First off what did I get my self into doing this swap??


This started when the stock head pipe would not fit the log manifold on the truck, think motor is from a car? Well I got a deal from a member on a set of EFI manifolds.
I have looked at all the post on this swap and it looked like a simple swap but have run into issues that bring up the questions.


Subject:
1981 F100 flare side with 300/six (don't know the year motor but lets say newer then the truck) and T18 trany.


Issues/questions:
1- Are the intake bolt holes in the head metric or SAE? I went to chase the holes and the tap would not go in as I thought it should for cleaning. I cant tell from the bolts but it looks like they don't match the pitch gauge I have.
If metric what is the size so I can get a tap to clean the holes and get the right size studs & nuts.


2- What size studs for the manifolds do people go with and where did you get them?


3- The studs on the manifolds the Y pipe flange bolts to is that metric or SAE and the size as I ran into the same issue as the head bolt holes.


4- The sender on the right side rear of the block what is it? Looks like maybe oil? What ever it is the rear manifold hits it and yes I have the right manifold in the right place as I set the Y pipe in place just to see what fits or does not like now.
If this is normal how come it has not come up in posts and what have others done to get around this?


I cant go back with the log with out work as 2 bolts broke off that hold the intake & exh manifolds together and I know would be a bear to get out.


Thanks ahead of time for any information you can give.
Dave ----

 

Dave, according to Dorman the manifold to head pipe studs are 7/16-14 right up through 1996. (Kit 03135)

Have you already gone through the rear pipe with a hole saw on an extension to clean up the restriction?
I think a 1 7/8" hole saw fits but it has been a long time.

 

I tried the 7/16-14 die on the pipe flange studs and after going up 1 stud about half way and fighting me the whole way and the threads not looking that great I stopped. I also did not do the others till I checked.
Guess I can do all of the pipe studs with the 7/16-14 die.


I found this post on the manifold to head studs
https://www.ford-trucks.com/forums/1...ich-studs.html
and it list them as SAE so now I don't know what to think?
Hate to use the SAE tap and ruin all the manifold mounting holes and junk the head.


As for the rear pipe on the Y pipe it is in good shape unlike what I hear some are like.
I saw how Kurt's was and his does need cleaning but was not as bad as I have heard. I was lucky mine is good to go as is. I will try and get a picture of it.

Dave ----

 

Dave,
The head is a 3/8-16 and the manifold is 7/16-14

 

Kurt, thank you I was thinking of reaching out to you on this.


Would you have the Dorman part number of the studs you used and the size if you would.
I did see they were fine thread on the manifold side just did not know how long they are.
Also you planning on using the stock thick washers or thinner grade 8 washers?
Dave ----

 

Just to let you know, from what I have seen working on these older engines (Ford and GM), the older generation of engines were standard american thread, and stayed that way their whole life till they were discontinued. That is the threads going INTO THE BLOCK or HEAD.

Other stuff is metric. Threaded holes in brackets and anything external to the engine can be and usually are metric. But if it threads into the block or the head, and the engine is a older one, it's standard threads.

This should hold true for the 300, 302, 351w, 460. I am not sure what the 3.8 engine is. The 2.9 v6 in my ranger is a newer style engine, it's metric and every thread on it is metric.

I have something I have never seen before. On my 99 tahoe, it has the 350 vortec. Down under all that newer stuff is the older style 350 block. All the threads going into the block are standard. What is weird, the pan bolts are 1/4-20 threads, but instead of taking a 7/16 wrench, they take a 10mm wrench. Someone has lost some of the bolts along the way, so to take the pan off, I need a 10mm wrench and a 7/16 wrench.

 

Yeah, they never converted the iron castings to metric, just phased them out.

My 1986 2.3L Tempo was all metric.

 

Ok then Non-metric it is.
Just was strange the tap & die did not feel like it was cleaning threads but making new ones.
Thanks guys
Dave - - - -

 

Dave,
The studs that you saw in my head are Dorman 675-003.
I'll be using the http://https://www.nutty.com/12-Grad...r_p_13819.html washers.
You shouldn't be having an interference problem with the EFI mannys and the temp sensor as it is located the same on a carb or EFI block.

 

Kurt, thanks for the Dorman number.

Now that I think of it the oil sender is on the other side right?
Then what is this sender on the manifold side of the block to the rear that the rear manifold hits?
Dave - - - -

 

Coolant temperature sensor.

 

Great something I cant do with out
I am going to check this more to make sure I am not doing something wrong and causing this issue.


If I am not the cause and say the EFI manifold hits the sensor what have others done to get around this?
Dave ----

 

Kurt, In another post and here it is the temp sensor on the right side rear of the block.

I am going to check again but I am sure the rear manifold hits it. Where is this sensor on your EFI block? Someone said it may be in a different location on the EFI blocks and why I ask.

If it is not in a different location then why have I not heard of anyone else having this issue?
The way I hear it, EFI manifolds are the best think since sliced bread!
At this point I am having a hard time believing this.
Dave ----

 

Ok as my wife know I have S for B (s4brains)
I rechecked the rear manifold and the temp sensor issue and it was all me.
I was lining it up to the wrong ports. It's hard as you are leaning over the fender holding the manifold to the head the best you can.


Also the EFI manifolds have other mounting points that are not used on a carbed motors that are on the EFI motors.


I also stopped at a local auto parts store that knows how to look up parts and they are young too, and ordered studs for mounting the manifolds.


I ordered Dorman 675-006 that are 3/8-16x3/4" by 3/8-16x2"
The other Dorman that was listed is 675-003 that are 3/8-16x5/8" by 3/8-24x1"
I plan on using the thick washers (1/4" thick) with the manifolds (1/2" thick) and the 1" I felt was not long enough.
I could not find 1-1/2" long studs with all the looking we did and why the 2" long ones.
When installing if I find the 2" studs are too long I will "trim" them to fit.
Dave ----

 

Being the rear manifold now fits the block/head, I was told 1 of the EFI hits the intake so I took care of that.


Next thing I have to fix is the intake & exh mounting points are two different heights.
I seen it posted to grind down 1 side of the thick washers but then you need to make sure it is lined up right and we know that is not going to happen.


It would be nice if I could mill the face as it would do 2 things, make both the same height and make sure the face is flat.
I will post what I do as I am still thinking on this.
Dave ----