Building a 1971 351W -2v need more help..going to machine shop

chgovfk · Nov 16, 2009

Hello again......
The motor is pretty much ready to go out....I'm using the stock heads with upgraded valve springs / stock rockers .....my question is ...I would like to buy this cam and lifters ....its a thumpr cam....I have an engine kit that I'd like to buy with flat top pistons w/four valve reliefs....going 40 over...molly rings ....will I be able to run this cam??...I heard I should have this all figured out before I commit the motor to the shop...it's going into a 90 coupe...I will probably change out the gears ....running the stock converter....automatic....any help would be great...thanks!

CAMSHAFT SPECIFICATIONS:
HUMPR™ for Small Block Ford 289-302-351W
DURATION
VALVE LIFT @ 1.5:1
LOBE SEP. ANGLE

ADV.@ .050”

IN. EX. IN. EX. IN. EX. IN. EX.
HYDRAULIC FLAT TAPPET: High performance street, stock converter ok, best with 2000+ converter and gears, choppy/thumping idle.
Hyd
Hyd
2000-5800
35-600-4
279THF7
283
303
227
241
.490
.475
107°
INCLUDES #832-16 HYDRAULIC LIFTERS

rbohm · Nov 16, 2009

i would not run that cam with stock heads. you will need some decent heads, like the world products windsor sr or other head with a 200cc intake runner. you will also need a healthy header and at least a performer rpm intake with a 750cfm carb. the 107 degree lobe separation means that motor will have a lumpy idle, and it wont have very good low end response.

another problem i have with the cam you selected is that it is schitzo in that is favors the intake side with the valve lift, and the exhaust side with the duration. not a problem with the right after market head, but with a stock head it will only hurt power production. a better cam would be something like this one;

COMP Cams 35-409-3 - COMP Cams Dual Energy Camshafts - Overview - SummitRacing.com

it is a much better street cam with stock heads, or even after market heads than the one you selected.

chgovfk · Nov 16, 2009

Thanks ....I chose this one because of it's lumpy idle....what's the best cam I can get that has that lumpy idle but works with my set up...when I asked before ....someone had said a magnum 280 cam would be ok.....or the 275 / 265 rv comp cams are decent....or is the one you suggested the best I can get...no drag strip ....this is going in a street /cruzer ....but I like the sound...was planning on long tube headers as well...let me know...thanks!

brianj5600 · Nov 16, 2009

The cam listed has 14* more exhaust at .050". That is hardly favoring the intake. It seems odd that they list it at 1.5 rocker ratio.

brianj5600 · Nov 16, 2009

It is also ground on 102* icl. I have seen a bunch of opinions on the thumper cams, but no data. I will give Comp Cams the benefit of the doubt as to if they work or not.

D.Hearne · Nov 16, 2009

If you're going to run the stock heads, then at least have the exhaust sides ported out and screw in studs and guide plates installed. That cam's liable to pull the stock pressed in studs out over time.

rbohm · Nov 17, 2009

chgovfk said:
Thanks ....I chose this one because of it's lumpy idle....what's the best cam I can get that has that lumpy idle but works with my set up...when I asked before ....someone had said a magnum 280 cam would be ok.....or the 275 / 265 rv comp cams are decent....or is the one you suggested the best I can get...no drag strip ....this is going in a street /cruzer ....but I like the sound...was planning on long tube headers as well...let me know...thanks!

the 289 magnum cam would be another good choice. what you are looking for with stock heads is either a single pattern cam, or a dual pattern cam that favors the exhaust side in both lift and duration. for the street i would keep the lobe centers at 110 degrees.

brianj5600 said:
The cam listed has 14* more exhaust at .050". That is hardly favoring the intake. It seems odd that they list it at 1.5 rocker ratio.

brian reread what i wrote, i said the cam favors the intake side on lift, but the exhaust side on duration.

chgovfk · Nov 17, 2009

Thanks guys....I'm trying to avoid putting a lot of money into the heads at this point ....I would rather do an up-grade down the road and completely replace them ...I was hoping to get the best Lumpy cam ...choppy idle ....that the stock heads can handle ...with going 40 over and flat top pistons....at least the bottom end is done....any help would be great!!

chgovfk · Nov 17, 2009

Here's the cam I would like to buy...

280H Magnum™ is best for the more serious street machines. This cam has a definite rough idle and will sometimes affect power accessories. It can be driven extensively on the street or raced on the weekends. The 280H needs an aftermarket torque converter, intake manifolds and headers.
RPM - operating range 2000-6000
cam grind 280H
Duration ADV- IN - 280 EX - 280
@ 50" IN - 230 EX - 230
vavle lift is @1.6:1 ...don't I have 1.7:1 with the stock rockers?
valve lift - IN .512 - EX .512
Lobe separation is at 110 degrees......
let me know what you guys think...really lost on what to do here....I have an expericenced engine builder that's going to help me....but he's more of chevy guy....so I don't trust him on spec's....

D.Hearne · Nov 17, 2009

Any cam over a 268H will pull the stock pressed in studs out of the heads. As far as it being a Ford built by a Chevy guy, if he's worth his salt, he shouldn't have a problem with it. The Windsor has a better firing order than the SBC, but the SBC has better heads. That's about the only major difference between the two, other than the distributor being on the wrong end of the engine on the Chebby. Both that and the firing order were borrowed from Ford to fix the Chevy in the past ten years.

htwheelz67 · Nov 17, 2009

exactly what Dhearne said, a comp cams high energy 268 is max, it will slightly lope and they run really good, why would you want to sound fast and be slow? except for the thumper cams usually a big lope comes from a big cam which unless properly matched with the rest of your combo wont run too good. I seen and done the same, put a big cam in a basically stock engine and the car was slower than it was stock but sounded fast.

