im doing a swap 305 to 350 but my stock manifold on pass side wont line up on the last bolt towards firewall,this has not been a fun job by the way lol this swap has fought me on just about every thing.kinda wish i just left 305 in there by the way the 350 was from a 72 chevy truck but it had hooker long tube headers on it,only part # i can find is 205 001? i did a search at hooker site but no luck?currently car has new stock exhaust on it,and was hoping to keep it on there but now im frustrated with what to do now

i don't see why the stock manifold wouldn't line up, I think you need to loosely install all the bolts starting with the 2 outer ones then install the middles ones THEN start tightening them down.

You have one of 2 options. Use 350 style exhaust manifolds on your new motor ( and redo your new exhaust from the manifold outlet to make it work)
or, buy a adapter to use your 305 manifold on your 350 head. I kinow it sounds crazy but if you compare both manifolds you will find the 305's last bolt hole is about 1/4" or so (it maybe more) off toward the firewall.

please don't post such utter BS anymore.

I would suggest a manifold spreader. If the manifold is warped just a bit a spreader will fix you right up. Here is a link to one from Summit. Spreader

The 305 and 350 heads and manifold bolt holes aren't in different positions. Plenty of people have swapped 350 manifolds onto their 305s with no issue, and plenty have swapped 350 heads to 305s and vise versa. Do what Steve said and start with the two outside bolts and loosely install them all before you tighten any down. Is there a chance that the bolt hole is stripped maybe? Pull the manifold and see if you can thread a bolt in that hole easily enough.

Actually I think, even if he were to get 350 manifolds, as long as they are out of a thirdgen, they should bolt up to the rest of his factory exhaust just fine. The 350 manifolds (and...L69 manifolds I think) were the exact same on the outside, they were just opened up a bit more on the inside. That's neither here nor there though seeing as this wouldn't make a single difference in terms of bolting them to the motor.

Well, I guess I dreamed about running into this problem with my 81 Malibu, and I guess it was a dream I had finally buying the last set of adapters in the city I live in to hook up my stock exhaust manifold (305 cu) to my 350 heads.
Before you go off on someone trying to help solve a person's problem xpndbl3,
you should do a little research. I had the same problem one wheel peel had and those were the options available. Granted, this is an odd occurance but believe or don't, Murphy's law prevails.
I don't see how you can stretch a cast iron manifold to make it fit before the manifold breaks, cold or heated, due to cast iron brittleness,,,,,,,,

By the way, I have 1 adapter left, and no, it os not for sale........

post a pic of these mythical adapters, considering ALL 283-400 cubic inch SBC heads are IDENTICAL in outside dimensions. I'd toss the title of my camaro on the line for this. Especially the 305 and 350 heads, all the same sheesh.

As for one wheel peel, PM 88blkiroc as I believe he has some stock exhaust manifolds laying around his shop if you'd like to see if he'd be willing to sell them, although at this point a nice set of headmann headers and a y-pipe are only $200 and will add performance as well. Don't forget they fit the 305, 350, and 400 engines WITHOUT needing adapters.....thanks again woody.

The point is that the bolt holes are the same pattern, so if he is having difficulty installing the manilfolds there is a possibility the they are warped a bit. You can only stretch a cast manifold about 1/8th", which would be enough to install the manifold.

Its also possible that during the engine swap the y-pipe was bent in some fashion and now it doesn't want to line up correctly

There are some aftermarket heads that have raised exhaust ports, but even those heads fit manifolds JUST fine, the issue with the raised exhaust ports is generally related to clearance issues by the trans when using long tubes, nothing that a hammer and some heat usually won't fix.

The ports should be the same distance apart and the manfold bolt spacing should be the exact same for any factory small block head.

I have 350 TPI manifolds around, but generally I wouldn't consider the power gain from swapping them onto a car be worth the effort, I'd just wait for headers. However if its all apart, it might be worth it for someone.

ok i unbolted manifolds from motor b4 swap and left them still connected to exhaust complete and pull out motor and reinstalled new motor and there is no way these are warped the manifold actually hang out past the block on the back side about 1/4 inch aprox ,i measured the headers from bolt to bolt and its appro 18 1/2 inches front to rear bolt ,and the headers that were on there measure about 19 inches on that side.absolutly make no sence at all why there diff from side to side,while driver side went on with no prob.on a side note will hooker long tubes from a 79 camaro fit in a third gen?and thanks to all of you for your help,i appreciate it greatly

The adapter. As anyone can plainly see the last port has 3 holes (one has the bolt in it that you bolt to the head). You bolt this adapter to the head, then bolt the exhaust manifold to the adapter. So, I guess I didn't offer off the wall advice..........One wheel peel....you might have heads other than 305 on your Camaro eg 267cu.

yep that looks like what i need,why do i get those? and the motor is from a 72 chevy truck 350

I would start with auto parts stores, and then try wrecking yards..........I bought mine at a wrecking yard.......hth...good luck.

