4.3 V-6 Question

[The Hedgehog]

We are starting the freshening process and I need to get some parts together for the 4.3 build up. Initially we are going to do the heads, cam and manifold. Want to end up with a pro-charger but got to work our way up to it.

I was thinking about starting with the Edelbrock Performer combo with maybe a 600cfm carb (let me know if this is not enough).

Here are the cam specs:

Duration at .004 Lift: Intake 272° Exhaust 276° Centerlines
Duration at .050 Lift: Intake 210° Exhaust 214° Lobe Separation: 112°
Lift at Cam: Intake .319 Exhaust .325 Intake Centerline: 107°
Lift at Valve: Intake .479 Exhaust .488
Timing at .050 Lift: Open Close
Intake 2° BTDC 32° ABDC
Exhaust 44° BBDC 10° ATDC

You guys see anything wrong with this cam? Will I have to worry about reversion issues with the IMCO Thumper exhaust we are using?

I was hoping that maybe someone like Buizilla will speak up.

[BUIZILLA]

I think the cam choice is perfect.... be sure and degree it at a 108-109* IC number...

You may have to lean out the 600 carb, at some point, but stick it on out_of_the_box first and see what happens. Performer intake is fine, With a blower, I would use a 650 mech. Demon.

The IMCO Thumper exhaust is a very good compliment to the package your preparing.

JH

[LKSD]

I too would use a holley or a demon.. I can get you either.. The Demon is more tuneable & refined compared to the holley and they are priced comperably.. & like JH said definitley a Mechanical secondary.. Jamie

[mikev]

I have that intake and carb on my 4.3 and it works great they sell a kit to rejet the carb for the 4.3. I did mine 5 or 6 years ago and it still works great have not had to do a thing to the carb accept for normal adjustments during the yearly spring tune up. what brand cam is that the edelbrock one i would love to know how it works out for you.

[Donziweasel]

Cam looks alright, what kind of heads do you have? What manufacturer of camshaft? 600 cfm is actually a little big for a 4.3, and might want to lean, but is still a big step up from a 2 bbl. I run Edelbrocks, (don't kill me holley and sea-demon guys) and have found that they are very simply, easy to tune (most adjustments can be made in under 5 minutes and the rest under 10). Who is doing the work, you or someone else? If you are doing it, the biggest thing you need to watch out for is putting in the new cam. Knick a bearing and you are screwed!

[smokediver]

yeah , i did the intake and carb also when i had the V6 . I gained a solid 4 mph and got a little more in the midrange as well . I went the edelbrock route and put the 4.3 kit that they have for that carb . It was just right but with that cam it may need a little more so I would try the carb as is and then go from there . Rod changes are easy as well as changing the jets and I am no carb. mechanic ! But if were me .... I would save yourself the hassle and drop in a V8 ... Unless you are wanting to stay with the 6 and see how far it will get you .... I picked up 17 mph going from the 4.3 to the 383 ... with a shortie even more is possible .... I don't think you will get that far with the 6 but it is cool you are doing the build up ... I will probably end up kicking myself with jealousy when you get it all done !!!!

[The Hedgehog]

yeah , i did the intake and carb also when i had the V6 . I gained a solid 4 mph and got a little more in the midrange as well . I went the edelbrock route and put the 4.3 kit that they have for that carb . It was just right but with that cam it may need a little more so I would try the carb as is and then go from there . Rod changes are easy as well as changing the jets and I am no carb. mechanic ! But if were me .... I would save yourself the hassle and drop in a V8 ... Unless you are wanting to stay with the 6 and see how far it will get you .... I picked up 17 mph going from the 4.3 to the 383 ... with a shortie even more is possible .... I don't think you will get that far with the 6 but it is cool you are doing the build up ... I will probably end up kicking myself with jealousy when you get it all done !!!!

Wanting to do something different. Building the base for a Pro-charged motor. Wanted to go blower this year but doing this for my father. He got side tracked on a few other projects so we are going to start with a good base. Bet we can hit that 17mph with that! (after boost of course)

Buizilla - Thanks for the input on the cam. That is just what I wanted to know. From what I have read about your knowledge on V-6's, I respect your opinion. Anyone that can derive 700+hp from one knows his stuff.