Absolutely dont buy flat top pistons because you wont be able to run a high energy cam and will have to run a cam that wont work with your stock rockers and you will have to upgrade your heads at least with studs/guideplates/roller rockers and hardened pushrods.

I years ago tried to run a high energy cam with flat tops in a 351w, the engine detonated it self to death but sure ran good with 92 octane and water injection but way too high of cyl pressure. The 268h will run excellent with 9.1 compression you will be real surprised.

chgovfk · Nov 18, 2009

thanks guys....I'll get the 268 high energy...I do want it to "run" well....I have the mutha thumpr's stage II's ready to go for my 07 Gt....so I'll get the 'sound" I'm looking for...

What piston type should I get that matches this cam?......

I know these questions are basic....but I worked in a body shop as a kid....the first motor I built ...blew up...a 307 SBC....it actually ran quite well....but it was in a true chevelle ss...piece meal car...Big block....after I built it ...it still had the BB rear end...took it on the highway...and boom...but the motor was just to keep it driveable...my neighbor buddy and I built it in his garage...using hand tools..."we" bored the cylinders with a hand drill our selves ...and it sounded "tight"

...after that...I sold the shell + used the money for the down and bought my first mustang...a 93 GT.....after that I was hooked....I've had a about (7) seven 5.0's.. 96 cobra - 03 mach...anyway ...after 16 years of owning mustangs ....I hoping to build one...so I do appreicate the help....thanks

D.Hearne · Nov 18, 2009

Pistons for a 268H and stock heads? Look at those spec'd for a 70 or 71. They were rated at around 9 to 1. 72 they dropped to 8 to 1. The 69 4 bbl flat tops will yeild 10 to 1 or better. The 70-71 are dished.

chgovfk · Nov 19, 2009

OK thanks....I thought someone had said Not to use flat tops....that it runs slow sluggish unless you use 93 octane....I had an engine kit that had the flat tops with the 4 valve reliefs ..came up as the best for the money....molly rings .40 over ....going 40. or .30 or even .60 over really...what does that do for you...I assume it gives you more punch..HP...plus to hone the cylinders @ the shop...you have to go over a small amount....just wondering.....

htwheelz67 · Nov 19, 2009

stick with the dished pistons 9.1 compression, if you had aluminum heads I'd say yes but with your combo no, the high energy cams make cylinder pressure so it makes low compression higher.

D.Hearne · Nov 20, 2009

chgovfk said:
OK thanks....I thought someone had said Not to use flat tops....that it runs slow sluggish unless you use 93 octane....I had an engine kit that had the flat tops with the 4 valve reliefs ..came up as the best for the money....molly rings .40 over ....going 40. or .30 or even .60 over really...what does that do for you...I assume it gives you more punch..HP...plus to hone the cylinders @ the shop...you have to go over a small amount....just wondering.....

I never recommended for you to use flat tops. Unless you're going to run premuim fuel only, 9 to 1 dished are the ticket as already advised by htwheelz67 with the 268H

Wicked65 · Nov 20, 2009

Anderson Ford motorsports has some VERY good cams as well. I would make sure you take a look there too.

69Rcode_Mach1 · Nov 20, 2009

Just be careful, I am with D. Hearne on at least upgrading to screw in studs, guideplates, and hardened pushrods. Very cheap insurance, you will be hating life if the studs manage to wiggle their way out and you drop a valve or something. Do it right the first time around trust me. I have rushed an engine build before only to have to pull the whole thing out again and start over.

chgovfk · Nov 21, 2009

Thanks....there's a guy here in AZ who sells Aluminum heads on craigs list for $799 + tax new ...I forget the brand but I researched it a long time ago..and they are pretty nice...I asked the machine shop who's doing my heads ....they want $349 to completely re-do them...including the upgraded valve springs for the 268 cam....plus $250 to expand the exhaust port sides ...plus $200 to switch over to screw in.....so when I do the math I might as well..just buy em new...save the trouble...when I took this motor out....b/c I loath motor work....I was going to leave the bottom end alone (a 1971 351w w/90k on it) ....stick a cam in it...redo the heads for $350...and just run it...but then my Dad came in from Vegas and took a look at it on the stand...and he's like after all this you might as well rebuild the complete motor....do it right...so I agree... ..it's just economics ...my headers for my 07 came in the other day and my wife had a poop fit...so I obviously have to have all parts now shipped to the office...I thought I could get out w/o having to spend $1G on heads ....when you include the rods and the rollers...but it sounds like I have (2) two choices ....flat tops and the new heads ...or dished ...stock heads ...anyway I appreicate all of the help...I'll post some pictures....once it gets going...

D.Hearne · Nov 21, 2009

If you go with the 268H, you can keep the stock heads stock. No need for new springs, studs or anything else. Just have a basic valve job done on em. If you've got the tools, remove the Thermactor bumps inside the exhaust ports and call it good. This operation will take you all of 30 minutes to an hour to do on your own.

Building a 1971 351W -2v need more help..going to machine shop

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