Porting 302's
- Thread starter Hysteric
- Start date
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Cracks and don't flow well unless ported.
Plymouth 65
I'll be in the shop
Flow okay but you have to narrow the area around the intake valve guide. Porting alone won't do much. 65'
There fine on a small displacement engine. A few here have thrown caution to the wind and used them on 360’s. NOT! Ideal IMO.
I know there has been a lot of talk about these heads on here, both good and bad.
With all else being equal, same car, same engine, same gear, tire size, carb, intake, exhaust, cam,etc.... would there be a noticeable improvement on a 78 318 in a that now has #163 open chamber heads
Talking about adding a set of 302s, "just bolted on" without the porting? Talking cruiser car, 3 season daily driver, only mods are lean burn delete and true duals to the back bumper vs original single exhaust?
Said heads fresh from machine shop, "standard valve job" , crack checked, all new (stock replacement) valves, minimal shave just to assure flatness I think the number thrown out was like 0.007" shave.
With all else being equal, same car, same engine, same gear, tire size, carb, intake, exhaust, cam,etc.... would there be a noticeable improvement on a 78 318 in a that now has #163 open chamber heads
Talking about adding a set of 302s, "just bolted on" without the porting? Talking cruiser car, 3 season daily driver, only mods are lean burn delete and true duals to the back bumper vs original single exhaust?
Said heads fresh from machine shop, "standard valve job" , crack checked, all new (stock replacement) valves, minimal shave just to assure flatness I think the number thrown out was like 0.007" shave.
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Stock intake and cam? There would be a slight bump in compression, but I don’t see it as desirable with the pistons that are probably .045 down the hole. I’ve got several pairs of both of those heads, and at first glance the 163 looks like it would flow better as cast than the 302. If I we’re going through the trouble, I myself would use 360 smog heads with .100 longer 1.94/1.50 nail head valves and a .030 cut.
I'm probably going to chance messing up a fresh valve job and pull them apart, clean them up a little at least. Like the Saturday afternoon car shows on tv that restore a rust bucket in a 1/2 hour show, the ones that want to "test 1 modification at a time" idea, I'm just asking the way I did, to try and see what each thing I want to do will help in the way I want to help this engine improve, but in actuality I'm gonna do the cam and intake swap at the same time as I swap the heads. Just curious how much each part I do, adds to or (? Hopefully not!) takes away from the current configuration, without actually having to the things apart 3-4 times and install1 part at a time while taking the last part installed back out, to break it down and see what I'm curious about.
I know that as long as the overall package is an improvement vs how things currently are, that's the main thing/
Engine in question is in a '78 b body sport fury, 56k original mile car. Currently 2.71 rear.
I've talked about what I'm thinking about doing to this car on here before. Cruises great at speed, just want a little bit more oomph than it currently has, in getting there without having to have it winding out a gazillion rpm once it's there so I don't have the feeling I'm gonna get run over, in getting out in traffic. Other than that one thing, I'm pretty happy with how this engine runs as it is. I have 2 possible cams here I'd like to use (one of), and 4 possible 4 bbl carbs here that are ready to bolt on. Thinking of the melling SPD25 which is a stock replacement 360 cam. Other choice is a comp 260. Carbs are 2-TQ (demon sizzler tweaked) a 500 AFB or a 625 AFB. Intake will be a performer (not airgap or RPM cuz that's what I have). And the 302 heads.
I know that as long as the overall package is an improvement vs how things currently are, that's the main thing/
Engine in question is in a '78 b body sport fury, 56k original mile car. Currently 2.71 rear.
I've talked about what I'm thinking about doing to this car on here before. Cruises great at speed, just want a little bit more oomph than it currently has, in getting there without having to have it winding out a gazillion rpm once it's there so I don't have the feeling I'm gonna get run over, in getting out in traffic. Other than that one thing, I'm pretty happy with how this engine runs as it is. I have 2 possible cams here I'd like to use (one of), and 4 possible 4 bbl carbs here that are ready to bolt on. Thinking of the melling SPD25 which is a stock replacement 360 cam. Other choice is a comp 260. Carbs are 2-TQ (demon sizzler tweaked) a 500 AFB or a 625 AFB. Intake will be a performer (not airgap or RPM cuz that's what I have). And the 302 heads.
