Intake & Carb Recommendation for 481" BBC

Tim H · 07-30-2009, 06:36 PM

Quote:

Originally Posted by Michael Pliska

I'm running a 481" BBC, with a 0.714" lift, 292°/292° duration cam, Patriot Performance match-ported 320cc heads (2.300/1.880 valves). I'm currently running the stock 850 Holley and Holley Strip Dominator from my old iron-head motor, but figure that I'm under-carbureted for this combination. I've noticed when running against similar speed cars (5.90's in 1/8 mile) I can 60' and 330' quicker, but they start pulling away in the top end, and it will only be worse in the 1/4 mile.

Any recommendations for a cost effective carb & intake to pick up a little HP?

Regards,

Off topic slightly, are you happy with the cyl. heads ? I have been looking at them and the pricing is hard to beat. I ran a 468" RAT with "990" GM heads and a Victor Jr. w/ 850 Bill Mitchell carb and felt that I might have been slighty undercarbed ?

Michael Pliska · 07-30-2009, 11:42 PM

Quote:

Originally Posted by Tim H

Off topic slightly, are you happy with the cyl. heads ? I have been looking at them and the pricing is hard to beat. I ran a 468" RAT with "990" GM heads and a Victor Jr. w/ 850 Bill Mitchell carb and felt that I might have been slighty undercarbed ?

Tim,
So far I am happy with them. The chambers seem to have more of a "point" between the valves than others (the inside point if you think of it as being heart-shaped), which required a little surgery on my pistons. Another friend who used the same heads just dremeled out the combustion chambers, but I figured my pistons were old and the heads were new. In retrospect I would have probably cut on the heads instead. I previously ran iron LS7 heads and a smaller cam (0.660" lift), everything else the same. The older combination ran a best of 6.08 in the 1/8 mile, typically 6.15-6.20. With the head and cam change it is running 5.98-6.00 in the same conditions the old motor ran 6.20 or so.

My only gripe with Patriot was in getting my order straight (I added some parts to the order and they didn't catch them in the first shipment), otherwise they were great to deal with. I got the equivalent of their "0.800 lift" heads, which come with 2.300 intake valves despite the website indicating 2.250. They were willing to work with me on a custom package, as I didn't want the springs (using a near-new set I had), and cutting for my bigger springs. They had great prices on the other components like ARP head bolts & chrome-moly pushrods. Keep in mind that they require longer pushrods and head bolts/studs (which their website should mention but doesn't).

Regards,

Tim H · 08-02-2009, 09:53 AM

Ok, thanks for the feedback. Good to know about the pushrods and head bolts up front. Their heads also have a raised exhaust port I believe,which I think is not really prominently mentionned in some of the descriptions.

Michael Pliska · 08-02-2009, 12:27 PM

Quote:

Originally Posted by Tim H

Ok, thanks for the feedback. Good to know about the pushrods and head bolts up front. Their heads also have a raised exhaust port I believe,which I think is not really prominently mentionned in some of the descriptions.

Yup, they are 0.400" raised, which was a pain for me as I had just built a set of headers using both stock LS6 heads and angle-milled L88 heads to mock up for. I eyeballed it for fitting raised-port heads, but ended up having to do some surgery to get them to work. Glad I hadn't had the headers coated yet!

Charlie Yannetti · 08-04-2009, 03:07 PM

I'm going with the 454R and a decent 1050 on this one..... ran that set up on my 472 and it was great..... 1050 was almost out of the box too.......

Michael Pliska · 08-04-2009, 03:47 PM

Quote:

Originally Posted by Charlie Yannetti

I'm going with the 454R and a decent 1050 on this one..... ran that set up on my 472 and it was great..... 1050 was almost out of the box too.......

What model 1050 are you using, and what types of changes did you need before?

Thanks,

66chevron · 09-09-2009, 08:57 PM

I am running a 468" with port matched GM aluminum heads, .712/.712 cam around 274/278 duration. Goes 6 flat @ 3000#. Using the Edelbrock 454R out of the box, Holley 9375 1050 out of the box with a little more jet. Decided on the 9375 because it is annular discharge, supposed to work better than the 8896 with a stop. Have been very satisfied with what I use, but haven't really tried anything else. Good luck.

08-02-2009, 09:53 AM	#3
Tim H VIP Member Join Date: Jan 2007 Posts: 1,042 Likes: 1,076 Liked 482 Times in 159 Posts	Re: Intake & Carb Recommendation for 481" BBC Ok, thanks for the feedback. Good to know about the pushrods and head bolts up front. Their heads also have a raised exhaust port I believe,which I think is not really prominently mentionned in some of the descriptions.

08-04-2009, 03:07 PM	#5
Charlie Yannetti Senior Member Join Date: Jan 2005 Location: Alpine, NJ Posts: 568 Likes: 188 Liked 192 Times in 83 Posts	Re: Intake & Carb Recommendation for 481" BBC I'm going with the 454R and a decent 1050 on this one..... ran that set up on my 472 and it was great..... 1050 was almost out of the box too.......

09-09-2009, 08:57 PM	#7
66chevron Junior Member Join Date: Mar 2005 Posts: 13 Likes: 1 Liked 0 Times in 0 Posts	Re: Intake & Carb Recommendation for 481" BBC I am running a 468" with port matched GM aluminum heads, .712/.712 cam around 274/278 duration. Goes 6 flat @ 3000#. Using the Edelbrock 454R out of the box, Holley 9375 1050 out of the box with a little more jet. Decided on the 9375 because it is annular discharge, supposed to work better than the 8896 with a stop. Have been very satisfied with what I use, but haven't really tried anything else. Good luck.