I have a 71 302 that is stock except for ARP rod bolts and maybe a 270H Comp Cam, which heads are better? I plan on gasket matching and grinding out the thermactor boss if they are there. The intake will either be a Torker II (because I have one) or a Performer RPM. If I use the J-code heads I will get a compression of about 10 to 1. If I use the 70 351W heads I will get about 9.3 to 1. Will the bigger valves breathing out weigh the advantages of the smaller combustion chambers?
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68 S-code FB GT 4spd(now C6)/3.25 PS PDB
68 J-code(now 289) Cp Sprint"B" C4/3L00-9" PDB PS AC
99 F150 XLT Ext/cab, 4X4, 5.4L, 3L55

In my experience, you will get better performance using the 351 Windsor heads even with the lowered compression. They have larger intake runners. Clean out the exhaust ports completely and open them up to match the gasket, and grind out the ridges under valves in all pockets. RPM intake, Holley 600, pointless ignition, and 5/8" headers would round out the package nicely.

But, before you go to all this trouble add up the costs. It's not hard to spend $500-600 on stock heads. Good luck,

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Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator

Thanks

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Originally posted by bluestreek:
First off, the 270H cam will need the recommended springs and solid retainers if you don't have them.

BS

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Thanks

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Originally posted by steve'66:
Milling .040" off the 351w heads will give you 10-1 compression.

But, before you go to all this trouble add up the costs. It's not hard to spend $500-600 on stock heads. Good luck,

SteveW

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quote:

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Originally posted by Moneymaker:
351W.

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Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator

My proposed combo is a 302 block, balanced rotating assembly, 1969 351 heads (home port job, 1.9/1.5 valves), 270S cam (282S possibly?), roller rockers, 1968 Shelby hi-rise intake (or Performer RPM if the Shelby intake falls through) and a 650 DP carb. Exhaust will be shorty headers, 2.5" X-pipe and either Superturbos or 2-chamber Flows (still undecided here... rumble or raunchy). I am looking for between 10:1 and 10.5:1 compression from the combo, and would like to rev it to 6500. It will be going in my 3000# 79 Pace Car with a T-5 tranny, 8.8 trac-loc rear diff with 3.73 gears. Use will be mostly street/show, but I want to hit the 1/4 mile occasionally, just for fun.

This thread has been perfectly timed for me!! Any further advice on the heads and set up would be appreciated.

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Cheers,
Ian
M&M Member #395
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'79 Mustang Indy 500 Pace Car
Ian's Pace Car Website
Vancouver Island Mustang Association Website
Indy Pace Car Registry of Mustangs Official Website

quote:

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Originally posted by 68 S-code GT:
I intend on getting the K-kit and I already have a 600 and headers on the shelf. Do you think I need hardened push rods and guide plates?

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I have used cams as much as 290 adv.duration with .512 lift on stock adjustable 54-58cc heads and stock block with flattop pistons. Like I stated earlier, the CompCams roller tip "rail" rockers and recommended springs, retainers, and good pushrods are all I ever used for a nice cheap 6500 rpm setup. I have did this on 4 different engines without any problems. Modifying heads for studs and guide plates is very costly these days but IF you can afford it, by all means get it done or buy aftermarket heads. Your heads can be flat milled as much as .030 without any major intake mismatch. I always like to gasket match the port opening in the head and not the intake. This will eliminate the chance of any slight port mismatch.. Just make sure you throw away the end gaskets and seal with a bead of silicone instead . Also I found that the stock coil and points is only good for 6000 rpms, so I used the Pertronix module and matching coil with the stock distributor for a cheap dependable ignition good to 7000 rpms!! Believe it or not, Low 13 or even 12 second 1/4 mile times is possible without spending a lot of dough. I have timeslips and trophies to prove it!!

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Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator

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Originally posted by chips67:
i ran 8.30's at 83 mph (in the 1/8) with 2.0 second 60 ft. times (very crappy traction) with a badly tuned 100k mile carbureted 5.0. the only thing that wasnt stock in the long block was the e-303 cam.....12's are not only possible.........good luck, even though you dont need it.

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Originally posted by bluestreek:

Roller cams rule!! Chips has an excellent idea. Start out with a roller block and you can gain about 10% more torque and HP on the lower end with the same duration of cam.

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Hmmm... that's doable too!! I guess that with a hydraulic roller cam motor I wouldn't have to go to a fully adjustable valvetrain either. A good set of bolt-on rockers should be able to handle lift in the mid 500's, couldn't they? Which cam would you recommend with a combo like this?

Comp Cams XE274HR: .555 int./.565 exh, dur. @ .050 224 int./232 exh 112 degree lobe separation

Crane Cams Powermax HR-226/320-2S-14: 0.544 int./.559 exh, dur. @.050 226 int./232 exh. 114 degree lobe separation

Too much cam? Other suggestions?

I can't wait to get started on this engine build!!

Ian