what is the differance between 153 cid head and the 181 head???? and a camshaft ques

[alilley]

i have a 66-72 153 cid 2.5 block that is not crack or anything but had a bad set of rods in it. my 181 3.0 is cracked both internally and externally(bought it that way hoping it was jsut external.....boy did i learn). all of the internaly on the 3.0 are good. after running some numbers i have found out that the crank out of my 3.0 will fit and blolt in to the 153 block, rods are the same legnth, all i have to do is find a set of pistons for the 153 (which should give me a cid close to 174 cid...if i did the math right)

now for the question...will the head off of the 2.5 work with the intake on my 3.0? what is the differance between the 2 differant heads?

now for the camshaft question....is it the same camshaft between both motors? if not which one should i run providing that they are both good cams?? or should i just find a new cam all together? if that is the case then where would i go? what size lift duration?


and i guess i should of thought of this before i started this project but will the 153 cid block bolt up to my alpha 1 out drive???? they are both chevy based and chevy has not changed thier bell housing bolt pattern in eons. thanks again for your help out there

 

[Alpheus]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

Go HERE and compare the part numbers...

 

[fishrdan]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

Check out this reference.

 

[LilRedNeckGirl]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

I read a post on here about a guy putting in a used engine. His problems started with the head to manifold connections. It started out " It looks the same", then went to " I can fix that". he ended up fixing this to fix that for months. Ultamatly, he pulled the head and bought the right one. Be sure its ABSOLUTLY the right one before you " Endeavour to persevere"....

 

[alilley]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

does anyone know that the combustion chamber size differance would be between the 2?

 

[alilley]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

what about the camshafts? are they the same between the 2? where could i get a new one @? we have a regrind shop that is some what well know in my town what are the odds of them having a replacement cam for this puzzle?

 

[Bondo]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

Ayuh,... You're treading in uncharted waters,...

I can tell ya, the crankshafts are very different,...
The 153 has Only a pulley on the front, 'n the 181 uses a harmonic balancer....

I'd sooner think, just finding a 3.0l would make yer life, Much more livable...

 

[zbnutcase]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

Cobble, cobble!

 

[alilley]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

Cobble, cobble!

how is this a cobble cobble?
hottrodders have been taking a 350 cid block boring it .030 over and put a 400 cid crank in it producing much more torque and hp. so would that be a cobble job then?

that is bascally what i am doing here. Using the 2.5 block and head, putting my 3.0 crank in it (all the jernal numbers match up so it will bolt in using standard bearings), having the block slightly bored over to fit new pistons and have good seating on the rings, and going to have the head reworked so it is good to go. how is this going to be a cobble job?

but this is getting this thread way off track from the orignal questions here which was the differance but in reality i should have askled if the 3.0 itake will work on a 2.5 head? if so which gasked do i need to run? the 3.0 or the 2.5?

lets keep this thread with the orignal question on hand here and to make things a little easier in this rebuild i will start a new thread with all the details that i have found for this deal here

 

[fishrdan]

Re: what is the differance between 153 cid head and the 181 head???? and a camshaft

hottrodders have been.........................

Something I learned oong ago, high performance usually does not equal high reliability. For a marine engine you need high reliability since the engine is being spun at high RPM all the time.

For the 2.5L/3.0l question, there have been several others who have tried to "cobble" something together, some worked, some got frustrted and we never heard back. There are lots of pit falls and not only do you have to worry about 2.5L/3.0L differences, you also have to worry about M1/Alpha1/Alpha1 Gen2 differences. Start throwing mismatched parts together and you could be fighting one problem after another.

BTW, the cams are supposed to be the same grind, from what I've read/seen.

As others have said, go find a 3.0 block and you will know everything will fit correctly.

I'm not saying you can't get a 2.5/3.0 cobble to work, but don't expect it to be easy or cheaper than finding a 3.0 block.

It sounds like you are taking offense to the word "cobble", well don't, as this is what you are trying to do. Once you get this thing put together it's going to be a nightmare for someone else to figure out "what's - what" with the engine. I have somethings cobbled on my boat and it would certainly throw a wrench in the works for someone else if they had to work on my boat.