod/newmotor2.html the D5 casting has a different water jacket from the previous version of the 2V head. the water jacket takes up some space in the exhaust port, causing some resriction, it can't be 'ported' out or you'll hit water. if you do use that type of head you'll want to make sure your camshaft has significant exhaust bias, more duration on the exhaust side to help compensate for the less than awesome exhaust port they also may have Thermactor provision, an access hole in the end of the heads for an 'air tube' to deliver air from a pump that was originally mounted on the front of the engine. then there are passages through the inside of the head to each exhaust port, some had Thermactor and some don't. if yours do have the access hole you can get special plugs to seal them up, some guys use gasket sealer or epoxy but i wouldn't rely on that long term. $1.99 each here, http://www.store.partsdinosaur.com/product1521.html $10 each at Summit, $11 something on ebay... no way
	72 GT Ute

JavierV Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 15-May-2012 Location: New Mexico Status: Offline Points: 118	Post Options Post Reply Quote JavierV Report Post Thanks(0) Quote Reply Posted: 31-May-2012 at 2:23AM
	Yes I have and "M" on the corners. Sorry Im just learning about engines so not the most knowledgeable. Would it be more beneficial to go with cleveland heads?

torkair Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 01-May-2010 Location: Tucson, Az Status: Offline Points: 430	Post Options Post Reply Quote torkair Report Post Thanks(0) Quote Reply Posted: 31-May-2012 at 10:02PM
	The only reason I can think of to go with the "M" heads is because they were available and the original ones were too expensive to repair. If you have the chance to get a set of pre '75 heads for good price then go for it! The main reason is because the "M" heads have a water jacket running through the roof of all the exhaust ports, and this causes a flow restriction and hurts power production. However if the M heads you have are just fine and you're not looking to make 400+ hp then they will suit the bill just fine.
	72 Gran Torino "sport"- in progress 73 Ranchero GT- Q code-460/C6/3.25 open rear

JavierV Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 15-May-2012 Location: New Mexico Status: Offline Points: 118	Post Options Post Reply Quote JavierV Report Post Thanks(0) Quote Reply Posted: 01-June-2012 at 2:14AM
	Well i can get a cheap set of already machined 72 cleveland heads. I had these "M" heads machined shortly after i got the car so they too are in great shape. Though i would rather have the clevland heads on it i think i will just stick with what i got for now seeing as how i just came across a very cheap 429 (casting # C8VE-F). Only reason i posted this was because i was unsure if I was currently losing power on my vehicle but seeing as how i dont even think im pushing close to 300hp i think i should be fine.......right?

Rockatansky Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072	Post Options Post Reply Quote Rockatansky Report Post Thanks(0) Quote Reply Posted: 01-June-2012 at 7:38AM
	you got it
	72 GT Ute