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Author Topic:   Carb/Converter/Cam/Gear question
mvierow
Gearhead

Posts: 209
From: Bay Area, Ca
Registered: Apr 2001

posted 05-02-2001 09:02 PM     Click Here to See the Profile for mvierow   Click Here to Email mvierow     Edit/Delete Message   Reply w/Quote
I just wanted to see what you guys though of this combo on my 289..

650cfm holley DP
2200rpm stall
Comp Cam FS 270H-10 (.5 int/ex, 110 lobe sep)
3.70/1 gear

It launches with a heavy bog, but still picks up a 14.3 @ 94mph. I was hoping for a little more from it, which getting it tuned should do for me, but other than that does everything sound in check?

I figure this is a fairly common combo based on what I have read here in the past month. If anyone has something similar to this, post your times so I can relate. Thanks.

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Moneymaker
Administrator

Posts: 27660
From: Lyons, IL, USA
Registered: May 99

posted 05-02-2001 09:38 PM     Click Here to See the Profile for Moneymaker   Click Here to Email Moneymaker     Edit/Delete Message   Reply w/Quote
Could use a little more stall speed for certain. The carb discharge nozzels are probably too small which might be most of your bog. Is you distributor curved?

------------------
Alex Denysenko Co-Administrator and Moderator NHRA/IHRA/SRA member
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link

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Nos351C
Gearhead

Posts: 3000
From: Rohnert Park, CA USA M&M member#591
Registered: Jul 2000

posted 05-03-2001 12:36 AM     Click Here to See the Profile for Nos351C   Click Here to Email Nos351C     Edit/Delete Message   Reply w/Quote
Alex beat me to it, I was going to say more convertor...
what kind of heads are you running?

------------------
Marcus
Warsteiner- Because Life is too short to drink cheap beer!
"You just got passed by a GIRL!" -A.J. Foyt
My World

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richard bohm
Gearhead

Posts: 373
From: tucson,az-luray,va
Registered: May 2001

posted 05-03-2001 04:16 AM     Click Here to See the Profile for richard bohm   Click Here to Email richard bohm     Edit/Delete Message   Reply w/Quote
a slightly higher stall converter would help
also i think you dont have enough cam to really support the dp carb. i would recomend
a 600 vacuum holley. i think you will get better throttle response from it.

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JAAZZY
Gearhead

Posts: 837
From: Bay Area, CA
Registered: Apr 2001

posted 05-03-2001 02:36 PM     Click Here to See the Profile for JAAZZY     Edit/Delete Message   Reply w/Quote

Well everyone has answered but since I ran almost the same combo at one time I thought I would jump in. Your stall is too low. I tried 2200 but it wasn't enough. I went up to 2600 and it worked much better. Actually 2800 would have been better. I also used one of those chromes holley 600 DPs. That worked a lot better than a larger carb. Finally I think the 270 cam is a little mild. If you go with a higher stall try the 280 Comp Cams, I think you'll like it. I eventually moved on to the 292 and now I'm switching to a larger Hydraulic Roller. Good luck.

quote:
Originally posted by mvierow:
I just wanted to see what you guys though of this combo on my 289..

650cfm holley DP
2200rpm stall
Comp Cam FS 270H-10 (.5 int/ex, 110 lobe sep)
3.70/1 gear

It launches with a heavy bog, but still picks up a 14.3 @ 94mph. I was hoping for a little more from it, which getting it tuned should do for me, but other than that does everything sound in check?

I figure this is a fairly common combo based on what I have read here in the past month. If anyone has something similar to this, post your times so I can relate. Thanks.


------------------
65 Stang - TFS SH Stage III Heads, Nash 5 speed, Fuel Injection, etc...
2001 - Z06

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mvierow
Gearhead

Posts: 209
From: Bay Area, Ca
Registered: Apr 2001

posted 05-04-2001 12:30 PM     Click Here to See the Profile for mvierow   Click Here to Email mvierow     Edit/Delete Message   Reply w/Quote
Thanks for the input guys.

Alex, I am running a MSD billet with 1 blue and 1 red (?) spring I think. I haven't looked in a while. I am also using the 2nd to smallest washer for more advance. I think I'm about 12 degrees inital and ~34 total.

Marcus I don't have heads yet, but I am planning on putting some on when I put my motor back together. Sounds like this forum heavily supports the World products, what is your outlook?

Jas, picking that cam was probably the hardest part of my engine build up. I was concerned with valve clearence, so I chose the 270, but I am definately planning something bigger as soon as I jump on swapping the short block. Probably a hyd roller.

