porting 2970 SBC intake

[1fast10]

Decided to sale my 2925 with plenum mod because of issues running a plate per class rules.and decided to do a 2970.I had a camshaft made for my combo by Pual at inductions solutions and he recmended this intake so that we could bolt on a plate system easily without a lot of custom transition spacers.he did recommended and milling 1" off the top right away and using a Wilson 4500to 4150 adapter upside down to run a 4150 carb to get a weight break and also recommended died taking the clover out and make a normal square 4500 opening. What's your thoughts on the this.I have a ultra HP 950 and it can bolt to either style intake so the spacer would be for a transition.any suggestions on porting these intakes and what yo look for. This will be on a 421 ci SBC.13.1 comp .heads are AFR 220 casting that have been custom cnced and now are at 242cc.punch has not been welded but has approx 2.6-2.7 pinch measured around 2.9 without the radius accounted for.(I'll have to veryify.this is off my memories) .cam is .471 lobe on both 283 in 300 exh and 115 lobe ground on 113.designed for large amounts of Nitrous. class rules permit only single stage nitrous plate unlimited jet.the plate I'm looking at an go 600ish on a large jet if needed .

[judgement_impared]

Couple things.
1. In my experience, nitrous LOVES larger plenums....so using the 4500-4150 adapter certainly adds to that. The added height also (typically) makes even distribution easier.
2. Removing the clover and making the flange square also allows you to match the intake to the spacer/adapter being used. You certainly wouldn't want to use that spacer/adapter and have 4 HUGE chunks of aluminum sticking out in the flow path.
3. Blend the tops of the runners right up to the carb flange to make for a nice transition. (you'll be surprised how much metal will be on your bench after this!!)
4. Leave the runner dividers alone--for the most part, just clean them up.

Tip:
I usually use a couple dabs of silicone to hold the intake gasket to the heads, then test fit the intake and find the best possible alignment. Then drill an 1/8" hole in each of the corners just deep enough that the bit just "touches" the head. That allows me to take the intake back off and transfer the gasket/template back to the intake perfectly using a couple 1/8" bits as alignment pins.

[1fast10]

Thanks for the info.what's your thoughts on taking 1 inch off the flange right away.he said to do this because the nitrous plate will be 1 inch tall and the combination of that and the ad later may be too tall.he did say I'll have to redrill the bolt holes for the carb doing this

[jmarkaudio]

Check the pictures here.

http://x/viewtopic.php?f ... 970#p14263

[judgement_impared]

Thanks for the info.what's your thoughts on taking 1 inch off the flange right away.he said to do this because the nitrous plate will be 1 inch tall and the combination of that and the ad later may be too tall.he did say I'll have to redrill the bolt holes for the carb doing this

It will most likely help with the "approach angle" of the nitrous....in other words, the angle of the spray pattern will be shooting into the runners instead of into the walls of the plenum.

Also, I would "Pin" the spacer on with a couple roll pins not only to guaranty the alignment of the adapter plate, but it will also allow you to use the mounting holes on the plate as alignment sleeves in order to redrill the intake after milling. If you are doing this by hand then I would recommend getting some cheap pilot bushings that you can drop in the plate's mounting holes and drill first with a smaller bit without worrying about damaging the plate or drilling straight. Then you can drill them with the larger bit ("F" if you have a numbered set or .257" ) and tap them with a 5/16" - 18 tap.

Nothing really hard......just TIME consuming.

Hope this helps!!

JMark,
Nice pics!!!! Chad does some nice work.

[1fast10]

That ks that's some good info.I wasn't sure if the adaoter would be worth it with a 4150/4500 base 4150 carb.Paul at inductions solutions who designed my cam and gave me this info was very informative but was curious as what others had done

[1fast10]

Here's a little update.started on intake today.the plans are to use a wilson 4150-4500,adapter on top if the intake.and a sledgehammer nitrous plate.Pual at induction solutions has gibene me dome good info and I took his suggestions .so first thing is to take a inch off of the intake to.compensate for the nitrous plate which is 1",thick.this require new stud locations.I took suggestions from this post and did the dowel pins as a locator that worked great.I also bought a nitrous
solenoid bracket that matched the sledgehammer nitrous plate to use as a template for cutting the intake .the 2970,opening was smaller than the plate size which has larger corners for large bore carbs.here's a few pics of the process .and some quick blending.criticism is welcome.
[/URL[URL=http://s214.photobucket.com/user/sterry ... 5.jpg.html]

[1fast10]

Some.more progress pics
Added dowel pins
Matching the large bore plate to intake
[URL=http://s214.photobucket.com/user/sterry ... 8.jpg.html]

[af2]

Pretty much the same as I did with the Motown intake I run. Made a big difference with the plugs being the same or very close.






The dividers were cut back in relation to the carb butterfly's to equal the distribution and it worked.

I can not find the final pic where the edges were knocked down to round as yours are. Nice work on the intake!!!

[1fast10]

Yeh this intake had a ton of casting that's mostly gone.I still have all of blendng to do.in the runners allmim going to do is gasket match. Then clean the runners up.not size them or.make them bigger

[user-9274568]

Here is a Holley 300-110 that I cut back and made both runners the same length at 5"..

[1fast10]

Chad how do you measure runner length.I had to match to.the nitrous plate which is made for a big bore dominator.as you can see in oics how much I had to cut out .so the roof is shorter .also how much radius on the roof should I go.I wanted to be conservative but I'm jot expert

[user-9274568]

Chad how do you measure runner length.I had to match to.the nitrous plate which is made for a big bore dominator.as you can see in oics how much I had to cut out .so the roof is shorter .also how much radius on the roof should I go.I wanted to be conservative but I'm jot expert

I do it center of runner, both right side and left, from the divider edge to the flange. Add and divide by two.

[1fast10]

Is there a formula for the length needed

[1fast10]

Here is a few note.very close to being done.