Planning a mild engine rebuild, '65 A-code. Decent approach?


New Member
Nov 14, 2006
Hey everyone,

Drove my '66 coupe this summer and put it away for the winter (no rain shall rust my baby!). A while ago, I was given a '65 A-code engine from a GT and would like to rebuild it myself and swap it for the 289 currently in the car. I'm proficient with my hands and my ability to learn anything I need to complete a given task and have a garage with the necessary tools so I'm not questioning the feasability just the decisions to be made. Been reading endlessly and thinking about how I want to go and I wanted to solicit your thoughts!

My goal: a reliable, strong running, quick engine driven around town and some occasional freeway driving. No track or street races (unless I think I can smoke 'em!). So this leads me to believe I'm not gonna be revving this thing to its upper limits. I'm not into flashy, lopey idle or excessive exhaust roar. Just smooth running but can open it up and really feel good doing it. I will also be swapping to a T5 from the current C4 (and rear gears too). Budget of $2k in the engine, perhaps.

My plan: tear engine down, noting what needs to be replaced on the bottom end (bearings, recondition crank, etc), taking the block to a shop to have it tanked and cleaned so I can paint it, assessed, bored/honed if needed. For heads, I've read the '65 heads have good compression and decent valvetrain. Aluminum heads would require new pistons to regain lost compression so I just think they're an added expense that I don't really need. I plan to port the stock heads and upgrade to headers of some kind. I have an edlebrcok F4B intake I plan on using since I already have it. I want to use an Autolite 4100 tat I have. For cam, was thinking the C9OZ-C hydraulic cam but I'm just learning as I go and am open to any suggestion. I plan to pull the rocker studs and tap for screw-I'm studs. I've read endlessly about that and I know I can do that part correctly. I was set on using the stock heads, but then recent reading made me question if I should go through the effort with this 289 heads or go with either other used iron or aluminum heads. Price is important with me but so is a decent performance upgrade and longevity. With upgraded cam, intake, valvetrain (stock valve sizes but maybe roller tips), and ported heads, will I orchestrate these parts well enough to see gains or will I be leaving performance on the table by using mismatched parts (i.e. any power/torque gained is up in the high RPM's where the heads are then the weak point)? From what I've learned, you can create power and torque by bolting on parts that help here or there but unless they all work together, you could be throwing away a lot of potential if they fight each other. Still trying to visualize the "ideal" group of components for my situation given engine and goals.

Am I on the right track? I want to formulate a plan of all the parts needed and stick to it. I'm knee-deep in the research and planning/dreaming phase. Woo! Thanks for any advice you can offer!

Here she is:
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Active Member
Mar 21, 2014
about 30 years ago I had a 69 fastback with a 4bbl 351 W. I pulled the heads and "ported" the exhaust side, and added 1.94/1.60 valves. I didn't have any info on how to do it, and learned as I ground. (Turns out I actually guessed fairly closely). That is all I did to the engine - I kept the stock manifolds, carb, evertyhing just as it was. The difference in just that operation was tremendous! It was amazing the difference in the feel from non ported to ported.

I would reccomend looking up some info on porting those small chamber heads and doing a mild port job. adding a cam is a great idea too, to take advantage of the porting job. With studs and guideplates, you can use 1.94/1.60 valves (Chevy valves will fit Ford heads as long as the rockers aren't "rail" type) with budget roller 1.6:1 rockers and make plenty of power. If you don't have Tri-y headers, you might consider them. If staying with the stock exhaust manifolds, port match them to be slightly bigger than the ports on the heads to help combat reversion of the exhaust into the chamber.
Aim for between 9:1 and 10:1 compression when you buy pistons (if you're going for a total rebuild)


SN Certified Technician
Apr 12, 2002
first remember that your engine is a system, and you need to take a systems approach when building it. that means first deciding what rpm range your engine i going to spend 80% of its time in, and then buy parts to compliment that rpm range. since this is a street motor you want your parts to work best in the off idle to 5000 rpm range. your edelbrock intake will do just fine. cam selection here will be important as it is the heart of the engine. picking too big a cam is worse than picking too small a cam. the cam manufacturers will tell you what rpm range their cams are designed to operate best in. now you can fudge that number a bit, say about 500 rpm either way, and still have a solid package that makes good power where you need it.

regarding the heads, in the old days, we had to work with what the factory put out. thus you see old articles where 351w heads were ported and milled for better flow on the smaller 289/302 engines. later on people figured out how to install 351c 2v heads on the windsor blocks, thus creating the cleavor engines. they did work quite well, but required some machine work, and blocking off a few coolant passages, and adapters, or aftermarket intakes designed for the combination.

these days you can pick up good aftermarket heads, fully assembled, for about the same price as all the machine work to upgrade your stock heads. and you have a lot of choices here as well. my advice, find a nice set of aftermarket heads that have no more than 185cc or so intake runners, that way you dont have too much port volume for a mild motor.

i would dump the stock exhaust manifolds and go with a set of tri-y headers, they work great in the mid rpm range, in fact shelby used them on both his street and race cars.

when building the short block, spend your money on items that will improve durability and leave the flashy stuff for later. ARP rod bolts and main studs are excellent upgrades. have the rods rebuilt and polished and shotpeened. this will improve the durability of the rods. you dont need forged pistons, so save some money there, unless youa re going to use nitrous oxide or real forced induction. a good set of cast pistons from TRW, badger, triplex, federal mogule, or ross will do quite nicely. remember to take the sharp edges off the pistons before installing them. a small file does nicely, just be careful when doing that job.

moly rings, and good federal mogul bearings to round out the package, and a good standard volume/pressure oil pump and an ARP oil pump drive shaft will do just fine as well.

dont forget the ARP head bolts, and if you go with aluminum heads, use a good cometic head gasket to handle the abrasion that happens due to the different expansion rates of aluminum and cast iron.


New Member
Nov 14, 2006
Hey guys,

Thank you so much for your advice. Was out of town for a bit and just yesterday got to take the engine apart to see what I actually have. Turns out it's just a standard '66 289 with low comp pistons, '66 heads with rail rockers. Was expecting a '65 engine with pushrod guide slots and higher comp flatop pistons. So, now that changes my plan. I will definitely upgrade the main bolts to ARP and replace the bearings with quality ones. Now the decision is to either rebuild/modify the iron heads now with guideplates and hardened pushrods and get new pistons to up the CR, or just go aftermarket Al heads and new pistons anyway. I like the idea of doing the work myself and modifying the iron heads but maybe it's just not worth it. It looks like the Edlebrock E-street heads are the cheapest option and then up from there are AFR and Trickflow. I'll stay away from the half-priced ebay Al heads I see all over there.

Tri-y headers are certainly on the list too.