I originally wanted a 2800 rpm stall and was convinced it was too much from a local mechanic. Goes to show you what they know.

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Tom351
Journeyman

Posts: 93
From: Marietta,GA
Registered: Mar 2001

posted 05-04-2001 12:49 PM     Click Here to See the Profile for Tom351   Click Here to Email Tom351     Edit/Delete Message   Reply w/Quote
Are you launching by loading up the converter or by flashing it? By flashing, the stall speed will be slightly higher, and you will not use up part of your accelerator pump travel by holding the throttle partly open. Remember, the accel. pump pumps as the throttle moves, and if the throttle is halfway open already, you are getting half of the shot.

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67 Fastback - Arctic White Pearl paint
351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Carter 750 CFM, Comp. Cam 477/510 219/[email protected], Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars.

[This message has been edited by Tom351 (edited 05-04-2001).]

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n2oMike
Gearhead

Posts: 2840
From: Spencer, WV
Registered: Jan 2001

posted 05-04-2001 01:29 PM     Click Here to See the Profile for n2oMike   Click Here to Email n2oMike     Edit/Delete Message   Reply w/Quote
Your engine sounds like it has a good combination (for a stock set of heads). Going to a larger cam with stock heads will only kill off the low-end power. Stock heads are all done at 5k, regardless of cam.

The first things I would change are the heads and torque converter. Personally, I like Airflow Research heads. The AFR 165's would be perfect on that engine. WP Jr's get a lot of support here... but don't work with all the headers out there. You'll need to check around, but if you're running Hooker headers, (from their footnotes) you'll need to purchase their expensive Super Comps, the regular Comps won't work. As for other brand headers, I don't know... The spark plug location is what gets you. They moved it, which places the plug right up against the header tube.

AFR heads have the elongated steam hole, which keeps you from having to drill new ones in the head or deck. (different heads and blocks have the steam holes in different locations). AFR also has the PRETTIEST factory CNC porting I've ever seen. It is truly first rate. I've ordered three sets for engines I've built, and have been 100% happy every time. Tell them your engine combination, and they will happily set the heads up with QUALITY hardware, and springs to match your cam, usually at no extra charge. They are a TOP NOTCH company. You just take the heads out of the box, and install them on the engine. You're done! Measure for proper length pushrods (required on any hotrod engine) and you're ready to go! Most WP heads (if purchased complete) come with really CRAPPY hardware. Beware of this if you go that route. You get what you pay for.

The 270H cam is NOT overly small. It measures 224 degrees @ 0.050" and will make the engine want to shift at around 6300 rpm. Unless you have 10:1 compression or so, I wouldn't even think of going any larger... especially with an automatic. A larger cam will only want an even looser converter. You might get by with a 2800rpm stall converter with the current grind, but if you go with something bigger, you'll need around 3500+ stall for a good launch.

The 650DP will be just fine. As has already been recommended, the installation of larger shooters should help.

Install the bushing in the distributer that allows for the LEAST distributer advance. This will allow you to dial in more initial timing. With an MSD Billet, I believe that bushing is 19 degrees. This will allow you to run around 17 degrees of initial (36 total), which will pick up the launch.

The cam on my mustang only measures 236 @ 0.050" on the intake, and easily spins the engine 6800-7000rpm. It doesn't take a lot of cam to spin a good street/strip 302 over 6k rpm. A cam that is too large really kills the low-end and mid-range... especially if the engine doesn't have a really high compression ratio. You NEED this low-end and mid-range to launch the car when using a streetable converter. The 1/4 mile e.t. is made or killed in the first 60ft.

Good Luck!

------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/motorcitymustang/cmml/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367

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JAAZZY
Gearhead

Posts: 837
From: Bay Area, CA
Registered: Apr 2001

posted 05-04-2001 01:48 PM     Click Here to See the Profile for JAAZZY     Edit/Delete Message   Reply w/Quote

I guess I should have mentioned in my post that I didn't choose my parts for drag racing but rather all around street performance. I also did have 10:1 compression forged pistons. My stock heads had a mild port job but and I shifted my motor at around 6600 rpm.

------------------
65 Stang - TFS SH Stage III Heads, Nash 5 speed, Fuel Injection, etc...
2001 - Z06

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mvierow
Gearhead

Posts: 209
From: Bay Area, Ca
Registered: Apr 2001

posted 05-04-2001 09:10 PM     Click Here to See the Profile for mvierow   Click Here to Email mvierow     Edit/Delete Message   Reply w/Quote
Good point Tom, I have been loading up the converter before launch, and have been using the stock pump. The bogging however comes in regardless of launch method.