Try this http://www.goodson.com/technical_sup...nst/CHC-10.pdf
I think this is what you are looking for.

that 7th bolt hole is NOT needed even remotely. In fact on newer heads it is deleted.

From one peel wheel:

ok i unbolted manifolds from motor b4 swap and left them still connected to exhaust complete and pull out motor and reinstalled new motor and there is no way these are warped the manifold actually hang out past the block on the back side about 1/4 inch aprox ,i measured the headers from bolt to bolt and its appro 18 1/2 inches front to rear bolt ,and the headers that were on there measure about 19 inches on that side.absolutly make no sence at all why there diff from side to side,while driver side went on with no prob.on a side note will hooker long tubes from a 79 camaro fit in a third gen?and thanks to all of you for your help,i appreciate it greatly

xpndbl3, you are wrong. You are not the chevy gru you think you are or you are not reading the posts. I provided the picture you asked for: one peel wheel confirmed what I said was the problem. Talk about stubborn or brain dead.............

when i bolted up my headers they didn't line up too well either, so I just slotted the last bolt hole all the way off the end, worked like a charm.

if one side fit then the other side should fit. Your adapters would only be needed if both sides had that issue. Do I need to take a pic of a 7 bolt head with me bolting on a 6 bolt factory thirdgen camaro manifold? The last bolt hole just won't be used. Maybe I'm extremely brain dead then since I've done it half a dozen times on others cars.

I've looked at your adapter picture and showed it to others. All that adapter is doing is bolting the 7th hole to the head. You are then using the other 6 bolt holes to bolt on the factory manifold. So unless he needs that 1/8" spacer off the head, that adapter isn't doing anything else. You may leave that bolted hole on the adapter empty. My guess is he left the y-pipe connected to the manifolds and he slightly tweaked the y-pipe connection because the block gets wider where the cylinder head bolts down, now he needs to bend it back or unbolt the manifold/y-pipe connector flange and reinstall that way.

Last option is ditch the restrictive factory exhaust and buy some headers, which by the way will only have 6 bolt holes on them as well.

Alright, I have to say, in all my years as a shop owner I have never seen anything like those adapters. I just swapped from a 305 to a 350 in my Fomula and didnt have any problems with anything bolting up. The small block heads are all the same, the 7th bolt hole is only for a support bracket used on the older engines. You tweaked the pipe, unbolt the manifolds from the pipes, bolt the manifolds to the heads starting at the outside bolts and working you way in and do not tighten the bolts down until they all are started in the holes. One wheel peel, you have a bunch of guys telling you to do this and one crazy talking about exhaust adapters and finding Jeebus, guess who you should listen to.

If I understand this correctly, the problem is that some of the 305 tbi camaros had what is referred to as the long exhaust manifold on the passenger side only. The last bolt hole on the exhaust manifold nearest the firewall is located to line up with the 7th bolt hole on the heads. There is NO 6th bolt hole position on the exhaust manifold. Therefore the exhaust manifold only has 6 bolt holes but the 6th bolt hole lines up with the 7th bolt on the heads.

Therefore if you use the stock 305 tbi exhaust manifold your choices are:
1. Use 7 bolt heads
2. Try to use sealant and use only 5 bolts
3. Use the adaptor shown above

Or get rid of the 305 exhaust manifold, put on headers, and use the 6 bolt heads you got.

alvanwie FTW.... ...and woody, really

click

note the mark on the manifold from the 6th (unused) hole of the 7 hole gasket...

NOOOOO because the factory thirdgen manifolds are of the SIX bolt variety....therefore the last bolt hole is NOT used.

Yes, they are 6 bolt but on the passenger side long exhaust manifold the 6 bolt lines up with the 7th bolt position on the heads.


