350 heads on 400 questions

[chris.c20]

looking to put 350 heads on my 400, how much does it cost at a shop usually to have steam holes drilled in the 350 heads? and should these be aluminum heads or cast iron? engine has a mild cam, holley 600, edlebrock performer intake.

not trying to gain anymore power (unless it naturally happens) just trying to replace the heads instead of rebuilding the current ones (PO overheated the engine and fried the valve seals i think).

[chris.c20]

i guess cast iron would be cheaper..... eh

[chris.c20]

and also, can i reuse the cam thats on my engine, when installing the 350 heads?

[Don5]

Have you had the original 400 heads looked at by a shop? Have they been checked for cracks? If you can reuse them, that is what I would do. I suppose a competent shop could drill the holes in a 350 head. I have no idea what the cost would be.

As far as reusing the camshaft, if the lobes are OK I don't see why not. You are aware that this engine is going to be a really good torque  motor? Your cam should be good from 1500 rpm to 5500 rpm. It will set you back in the seat. Years ago when I ran a 400 I used a Crane Fireball 290 .454 lift camshaft with Performer intake, Qjet, headers.

The 400 engine will need to be externally balanced as well. You cannot use your 350 harmonic balancer and flexplate with it.

[chris.c20]

nice thanks, what kind of harmonic balancer would be preferred? they havent been inspected, but i get like a greyish smoke on start up sometimes and im losing coolant somewhere and cant find where its leaking. its also been running hotter since its getting warmer outside and causing my transmission to get hot as well. my ford did the same thing and it was prone to cracked heads until i upgraded, so i figured id just take care of the guess work and rebuild a set of $100 picknpull heads.

[chris.c20]

what year of vehicle should i take the heads off of? or anyone have a casting number that i can go off of....?

[Captkaos]

You are contemplating swapping heads but don't have the replacment yet, correct?  The only difference in 350 vs 400 heads are the steam holes.  Technically you can drill them yourself using a 400 head gasket.
Are you doing this because of the startup smoke?  It could be the valve seals.  Or if you are loosing coolant it could be cracked heads?  Have you done a compression test and leak down test on it already?

If you don't have the replacement heads yet, why not get the existing ones inspected and rebuilt if they are ok?

[chris.c20]

well i initially thought i could go get some older 350 heads that flow better than the ones i have now, but decided not to. just want more torque, more power. efficiency etc etc. so im getting some aluminum heads.

and my new worry is the compression. i ran a compression test yesterday and all of the cylinders on the drivers side head were from 150-155. the passenger side not so much. 105 being the lowest and 135 being the highest. didnt do a wet test but i did notice that under the head looks like its leaking on the front of the engine and the back of the engine. cant tell if its the intake manifold or head gasket. i plan on removing the heads next week maybe to clean them up a bit and have them inspected and rebuilt maybe. my uncle can do it i think.

as of now, it runs ok. it has a miss in the idle at 6* initial timing, any more will pop out of the exhaust. not sure of total timing, im using a crappy light. no dial. and also it has stopped smoking. figured out the intake needed a square bore attachment for the carb.