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425 engine 1966 delta 88 hp upgrades and exhaust manifold recommendations
I have a 1966 delta 88 I’m looking to get a little bit more of power out of the original motor it runs great but I want to put duals on it and get more hp out of it nothing to crazy. What’s the suggestions
Timing chain been replaced before going for extra power? Replacing it will give better performance and reliability. Transmission original? Does the switch pitch converter work?
Timing chain been replaced before going for extra power? Replacing it will give better performance and reliability. Transmission original? Does the switch pitch converter work?
2 bbl or 4 bbl originally?
NICE, SHARP looking car.
Good luck!!!
everything is original the intake was upgraded it was a 2 barrel original and the timing chain wasn’t upgraded at all only thing new in the car is the carb and intake if this was your engine what would you do to upgrade it the trans is stock and original aswell
These should do the job for duals; 65 66 67 68 69 70 Starfire Delta 88 98 Dynamic B&C body dual exhaust manifolds | eBay
I bought my exhaust pipes from Waldron's Exhaust.
A little pricey but superb quality.
The only other thing needed is a camshaft.
Something about .475 to.500 lift with about 225 to 230 degrees duration at .050 lift.
And a new timing chain and gears.
Do a compression test to check the ring, valve and piston condition. I'd also recommend an oil pressure test. If the are good replace the timing chain and gear set to gain some performance and prevent damage to the engine.
As far as what carb and intake I'll wait for others to recommend which one, I'm not the guy for that recommendation.
My concern is that when it was converted to a 4 bbl is that the variable vane torque converter system a/k/a "switch pitch" was not reconnected. Start with removing the air cleaner and posting a picture of the linkage on the driver's side of the carb all the way back to the firewall. 65-67 TH400 transmissions had this system, a lot is left on the table when it doesn't work.
I'd also pull the distributor and send it to a vintage car distributor rebuilder that has a Sun distributor machine to get it dialed in.
Check the harmonic balancer to confirm that it hasn't slipped so that when it reads zero the #1 piston is exactly at TDC. If the balancer is off it will never be timed properly.
You need this left hand exhaust manifold to easily install dual exhaust on your Delta.
Originally Posted by Sugar Bear
Do a compression test to check the ring, valve and piston condition. I'd also recommend an oil pressure test. If the are good replace the timing chain and gear set to gain some performance and prevent damage to the engine.
As far as what carb and intake I'll wait for others to recommend which one, I'm not the guy for that recommendation.
My concern is that when it was converted to a 4 bbl is that the variable vane torque converter system a/k/a "switch pitch" was not reconnected. Start with removing the air cleaner and posting a picture of the linkage on the driver's side of the carb all the way back to the firewall. 65-67 TH400 transmissions had this system, a lot is left on the table when it doesn't work.
I'd also pull the distributor and send it to a vintage car distributor rebuilder that has a Sun distributor machine to get it dialed in.
Check the harmonic balancer to confirm that it hasn't slipped so that when it reads zero the #1 piston is exactly at TDC. If the balancer is off it will never be timed properly.
Good luck!!!
it has been modified on the carb set up I believe it’s all gone so edelbrock has a cam upgrade and lifters for this engine I believe my uncle did those test on it and said the compression was good but idk about the oil pressure I have video of the car running it runs good
You are wasting your time and money putting a cam and lifters in it, if you dont follow the above advice. That car properly tuned, with the switch pitch working, will surprise you with its power. Of course that all depends on , he internal condition of the engine. Check the compression.
You are wasting your time and money putting a cam and lifters in it, if you dont follow the above advice. That car properly tuned, with the switch pitch working, will surprise you with its power. Of course that all depends on , he internal condition of the engine. Check the compression.
I will and I have no clue what a switch pitch is I will up load pictures to this thread asap
Definitely dual exhaust, get free flowing mufflers (I use vintage Hush Thrush), You need to tell us what Carburetor you have (should be 750+ CFM 4 bbl). When you bolted on the new manifold and carb did you change the cam? Stock 2bbl cam is pretty mild.