JW - What carbs to you like for pro-chargers? Also, I like the hat idea. I know it is not USCG approved but others get good results. I seem to remember you liking Barry Grants. Will probably want to talk to you about that since I will be working with you on the blower also when the time comes.

Additionally, we are probably going to port and polish the heads. Not expecting huge gains from that but I heard it helps when the boost comes up.

Got a good mech down here in Eufaula to do most of the work. He has done a few blower motors and knows his stuff. Last Real Texan has a good head & machine guy.

[LKSD]

JW - What carbs to you like for pro-chargers? Also, I like the hat idea. I know it is not USCG approved but others get good results. I seem to remember you liking Barry Grants. Will probably want to talk to you about that since I will be working with you on the blower also when the time comes.
Bill,
I like using the Demons & Holleys.. It's what I am mainly used to for forced inductions.. It's also what I feel is the most tuneable & best suited for these applications.. I am not a huge fan of the Edelbrock's (carter afb style) carbs or the Weber Or Rochester Qjet stuff. I donlt like hou they opertate & I dont feel they fuel adequatley or can be fine tuned as well as the Demon or holley carbs.. (It's just my opinion & preference, cause I know that may PO some people even though it's not my intent :) )

If you do go the Demon or Holley carb route when you do go to have the Procharger put in I would have the carb redone to have the floats & some other components changed.. Otherwise you're asking for trouble.. Let me know if we can get you anything..
:) Jamie / lakeside

[BUIZILLA]

If your gonna do some head work, and you should, then drill the pushrod holes out a tad, and use 1.6 COMP Pro Magnum self aligning rockers as well. If a huffer is in the future, then just order a huffer based Demon and be done with it, that way later on it's only jetting changes on the table.. :wink:

Your finally doing what i've wanted to see done... for a L_O_N_G time... curious to see how it plays out against a black box equipped 16..

JH

[d1mbu1b]

I guess I'll be the sole dissenter.

That cam is perfect if your not going to add a blower.

That cam is quite tame with very non aggressive ramps.
It will create high cylinder pressure which does not leave a lot for a blower to work with.

comp has a "blower performance cam" for v6 264HR15
264/274 210/220@0.05 and 115LSA for a later intake closeing event,
lower cyl pressure (w/o blower) and higher potential for a blower motor.
Also the 115 LSA will elimante any concern for water reversion

The more aggressive ramps on this cam will require better valve springs.

[Cuda]

I have a 4.3 question. What do you have to change when you swap to a 350? I have a 350 for sale, and a guy asked me that question, and I couldn't answer it.

[smokediver]

I have a 4.3 question. What do you have to change when you swap to a 350? I have a 350 for sale, and a guy asked me that question, and I couldn't answer it.
The engine mounts need to come forward .. I got lucky and was able to move the back of the mount to the forward hole . only had to drill new front holes . I would also recommend cutting a hatch hole behind the rear seats . Makes life alot easier ! other than that nothing really except possibly a gear change in the drive . Go with the 1.47 ratio ... It seems to be the stronger setup. I only say that as i went through 2 no 3 sets of the 1.62 ... I think there are less teeth and therefore a little thicker ... Also propping is a lot easier ... the accy's except for the drive resevoir and exhaust can stay on . the motor needs to be dropped in , then pointed to starboard , then with a couple of come alongs can be set into place . I would also switch to a bravo coupler as it is shorter in length versus the alpha with that metal tube . Believe me , every inch counts !!! Do it a couple of times and it actually isn't that bad ...

[Cuda]

I can't remember what model boat it was, but I do remember thinking that forward space wouldn't be a problem.

Thanks!

[The Hedgehog]

I guess I'll be the sole dissenter.
That cam is perfect if your not going to add a blower.
That cam is quite tame with very non aggressive ramps.
It will create high cylinder pressure which does not leave a lot for a blower to work with.
comp has a "blower performance cam" for v6 264HR15
264/274 210/220@0.05 and 115LSA for a later intake closeing event,
lower cyl pressure (w/o blower) and higher potential for a blower motor.
Also the 115 LSA will elimante any concern for water reversion
The more aggressive ramps on this cam will require better valve springs.

I like that idea. How would this cam work pre-blower?

So far it looks like we will be going with the Demon 650 with mech secondaries and the Edelbrock Performer manifold. Getting the heads done, probably port & polish along with some Inconel exhaust valves.