And they say the 714s are the same as 302s. Are they really? I just got a set of 714s, those would need the machine shop treatment still. Any difference between, besides that cast in number? Are either, more or less likely to crack? I do know that the 714s have the rotators on them, the 302s Don't (any more) for my purposes I don't think those are a deal breaker, but the answer may help someone else reading along
The particular 714s I have came from an engine that would be a fantastic mosquito fogger, engine had been replaced in the truck I took them from, heads have the telltale overheat buttons on them/ I don't know if it was a used junkyard replacement or a reman (such as a jasper, etc)/// all I know, is the guy who had the truck I pulled them from had the motor changed because the old one was a mosquito fogger, and said it's no better with this "new" engine, he's been driving it 10-12 years by his estimate on this "new" engine he paid "a bunch" to have installed at the time.
I sày this, not knowing at the moment whether the smoking tendencies would be in the heads or the block, as the block has gone across the scale already, so I may never know what caused it to be a smoker..... We're on a 91 Dakota, that I bought for it's A500 and a few other goodies/ then scrapped, had a weak fuel pump and lotsa rust in all the wrong places. I did have it running, put a jump on the battery and it started right up. Seemed to run ok despite the smoke.
Is there anything about these heads that is known to go bad (weak guides that wear out prematurely maybe?) that would cause an engine to be a smoker? I realized it could have had a cracked ring or 2 but again no longer have the short block handy that I can pull apart to eliminate as a cause. Just need to know if there's something else that need "special attention" from the machine shop once I take them in? Being as how this is the first of these heads I have ever messed with.
The particular 714s I have came from an engine that would be a fantastic mosquito fogger, engine had been replaced in the truck I took them from, heads have the telltale overheat buttons on them/ I don't know if it was a used junkyard replacement or a reman (such as a jasper, etc)/// all I know, is the guy who had the truck I pulled them from had the motor changed because the old one was a mosquito fogger, and said it's no better with this "new" engine, he's been driving it 10-12 years by his estimate on this "new" engine he paid "a bunch" to have installed at the time.
I sày this, not knowing at the moment whether the smoking tendencies would be in the heads or the block, as the block has gone across the scale already, so I may never know what caused it to be a smoker..... We're on a 91 Dakota, that I bought for it's A500 and a few other goodies/ then scrapped, had a weak fuel pump and lotsa rust in all the wrong places. I did have it running, put a jump on the battery and it started right up. Seemed to run ok despite the smoke.
Is there anything about these heads that is known to go bad (weak guides that wear out prematurely maybe?) that would cause an engine to be a smoker? I realized it could have had a cracked ring or 2 but again no longer have the short block handy that I can pull apart to eliminate as a cause. Just need to know if there's something else that need "special attention" from the machine shop once I take them in? Being as how this is the first of these heads I have ever messed with.
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I think the 714 is just an earlier variant that became 302 casting. They’re identical in every way that I can tell. One jasper rebuilt 318 I have had a 714 on one side and a 302 on the other. As far as guides; Most rebuilder 302 heads I’ve come across have had replacement bronze guides. The last core pair of 302 heads I sold to a member had a couple of those guides needing replaced, but those heads came out of trucks that probably had more abuse than use. The only ones I have know of having cracks have been because of overheating. As far as knowing if the heads will be an improvement, you answered your own question with the cam and intake swap conundrum. But it’s the same exact thing I would do, because I think what you gain on compression with the closed chamber heads you’ll give back on flow. But, with a little cleanup work,
The 302 fast burns will be a win. And aside from that, I also wouldn’t bother with changing heads first and then cam and intake later, because with the stock cement mixer cam, I doubt you would see any difference. I would run the comp 260 cam (440 lift and [email protected] on a 110). And I would get a torque converter that would compliment it. Not just any torque converter, but one that you talk to someone on a phone about. Precision of New Hampton will be the good. That should also be a lockup torqueflite, so that’s really a no brained when the budget allows for it. Of those carburetor choices, I would go with the smallest ThermoQuad of the bunch, but I would be more willing to use one of the Mopar HD truck QuadraJets based on my own personal experience in similar builds, or even on a bo e stock 360 HD truck engine. They work very well in heavy vehicles with highway gears. Use these head gaskets. 4 inch bore and somewhere close to .040 compressed thickness. Military surplus Dodge M880 gaskets.