Note: if you get a cam you need lifters, pushrods, rockers,, timing chain and you need to get the heads rebuilt, new valve springs etc.... I would not put a performance cam on original 57 year old valve springs. All it takes is one spring to break and you'll punch a hole in your piston and perhaps blow your block. Keep it mild if you don't replace the pistons and rebuild the bottom end you can't go too wild.
I agree with everyone, if you are not willing to at least do all the above work, you should stick with dual exhaust upgrade. Make sure your carb is big enough. And get the switch pitch working if you can. Also check your rear end, if you have highway gears you might want to get to 3:23 or 3:42 rear.
Switch pitch is a transmission setup to have two stall speeds. Low like a normal engine and high to increase torque multiplication off the line. You get the best of both worlds, great acceleration with sufficient throttle application and efficiency of low stall speed in normal driving. It is all controlled by a round rotary switch in the throttle linkage near the firewall (which also controls downshifts).
I have a 1966 Starfire with a 425 totally rebuilt and balanced years ago. Forged pistons, mild performance cam, stronger valve springs, mild porting, Holley 750 double pumper, Edelbrock 04B intake, MSD ignition. Modified switch pitch Turbo 400 using ST300 pump and switch pitch torque converter for higher stall speeds.
naw I just want more power in it the car is barely driven. It’s got 78000 on it
A 57 tear old motor is not built like a a 20 year old motor you will break it, if you flog it. My 69 cutlass in 73 stripped the cam gear when I banged 2nd gear car had 35000 miles on it. you want more power, Make sure the switch pitch works. Make sure the tune is right. If that doesnt suit . Buy another motor already rebuilt or get a core and rebuild it. Cause the original motor will break
If it was originally a 2 barrel, it has Grocery Getter" cam and low compression pistons (lower compression than high compression). What brand carburetor is on it ?
#1. Find out if the "Switch pitch" is working correctly.
#2. Install a "Quick Advance" set of counterweights and lighter springs.
#3. Tune the engine to factory specs and add 2-4 degrees of initial advance to factory specs.
#4. Add dual exhaust system.
#5. Use good motor oil and oil filters.
Those 425's were a rugged motor and will run just fine. They are not as "fragile" some want you to believe. Look around at how many are still running at 100,000 miles. The weak link are those nylon toothed cam gears, just like the Small Boy Olds engines. Replacing the crank gear, cam gear, timing chain might be a good time to consider a cam change and new valve springs. If the rocker arm pivots are worn, replace them with stock replacements. .
If it's an "excellent" motor, why the fear that it will break?
Joe, My point is that overall a 425 is/was an excellent engine that is worth protecting. Are you in agreement or disagreement?
My suggestion to the OP is that if the timing chain is original the gears and chain should be replaced before trying to get more power from it. Are you in agreement or disagreement?
My suggestion to the OP is that if the timing chain is original the gears and chain should be replaced before trying to get more power from it. Are you in agreement or disagreement?
Except that's not what your prior post said. You gave a X2 to replacing it because "the original motor will break". Sorry, but I'm with Ralph. The 425 is nearly bulletproof. Any Olds motor needs the timing set replaced by 80K miles.
Originally Posted by jmcghee
A 57 tear old motor is not built like a a 20 year old motor you will break it, if you flog it. My 69 cutlass in 73 stripped the cam gear when I banged 2nd gear car had 35000 miles on it. you want more power, Make sure the switch pitch works. Make sure the tune is right. If that doesnt suit . Buy another motor already rebuilt or get a core and rebuild it. Cause the original motor will break
Originally Posted by Sugar Bear
^^^X2 and you don't want to break an original 425 because it is an excellent motor.
Kindly re-read post #15 and note line #11 which states "if that doesn't suit". jmcghee is saying that if the OP doesn't want to do the nylon gear replacement, confirm the switch pitch works and tune the engine THEN he should get another engine. That is what the X2 referenced.
You said "The 425 is nearly bulletproof" I cannot comprehend how that doesn't warrant the "excellent" category.
January 17th, 2023, 04:39 PM
