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1965 421 Pontiac

3K views 29 replies 6 participants last post by  421guy 
#1 ·
Hello guys I'm new to the site and I'm building a 421 four bolt main engine to put in my 65 Gto convertible. Thanks
 
#7 ·
I have a little story for Pontiac fans.

I grew up in central Illinois... the stomping ground of Arnie Beswick! In the early seventies I had the chance to buy the "Famous Grocery Getter" Tempest wagon! I went to arrange the purchase only to find that the local racer who then owned it had stretched the nose, and put a glass doghouse on, and a conventional rear axle in it! It still had the Super Duty 421, plexi windows, and original paint and lettering... but I felt he had ruined it!

A few decades later I talked to Beswick who was racing the tiger-striped Tempest coupe at a local track here in Tucson. I told him the story, and his comment was "Do you know what that car would be worth today!" Of course, I did not need to hear THAT! {:-( (I still don't know how I could have replaced the original hand-built transaxle.) Oh well.
 
#9 · (Edited)
I am mid-sixties and grew up near Indy! ...and also got to the Chicago area events occasionally! I was lucky to be there for the "Golden Age". I got to see most of the famous racers like Beswick, Dick Jesse, Don Gay, Mickey Thompson and others, in their best years! In those days the Pontiacs used to be right in the middle of the action!
 
#10 ·
Yes those were the days! Pontiac never really dominated at the drag strip other than the early 60's with the super duty cars. They were better suited for the stop light Grand Prix with tons of low end torque. Oh the money I spent on tires, clutches etc. Crazy but back then every stop sign or red light had to turn into a long smoky burnout lol .
 
#11 ·
I was wondering if anyone could help me decode a 421 four bolt main motor I bought. Raised numbers on the side of the block read 9778791. I understand this to be a 1965 421. Also the date code by the distributor is B195 which translates to Feb 19th 1965. Where confusion sets in is that the front of the block on the passenger side is stamped SX then the serial number. Also on the front of the block between the camshaft and crankshaft is stamped SX-1. The guy I bought it from mentioned it was a " 172 same as they used in Nascar then. Any help with this would be greatly appreciated
 
#13 ·
Thank you LATECH. I've looked there before and there are no 421 motors codedSX. The only explanation I can come up with is that someone resurfaced the front of the block and stamped it SX. The guy I purchased it from did drag race in the late 60's early 70's and said that he had the tech guys believing it was a 389 but doesn't remember stamping the block as such or that maybe it was stamped by a machine shop
 
#14 ·
The guy I purchased it from did drag race in the late 60's early 70's and said that he had the tech guys believing it was a 389 but doesn't remember stamping the block as such or that maybe it was stamped by a machine shop
Cool.:cool: Sounds like Jim Wangers little escapade LOL. He put a 421 in a 64 GTO and fibbed about it being a 389.Who knew?
 
#17 ·
Code is only important if you are doing a numbers matching resto.
Bingo! Building an all out race car is less expensive than a numbers matching restoration and I would never again use a 3.25" main block for serious performance. I had one start to split between the main and the cam journals, at about 720 horsepower. Now I only build aftermarket Pontiac blocks for the track. I have three, two tall decks and one standard deck block.
Here's a picture of my son in my car right after he completed his license runs.

 
#18 ·
Wow LATECH awesome photo. Brings back 1960's memories of my local track Englishtown in NJ. I'm not a real big #'s matching guy and wouldn't try to present the car as such but I will try to make it look period correct other than maybe putting a set of ram air 3 heads on it but keeping the tripower, timing case cover etc stock appearing. Fortunately the guy I bought it from called me the other day saying he had found the set of stock 428 pistons he had purchased for the motor. It's standard bore block now but I'll have to almost .30 over. I'm really just looking to have a goat for street that won't get embarrassed by a new vette or mustang even if does take a little Jim Wangers bait & switch. Do you still the the 64' in the picture?
 
#20 ·
Thanks for heads up. That's great I always liked the 64 goats. I had a #'s matching 64 tripower hardtop I sold in 1990 Out of the six Gto's I've owned (all stock) that one was the fastest. It must be be the couple hundred pounds difference between the 65's I've owned that made the difference. I really had a hard time deciding whether to get a 64 or 65 this time. I bought the 3rd 65 convertible I looked at because the body was in such good shape with the original floor pans & trunk with minimal putty in the quarters
 
#24 ·
Early heads were closed chambered heads. They were a small chamber with a large quench pads. The valve are in the heads at a 22 degree angle. Changing the valve angle, changes the relationship of the location of the area on the piston of the valve relief and also pushrod length.
Later open chamber heads , 67 up (except some 670 I think) have the valves in at a 14 degree angle, changing the relationship of the valve to piston clearance placement of the relief. This is why you see those cheezie 8 valve relief pistons . One size fits all. Don't use them.
Run flat tops and get heads with the right size chambers to give you 9.5 to 1.
 
#22 ·
421guy, you are correct about the weight of the two different years of the GTOs.The '64 convertible had a shipping weight of ~3360 lbs and the '65 was ~3700 lbs. Yes I do still have the car. I bought the gutted out roller from a friend after I flipped my '63 LeMans at the track in '90. After three years and a pile of money, I got it to the track with a factory block stroked 455 and tube chassis. After about 150 passes the block started to split, so after another pile of $$ I now have three Indian Adventures Pontiac blocks. One standard deck and two tall deck blocks, three pair of Wenzler aluminum heads, one Scat forged 4.25" stroke crankshaft, one 4.5" forged Oldsmobile conversion for a Pontiac, by Moldex, and one 5" stroke Moldex billet crank.
more pictures;





Bill
 
#26 · (Edited)
The quickest that it has run with the smaller engine (474 cu in) was 8.942 in the 1/4 mile @ 2650 lbs. The best pass in the 1/4 with the big engine (606 cu in) was 8.255 @ 2750 lbs and both are all motor, no nitrous. The car has a mild steel round tube chassis and fiberglass bumpers, deck lid, doors, hood and front clip.

By the way, I run pop-up pistons in both of my engines. As long as you don't run a dome, It doesn't interupt flame travel.

Bill
 
#28 ·
Those 96 heads would be a great candidate for a 428.
Need to check the chambers to be sure of the size.
428 with those heads (shows to be 96 CC chambers ) stock is 8.51 to 1
Mill the heads, zero deck the block, mild porting/cleanup.......:thumbup:
 
#30 ·
Yes LATECH I also purchased a 69 428 when I bought the 421. The 428 has a 455 crank and 455 pistons. The guy I bought everything from said the heads are perfect for that engine but I couldn't remember if he meant the 421 or 428. Thanks for clearing that up as I'm sure you guys can tell I'm no mechanic. The 428 I bought for my cousin who is a mechanic ( like just about everyone else in my family but my dumb self lol) to put in 1960 ford f100 he bought cheap down in South Carolina. With the 421 it seems as if the 670 heads or for a more stock appearance the 77's I have on the 66 389 in the car now with a spun bearing would be the best bet. Shame about the 389 that's in car now. Guy I bought the car from spent $4000 on it thinking was a 65 WS tripower motor to make it #'s matching to the car. But I checked the date code and it was a 66. The car ran rough and it turned out the cam was shot. When I took off the intake to my horror I saw that there was a crack repair high on the lifter valley as is common to these motors. My cousin and I put a 068 cam in it and broke it in properly. A week later I attempted my first trip over ten miles since I bought it. The car overheated and the bearings been making noise ever since. Oh the pain!
 
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