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Author Topic:   New Engine Help
Scoot
Dirt Freak

Total posts: 330
posted December 20, 2001 07:11 PM
ok guys I'm going to have to build a new motor for my car and I want your input on what parts etc to put in it. What bore, cam and all that. I don't know much about the mechanics of motors. That's why I have my brother and friends to ask. But I wanted some outside input. I'm going to list my rules and you tell me what you would build. I have a set of double hump heads that need work and a bowtie highrise intake, but other than that it will be from scratch. Must have stock distributors-no MSD's, any 2bbl carb 500cfm with throttle bore no bigger than 1 11/16, cams must not pull less than 16 inches of vacuum at 1000 rpm, must have cast iron manifolds, no headers, must have stock cast iron intake, no more than 1" carb spacer, no roller rocker arms,roller cams, no more than 360 cubic inches. Thanks in advance guys.

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Scoot

[This message has been edited by Scoot (edited December 20, 2001).]

Racer B
Dirt Roller

Total posts: 8
posted December 20, 2001 07:55 PM
First and foremost I would get some excellent block and head work done. As far as heads, w/your DH head, I would have them machine out the valve size to 2.02 and 1.60. This will cost money, but it will be some of the best money spent vs. HP & torque. Next I would use 6inch rods and lightwt pistons. For an intake, if you can use a corvette high rise cast iron, it would be a good add on. The distributor should be packed w/a 50k volt coil and use some good wires. A word a caution, a good motor w/an excellent set up will win more than an expensive motor w/a bad set up. I learned after the 1st couple of years that money spent in and time to learn about your suspension will pay off more in the long run. Have a good time.

KPLugnut
Dirt Freak

Total posts: 408
posted December 21, 2001 07:27 AM
Hey Scoot,
We can help you pick every part along the way, if you wish. I'd recommend a 4412 Holley 2bbl, set up for the needs of the rest of the motor, a 1" phenolic spacer, or if you are allowed an aluminum spacer, and that hi-rise intake is an open plenum design, we can set you up with a combination that will vastly improve your torque curve as well as make more HP.
I also have laying in the shop, a set of Corvette center-dump cast iron manifolds I'd let go for $50 plus shipping, if you're interested.
As others have said, the double hump heads will work well, especially if opened up for 2.02/1.60's, and even better if some port work is done.
As for cams, Charles at Camcraft will set you up with the perfect cam for that vacuum rule (see his link on these pages).
6" rods, good pistons, and gapless rings will help as well.
Deck the block to zero or wherever it is that gives you about .035-.040" of piston to head clearance with the head gasket installed, and you'll make good power.

Any other questions along the way, just ask.

Let us know if you need help in the carb dept as well as any other area, too.

And most of all, have fun!

KPLugnut

ford5
Dirt Freak

Total posts: 298
posted December 21, 2001 07:49 AM
KPlugnut do you have any experience with building alky carbs for dirt track modifieds that are similar to IMCA mods but more liberal rules and higher hp motors no claim let me know i have 2 of these and am in the market for 2 new carbs thanks ford5

c21
Dirt Freak

Total posts: 346
posted December 21, 2001 09:55 AM
Scoot, If your rules allow it, use the centerdumps that KPlugnut mentioned. That price he offered you is is a very good deal (1/4 of what that pair should cost new, I just sold 2 used sets recently for $90 a pair). I would recommend that you buy his manifolds (assuming they are the 2 1/2" outlet style) and use part of the savings to have him set you up a good 4412, having a carb that is set-up properly will save you a world of headaches.
Other than that if they allow an aftermarket Rod use a 6" eagle (or equiv). 4 bolt block and forged crank are nice, but probably not required in a motor with a 16" vacuum rule. Have the motor balanced properly and get nice light flywheel.
Most importantly make sure your car is safe, set-up properly and...
have fun


Good Luck

KPLugnut
Dirt Freak

Total posts: 408
posted December 21, 2001 11:11 AM
Hey Ford5,
We've done several carbs similar to that, and a "hybrid" carb or two that would probably fit that category as well.
Do you have existing carbs that you want fixed up/improved? Or are ya looking for something along the lines of an alky 850 or bigger? We can do nearly anything requested, and even some stuff nobody wants! LOL!
Gimme an idea of the carb size, and we can take it from there, ok?
Be glad to help ya out!

KPLugnut

p.s. - Thanks for the kind words, C21! And yep, as far as I know, the manifolds are 2 1/2" outlets, I'm just sick of having to move them outta my way, and nobody uses them locally anymore....I'd just like to see someone get some use out of 'em.

