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Author Topic:   Boss 302 engine questions
Gearhead
Gearhead

Posts: 1622
From: Vancouver Island, Great Wet North
Registered: Mar 2000

posted 08-29-2001 12:40 PM     Click Here to See the Profile for Gearhead   Click Here to Email Gearhead     Edit/Delete Message   Reply w/Quote
I was chatting with my buddy who has a 70 Boss 302 (well, it's a clone, but has all the Boss 302 parts, including the engine/close ratio toploader), and he is planning on pulling the engine this fall to giving it a freshening, and turn up the wick a bit. The engine is a 30,000 mile original Boss 302 crate motor that is basically stock. He does occasionally rev it to 7,000 rpm when he really gets on it, but I figure that this is too high for the unbalanced lower end. I recommended that he get the entire rotating assembly balanced while he has the engine apart (which he agreed was a good idea).

Ok, so what's my question... I was wondering if the Boss 302 crank is stronger than a regular production crank, and same with the rods. He is planning on having this motor redline at 7,500+ when he is done, and I wonder if the stock crank and rods can take this, even with a balance job. Should he be moving up to a forged crank? H-beam rods? He's looking for a solid 400 hp from the engine when it's done.

Any advice that I could pass along to him would be appreciated! Thanks!

------------------
Cheers,
Ian
M&M Member #395
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'79 Mustang Indy 500 Pace Car
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"If you get to thinking you are someone of some importance and influence, just try ordering another persons dog around." - Author Unknown

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kcode
Gearhead

Posts: 1980
From: alvaton,ky,usa Suburb of Bowling Green, M&M #79, MCA #29208
Registered: Jun 99

posted 08-29-2001 01:11 PM     Click Here to See the Profile for kcode   Click Here to Email kcode     Edit/Delete Message   Reply w/Quote
Ian,
there are alot of "ifs maybe". When you say Boss 302 crate, does it have the screw in freeze plugs on the side of the block, 4 bolt main caps on #2-3-4?
Boss rods are basically the same as Hi-po rods, both have the 3/8 bolts, different spot facing but close. Factory piston were not the best, had skirt breakage problems, if TRW replacements are used it should be ok.

Will the engine be built to continue to build HP in 7500 rpm range? If it isn't why rev it?

Mike

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Gearhead
Gearhead

Posts: 1622
From: Vancouver Island, Great Wet North
Registered: Mar 2000

posted 08-29-2001 01:33 PM     Click Here to See the Profile for Gearhead   Click Here to Email Gearhead     Edit/Delete Message   Reply w/Quote
Yup, it's a 4-bolt block and has the screw in freeze plugs. Basically it was a full factory Boss 302 motor, bought directly from Ford in the 70's sometime.

His plan (as I understand it) is to have the heads fully ported, upgrade the cam and intake to allow for more breathing up high. This guy loves rpms. Ok, realistically I would limit redline to 7,000, or just over, but I know this guy would like to go higher. I just want to help him so he doesn't break it.

Thanks Mike!

Ian

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kid vishus
Gearhead

Posts: 1877
From: between the end of the road, and the middleof no-where
Registered: Oct 2000

posted 08-29-2001 03:12 PM     Click Here to See the Profile for kid vishus   Click Here to Email kid vishus     Edit/Delete Message   Reply w/Quote
Unless I'm mistaken, Boss 302's had a steel crankshaft from the factory.

I know of one guy here that runs with our local stickshift club, and he twists a Boss 302 9600 rpms. It has the factory crank, but aftermarket rods and better pistons.

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JAAZZY
Gearhead

Posts: 649
From: Bay Area, CA
Registered: Apr 2001

posted 08-29-2001 03:35 PM     Click Here to See the Profile for JAAZZY     Edit/Delete Message   Reply w/Quote
I don't know anything about the Boss but I can give you a little info on stock rods. I had a 289 in my 66 which was later transfered to my 65 with stock rods that were polished from about halfway down to all the way around the bolts. Additionally I upgraded the bolts but that was it. I used these rods in 5 different motors starting back in 1987. I even once kept them between 6600-6800rpm for 100 miles straight. On the street this motor routinely got up around 7000rpm daily. I never once had a rod failure.