New NOS Mopar DODGE PLYMOUTH CHRYSLER 318 V8 Engine CYLINDER HEAD GASKET 4186348 | eBay
A better head gasket for more compression would be what the factory used on 1986 and up engines with 714/302 heads. They’re of the same construction and bore size except for black gasket material and around .028 thick. I haven’t seen any bulk supplies for sale yet, but there may be some surplus items that will come up eventually. The Navy and AirForce (and maybe others?) used mostly Chrysler vehicles and Dodge trucks after the Chrysler bailout up unit at least 1987, so there’s some waiting to come out of a surplus sale sometime. I don’t remember you mentioning anything about exhaust, but this would be a very good place to use magnum manifolds, or even a set of eBay stainless magnum headers. If you go with the $100 Chinese stainless magnum headers, expect beforehand that they may need removed after about a year of use and the flanges reground parallel on your machinists table top belt sander.
The 302 fast burns will be a win. And aside from that, I also wouldn’t bother with changing heads first and then cam and intake later, because with the stock cement mixer cam, I doubt you would see any difference. I would run the comp 260 cam (440 lift and [email protected] on a 110). And I would get a torque converter that would compliment it. Not just any torque converter, but one that you talk to someone on a phone about. Precision of New Hampton will be the good. That should also be a lockup torqueflite, so that’s really a no brained when the budget allows for it. Of those carburetor choices, I would go with the smallest ThermoQuad of the bunch, but I would be more willing to use one of the Mopar HD truck QuadraJets based on my own personal experience in similar builds, or even on a bo e stock 360 HD truck engine. They work very well in heavy vehicles with highway gears. Use these head gaskets. 4 inch bore and somewhere close to .040 compressed thickness. Military surplus Dodge M880 gaskets.
New NOS Mopar DODGE PLYMOUTH CHRYSLER 318 V8 Engine CYLINDER HEAD GASKET 4186348 | eBay
A better head gasket for more compression would be what the factory used on 1986 and up engines with 714/302 heads. They’re of the same construction and bore size except for black gasket material and around .028 thick. I haven’t seen any bulk supplies for sale yet, but there may be some surplus items that will come up eventually. The Navy and AirForce (and maybe others?) used mostly Chrysler vehicles and Dodge trucks after the Chrysler bailout up unit at least 1987, so there’s some waiting to come out of a surplus sale sometime. I don’t remember you mentioning anything about exhaust, but this would be a very good place to use magnum manifolds, or even a set of eBay stainless magnum headers. If you go with the $100 Chinese stainless magnum headers, expect beforehand that they may need removed after about a year of use and the flanges reground parallel on your machinists table top belt sander.
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And here’s a link to some videos posted by a generous member here about porting the 302 heads.
Is it a 727 or a 904/998? I would be tempted to only change the intake and add 3.73 gears with an A500/42RH swap.
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It's a 904 series not sure if it's the 998 version or not.
One thing about this car as it sits is I can't believe how well it does on gas while cruising as it sits. I've had it since 2007 and 38k on the odo. I'm 2nd owner.
One thing about this car as it sits is I can't believe how well it does on gas while cruising as it sits. I've had it since 2007 and 38k on the odo. I'm 2nd owner.
I ran some figures on the Stan Weiss compression ratio calculator for you based on stock 1978 318 figures. If your fortunate enough for your heads to clean up to 60cc chambers and you use the NOS head gaskets, then you will have a bump in compression from 7.8 to about 8.6:1. If you have them cut .030, you can get about 8.9:1. I have a friend who has a set cut .050 to a 55 cc chamber, but he discovered he had to correct the rocker geometry with a flat tappet hydraulic. That would give you close to 9.2:1. That motor is in my possession now, it gulped water going dashboard deep through a creek, but those heads got a new set of stem seals and swapped onto another 318 and are still going with another owner now. Another option I have came across lately is a Chrysler LA marine .018 stainless shim head gaskets of unknown origin (at a marine parts warehouse, I suspect they’re offshore). But I would have to use them first myself before telling someone else to risk them. They would give you right at 9:1, but I wouldn’t even think about running them without getting the decks cleaned up, too.
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That was with the 302s. I haven’t measured the chamber volume of the 163s, but the set I got looks like they’ve been resurfaced and are probably in the 66 cc range. There are differences in how much cut it takes to remove one cc from an open chamber vs a closed chamber. My source shows .0053 cut / CC for a closed chamber and .0048 cut/CC for open chamber heads. Both heads show .0095 head intake flange cut for each .010 of deck cut for proper intake fitment.
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