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Gain 50-60 HP?

5K views 44 replies 11 participants last post by  BuzzLOL 
#1 · (Edited)
When I bought this engine it was advertised with 440HP with 10.8:1 compression. It runs very well with no signs of detonation. About 5000 miles now. Right now the heads are off for valve guide replacement (a whole other story), so the engine is apart. I might as well take advantage of the situation and see if I can make a little more HP. I would like to see it in the 500+ range.I go nostalgia drag racing once a year with the club. I like to do a little better each year.
I figure an 850 or so carb would help, but may lose some driveability.
A port job on the stock Dart SHP 200 heads would help some, probably expensive.
A bigger cam would also help, probably the cheapest route.
Best bang for the buck, what route would you go? Suggestions?
Also, I am coming up with more than 10.8:1 compression. Can someone calculate the compression for me? If it is as high as I am getting, I am surprised that there is no detonation.

Car:
2280# with driver
3.55 rear gear, (Frankland quick change)
26" rear tire
TH350C w/ 3500 stall


383 SBC, 4.030/3.75
Flat top forged pistons w/ 2 valve relief, 4cc, .005" out of the hole
Felpro 1003 head gaskets
200CC Dart SHP aluminum heads, 64cc, 2.02/1.6 (untouched)
Howards hydraulic roller cam: 180265-10
Lift: w/1.5 rockers .530/.545 (.565/.581 w/1.6 rockers installed)
Adv dur: 286/294
dur @ .050: 233/241
LSA: 110
Procomp Hi-rise air gap intake
QFT SL-750 carb vac.2ndary
HEI w/initial 24*+ mech 10* = total 34* +14* vacuum advance=48*
Autolite 5224 plugs @ .035
1-5/8 lake style headers into 2-1/2 exhaust in front of rear tires
10-11" Hg @ idle
93 octane only

Sorry this is so long. Sitting here bored tonight with nothing to work on.
 
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#30 ·
4jawchuck, those jayski's are pretty nice. I like that they have a cap and exhaust pipe flange. They are just a little salty. I might work on copying a set of those.
Vinniekq2, no it doesn't ever even offer to push, in fact it is just a little on the loose side from neutral. I wondered about the spool, if I would need to put a diff in it while I was putting it together. It chirps a little on a real sharp turn, but I kinda like it, that and the whine, but that's not really too bad. Depends on what gear you got in. But no, no push.
 
#31 ·
Just realized the quickchange axle, don't drag race it man...ain't worth it.

Nothing wrong with dialing in but roll ons are a lot safer on parts.
 
#32 · (Edited)
You know I try to answer some of the questions on here that I feel I am qualified to answer, but I feel like I am reaping more than I am sowing. The one good thing about that 30 year old Frankland QC is that you can still get parts for it, but I did have to have a custom axle made for the right side. I have personally tested this rear end with 750hp as hard as I could drive it on dirt for several years. Broke an axle once. That's it.
I just want to drag race it one time a year with the club. But you know how it is with the friendly "grudge" matches and the braggin' rights.
 
#33 ·
This should go in the suspension section, but the thought just occurred to me that if I make a ladder bar to fit my 4 bar setup connection points, I could make it a whole lot better for launches real easy. I'm going to think about it and make a post in the suspension forum.
 
#34 · (Edited)
. Looks like I'm coming late to the party... and, as usual, Eric and Chuck already have you well squared away... I'll give some thoughts, but you don't have to follow any of them... the car looks great, fast, and fun just the way it is...

. You didn't uncap the headers at the drags? That exhaust system looks great... but is costing over 100+ HP... the short primaries are doing nothing for you... their right angle exit into the collectors hurts... the second right angle into the too small exhaust pipes hurts even more... powerwise... (the stock exhaust system that came on a '67 L88 Corvette actually cost nearly 200 HP !!! )

. I get 11.35:1 with given spec.s... like Eric... looks like great quench setup... .037"... helps prevent ping...

. From the spec.s, I'm surprised that engine isn't at 500+ HP already... I didn't look up the flow numbers, but Eric is correct, those World/Dart as cast heads typically don't flow very well... and the exhaust ports are often just too small... there's some really great home head porting videos on youtube... show what to look for close up, what to remove, what not to remove, and tells why... do a good job yourself and it will outflow a CNC job... for peanuts... it's time consuming, but I enjoy it... but wouldn't want to do it for a living... those guys earn their money...

. Forget the 14 degrees of vacuum advance in your timing... at WOT there's nearly no vacuum and no vacuum advance... that's just for good MPG while cruising (at sane speeds... LOL!)

. Bronze valve guides are OK for racing, but sometimes won't last long on the street... and some of them tear up valve stems... cheaper iron guides last longer... yours wearing out at 5000 miles reminds me of years ago getting a steal on a '75 Ducati 750 motorcycle with 5000 miles... guy was disgusted with it, no tuning would get it over 60 MPH... I put 4 of the new, improved material aftermarket guides in and it was back over 130 MPH... guy was really disgusted when he learned his new Honda 750 wouldn't keep up with it...

. Your 750 Carb. should be enough... but as the guys said, there may be some simple, quick, easy tuning HP in there... did the engine come with recommendations for jetting?

. I agree with Eric, an 850 carb. would do nothing for you... unported heads are the bottle neck...

