Q-jet jetting help please
07-28-2014, 06:56 AM
#11
Mike tkach
how do i get ahold of allstate?
Budmann ii
my machine shop said he mills them to 100 cc's and i am guessing (hoping) for a compression boost to about 9.5. And was thinking that would make diff.. Don't know about the valve size until this weekend, i am guessing they are stock small valves.
How bad do they compaire to the 2.19 ones.
I need new heads and found a very reasonable priced low milage take offs from another kind and gracious oso member.
Boat is 1987 and was used in salt at early life. Po "kept it running" if you know what i mean. Intake rotted, exhaust rotted lower end rebuilt 2 yrs ago kept same heads. I took a lot of pics of valves from intake and exhaust ports and they look terrible and water jackets looking worse for ware. If i need to replace things i hunt for the best i can find usually quality take-offs from here. Any performance i gain in process is great. My boat is always way to darn slow.
Any thoughts options i am open, making final decisions regarding now what to do, i need to get on the water
how do i get ahold of allstate?
Budmann ii
my machine shop said he mills them to 100 cc's and i am guessing (hoping) for a compression boost to about 9.5. And was thinking that would make diff.. Don't know about the valve size until this weekend, i am guessing they are stock small valves.
How bad do they compaire to the 2.19 ones.
I need new heads and found a very reasonable priced low milage take offs from another kind and gracious oso member.
Boat is 1987 and was used in salt at early life. Po "kept it running" if you know what i mean. Intake rotted, exhaust rotted lower end rebuilt 2 yrs ago kept same heads. I took a lot of pics of valves from intake and exhaust ports and they look terrible and water jackets looking worse for ware. If i need to replace things i hunt for the best i can find usually quality take-offs from here. Any performance i gain in process is great. My boat is always way to darn slow.
Any thoughts options i am open, making final decisions regarding now what to do, i need to get on the water
To answer some of your questions directly: A bump to 9.25 CR won't do much without better cam, bigger valves, and better exhaust to take advantage of it, especially on a 454. And if you take that much off the heads, you will also need to mill your intake or you will leak water into your engine because it won't seal. Hell, you probably won't be able to bolt it on without also milling the intake, and then you are married to that intake. The Edelebrock 2.0 Performer is a slight improvement over the stock Merc mag (GM) intakes, but a better choice on a boat would be a Performmer RPM Air Gap.
For reference, I built a warmed over 454 for my boat 12 or so years ago. Put GM large oval heads on it, bumped the CR up to 9.25:1, added Comp Cams flat tappet cam, Performer RPM intake, rejetted Q-jet, etc. Motor ran great and was dependable, but in the end I gained maybe 2 mph over a stock 7.4 for my trouble and money. Engine eventually blew the ringlands off two pistons fromm detonation with that higher CR. IMO 9.25 is pushing the envelope on a marine engine with iron heads. You will always have to make sure you are running good 93 octane gas, which is not always available at the marina. Merc kept the CR on the HP500's at 8.75 for a reason.
07-28-2014, 07:15 AM
#12
Budman ii
i hear what you are saying and agree with you completely, however, this is what i have. The block was rebuilt 2-3 yrs ago and all fresh water sence he had to clean the block?, i am not looking for huge gains just warm up on the cheap as i have an alpha behind it. I would change the cam as it is apart but no roller take-outs been on swap for awhile
future will be bravo 1 then as you recommend a good strong take-out is in order.
Great point on the head milling, wonder what would be safe?
Thanks for the info
i hear what you are saying and agree with you completely, however, this is what i have. The block was rebuilt 2-3 yrs ago and all fresh water sence he had to clean the block?, i am not looking for huge gains just warm up on the cheap as i have an alpha behind it. I would change the cam as it is apart but no roller take-outs been on swap for awhile
future will be bravo 1 then as you recommend a good strong take-out is in order.
Great point on the head milling, wonder what would be safe?
Thanks for the info