Scoot
Dirt Freak

Total posts: 330
posted December 21, 2001 10:40 PM
I mentioned the 6" rods to my brother, he was unsure about clearance? Also what kind of pistons would you use? it had flat top, also what bore? i have some of the .060 flat tops that weren't damaged. I'm just unsure of boring one to .060 to start off with, also do i buy the lifters and pushrods with the cam? I just dont have a clue.

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Scoot

[This message has been edited by Scoot (edited December 21, 2001).]

[This message has been edited by Scoot (edited December 21, 2001).]

Eljojo
Dirt Freak

Total posts: 273
posted December 22, 2001 08:39 AM
Whatever ya do, don't try to save $ on machine work! The difference in a race engine and the motor in your grocery getter is infinate. Race motors better be machined right or you're going to be spending a LOT of money replacing "cheap" motors.
First off, I'd advise you to call up some of the guys who run up front. Ask where they get their work done. Go visit a few machine shops and talk with the motor guys.Don't pretend to know what you think ya might know--be up-front and ask questions, a lot of questions.
You don't need a rocket motor your first year. Build yourself a good, strong, dependable, motor so that you can focus on your car and your driving. Stay away from exotic stuff that might give you a nightmare trying to keep running.
I suggest:
Have your block bored .030 and a good finish race hone. Have the line bore checked and repaired if nessecary. Have it decked to 9.005.
Have your heads milled to the minimum cc's allowed by your rules. If there isn't a limit, have them cut to around, say, 48--53 cc's. Install 2.02 intake valves and 1.6 exhaust valves.Don't buy cheap valves! Spend some $ and get Manley or Ferra. Cheap valves will gauld to the guides and you'll be replacing parts. Go for ***** in studs and guide plates. I always use a lifter valley tray too---just in case you break a rocker arm--the pushrod and lifter generally stay where they are supposed to.Definatly use poly locks.
Get a reccomendation from your cam grinder as to what pushrods cam,lifters,springs and retainers to use. I think a lot of Reed cams (they're in Georgia) You'll want to talk to **** Short. Tell him everything you know about the car, the track, the weight, the intake and exhaust,the carb, he'll be asking you questions so be prepared.
Your first year I wouldn't suggest tieing up a chunk in an aftermarket crank. I advise using a stock cast piece. Don't use a steel one on a two barrel motor...they are too heavy.
I like Speed Pro Hyperteutectic pistons. For around $150 you can get a set of flat tops with teflon skirts and full floating pins. (www.dirtrackthunder.com) Coupled with a set of Eagle sir rods, you should be in for a decent reciprocating assy. BALANCE EVERYTHING You'll want to turn up around 7000 if you use a hydraulic cam,,,a little higher if a flat tappet is used.
Don't use junk. Put a good balancer and flexplate on your new motor. I run stock pulleys--but 30%reductions are ok.
You've already had the best advice given, but I'll take time to repeat. Have Fun! put safty first. I had a trottle hang and ran an asphalt car into the turn three wall --full throttle- trust me- a well built car is a whole lot better than a bad fast piece of cobbled up sh*t! It's a whole lot more fun making one go faster than it is just making one go!
Good luck!
Jon Cook z17

[This message has been edited by Eljojo (edited December 22, 2001).]

cage86j
Dirt Forum Racer

Total posts: 85
posted December 22, 2001 05:33 PM
hey scoot,
i ran a .30 over 350 w/flat tops (DOUBLE EYES)p&p 624 with a 535 lift cam cast manifolds and intake with well wprked 500 holley and gave me 16 pnds vac hope that helps ....hey one to to be sure HAVE FUN!!!!!

Scoot
Dirt Freak

Total posts: 330
posted December 22, 2001 07:02 PM
Thanks alot for all the great input guys. I'll let you guys know what I finally come up with. Again thanks alot. Hope to see you in March in Missouri.

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Scoot

Scoot
Dirt Freak

Total posts: 330
posted December 23, 2001 10:10 PM
OK guys I think I'm going to run dome pistons, what do you guys think about them?

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Scoot

Eljojo
Dirt Freak

Total posts: 273
posted December 24, 2001 05:05 PM
Why? You can get enough compression from flat tops to run great using track gas. Put domes in and you'll ***** up the purn pattern and have less power! If you could do a bunch of work on the combustion chamber to control the burn...maybe. I don't like domes!

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