Horsepower is just another number........what do you want your car to do??? A littler more get up and go over stock? Are you going to drive it daily, the odd stop light to end of block sprint, weekend warrior at the track??? Then there is the reliability part of building a "well balanced package", not just the engine, but everything else, transmission, rear end, suspension etc........if you could give us a better idea of what you want, then others may have a better idea of what to suggest. Going aluminum heads is a wise choice, not only modern upgrades, but the weight savings alone is worth it! In the old days (early 80's), used to always have car buffs tell me they had this much horsepower and could do this and that, I would always beat them from stop light to end of block or even on the track. Then they would always frown when I told them I only had a mildly worked over 302. I think most people do not realize just how much power a stock 302 actually puts out. A friend of mine (Brian Seaberg) races in the Pacific NW Division in stock class, where he runs stock 302, with original 2 barrel manifold/carb, C4 tranny, 8 inch rear with 4.62 and runs 13.25 ets @ 99mph and 6000rpm through the traps. Again, stock 302 with non-modified stock heads and 2 barrel motorcraft carb............has a mantle full of "Wally's". This is in his 72 Maverick. So again, what do you want your car to do................. David
Thanks for all the information guys. Seems like I preemptively bought some items that won't get me to my goal numbers but i'll just live with it for the time being. I'm sure it will still be pretty quick but not where I wanted it to be. I should have asked the questions before purchasing but oh well... I read the Holley 570 was an excellent carb for a slightly modified 302 so I bought it. I also read the weiand stealth intake was a great budget intake so I bought that. Didn't want to go too big on the cam because with the 1.7 roller rockers I have, I didn't want to impede on piston clearances (that might still happen) I'm sure with adding the aluminum heads and some limited slip 3.55 or 3.80 gears it's going to feel pretty good. Maybe not 300-350 good but still better than it does now.
adding the aluminum heads w/ intake/carb/headers and some limited slip 3.80 gears, it's going to feel like 300-350.........
I'm of the opinion your next mistake in the purchase of engine parts may be the purchase of aftermarket heads that will not be compatible with your yet to be purchased cam and 1.7 rocker arms. Be aware if you purchase heads with 2.0 intake valves rather than 1.96 in combination with a larger than stock cam you run greater risk of valve to piston contact assuming you are using stock pistons. Heads with 1.96 intake valves are less likely to cause VTP contact issues. I run 1.96 valves in my combination even though my non stock pistons will accept a larger valve. Before you purchase a set of heads you might consider contacting the manufacturer for maximum cam size suggestions with your 1.7 rocker arms and stock pistons. A Twisted Wedge head design is also an option, i.e. Trick Flow. As groberts101 says, make sure to check VTP clearance during your build.
Eeeek! Lol I actually already have the roller rockers and the cam. I will defintely check for clearances, I certainly will not just bolt em on and go. If I do happen to have clearance issues, what's the best way to eliminate that? Shorter pushrods or valve relief pistons? Not really wanting to dive into the lower end yet, was hoping to hold that off until next winter and do a complete rebuild with over bore and whatnot...
Cam specs are dur@.50 204 int 214 ex Adv dur int 280 exh 289 Valve lift int 448 ex 472 Lobe sep int 108 ex 116 Says power range is up to 4000 Picked this one for the lower rpm torque?
I would HIGHLY doubt that smaller cam will have any PTV related issues. You can easily tell how soft the ramps of those lobes are by looking at the number spread between advertised and @.050 duration numbers. Plus the wider LSA will make it even more docile and give greater clearances. Not saying it shouldn't be checked with clay to make sure.. only that the cam is relatively small and that shorter piston pin height mixed with piston below the deck should allow tons of room to stay out of trouble. And pushrod length could never affect PTV.. only used to create proper arc geometry and centralize the rocker sweep pattern on the valve tip. PS.. assuming those spec's were generated and based off Fords native 1.6 rocker ratio.. the lobes are a tick under .300" lift. Moving to the 1.7 ratio pieces will push just past .500" at the valve(exhaust side). With such a lazy lobe they'll help increase valve lift velocity a bit more but still pretty doubtful you'll have any PTV contact concerns.
As stated I am new to all of this pushrod engine stuff. Everything I've worked on up til now has been OHV vehicles (came from long time Jaguar X type and S type ownership(ford ownership era)) so I haven't had to worry about all of this yet lol. I have been doing some reading and video watching all day and have been brought up to speed about what pushrod length determines. I always assumed the longer the rod the more up and down motion the rocker is going to have but now I'm realizing it's about putting the rocker in the middle of the valve stem, correct? If someone were to have clearance issues, what do they do, different valve stem lengths so they dont intrude so far into the combustion chamber? Piston reliefs?