Mike, I read an article about those heads in a 5.0 mag around a year ago or so and was very impressed. Your the first person I have talked to though that has actually purchased a pair. Do you know if AFR offers them unassembled? I already have matched springs and all the associated hardware, but would need the valves and push rods. Do you know of any articles that describes how to determine proper push rod length?

How about those JBA shorty headers? They originally caught my eye when I noticed they fit a 351W and a 302/289 plus they have a spherical flange which I hear seals better. Anyone using these?

I think I am in same boat Jas, I plan on driving the car frequently so performance on the track is only half of my concern. I think I'll try the different converter and heads for now since the motor and tranny are both out and torn apart, then shoot for tuning once I get everything back together.

Final question, what does the difference in converter diameter effect in terms of performance and street-ability?

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n2oMike
Gearhead

Posts: 2840
From: Spencer, WV
Registered: Jan 2001

posted 05-05-2001 11:32 AM     Click Here to See the Profile for n2oMike   Click Here to Email n2oMike     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by mvierow:

Mike, I read an article about those heads in a 5.0 mag around a year ago or so and was very impressed. Your the first person I have talked to though that has actually purchased a pair. Do you know if AFR offers them unassembled? I already have matched springs and all the associated hardware, but would need the valves and push rods. Do you know of any articles that describes how to determine proper push rod length?
Final question, what does the difference in converter diameter effect in terms of performance and street-ability?

As for the AFR heads... I'm sure you can purchase them in any stage of completion. Just make sure there is no confusion, because if you say "Bare" they will probably come unported. Tell them exactly what you already have, and let them know that you want the ported heads with valves. You may even be able to send them your parts for installation. Who knows. But, they should be able to satisfy you. Treat them with respect, they'll treat you nice.
http://www.airflowresearch.com

To check for correct pushrod length, you'll need an adjustable length pushrod and some liteweight 'checking' valve springs. The adjustable pushrods aren't very strong, and can be bent by regular valve springs.

Anyway, with the lite springs and rocker installed, turn the engine over and see where the roller of the rocker rubs on the valve tip. It should roll right in the center, and not move back and forth across the valve tip very far. It should stay centered. Maximum recommended sweep is 0.080". Chances are, it's not centered on the valve tip, and there's too much sweep.

To bring things into 'spec', the pushrod length will need to be adjusted. As the pushrod length is adjusted, the centering and sweep can be improved. When it's as good as it will get, measure the length of pushrod, and you'll know what length to order. Check both intake and exhaust.

On some odd occasions, the intake and exhaust will need different length pushrods, but not usually. They are regularly pretty close. Sometimes off-brand rockers aren't made to the correct specs, which makes the geometry impossible to get perfect. Some Ford heads have even been designed for Chevy rockers... But these are the exceptions.

Valvetrain geometry is of utmost importance. Bad geometry causes all sorts of problems. If the geometry is way off, valve guides won't last any time. But if it's spot-on, a good set of bronze guides will last for years. Bad geometry can also cause a lot of valvetrain noise.

I built a 383 Chevy stroker recently that needed pushrods 1/4" longer than stock! Those guides wouln't have lasted any time!

Check it out!!!

As for converters, the smaller the diameter, the higher the stall speed. Of course some 10" converters will stall higher than others, but the general rule of thumb applies. A good converter isn't usually the cheapest one. I've heard a lot of people say to stay away from GER. Buy quality here.

Good Luck!

------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/motorcitymustang/cmml/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367

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n2oMike
Gearhead

Posts: 2840
From: Spencer, WV
Registered: Jan 2001

posted 05-05-2001 11:40 AM     Click Here to See the Profile for n2oMike   Click Here to Email n2oMike     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by n2oMike:
To check for correct pushrod length, you'll need an adjustable length pushrod and some liteweight 'checking' valve springs. The adjustable pushrods aren't very strong, and can be bent by regular valve springs

One addition. A pair of solid lifters is handy for checking the geometry. Hydraulics will often just compress as the engine is turned over, not opening the valve all the way. Just be sure to swap the hydraulics back in before running the engine.

An old hydraulic lifter can also be modified to "solid" status by taking it apart and filling it with something or welding it. These can also be handy for degreeing the cam, if the dial indicator is placed at the valve.

Good Luck!

------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/motorcitymustang/cmml/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367

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