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Gearhead
Gearhead

Posts: 1622
From: Vancouver Island, Great Wet North
Registered: Mar 2000

posted 08-29-2001 03:56 PM     Click Here to See the Profile for Gearhead   Click Here to Email Gearhead     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by kid vishus:
Unless I'm mistaken, Boss 302's had a steel crankshaft from the factory.

I know of one guy here that runs with our local stickshift club, and he twists a Boss 302 9600 rpms. It has the factory crank, but aftermarket rods and better pistons.


9,600 rpm!!! Now that's spinning it up all right.

If it is a steel crank and he insists on upping the powerband on the car I will recommend that he got to some better pistons and at least have the stock rods polished. A little extra fortification can't hurt.

The sound that engine makes at 6,800 rpm is like music.

Thanks for the advice!

Ian

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Rory McNeil
Gearhead

Posts: 534
From: Surrey, B.C. Canada
Registered: Nov 2000

posted 08-30-2001 02:17 AM     Click Here to See the Profile for Rory McNeil   Click Here to Email Rory McNeil     Edit/Delete Message   Reply w/Quote
Tell him not to bother porting those Boss 302 heads! Thats the last thing an engine that size needs. Also, I don`t know what intake manifold he plans to upgrade to,other than a tunnel ram or single plane Roush or prehaps a fabricated sheet metal intake, theres not much available for the Boss 302.

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Wicked-Toy
Gearhead

Posts: 130
From: Richmond, VA USA
Registered: Jun 99

posted 08-30-2001 08:26 AM     Click Here to See the Profile for Wicked-Toy   Click Here to Email Wicked-Toy     Edit/Delete Message   Reply w/Quote
I used to spin my Boss to about 8000 RPM. It had the stock crank and rods with forged aftermarket pistons in a 30 over block. I left the heads stock with an 850 Holley.
Th more Rpm you turned the more power it made.

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Scott Akom
65 Coupe (Modified)
68 Coupe (Son's)
2000 GT Conv. (Wifes)
1987 GT Conv. (Son's)
1966 Project Conv.[URL=http://www.geocities.com/motorcity/flats/3845/65dsde2.jpg
www.mustangsandmore.com/ubb/WickedToy.html

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unklshu
Gearhead

Posts: 514
From: San Bernardino, Ca
Registered: Jul 2001

posted 08-30-2001 08:56 AM     Click Here to See the Profile for unklshu   Click Here to Email unklshu     Edit/Delete Message   Reply w/Quote
Wow to turn 8000-9000 rpms in with a v8! that's got to be some sweet music!!

joe

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Gearhead
Gearhead

Posts: 1622
From: Vancouver Island, Great Wet North
Registered: Mar 2000

posted 08-30-2001 02:49 PM     Click Here to See the Profile for Gearhead   Click Here to Email Gearhead     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Rory McNeil:
Tell him not to bother porting those Boss 302 heads! Thats the last thing an engine that size needs. Also, I don`t know what intake manifold he plans to upgrade to,other than a tunnel ram or single plane Roush or prehaps a fabricated sheet metal intake, theres not much available for the Boss 302.

I guess that's true... how about the exhaust side though?? Would it benefit to make sure that is not restricted? He already has headers and full 2 1/2 duals with 2-chamber Flowmasters on it. Any benefit upper rpm flow by just smoothing out the bowls?

I have never looked for a Boss 302 manifold, so I didn't even think of that. Is the stock item fairly good? Maybe a port-match between the intake and heads to smooth things out.

The cam that he is thinking of is the Comp Cam 294S (248 @ 0.050 and .560 lift on both intake and exhaust, 110 lobe seperation angle). He will be stepping up to 4.10 gears as well. Any comments on the cam and how it will work in this engine??

This should be an interesting engine when it's done! I can't wait to get a ride in this machine. Thanks for all the insight and advice here people!!

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