454 investigation...well last hope..

[Okimbackkinda]

The original engine gave up the ghost...And what i found was a 454 in a rv...1983 rv to be specific. Compression and leak down test came out surprisingly well, however a new timing chain is order and the tinker bug has struck again. Dropping in a new cam could get some surprising results ive found and at the same time one key component is missing...Compression ratio.... it seems those old engines run 7.8/1 and what i need to get to is 8.5. And no i am not willing to go as far as new piston assy...frankly nor am i willing to go to Ovals...im fine with 4500 rpm...It seems milling is not the answer....actually i seem to be stuck here...Any thoughts or suggestions as to how one bump the C/R without a major rework...Smiles i do get what i am asking here...but if i could get to a smidge over 8...i could get big gains on the cheap so to speak.

And yes the engine will be marianzed....

 

[Scott Danforth]

You need to start with what heads are on it, what combustion chamber, and what pistons.

what is your issue with oval port heads? If you say you cant make power, you need to rethink that.

 

[Okimbackkinda]

There factory peanut heads...flat top pistons all factory stuff..If one can get the C/R up to 8.5 it is quite possible to get 420/40 hp but most importantly is very close to 500 ft lbs of power...and really inexpensively... And yes i do grasp the Ovals potential..

 

[Scott Danforth]

"peanut heads" were only available on gen V motors. which is 1990-1995.

specifically post your head casting numbers. most likely you have 049's which are not a bad head and will easily support 500 lb-ft. however you will need to mill them .030 to get the combustion chamber down to 114-115 range. you could have 781 heads.

you need a smaller chamber. I would consider the L29 head (vortec) used on the 1996-2000 gen VI motors with flat tops. the heads flow well to about 5200 rpm and they have a 99cc combustion chamber

 

[Okimbackkinda]

At this point there is hope...last night i used a site to identify what was made during that time. I believe you to be correct which would be a happy moment...it seems marine ovals with small valves and a 4 bolt main was built during that time frame it also seems it is a bit haphazard. I need to go out to the garage and pull the head covers and get the block numbers...My personal experience with the 454 is very limited and the available information on... online sources are all over the place. I came back to this site for clarity and your depth of experience on this subject...i really enjoyed the overall build on your cruiser..very well done This will take a day or so in the meantime i thankyou for your clarity.

Respectfully
Tail_Gunner

 

[Okimbackkinda]

Well, that trip to the garage was a smidge long, the heads are 781 heads will be milling them down...use a .020 head gasket and run a xe268 comp cam. Then on to a marine distributor...As to these heads...I am simply going to have a valve job done new spring and lifters...spring to there cheap enough...the rods roll as flat at one could hope I guess that would be wrap so to speak.

 

[Scott Danforth]

clean the casing flash from the intake runners and exhaust runners. leave the intake runners rough, the exhaust should be smoothed and blended.

 

[sdowney717]

Is cam overlap increase by changing to a higher performance camshaft going to cause riser reversion, meaning raw water more likely to be sucked back into the exhaust manifolds? After discovering some water sitting in my exhaust manifold I found the lip had rotted away inside the riser and so then water can flow back over the hump, cause engines actually suck part of the cycle on the exhaust stroke. I have been wondering about a mild performance cam in my v8. On my Palmer V8 392, the exhaust manifold chamber is below the exhaust ports, so water sitting there wont easily go into the engine. But it causes rust on the inside surface.

 

[achris]

Is cam overlap increase by changing to a higher performance camshaft going to cause riser reversion, meaning raw water more likely to be sucked back into the exhaust manifolds? After discovering some water sitting in my exhaust manifold I found the lip had rotted away inside the riser and so then water can flow back over the hump, cause engines actually suck part of the cycle on the exhaust stroke. I have been wondering about a mild performance cam in my v8. On my Palmer V8 392, the exhaust manifold chamber is below the exhaust ports, so water sitting there wont easily go into the engine. But it causes rust on the inside surface.

This is a hi-jack. If you have a question of your own, start a thread of your own.

Chris.
iboats mod team.