Thread: Need My Head(s) Examined

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Here goes...I've got a MkIV 454, with a 770 Holley Avenger sitting on a Weiand Stealth dual plane manifold, 9.5:1 CR, Voodoo 213/219 @.050 (256/262 adv), .515/.530 lift, 112LS, 6272990 heads (2.19/1.88 valves, rect port), ceramic coated headers into 2.25 dual exhaust through a set of FM 40-series mufflers, HEI, ...all this is connected through a TH400 to 3.36 gears in the rear. The cars primary purpose will not be that of a daily driver (gas$$) but it will be street driven with an occasional trip to the track for fun.

I know this is not the best combo in the world and that I have some parts working against each other. Let me just say a few things about that...

1. I got a good deal on the heads
2. the exhaust is brand new, aluminized umm...steel? anyway, it's new and came with the car (for the previously installed SBC)
3. I know alot more now than I did when I started this project.
4. I have a tight budget
5. I have a tight budget
6. I have a set of peanut ports (14092360) that I almost installed in lieu of the RP's

My question is, how well do you think this will behave? Will it be a total dog? Will I be fouling plugs? Street manners? Should I have used the peanuts?Exhaust big enough for decent performance? What changes would you suggest in terms of increasing performance without having to tear the whole motor apart? Any input is appreciated....I am basically wondering if this combo will perform respectable enough to give me some braggin rights and drive for awhile until I can find a decent set of oval ports (plus time and more $$) to put on there. This is my first real build project and turning back is not really an option at this point (I have a kid on the way...need to finish pronto). What do you all think? Has anyone ever thrown together a "bad" combo and been relatively happy with the performance?

It's a real nice looking motor anyway......Does that boost my hp?

-cayne

What's your problem? That car is gonna run good. It may not operate at it's full potential, but what does? You're gonna have a blast driving it. Fouling plugs? Only after you wear it out for a couple years. Street manners? Don't sweat it, it is a big toy. Exhaust big enough? Hell yes!! It ain't a school bus. What I'm trying to say is have fun with it. It is the best one you've ever built. When it breaks, call me; I will be glad to tow it home behind my big ol' hooptie.

Cayne -

I can't claim to know much about what I'm talking about... and as 65ny stated above, the car will probably be drivable if not pretty fun. I would say there are some fairly glaring mismatches among the rect heads, small exhaust, and tall rear gear... I'm not sure how much pain any of this will cause. I don't know a whole lot about cam-shafts but it seems this one is ground more for low end torque which compliments the size of your exhaust and the rear gear. I would probably lean toward oval port heads to bring everything in line for good lower rev combo, the peanuts might overdo it.

The other route would be keep the heads, go bigger on the exhaust (at least 2.5" probably 3" better) and a shorter gear in the rear (maybe 3.80:1+) but I don't think that cam is meant so much for the high end.

I'm fairly new to this stuff so I may be off base a bit... there are some really sharp BBC guys on here that will probably chime in with more reliable info.

At any rate, have fun!

Chris

BTW: My combo is not well matched either with stock oval heads, short duration hydraulic cam, big headers/exhaust (2" into 3") and too-short gear 4.56:1 with 29" tire but it is still a lot of fun and a good bracket racer except I'm running out of gear at the traps.... I'll be making some changes now that the season is over.

Originally Posted by skids72

Cayne -

I can't claim to know much about what I'm talking about... and as 65ny stated above, the car will probably be drivable if not pretty fun. I would say there are some fairly glaring mismatches among the rect heads, small exhaust, and tall rear gear... I'm not sure how much pain any of this will cause. I don't know a whole lot about cam-shafts but it seems this one is ground more for low end torque which compliments the size of your exhaust and the rear gear. I would probably lean toward oval port heads to bring everything in line for good lower rev combo, the peanuts might overdo it.

The other route would be keep the heads, go bigger on the exhaust (at least 2.5" probably 3" better) and a shorter gear in the rear (maybe 3.80:1+) but I don't think that cam is meant so much for the high end.

I'm fairly new to this stuff so I may be off base a bit... there are some really sharp BBC guys on here that will probably chime in with more reliable info.

At any rate, have fun!

Chris

Thanks for the input skids. Being on a budget, I toyed with the idea of throwing those peanut ports on there for quite some time and asked several people their opinions. Generally speaking...people either loved them or hated them. My biggest fear was running out of air around 4000rpm but I could not find a set of good ovals for a decent price so when I came across the rectangular ports I snagged them thinking I could resell them if I decided not to use them. After SEVERAL WEEKS of trying to make up my mind, I finally decided to sacrifice some low end torque and go with the 990's. You offer two very good future options and I totally agree with you.

Funny thing is...I spent weeks and weeks reading everything I good about building engines and the "marriage of parts" and I think that I have thrown it all out the window. I am still curious as to what I can expect in terms of problems with this setup. I have heard that (bad) setups can be a bear to tune and will generally be a pain to keep running and so I am hoping that is not so. Hopefully I will get some more insight from other members so I can see what the general consensus is.

I think the main problem you might run into is not so good throttle response/off-idle performance. A higher rev torque converter (3000+?) will help with that. Add a shorter gear will help more.

Of course, why not put it together and see how it goes? You may be quite content with it as it is...

You'll get some better advice if Pat McCarthy shows up....

Good luck,

Chris

Funny thing is...I spent weeks and weeks reading everything I good about building engines and the "marriage of parts" and I think that I have thrown it all out the window.

I don't think you've tossed it all out. For example, those heads were used on 425 HP 454 CID big blocks in '71, and those cars certainly didn't have 3" exhausts or 3000 stall converters. And, the current 425HP 454 uses a little shorer cam (211/230 - 510/540). So what if it ain't perfect. It isn't a mile off, in my opinion - but I'll defer on the finer details to Pat or Johnny 0.

Thanks, Henry, for the sanity check... as I mentioned earlier, I barely know what I'm talking about... if at all Need you experienced guys to keep me honest!

Originally Posted by skids72

Of course, why not put it together and see how it goes? You may be quite content with it as it is...

I am almost there... (hopefully a picture will post here)...

Cool . . . so quit second guessing, finish it off - then go out, kick ass and take names.

Originally Posted by Henry Rifle

I don't think you've tossed it all out. For example, those heads were used on 425 HP 454 CID big blocks in '71, and those cars certainly didn't have 3" exhausts or 3000 stall converters. And, the current 425HP 454 uses a little shorer cam (211/230 - 510/540). So what if it ain't perfect. It isn't a mile off, in my opinion - but I'll defer on the finer details to Pat or Johnny 0.

I dont have 11:1 cr though but I see your point Henry.. I did not know that about the newer 454HO. Dont those use the Rect-ports also?. So nobody seems to think that I will have any serious repercussions other than not realizing the full potential of the motor?... Based on the combo, is there any special tuning I should consider like running it a little leaner/richer, or more advanced/retarded or should one follow the same guidelines as with any other motor? I am trying to get this thing fired up in the next few weeks and am trying to avoid any surprizes.

Nice lookin' motor!

Thanks Skids !...not bad for my first I think...Off topic, but What do you think about my accessories set-up (minus the wire nuts...those are temporary) ? It's kind of odd ...gives it umm...character ?

Accessories look great. I'm assuming that's power steering at the bottom of the photo? Looks very clean compared to the 2 small v-belts I'm running (on a warped water pump pulley ) Very nice and I love the bowtie orange valve covers.

Dont those use the Rect-ports also?.

Yep. They sure do.