Sorry, but I'm usually pretty tight on time lately which prohibits my typical 1,000 word blogging responses on these kinds of subjects. LOL Here's a good vid and show that it's not necessarily always about centering the rocker/valve tip sweep pattern but adjusting/allowing the greatest rocker multiplication factor to better take advantage of the ratio that you chose to use. Aside from maximizing ratio/valve lift, proper rocker arc geometry also typically reduces valve stem and tip wear as well. No offense intended here.. but I'd be perusing youtube and reading tons of engine building books to get the basic understandings of how everything works together, mechanically(geometry,construction,measurement related) and through mass particle movement physics(gas and fluid flow) to build a properly matched combination of parts. Sounds hard but it's more time consuming than anything and that will give you the overview you'll need to tackle these kinds of things yourself. Otherwise just plan on budgeting towards a shop doing it for you or things can go sideways pretty quick and take all your hard earned cash and time with it. The 2nd part can be fastracked by copying a known good and proven recipe to the T. You may not fully understand why certain combinations are being used in conjunction with one another.. but the end result is like following a good food recipe and never substituting ingredients(or parts in this case) to get to the final end result. Aftermarket performance pistons will have diametrically larger and considerably deeper valve reliefs to allow larger duration/lift camshafts to be used without PTV contact issues. PS. Hotrock was right on target in his above response(well besides fudging up the valve sizes by .020"..lol).. a smaller port CC entry level head will generally have smaller 1.90 - 1.94" valve sizes which help reduce PTV related concerns. Only real difference between the smaller and bigger port/valved heads will be maximum flow potential and the need for slightly more camshaft with a smaller port/valved head compared to a 2.02" valved/larger port combination to achieve any particular horsepower number. Everything's a compromise so you just need to decide if you want a bigger bullet later on which may like and prefer the larger port/valve diameter head and deal with slightly less performance now with full intent on growing into them later on. Either way I'd definitely stick with a smaller combustion chamber(58cc is typical) which works well with this smaller CID stock blocked combo.. but can still allow final compression ratio adjustments via gasket thickness increase and/or dished pistons later on if you decided on a 347 and had concerns about pump gas compression/fuel octane related issues.
Let's make this a little easier. The following link will take you to a set of heads that are quality items, 58cc chambers, 1.94 intake valves, 178cc intake runner and should work with your combination. The price is for one head. https://www.summitracing.com/parts/fms-m-6049-x307/overview/make/ford There are probably less expensive heads available with these specs but they may not have the quality. You can also bolt your 72K stock heads and rockers back on with your new cam assuming there are no issues with the heads. I'm of the belief your selected cam lift will work with the stock springs. Save your money and install aftermarket heads and your rockers at a later date.
I usually don't shy away from opportunities for more power but given the OP's experience factor here.. I'm probably going to flip flop back over and fully agree with you here on just socking cash away till later and making the best of what he's got to work with right now. But.. and this is just my inner gearhead speaking.. if the heads are already removed?.. I'd keep it lower budget for the time being by milling them around .030-.050".. followed by a much thinner head gasket(+.040" bore and no bigger than +.060" bore size.. Cometic makes .023-.027" thick MLS but they're pricy!) under them to push compression up to better match the cam, induction, exhaust capabilities.. advance that cam 4°.. install around a -.050" length pushrod and run the stock rockers. If they are pedestal mounts?.. don't waste you time or money and just run em'. Then maybe spend the money on a better rear gear and posi setup, say around 3.55-3.80 ratio(just because you'll need those later on for any sort of performance application anyways.. tune it much closer to where it needs to be(whole other new can of worms right there alone! LOL) with the milder bolt-ons.. and go have fun till you can do things right and in proper order of importance. And whatever your budget allowance is.. add about 20-25% for the unforeseen's and typical machine shop hassles. PS. Rick, those X307 heads note pedestal mount rocker setups. Is that what the OP has for 1.7 rockers? Seems this year wouldn't be pedestal mounted yet(around '76 IIRC?).. but sure is important to know if they're stud or pedestal mount before buying any more parts. Those are pretty decent heads though. PSPS. old chevy Z28 spring kits are cheap at around $60 and work well with lower lift cams like this one. And if using stock rail rockers with that cam?.. the rocker stud slots need to be checked for potential bind at full lift as well. Doubt that cam will give any issues but still needs to be checked anyways.
