[gripperrat71]

Ok to start with the car: 71 chevelle weighing approximately 3750. I basically drag race only so not worried about streetability anymore. Currently I'm running a BBC 427 tall deck, bored .125, stock crank, trw 13:1 pistons, standard rectangle port cast heads with harland sharp 1.7 roller rockers, comp cam that I would have to look at the comp book to tell you exactly which one it is. Its around 651 lift, 264 @ .050 on a 110. Carb is a pro form 950, intake is a weind standard deck with the spacers, MSD 6al with all the add ons and an adjustable collar MSD billet distributor. Tranny was 350 w/ brake and 5000 stall, rear is a 4.10 gear solid bars adjustable uppers with comp engineerings 3 way adjustables.

In our drag series which I would like to pimp is the VAMP Heads Up Series in Kansas City we have index classes. They have moved around the last couple of years and my class Hot Street keeps getting slower(this year will be 12.00 second class) I would like to possibly do a cam intake head swap that comfortably puts me in the 10's on motor. Right now I can run all out in the 11.50 to 60's depending on weather. Another part of me says what if I just buy a bigger rotating assy? What do you guys think?

 

[gripperrat71]

Re: Ok engine gurus and drag racers.. engine/setup question.

To add to this I was thinkin also about springs or spring/shocks in back also. I am purchasing a new 400 tranny with brake and probably a different stall depending on the cash flow.

 

[bracketchev1221]

I'm thinking, a bigger cam and more gear would help. My car was similar, 3675 with 5500 converter and a powerglide. 11.5-1 compression, .628/.648 260/268 flat tappet cam. I ran 4.88's and a 10X29 tire. Mine went 11.20's at 118, with a best of 11.05. I used a strip dominator and an 850.

 

[gripperrat71]

well I've been lookin at Dart 345's with new intake and cam. or the other way keep my heads for now and buy the 4.25 throw rotating assy and a cam swap just don't really know the best route to go. I have punched the #s on the head cam combo and it should run 11.30's in the heat(which is our next index down) but I think I want to go for the 10.70s index am I dreamin without puttin the car on a diet?

 

[gripperrat71]

I'm thinking, a bigger cam and more gear would help. My car was similar, 3675 with 5500 converter and a powerglide. 11.5-1 compression, .628/.648 260/268 flat tappet cam. I ran 4.88's and a 10X29 tire. Mine went 11.20's at 118, with a best of 11.05. I used a strip dominator and an 850.

What heads were you runnin with that? Combos are very close I'm runnig a 10.5s x 28 slick

 

[bracketchev1221]

I ran Merlin Rect port heads, which were modeled after open chamber rect port heads. There is nothing wrong with the heads you have at your size. If you are going to go aluminum I would go for like a 305 head. 345's are too big. I ran 325's on my 509 that went 9.50's.

 

[gripperrat71]

I know they are way too big. I would be preparing for more cubes down the road.

 

[gripperrat71]

Ok so 345's are too big and there will be decreased torque for now. So if I go with310-325 range it should be a better choice. What are the specs of rectangle port cast heads? I don't know I have a budget of around 2,000 to 2,500 possibly to buy go fast parts so that's why its one or the other. The realistic part of me says buy the rotating assy and maybe like sniper jr. intake to get rid of the spacer plates on the heads. Anymore thoughts. More of you have similar set-ups tell about them, please.

 

[DougA]

Is this your cam grind? http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=497&sb=0
Same cam I'm running in my 427,love it.

 

[gripperrat71]

yep, thats the one. I love it too. I'm considering some pro top line aluminum heads, with 512 stroker kit now I think. Anyone sell or know a good tall deck rotating assy kit w/ 4.25 throw and 4.375 bore?

 

[Tom Mobley]

you might wanna sonic check the block if you're going to go .125 over.

Pro Topline heads have a real mixed reputation. Plan on buying them bare and having them assembled at a reputable head shop. AFR 325s are nice.

 

[gripperrat71]

It's already bored that far sorry. I went through four different blocks sonic testing before I found a good thick one. I have ran it that way a few years. I don't plan on doing anything to the bore size. I want to change the stroke to 4,25. I'm lookin for some torque with my horsepower. I want to run the 10.70 index class even when its 100 degrees outside. So it will really need to run somewhere in the neighborhood of 10.50's.

 

[gripperrat71]

update. I've got my mind set up with the stroker kit. Maybe I'll be able to squeeze for some heads IDK. What size heads should I be lookin at? I'm thinkin somewhere around 320 or so intake runner, 225 or 230 valve but definately rectangle ports. Should I look for the raised exhaust port?

 

[Harold Sutton]

I'd leave the bottom end alone and get a good set of heads. I think the Brodix 270 cc ovals are on sale right now. PM Mike Lewis ( aka. Wolfplace) on this board and also ask about the Brodix 270cc ovals and the 290cc AFRs. The heads will help more than the stroker crank.

 

[sleeper]

Be prepared to do a bit of grinding on the block if you put in a 4.25 crank. I take it you have .400 long rods?

I ran a lot of 481's (4x4.375) and they worked well. I tend to agree that you should get the cam lift in the .780-.820 range on the intake. Duration in the 268-272 on the intake if you go with the 481, maybe a coupe degrees more with the 512. Exhaust in the 282-286 range with around .740 lift. Shift in the 7200-7400 range and cross the stripe at least 7200. Figure your gears and tires for that.

The 454R is a good choice for intakes.

I ran 9.60's in the mid 1980's with a similar above combination in a 55 Chevy, powerglide, that weighed 3450 with me in it. I used the old 840 closed chamber heads because that was all I had. I really think the T350 will be faster than the 400 with the same converter if you can keep sprags in it.

 

[gripperrat71]

I thought 4.25 stroke clears the block, am I wrong? I would love to keep the 350 in it but its not lasting so im goin w/ the 400.

 

[Tom Mobley]

the 454 block has reliefs for the rods cast into the pan rail and the bottoms of the cylinders. other prod blocks, not so much. maybe the 512 block that was used for both. A few guys have reported dropping a 4.25 crank into a 396/427 block, but it's not reliable.

 

[sleeper]

I thought 4.25 stroke clears the block, am I wrong? I would love to keep the 350 in it but its not lasting so im goin w/ the 400.

As Tom said the 9.8 block has reliefs(notches) that make putting the 4.25 crank in very easy. The truck block does not have those reliefs, thus the extra work.

 

[gripperrat71]

I have a buddy that has had one together for a few years now(about 3or4 years) with no problems, but I didn't think he had the block clearanced. So I'm not worried about reliable.

 

[427L88]

I ran some 990 heads, and frankly, they outright suck unless messaged by a pro ( maybe?). Mine were as cast. Low velocity, not much top end. Ovals feel better, my old small rect port 074 felt great as compared to the 990s. But they had smaller ports and were very well worked on their short sides. I miss those old heads actually. They put the lil' 427 in the 525-530 HP category. I bet the 990s dropped it to well under 500hp, but no ET's to prove it.

Get some head man. And not too big. I mean a 427 is different creature with that 3.76" stroke, it needs to see 5-7000 to make bacon. Its a HP type mill. 4" and 4.25" stroke DO NOT. THey are huge TORQUE pumps by design, so I might encourage you to use that basic characteristic in your over systems design, i.e.. Msot BBC's are TQ motors and dont need to see much over 6000 rpm to get it done. Head and cam accordingly.

I.e, no more than 320cc, pref 280-300cc, and a cam at almost [email protected] for a nice 6000 rpm 482-496.