Thanks for adding the picture Dodger65. That should finally clear this up.

well, it's on a 305 camaro... click i've seen similar manifolds on monte carlos, and it doesn't really matter whether it came off a camaro or not b/c this manifold is on one wheel peel's camaro and is also attached to his exhaust (which presumably has a factory y-pipe) and that is what his problem is...

one wheel peel, if you can get a casting# off of that manifold, we can (possibly) know for sure what the manifold is off of and really put this to bed... but since according to some, every v8 3rdgen in the world has the normally spaced holes excluding your car, the guy in the link and my brother's 87 tbi formy you shouldn't have a problem finding a manifold that fits... good luck

Guys, read one wheel peel's post!!!
It's a 72 TRUCK motor.........not a 80's 90's Third Gen.........All I know is it worked for me and he is having the same problem I did it will work for him.....

right, i understand... he's got 1972 heads with 6 bolt holes and manifolds designed to use the 7th bolt hole that later heads have... i think we're on the same page here...

The bolt holes on newer 305's and 350's were revised, (same spacing, different location) in the late 80's or early 90's if I recall. Many headers now have an elongated 2nd and 5th hole to rectify this problem.
Here's a good article. 4th paragraph down mentions it.
http://www.carsinc.com/mr.bowtie/6896/

ididnt mean to cause arguments with my problem ,lol ok what i have is a 84 l69 305 i pulled it out and left the manifolds hanging in there still bolted to exhaust pipes,put in 72 motor and the last bolt hole on manifold hangs out past block at firewall end of it.now i hope this makes my problem a little clearer? ok now my other option is the 350 motor i got had hooker long tubes on it,i know they fit into a 79 firebird ok because that was last vehicle this motor was in,but never made it past dropping into engine bay b4 co-worker gave up on project so now i got it all and wanted to put motor in my 84 sport coupe wheew,lol now thats the whole story on this thing,1 last question is will these long tube headers that i know bolt up to this motor fit into my thirdgen?.and thanks to all of you for trying to help me out on this

OK, I think I can clear this up (or muddy the water some more). I don't know if the issue is with the heads or the exhaust manifold. Apparently GM made small block chevy heads that required the exhaust manifold on the passenger side to extend 1/4" or so rearward toward the firewall consequentally that forced GM to make a exhaust manifold that had to bolt into that last hole 1/4" or so farther to the rear. One wheel peel, if you can please post a photo of the head of your 305 and one of the exhaust manifold so the naysayers can see the problem you are having........If you want to buy the last adapter I have I will sell it to you for $25.00 plus shipping.
The newer 305 and 350 end ports had the bolt hole location revised for later models (where you bolt the headers or exhaust manifolds to the cylinder head) and they do not interchange. Therefore if you already have a set of exhaust manifolds or headers you plan to use, make sure the heads have the matching holes, otherwise you will either need to make a set of plates for the heads, so the headers/manifolds will bolt on, or you will have to modify the headers/manifolds. Thanks CYARS92 and Dodger 65 for the post and the photo!!

See that little black allen head screw in the 7th hole (my second photo) that screw bolts into the head in the 6th bolt hole (notice the recessed area around the sixth bolt hole in the adapter so that the exhaust manifold will fit flush with the adapter) and the 7th bolt hole is threaded so that the 7th bolt is bolted into the adapter....but not screwed into the head. I have had blown one exhaust manifold gasket in almost 9 years of driving the car. It was the one between the manifold and the adapter.

no 2nd gen longtubes don't fit thirdgens obviously. I sent you a pm to either buy a working manifold or to buy headmann shorties and a y-pipe.

Headmann longtubes are $120ish and you'd have to run true duals would be another option as well.

I wonder when this change was made because I had the SLP 1 3/4" headers on my stock '88 305 TPI heads, and they also bolted right up to my aluminum LT1 (as in 93-97 F-body, not old-school LT1) heads just fine as well.

I say pop the heads off both motors and bolt those 305 heads onto the 350. Solves your manifold problem (buy headers anyways ), plus the 305 heads will jack the compression up a bit, probably from mid 8s to close to 10, and they probably flow better too Of course I'm just guessing at the compression, not exactly sure what heads a 74 truck motor would have come with...

76cc smogger junk. probably 8.5:1, with 1.84 valves
165hp engine....which the 305 should be rated about identical

Actually seeing as he says it was an L69, the 305 was probably closer to a 190hp motor, so it seems things went backwards.

I was under the impression it was an LG4, at which point this could somewhat be called an upgrade. But going from an L69 to this? I don't know man..

great,so i took 1 step forward and got 2 steps further away from my goal

if your goal is too have a fast car, then putting a completely stock smogger motor isn't the answer. While the 305 is out, pull the heads and do a quick bowl cleanup then slap them on the 350 and it'll help out the power department greatly. Then your manifolds will fit too but ultimately if you want speed it costs money and the headers/y-pipe/3" catback should be a mod regardless.

just ordered the hedman shortys and y-pipe from jegs $249.67 be here tomorrow.