Intake manifold question
01-09-2004, 08:49 AM
#11
Guest
Posts: n/a
large intake to smaller head opening is very disruptive to airflow but merc used large oval port manifolds with the peanut port heads on the 330's. This was just as bad a mismatch the mainfold being 1.5" x 1.9" and the peanutport head being 1.5" x 1.4"
as for going the other way small intake to large head opening its not as disruptive to air flow and again on mag mpi motor the merc intake manifold is 1.4" x 1.9" and the large rec port heads 1.5" x 2.2"
I always wondered about the merc mag mpi manifold, it doesn't match anything, it is much smaller than the rec port , actually being the same height/width as a large oval port but it is almost square in the corners and so is a mismatch for large oval port heads to
as for going the other way small intake to large head opening its not as disruptive to air flow and again on mag mpi motor the merc intake manifold is 1.4" x 1.9" and the large rec port heads 1.5" x 2.2"
I always wondered about the merc mag mpi manifold, it doesn't match anything, it is much smaller than the rec port , actually being the same height/width as a large oval port but it is almost square in the corners and so is a mismatch for large oval port heads to
Last edited by ursus; 01-09-2004 at 08:53 AM.
01-10-2004, 05:41 PM
#12
Guest
Posts: n/a
Merc's 7.4litre matched to a Bravo III was called a performance tuned engine and was rated at 300 hp but talk to anyone at merc and they really made about 310 hp. This was due to the use of a rectangular port aluminum intake (with brass water jacket inserts) and different jetting in the weber carb compared to the std 7.4. Both engines still used the small peanut port heads. I think they did this from 1994 to 1996.
01-12-2004, 08:59 PM
#13
Registered
Join Date: Jan 2001
Location: elyria ohio usa
Posts: 46
Likes: 0
Received 0 Likes
on
0 Posts
oval port mfd. on rect.heads
how canyou put an oval port manifold on rect. port heads? the manifold does not cover the rect. port opening.. just would like to know....Ken
02-06-2004, 01:06 PM
#16
Lab Engine in Lindenhurst N.Y. does this all the time.
there has to be a gasket that works. When I get a chance I'll check my stock. You might have to remind me as I'm going to work tonight. I love my Holley Cast Iron hi-rise squarebore manifold. Although having to open up the throttle bores with a die grinder. It's an excellent runner. I believe Lee at LAB uses a Merlin aluminum manifold with bronze passages. I think that if the holley squarebore large oval cast hi-rise manifold was not discontinued over 35 years ago it would have been found on factory Merc. motors. Another lesson learned by reading Dennis Moore's fine publications! Also depending on rpm range , using the oval manifold on Square port heads can increase usuable torque. It has been dyno proven. BBB
there has to be a gasket that works. When I get a chance I'll check my stock. You might have to remind me as I'm going to work tonight. I love my Holley Cast Iron hi-rise squarebore manifold. Although having to open up the throttle bores with a die grinder. It's an excellent runner. I believe Lee at LAB uses a Merlin aluminum manifold with bronze passages. I think that if the holley squarebore large oval cast hi-rise manifold was not discontinued over 35 years ago it would have been found on factory Merc. motors. Another lesson learned by reading Dennis Moore's fine publications! Also depending on rpm range , using the oval manifold on Square port heads can increase usuable torque. It has been dyno proven. BBB