. If making any changes at all, I'd suggest a Victor intake for your light vehicle... and since you don't have to worry about hood clearance, the ultimate would be a street-intended dual quad tunnel ram... perfectly streetable if don't go nutso with carb. sizes... dual 450's...

. Have you revved it to lifter pump up to see what RPM limit you actually have? With ported heads it should pull strong to 6500 R's...

. I suspect they would throw you off a 1/4 mile track... too fast...

. Also, those 1/8 to 1/4 conversion things prolly don't apply very well to your car... they assume stickies for good traction and the slicks will be slowing your MPH on the top end... also a full body... on the other hand, your light car and all that power and not pushing much wind means you will prolly crank more like 125 MPH in the quarter once the tires hook up... once... then they throw you off...

. Yeah, the instant center on your rear suspension is prolly somewhere's past Europe... maybe you can lift Ukraine up...

. Maybe your car is long enough the spool isn't hurting handling... can't get enough leverage way out there at the front tires...

. The automatic is prolly saving your Quick Change... as opposed to slamming it with a stick... (so is your exhaust system and heads... LOL!)

. Changing the rear gearing didn't make much difference in 1/8 because your exhaust system has you driving a low to mid RPMs torque engine...

. In another thread on here I told the guy right off the bat I was going to knock 15 10ths off his quarter time with basically just changes to his headers exhaust system... he was skeptical... most on here poo poo'd that... but if you look toward the end of the pages, you'll see we did even better than that...

http://www.hotrodders.com/forum/sbc-350-feeling-slugish-308994.html

. Hope I didn't come across as too negative... I just love analyzing this kind of stuff... staves off the Alzheimer's in my old age... LOL!
.
 
#35 ·
Dart SHP 200cc

Lift INT EX
.200 129 114
.300 185 145
.400 229 164
.500 261 172
.600 263 174
These are the numbers from the Dart website.

BuzzLOL, I knew the lake pipes were hurting me, but had no idea of the numbers you guys are talking. I did open the headers to race it. I'm gonna HAVE to change them out on a permanent basis.
The 14* of vacuum advance is because the motor likes more than the initial
18*at idle.
You are right about being too fast for the 1/4 mile. If I got it going to its potential, they would definitely throw me out. Don't know the rules but has to have a full cage somewhere in there. 11seconds or 11.5, somewhere in there?Thanks for your reply
 
#36 ·
I'd PM Chad, referenced earlier in this thread. He's in Hays, Kansas so its not going to kill you on shipping anyway; if you dont feel comfortable with cartridge rolls. He may have a more local recco as well.

Since you only drag it a little bit; I'd throw a bubbletop circle track aircleaner assembly on; and get some inexpensive headers for track day. This may require some jetting changes, so do your homework on the sly...show up, swap headers and aircleaner, maybe hunt craigslist for some used drag radials...

With an auto and hard tires; you're keeping that Frankland alive. Kudos. But, the F.A.S.T. crew runs on repop redline skinnys and most of them can run in the 12s (a couple in the 10s) if they have their stuff together. A little tire slip isnt bad. Wheelhop or a big torque spike will hurt parts though.

KILLER CAR; Love the vibe; especially the wide-5 hubs and stance.
Merry Christmas!
 
#37 ·
I know you hate to buy slicks and wheels for once a year, but they're really a pretty cheap investment for the ET gain they'll give you. I was in the same situation, and my BBC powered Falcon just overpowering the street tires at the strip. I started looking on craigslist, and found a pair of old Centerline wheels for $50. Then later I found a guy who had a pair of 10.5x15 Goodyear Eagles for $25. They had a number of passes on them, but still showed a lot left for my once a year trek to the Billetproof drags. They also were narrow enough to not hook so hard that I feared breaking parts, but much better than my street legal Hurst pie crust slicks. For $75 I cut a full second off my 1/8 mile ET, and started picking the front wheels up on launch. Well worth the small expenditure.
 
#41 ·
. Merry Christmas...

. Thanks for posting the flow numbers... for a street car, I usually look at the flow at .400" lift as a good average lift to use... the exhaust does look pretty weak there... instead of 164, would like to see more like 180 - 220 CFM...

. Yeah, I thought you might be running full vacuum instead of ported vacuum at idle with that cam size...
.
 
#42 ·
I would have the heads professionally ported the biggest restriction to air flow occurs right near the valve but unless your experienced and have a flow bench to check your work don't jack With them yourself.you can do more harm than good.
Slicks and gearing are your best bang for the buck find a gear ratio calculator on line and don't forget that auto transmission/torque converters slip about 5 percent. Be realistic about you RPM and MPH. ;)
 
#43 ·
Since you are familiar with the circle track world, another set of rear wheels and some dirt spec tires would do a lot for you and not stick so hard as to break something.

I did a lot of drag racing(and street) for several years using McCreary RoadStar IMCA spec tires(now named American Racer Tire) in "dirt" compound, as they were DOT legal and 1/3 the price of cheater slicks, and would run tubeless at 18-25 lbs. Put down 1.7 second 60" with a small amount of spin, at 3550 lbs car. Last a whole summer racing every other week and street driving, if I didn't do gratuitous burnouts on the street.

I loved 'em, got friends who still use them and I'd recommend them to anyone on a budget. Hoosier had similar in the Dirt Bozz line. Might be right up your alley, especially if you already have some leftover wheels.
 
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